US20100194248A1 - Piezoelectric oscillator and method for manufacturing the same - Google Patents
Piezoelectric oscillator and method for manufacturing the same Download PDFInfo
- Publication number
- US20100194248A1 US20100194248A1 US12/759,060 US75906010A US2010194248A1 US 20100194248 A1 US20100194248 A1 US 20100194248A1 US 75906010 A US75906010 A US 75906010A US 2010194248 A1 US2010194248 A1 US 2010194248A1
- Authority
- US
- United States
- Prior art keywords
- section
- piezoelectric oscillator
- oscillation
- semiconductor layer
- piezoelectric
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title description 57
- 238000004519 manufacturing process Methods 0.000 title description 32
- 230000010355 oscillation Effects 0.000 claims abstract description 107
- 239000000758 substrate Substances 0.000 claims abstract description 62
- 239000000463 material Substances 0.000 claims abstract description 14
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 13
- 239000010703 silicon Substances 0.000 claims abstract description 13
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims abstract description 8
- 229910021417 amorphous silicon Inorganic materials 0.000 claims abstract description 5
- 239000004065 semiconductor Substances 0.000 description 99
- 238000005530 etching Methods 0.000 description 27
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 10
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 9
- 238000005229 chemical vapour deposition Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 229910052814 silicon oxide Inorganic materials 0.000 description 6
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 5
- 238000000059 patterning Methods 0.000 description 5
- 238000000206 photolithography Methods 0.000 description 5
- 239000000853 adhesive Substances 0.000 description 4
- 230000001070 adhesive effect Effects 0.000 description 4
- 238000001312 dry etching Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 238000004806 packaging method and process Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000007740 vapor deposition Methods 0.000 description 3
- 238000001039 wet etching Methods 0.000 description 3
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 description 2
- 238000004380 ashing Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000003566 sealing material Substances 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000000608 laser ablation Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/05—Holders; Supports
- H03H9/0504—Holders; Supports for bulk acoustic wave devices
- H03H9/0514—Holders; Supports for bulk acoustic wave devices consisting of mounting pads or bumps
- H03H9/0519—Holders; Supports for bulk acoustic wave devices consisting of mounting pads or bumps for cantilever
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/05—Holders; Supports
- H03H9/0538—Constructional combinations of supports or holders with electromechanical or other electronic elements
- H03H9/0542—Constructional combinations of supports or holders with electromechanical or other electronic elements consisting of a lateral arrangement
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/05—Holders; Supports
- H03H9/0538—Constructional combinations of supports or holders with electromechanical or other electronic elements
- H03H9/0547—Constructional combinations of supports or holders with electromechanical or other electronic elements consisting of a vertical arrangement
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/21—Crystal tuning forks
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
- H03H2003/026—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the tuning fork type
Definitions
- the present invention relates to piezoelectric oscillators and methods for manufacturing the same.
- Tuning fork type 32 kHz quartz oscillators are used in oscillator sections of clock modules in clocks and information devices such as microcomputers in order to take advantage of the traditional design assets and their power saving property.
- the arm length of the tuning fork arm in the case of a tuning fork type 32 kHz quartz oscillator is several mm, and therefore the overall length including its package may amount to about 10 mm.
- piezoelectric oscillators having a driving section formed from a piezoelectric thin film sandwiched between upper and lower electrodes formed on a silicon substrate have been developed.
- a beam type structure see FIG. 1 of Japanese Laid-open patent application JP-A-2005-291858
- a tuning fork type structure equipped with two beams see FIG. 1 of Japanese Laid-open patent application JP-A-2005-249395
- the silicon substrate can only be made at most to a thickness of about 100 ⁇ m. Therefore, in order to obtain a resonance frequency in a several tens kHz band, the arm length of the beam needs to be several mm or greater, which may lead to a problem in that miniaturization of the clock module is difficult.
- a piezoelectric oscillator that is very small in size, and is capable of providing, for example, a resonance frequency in a several tens kHz band, and a method for manufacturing the same.
- a method for manufacturing a piezoelectric oscillator in accordance with an embodiment of the invention includes the steps of: forming a first semiconductor layer above a substrate; forming a second semiconductor layer above the first semiconductor layer; forming a first opening section that exposes the substrate by removing the second semiconductor layer and the first semiconductor layer in an area for forming a support section; forming the support section in the first opening section; forming a driving section that generates flexing vibration in an oscillation section above the second semiconductor layer; patterning the second semiconductor layer to form the oscillation section having the supporting section as a base end and another end provided so as not to contact the supporting section, and a second opening section that exposes the first semiconductor layer; and removing the first semiconductor layer through a portion exposed at the second opening section by an etching method, thereby forming a cavity section at least below the oscillation section, wherein the step of forming the driving section includes the steps of forming a first electrode, forming a piezoelectric layer above the first electrode, and forming a second electrode above the
- the oscillation section can be obtained by patterning the second semiconductor layer.
- the second semiconductor layer can be formed very thin above the first semiconductor layer. Therefore, according to the method for manufacturing a piezoelectric oscillator, the oscillation section can be formed very thin. Accordingly, in a piezoelectric oscillator that may generate a resonance frequency of an oscillator that is used for a clock module, the oscillation section can be made shorter in length. In other words, the piezoelectric oscillator can be made smaller in size, compared to a piezoelectric oscillator that uses quartz.
- the term “above” may be used, for example, in a manner as “a specific element (hereafter referred to as “A”) is formed ‘above’ another specific element (hereafter referred to as “B”).”
- A a specific element
- B another specific element
- the etching rate of the first semiconductor layer may be greater than the etching rate of any of the substrate, the oscillation section and the supporting section.
- the first semiconductor layer may be formed from silicon germanium, and the substrate, the oscillation section and the supporting section may be formed from silicon.
- the oscillation section may be formed to have a thickness of 100 nm or less.
- the oscillation section may be formed to have a length of 100 ⁇ m or less.
- the length of the oscillation section is a distance between the affixed end of the oscillation section and its free end in a plan view. Also, a distance between two ends of the oscillation section in a direction perpendicular to the lengthwise direction of the oscillation section is called a width of the oscillation section. Furthermore, for example, the length of the piezoelectric layer is a length of the piezoelectric layer in the lengthwise direction of the oscillation section, and the width of the piezoelectric layer is a width of the piezoelectric layer in the widthwise direction of the oscillation section.
- the piezoelectric oscillator may be formed to have a resonance frequency at 2 13 Hz (8.192 kHz) or higher, and 2 15 Hz (32.768 kHz) or lower.
- a piezoelectric oscillator in accordance with an embodiment of the invention includes: a substrate; a supporting section formed above the substrate; an oscillation section having one end affixed to the supporting section and another free end; and a driving section that is formed above the oscillation section and generates flexing vibration in the oscillation section, wherein the driving section includes a first electrode, a piezoelectric layer formed above the first electrode, and a second electrode formed above the piezoelectric layer, and the oscillation section is composed of a material different from a material of the supporting section.
- materials having different states such as, for example, single crystal silicon, polycrystal silicon and amorphous silicon, are treated as different materials.
- the oscillation section may be composed of semiconductor, and the supporting section may be composed of dielectric.
- the oscillation section may be composed of single crystal silicon, and the supporting section may be composed of polycrystal silicon or amorphous silicon.
- FIG. 1 is a schematic plan view of a piezoelectric oscillator in accordance with an embodiment of the invention.
- FIG. 2 is a schematic cross-sectional view of the piezoelectric oscillator in accordance with the embodiment of the invention.
- FIG. 3 is a schematic cross-sectional view of the piezoelectric oscillator in accordance with the embodiment of the invention.
- FIG. 4 is a cross-sectional view schematically showing a step of manufacturing a piezoelectric oscillator in accordance with an embodiment of the invention.
- FIG. 5 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment.
- FIG. 6 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment.
- FIG. 7 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment.
- FIG. 8 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment.
- FIG. 9 is a plan view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment.
- FIG. 10 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment.
- FIG. 11 is a cross-sectional view schematically showing a piezoelectric oscillator in accordance with a modified example of the present embodiment.
- FIG. 12 is a plan view schematically showing a piezoelectric oscillator in accordance with a modified example of the present embodiment.
- FIG. 13 is a circuit diagram of the basic structure of an oscillator in accordance with an embodiment of the invention.
- FIG. 14 is a schematic plan view of an oscillator in accordance with an embodiment of the invention.
- FIG. 15 is a schematic cross-sectional view of the oscillator in accordance with the embodiment of the invention.
- FIG. 16 is a schematic flow chart of an exemplary process of manufacturing an oscillator in accordance with an embodiment of the invention.
- FIG. 17 is a schematic circuit block diagram of a real-time clock in accordance with an embodiment of the invention.
- FIG. 18 is a schematic see-through plan view of a real-time clock in accordance with an embodiment of the invention.
- FIG. 19 is a schematic see-through side view of the real-time clock in accordance with the embodiment of the invention.
- FIG. 20 is a schematic circuit block diagram of a radio clock receiver module in accordance with an embodiment of the invention.
- FIG. 1 is a plan view schematically showing the piezoelectric oscillator 100 in accordance with the present embodiment
- FIG. 2 is a cross-sectional view schematically showing the piezoelectric oscillator 100 . It is noted that FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1 . Also, in FIG. 1 , illustration of a base layer 5 and a protection layer 6 to be described below is omitted for the sake of convenience.
- the piezoelectric oscillator 100 includes a substrate 2 , a supporting section 4 , an oscillation section 10 and a driving section 20 , as shown in FIG. 1 and FIG. 2 .
- a semiconductor substrate may be used.
- the semiconductor substrate for example, a single crystal silicon substrate may be enumerated.
- various kinds of semiconductor circuits (not shown) may be formed in the substrate 2 .
- the use of a silicon substrate as the semiconductor substrate 2 may be advantageous because an ordinary semiconductor manufacturing technology can be used.
- the supporting section 4 can supports the oscillation section 10 .
- the supporting section 4 may be formed, for example, in a rectangular frame shape, as shown in the figure.
- the oscillation section 10 may be formed from, for example, a single beam, and the piezoelectric oscillator 100 may be in a unimorph type.
- the oscillation section 10 may have a plane configuration that is, for example, rectangular (oblong or square), and is in an oblong shape in the illustrated example.
- the oscillation section 10 is, for example, 10 nm or more but 100 nm less in thickness.
- the thickness of the oscillation section 10 is desirably 100 nm or less for miniaturization of the piezoelectric oscillator 100 .
- the length of the oscillation section 10 is, for example, 10 ⁇ m or more but 100 ⁇ m or less.
- the oscillation section 10 may be composed of, for example, the same material as that of the supporting section 4 .
- the oscillation section 10 and the supporting section 4 may be composed of, for example, semiconductor.
- the semiconductor for example, single crystal silicon may be enumerated.
- the oscillation section 10 may be composed of, for example, a material different from that of the supporting section 4 .
- the oscillation section 10 may be composed of semiconductor, and the supporting section 4 may be composed of dielectric.
- FIG. 3 is a schematic cross-sectional view of the piezoelectric oscillator 100 in this case.
- the semiconductor for example, single crystal silicon may be enumerated.
- the dielectric for example, silicon oxide (SiO 2 ) may be enumerated.
- the oscillation section 10 may be composed of single crystal silicon, and the supporting section 4 may be composed of polycrystal silicon or amorphous silicon.
- the oscillation section 10 is formed over a cavity section 80 that is formed by removing a portion of a first semiconductor layer 60 to be described below, as shown in FIG. 2 .
- the cavity section 80 is formed on the substrate 2 .
- the cavity section 80 is surrounded by the supporting section 4 .
- the cavity section 80 has a plane configuration that is, for example, rectangular, and in the illustrated example is in an oblong shape, and its longer-side direction is in the same direction as the lengthwise direction (X direction) of the oscillation section 10 .
- An opening section 42 that allows vibration of the oscillation section 10 is formed around the oscillation section 10 .
- the opening section 42 is provided between the oscillation section 10 and the supporting section 4 .
- the opening section 42 and the oscillation section 10 when viewed as one body in a plan view ( FIG. 1 ), coincide with, for example, the cavity section 80 .
- the driving section 20 is formed on the oscillation section 10 .
- the driving section 20 generates flexing vibration of the oscillation section 10 .
- a single driving section 20 may be provided on a single beam section.
- the driving section 20 has a plane configuration that is, for example, rectangular, and in the illustrated example is in an oblong shape, and its longer-side direction is in the same direction as the lengthwise direction (X direction) of the oscillation section 10 .
- the driving section 20 has, as shown in FIG. 2 , a first electrode 22 formed above the oscillation section 10 , a piezoelectric layer 24 formed on the first electrode 22 , and a second electrode 26 formed on the piezoelectric layer 24 .
- the driving section 20 may further have a base layer 5 formed between the oscillation section 10 and the first electrode 22 .
- the major portion of the driving section 20 is formed on the oscillation section 10 on the affixed end side thereof, for example, as shown in FIG. 1 and FIG. 2 .
- a portion of the driving section 20 (more specifically, the base layer 5 and the first electrode 22 ) is also formed, for example, on the supporting section 4 .
- the base layer 5 may cover, for example, the top surface of the oscillation section 10 and the top surface of the supporting section 4 .
- the base layer 5 is a dielectric layer, such as, a silicon oxide (SiO 2 ) layer, a silicon nitride (Si 3 N 4 ) layer or the like.
- the base layer 5 may be formed from a compound layer of, for example, 2 or more layers.
- the first electrode 22 for example, a platinum (Pt) layer may be used.
- the first electrode 22 may have any thickness as long as it provides a sufficiently low electrical resistance value, and may be, for example, 10 nm or more but 100 nm or less.
- the piezoelectric layer 24 may be formed from piezoelectric material, such as, for example, lead zirconate titanate (Pb (Zr, Ti) O 3 : PZT), lead zirconate titanate solid solution or the like.
- the lead zirconate titanate solid solution for example, lead zirconate titanate niobate (Pb (Zr, Ti, Nb) O 3 : PZTN) and the like are enumerated.
- the thickness of the piezoelectric layer 24 may preferably be about the same as the thickness of the oscillation section 10 . When the thickness is in such a range, a driving force that can sufficiently vibrate the beam can be secured. For example, when the thickness of the oscillation section 10 is 10 nm or greater but 100 nm or less, the thickness of the piezoelectric layer 24 can be 10 nm or greater but 100 nm or less.
- the second electrode 26 for example, a platinum (Pt) layer may be used.
- the second electrode 26 may have any thickness as long as it provides a sufficiently low electrical resistance value, and may be, for example, 10 nm or greater but 100 nm or less.
- the driving section 20 has only the piezoelectric layer 24 provided between the first electrode 22 and the second electrode 26 , but may have other layers in addition to the piezoelectric layer 24 between the electrodes 22 and 26 .
- the film thickness of the piezoelectric layer 24 can be appropriately changed according to resonance conditions.
- the resonance frequency of the piezoelectric oscillator 100 in accordance with the present embodiment may be at 2 13 Hz (8.192 kHz) or higher, and 2 15 Hz (32.768 kHz) or lower.
- the resonance frequency at 32.768 kHz (also simply referred to as “32 kHz”) is suitable for clock modules.
- the flip-flop circuit can be formed not only from 15 stages, but also 14 stages or 13 stages, which can reduce the power consumption.
- the flip-flop circuit may possibly be formed from 16 stages, and therefore the resonance frequency of the piezoelectric oscillator 100 in accordance with the present embodiment can be 2 16 Hz (65.536 kHz) or lower.
- FIGS. 4-8 are cross-sectional views schematically showing a process for manufacturing the piezoelectric oscillator 100 in accordance with the present embodiment, each of which corresponds to the cross-sectional view shown in FIG. 2 .
- FIG. 9 is a plan view schematically showing a step of manufacturing the piezoelectric oscillator 100 in accordance with the present embodiment
- FIG. 10 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator 100 in accordance with the present embodiment. It is noted that FIG. 10 is a cross-sectional view taken along a line X-X of FIG. 9 .
- a first semiconductor layer 60 is formed on a substrate 2 .
- the first semiconductor layer 60 is formed from, for example, silicon germanium (SiGe).
- SiGe silicon germanium
- the first semiconductor layer 60 may be formed by, for example, a CVD (Chemical Vapor Deposition) method.
- a second semiconductor layer 11 is formed on the first semiconductor layer 60 .
- the second semiconductor layer 11 is formed from, for example, silicon (Si).
- Si silicon
- SiGe silicon
- lattice matching between the second semiconductor layer 11 and the first semiconductor layer 60 can be obtained, and the second semiconductor layer 11 can be formed with good crystallinity.
- various kinds of semiconductor circuits can be formed in the second semiconductor layer 11 , like the substrate 2 .
- the use of silicon as the second semiconductor layer 11 may be advantageous because an ordinary semiconductor manufacturing technology can be used.
- the second semiconductor layer 11 may be formed by, for example, a CVD method.
- an oxide layer 7 may be formed on the second semiconductor layer 11 .
- the oxide layer may be formed from, for example, silicon oxide (SiO 2 ).
- the oxide layer 7 may be formed by, for example, a thermal oxidation method.
- the oxide layer 7 , the second semiconductor layer 11 and the first semiconductor layer 60 are patterned, whereby a first opening section 40 that exposes the substrate 2 is formed.
- the second semiconductor layer 11 and the first semiconductor layer 60 in a forming region to form a supporting section 4 are removed.
- the oxide layer 7 , the second semiconductor layer 11 and the first semiconductor layer 60 may be patterned by, for example, photolithography technique and etching technique.
- the supporting section 4 that covers the exposed top surface of the substrate 2 , the exposed side surface of the first semiconductor layer 60 and the exposed side surface of the second semiconductor layer 11 , is formed inside the first opening section 40 .
- the supporting section 4 can be formed in a manner that the first opening section 40 is embedded entirely up to the position of the top surface of the second semiconductor layer 11 .
- the supporting section 4 may be thinly formed, and the supporting section 4 may be formed in a manner that the position of a portion of the top surface of the supporting section 4 is lower than the position of the top surface of the second semiconductor layer 11 .
- the supporting section 4 may be formed by, for example, a CVD method.
- the supporting section 4 may be formed from, for example, silicon (Si).
- Si silicon
- the supporting section 4 can be epitaxially grown on the substrate 2 , and the supporting section 4 can be formed with good crystallinity.
- SiGe as the first semiconductor layer 60
- Si as the second semiconductor layer 11
- the supporting section 4 can be epitaxially grown from the side surface of the first semiconductor layer 60 and the side surface of the second semiconductor layer 11 . By this, the supporting section 4 can be formed with good crystallinity.
- a covering layer (not shown) may be further formed on the supporting section 4 .
- the covering layer and the supporting section 4 may be formed together in a single step.
- the covering layer can be formed in a manner to cover the oxide layer 7 .
- the covering layer may be polished by, for example, a chemical mechanical polishing (CMP) method, until the oxide layer 7 is exposed.
- CMP chemical mechanical polishing
- the oxide layer 7 may be removed by, for example, a wet etching method.
- a base layer 5 may be formed over the entire surface of the second semiconductor layer 11 and the supporting section 4 .
- the base layer 5 may be formed by a thermal oxidation method, a CVD method, a sputter method or the like.
- a driving section 20 is formed above the second semiconductor layer 11 . More specifically, on the base layer 5 is formed a first electrode 22 , a piezoelectric layer 24 and a second electrode 26 composing the driving section 20 .
- the first electrode 22 may be formed by a vapor deposition method, a sputter method or the like.
- the piezoelectric layer 24 may be formed by a solution method (sol-gel method), a laser ablation method, a vapor deposition method, a sputter method, a CVD method, or the like.
- the second electrode 26 may be formed by a vapor deposition method, a sputter method, a CVD method or the like.
- the second electrode 26 and the piezoelectric layer 24 may be patterned into a desired configuration.
- the patterning may be conducted by, for example, photolithography technique and etching technique.
- the first electrode 22 is patterned into a desired configuration.
- the patterning may be conducted by, for example, photolithography technique and etching technique.
- a protection layer 6 (see FIG. 10 ) that covers the surface of the driving section 20 and the base layer 5 may be formed.
- the protection layer 6 may be formed by a CVD method or the like.
- the second semiconductor layer 11 is patterned into a desired configuration, whereby an oscillation section 10 and a second opening section 42 are formed.
- the oscillation section 10 may be obtained by forming the second opening section 42 that cuts through the second semiconductor layer 11 and exposes the upper surface of the first semiconductor layer 60 .
- the oscillation section 10 is provided with the inner side of the supporting section 4 as its base end, and in a manner that the other end of the oscillation section 10 would not contact the supporting section 4 .
- resist is coated on the entire surface over the substrate 2 , and then the resist is patterned by a photolithography method, whereby a resist layer 90 that covers the surface area other than the second opening section 42 is formed, as shown in FIG. 9 and FIG. 10 .
- the resist layer 90 being used as a mask, a portion of the protection layer 6 , a portion of the base layer 5 and a portion of the second semiconductor layer 11 are removed by a dry etching method.
- the first semiconductor layer 60 can be used as an etching stopper layer. In other words, when etching the second semiconductor layer 11 , the etching rate of the first semiconductor layer 60 is lower than the etching rate of the second semiconductor layer 11 .
- the oscillation section 10 and the second opening section 42 are formed.
- the first semiconductor layer 60 is patterned in a desired shape, whereby a third opening section 81 can be formed. More specifically, for example, with the resist layer 90 being used as a mask, a portion of the first semiconductor layer 60 is removed by a dry etching method or the like, whereby the third opening section 81 that cuts through the first semiconductor layer 60 and exposes the substrate 2 is formed. In this etching step, the substrate 2 can be used as an etching stopper layer. In other words, when etching the first semiconductor layer 60 , the etching rate of the substrate 2 is lower than the etching rate of the first semiconductor layer 60 . It is noted that the third opening section 81 and the second opening section 42 described above can be formed altogether in a single process.
- the first semiconductor layer 60 is removed through the portion exposed by the second opening section 42 and the third opening section 81 by an etching method, whereby a cavity section 80 is formed at least below the oscillation section 10 (see FIG. 1 and FIG. 2 ).
- the cavity section 80 is formed in a manner that the oscillation section 10 can have flexing vibration in a state where the free end 10 a of the oscillation section 10 is free from mechanical force of constraint (to be described below).
- the cavity section 80 is formed, for example, below the oscillation section 10 and the second opening section 42 .
- the etching rate of the first semiconductor layer 60 is higher than the etching rate of any of the substrate 2 , the oscillation section 10 and the supporting section 4 .
- the first semiconductor layer 60 may be selectively removed by a wet etching method, using, for example, a mixed solution of hydrofluoric acid and nitric acid (nitric-hydrofluoric acid).
- the etching selection ratio of Si with respect to SiGe can be set to about 1:100 to about 1:10000.
- the first semiconductor layer 60 may also be selectively removed by a dry etching method, using, for example, carbon tetrafluoride (CF 4 ) gas.
- the resist layer 90 is removed by ashing. By removing the resist layer 90 , the mechanical force of constraint to the free end 10 a of the oscillation section 10 is cancelled, whereby the oscillation section 10 can sufficiently vibrate.
- the piezoelectric oscillator 100 in accordance with the present embodiment is formed, as shown in FIG. 1 and FIG. 2 .
- the oscillation section 10 can be obtained through patterning the second semiconductor layer 11 .
- the second semiconductor layer 11 can be very thinly formed on the first semiconductor layer 60 , such that, according to the method for manufacturing the piezoelectric oscillator 100 in accordance with the present embodiment, the thickness of the oscillation section 10 can be made very thin (for example, 100 nm or less).
- the length of the oscillation section (beam) 10 can be made shorter.
- the piezoelectric oscillator 100 in accordance with the present embodiment can be further miniaturized.
- the thickness of the oscillation section 10 can be made to 100 nm or less
- the length of the oscillation section 10 can be made to 100 ⁇ m
- the package length of the piezoelectric oscillator 100 can be made to 1 mm or less.
- the thickness of the first electrode 22 is 50 nm
- the thickness of the piezoelectric layer 24 is 100 nm
- the thickness of the second electrode 26 is 50 nm
- the thickness of the driving section 20 is 200 nm
- the thickness of the oscillation section 10 is 100 nm
- the beam length of the oscillation section 10 is 80 nm
- the beam width is 40 nm.
- a resonance frequency of flexing vibration of the piezoelectric oscillator 100 having the structure described above, in simulation through solving an equation of motion using a finite element method is 32 kHz.
- the piezoelectric oscillator 100 can be fabricated by using, for example, an inexpensive Si substrate as the substrate 2 . Accordingly, for example, a SOI substrate, which is expensive, does not have to be used, such that the manufacturing cost can be reduced.
- the resonance frequency is proportional to the thickness of the oscillation section 10 . Accordingly, by the piezoelectric oscillator 100 , the resonance frequency can be adjusted by the thickness of the oscillation section 10 .
- the resonance frequency is proportional to the width of the oscillation section. Accordingly, in the case of a tuning fork type piezoelectric oscillator, the width of its oscillation section may be reduced as a measure to lower its resonance frequency, but its processing technology has a limitation.
- the thickness of the oscillation section 10 may be made thinner as a measure to lower the resonance frequency. Accordingly, a desired resonance frequency can be obtained without any limitation to the processing technology to be applied to the oscillation section 10 .
- the piezoelectric oscillator 100 in a unimorph type in accordance with the present embodiment one beam (oscillation section) 10 is provided with one driving section 20 .
- the piezoelectric oscillator 100 in accordance with the present embodiment is structurally advantageous in miniaturization.
- piezoelectric oscillator 100 in accordance with the present embodiment may also be used as a trigger generator in asynchronous circuits such as circuits that do not essentially require a timing device.
- another cavity section similar to the cavity section 80 of the piezoelectric oscillator 100 may be formed over the substrate 2 in areas other than the area where the piezoelectric oscillator 100 is formed, and a dielectric layer may be formed in the cavity section, whereby, for example, a SOI (Silicon On Insulator) structure can be formed.
- a SOI Silicon On Insulator
- a semiconductor integrated circuit may be formed on the dielectric layer of the SOI structure. Therefore, according to the piezoelectric oscillator 100 in accordance with the present embodiment, the semiconductor integrated circuit using the SOI structure and the piezoelectric oscillator 100 may be mixed and mounted on a single substrate thereby forming a piezoelectric oscillator module. As a result, the module package can be made smaller.
- an oscillation circuit can be formed on the dielectric layer in the SOI structure described above. Therefore, according to the piezoelectric oscillator 100 in accordance with the present embodiment, the oscillation circuit using the SOI structure and the piezoelectric oscillator 100 can be mixed and mounted on a single substrate. A device with the SOI structure can be operated with a low operation voltage. Therefore, according to the piezoelectric oscillator 100 in accordance with the present embodiment, one-chip clock modules with low power consumption can be provided.
- piezoelectric oscillators and methods for manufacturing the same in accordance with modified examples of the present embodiment are described with reference to the accompanying drawings. It is noted that features different from those of the piezoelectric oscillator 100 and its manufacturing method described above (hereafter referred to as an “example of piezoelectric oscillator 100 ”) are described, and description of the same features is omitted.
- FIG. 11 is a schematic cross-sectional view of the piezoelectric oscillator 300 in accordance with the modified example.
- a substrate opening section 82 may be provided below the cavity section 80 . More specifically, the cavity section 80 may be formed above the substrate opening section 82 formed by removing a portion of the substrate 2 .
- the process up to forming an oscillation section 10 and a second opening section 42 are conducted, in a manner similar to the example of piezoelectric oscillator 100 .
- the substrate 2 is patterned in a desired configuration, thereby forming the substrate opening section 82 .
- the substrate opening section 82 is formed by cutting through the substrate 2 so as to expose the first semiconductor layer 60 . More concretely, first, resist is coated on the entire upper and lower surfaces of the substrate 2 , and then the resist coated over the lower surface of the substrate 2 is patterned by a photolithography method, whereby a second resist layer (not shown) that covers areas other than the substrate opening section 82 is formed. Next, by using the second resist layer as a mask, a portion of the substrate 2 is removed by, for example, a dry etching method. In the step of etching the substrate 2 , the first semiconductor layer 60 can be used as an etching stopper layer. In other words, when etching the substrate 2 , the etching rate of the first semiconductor layer 60 is lower than the etching rate of the substrate 2 .
- the first semiconductor layer 60 is removed by, for example, a wet etching method through a portion exposed by the substrate opening section 82 , whereby the cavity section 80 is formed at least below the oscillation section 10 .
- the first semiconductor layer 60 can be selectively removed.
- the first resist layer 90 see FIG. 10
- the second resist layer are removed by ashing.
- the piezoelectric oscillator 300 in accordance with the present modified example can be formed.
- FIG. 12 is a schematic plan view of a piezoelectric oscillator 200 in accordance with the present modified example.
- the oscillation section 210 is formed to have a tuning fork shape composed of a base section 212 and two beam sections 214 and 216 with the base section 212 as a base end thereof.
- the base section 212 connects the supporting section 4 and the beam sections 214 and 216 .
- the base section 212 has a plane configuration that is rectangular, for example, as shown in FIG. 12 .
- the two beam sections 214 and 216 are disposed in the lengthwise direction (X direction) in parallel with each other, spaced at a predetermined gap (the width of the base section 212 ).
- the beam sections 214 and 216 each have a plane configuration that is rectangular, for example, as shown in FIG. 12 .
- Driving sections 220 in a pair is provided on each of the beam sections 214 and 216 .
- On the first beam section 214 is provided a first driving section 220 a and a second driving section 220 b formed along the lengthwise direction of the first beam section 214 in parallel with each other.
- On the second beam section 216 is provided a third driving section 220 c and a fourth driving section 220 d formed along the lengthwise direction of the second beam section 216 in parallel with each other.
- the first driving section 220 a disposed on the outer side of the first beam section 214 and the fourth driving section 220 d disposed on the outer side of the second beam section 216 are electrically connected together by a wiring (not shown).
- the second driving section 220 b disposed on the inner side of the first beam section 214 and the third driving section 220 c disposed on the inner side of the second beam section 216 are electrically connected together by a wiring (not shown).
- FIG. 13 is a circuit diagram of a basic structure of an oscillator 500 having the piezoelectric oscillator 100 described above.
- the circuit includes, for example, an amplifier 401 formed from a CMOS inverter and a feedback circuit connected between an input and an output of the amplifier 401 .
- the feedback circuit includes a piezoelectric oscillator 100 , a resistance 403 and two capacitors 404 and 405 .
- a voltage E is applied from a DC power supply to the amplifier 401 . As the power supply voltage E is increased and reaches an oscillation starting voltage, the current I rapidly increases and oscillation starts. When the power supply voltage E is further increased, the current I generally proportionally increases while maintaining the oscillation state.
- FIG. 14 is a schematic plan view of the oscillator 500 in accordance with the present embodiment
- FIG. 15 is a schematic cross-sectional view of the oscillator 500 . It is noted that FIG. 15 is a cross-sectional view taken along lines XV-XV of FIG. 14 . Also, in FIG. 14 and FIG. 15 , the illustration of the piezoelectric oscillator 100 is simplified for the sake of convenience.
- the oscillator 500 is sealed by a sealing material 502 .
- An IC (integrated circuit) 503 is connected to external terminals 570 by bonding wires 504 such as gold wires.
- the external terminals 570 are electrically connected to mounting terminals 541 through a lead frame 505 and a bonding material 506 .
- the mounting terminals 541 are electrically connected to electrodes of the piezoelectric oscillator 100 through wirings or the like (not shown).
- the piezoelectric oscillator 100 is sealed by a lid member 539 and a seal member 540 .
- FIG. 16 schematically shows an example of a process for manufacturing the oscillator 500 in accordance with the present embodiment.
- tape attaching and dicing are conducted on an IC wafer. Then, a chip with the IC 503 is mounted on the lead frame 505 . Then, wire-bonding is applied to the IC 502 using the bonding wires 504 .
- the mounting terminals 541 of the piezoelectric oscillator 100 are bonded to the lead frame 505 , using the bonding material 506 such as solder, thereby mounting the piezoelectric oscillator 100 .
- the piezoelectric oscillator 100 and the IC 503 are sealed by using the sealing material (mold material) 502 . Thereafter, characteristic tests, marking, taping and packing are conducted, and the product is shipped out.
- a semiconductor process may be applied to areas in the substrate 2 (see FIG. 2 ) and the second semiconductor layer 11 (see FIG. 4 ) other than the area where the piezoelectric oscillator 100 is formed, whereby an IC adjacent in the plane to the piezoelectric oscillator 100 may be formed, and thus the oscillator in accordance with the present embodiment may be formed.
- a one-chip type oscillator can be formed, and its packaging can be omitted.
- FIG. 17 is a circuit block diagram schematically showing a real-time clock 600 having the oscillator (OSC) 500 described above.
- An integrated circuit section of the real-time clock 600 is integrated in a single substrate 601 , and connected to a microprocessor (not shown).
- the oscillator 500 connected to timing connection terminals 602 and 603 outputs high frequency clock pulses (for example, at 32 kHz).
- the clock pulse is divided by a divider circuit 605 , whereby timing pulses at 1 Hz are inputted in a timing counter 606 .
- the timing counter 606 is formed from, for example, a second timing bit s, a minute timing bit m, an hour timing bit h, a day-of-week timing bit d, a day timing bit D, a month timing bit M, and a year timing bit Y.
- each of the timing bits is advanced.
- a selection signal is supplied from the microprocessor to an input terminal 607 .
- the microprocessor supplies to a data input terminal 608 external information composed of a data bit indicating information to be rewritten, an address bit indicating an address of the timing bit, and an operation bit indicating a write operation to be applied to the timing counter 606 .
- the external information is stored in serially connected shift registers 609 and 610 .
- a command decoder 612 sends a write-enable signal to the timing counter 606 , and outputs an address signal designating the timing bit.
- the data bit stored in the shift register 609 is written to the timing bit of the timing counter 606 , whereby real-time data is rewritten.
- the microprocessor when reading out real-time data from the timing counter 606 , the microprocessor sends external information having an operation bit indicating a readout operation. Then, the command decoder 612 sets the write-enable signal to the timing counter 606 to an inactive state. As a result, an inverter 613 supplies a write-enable signal in an active state to the shift register 609 , whereby the shift register 609 is set to a read-enable state, and the content of the timing counter 606 is read out to the shift register 609 .
- the real-time data read out to the shift register 609 is transferred to a data output terminal 615 in synchronism with a clock signal that is applied to the clock input terminal 614 , and then sent out to, for example, a register of the microprocessor.
- RAM random access memory
- FIG. 18 is a schematic see-through plan view of the real-time clock 600 in accordance with the present embodiment
- FIG. 19 is a schematic see-through side view of the real-time clock 600 . It is noted that FIG. 19 is a figure viewed in a direction of arrows XIX of FIG. 18 .
- An IC chip 651 having an oscillation circuit or the like is affixed with adhesive such as conductive adhesive to an island section 653 of a lead frame 652 .
- Electrode pads 654 provided on the top surface of the IC chip 651 are electrically connected to I/O lead terminals 656 disposed along a peripheral section of the package by bonding wires 655 .
- an oscillator housing 657 that stores therein the piezoelectric oscillator 100 is disposed next to the IC chip 651 .
- the piezoelectric oscillator 100 is air-tightly sealed in the oscillator housing 657 .
- the leads 658 are affixed with adhesive such as conductive adhesive to connection pads 659 of the lead frame 652 .
- the IC chip 651 , the lead frame 652 and the oscillator housing 657 are packaged in one piece with resin 660 .
- a semiconductor process may be applied to areas in the substrate 2 (see FIG. 2 ) and the second semiconductor layer 11 (see FIG. 4 ) other than the area where the piezoelectric oscillator 100 is formed, whereby an IC adjacent in the plane to the piezoelectric oscillator 100 may be formed, and the real-time clock in accordance with the present embodiment may be formed.
- the packaging can be omitted, and a one-chip type real-time clock can be formed.
- FIG. 20 is a circuit block diagram schematically showing a radio clock receiver module in accordance with an embodiment of the invention.
- a frequency filter 805 of the radio clock receiver module has the piezoelectric oscillator 100 described above ( 100 A and 100 B in this example).
- a radio clock is a clock equipped with the function to receive a standard radio wave including time information, automatically correcting the time and displaying the time.
- a standard radio wave including time information, automatically correcting the time and displaying the time.
- An antenna 801 receives a longwave standard radio wave at 40 kHz or 60 kHz.
- the standard radio wave is composed of an amplification-modulated (AM) 40 kHz or 60 kHz carrier wave and time information (time code) superposed thereon.
- AM amplification-modulated
- the received standard radio wave is amplified by an amplifier 802 , and filtered and tuned by the frequency filter 805 with the piezoelectric oscillator 100 A or 100 b having a resonance frequency that is the same as the carrier frequency.
- the filtered signal of the predetermined frequency is detected and demodulated by a detection-rectifier circuit 806 .
- the time code is retrieved from the signal by a waveform rectifier circuit 807 , and counted by a central processing unit (CPU) 808 .
- the CPU 808 reads information for, for example, the current year, the total days, the day of week, the time and the like.
- the readout information is reflected on a real-time clock (RTC) 809 , whereby correct time information is displayed.
- RTC real-time clock
- the piezoelectric oscillators in accordance with the present embodiment of the invention are suitable for the piezoelectric oscillators 100 A and 100 B of the frequency filter 805 .
- a piezoelectric oscillator having the following dimensions can be used.
- the thickness of the first electrode 22 is 50 nm
- the thickness of the piezoelectric layer 24 is 100 nm
- the thickness of the second electrode 26 is 50 nm
- the thickness of the oscillation section 10 is 100 nm
- the length of the oscillation section 10 is 92 nm
- the width of the oscillation section 10 is 40 nm.
- a semiconductor process may be applied to areas in the substrate 2 (see FIG. 2 ) and the second semiconductor layer 11 (see FIG. 4 ) other than the area where the piezoelectric oscillator 100 is formed, whereby an IC adjacent in the plane to the piezoelectric oscillator 100 may be formed, and the radio clock receiver module in accordance with the present embodiment may be formed.
- a one-chip type radio clock receiver module can be formed, and its packaging can be omitted.
Abstract
A piezoelectric oscillator includes a substrate, a supporting section formed above the substrate, an oscillation section having one end affixed to the supporting section and another free end, and a driving section that is formed above the oscillation section and generates flexing vibration in the oscillation section. The driving section includes a first electrode, a piezoelectric layer formed above the first electrode, and a second electrode formed above the piezoelectric layer, and the oscillation section is composed of a material that is different from a material of the supporting section. The oscillation section is composed of single crystal silicon, and the supporting section is composed of polycrystal silicon or amorphous silicon.
Description
- This application is a divisional of U.S. patent application Ser. No. 12/019,244 filed on Jan. 24, 2008. This application claims the benefit of Japanese Patent Application No. 2007-014836 filed Jan. 25, 2007. The disclosures of the above applications are incorporated herein by reference.
- 1. Technical Field
- The present invention relates to piezoelectric oscillators and methods for manufacturing the same.
- 2. Related Art
- Tuning fork type 32 kHz quartz oscillators are used in oscillator sections of clock modules in clocks and information devices such as microcomputers in order to take advantage of the traditional design assets and their power saving property. However, the arm length of the tuning fork arm in the case of a tuning fork type 32 kHz quartz oscillator is several mm, and therefore the overall length including its package may amount to about 10 mm.
- In recent years, instead of quart, piezoelectric oscillators having a driving section formed from a piezoelectric thin film sandwiched between upper and lower electrodes formed on a silicon substrate have been developed. As the structure of such piezoelectric oscillators, a beam type structure (see FIG. 1 of Japanese Laid-open patent application JP-A-2005-291858) and a tuning fork type structure equipped with two beams (see FIG. 1 of Japanese Laid-open patent application JP-A-2005-249395) are known. Even with such piezoelectric oscillators, the silicon substrate can only be made at most to a thickness of about 100 μm. Therefore, in order to obtain a resonance frequency in a several tens kHz band, the arm length of the beam needs to be several mm or greater, which may lead to a problem in that miniaturization of the clock module is difficult.
- In accordance with an advantage of some aspects of the invention, it is possible to provide a piezoelectric oscillator that is very small in size, and is capable of providing, for example, a resonance frequency in a several tens kHz band, and a method for manufacturing the same.
- A method for manufacturing a piezoelectric oscillator in accordance with an embodiment of the invention includes the steps of: forming a first semiconductor layer above a substrate; forming a second semiconductor layer above the first semiconductor layer; forming a first opening section that exposes the substrate by removing the second semiconductor layer and the first semiconductor layer in an area for forming a support section; forming the support section in the first opening section; forming a driving section that generates flexing vibration in an oscillation section above the second semiconductor layer; patterning the second semiconductor layer to form the oscillation section having the supporting section as a base end and another end provided so as not to contact the supporting section, and a second opening section that exposes the first semiconductor layer; and removing the first semiconductor layer through a portion exposed at the second opening section by an etching method, thereby forming a cavity section at least below the oscillation section, wherein the step of forming the driving section includes the steps of forming a first electrode, forming a piezoelectric layer above the first electrode, and forming a second electrode above the piezoelectric layer.
- According to the method for manufacturing a piezoelectric oscillator in accordance with the present embodiment, the oscillation section can be obtained by patterning the second semiconductor layer. The second semiconductor layer can be formed very thin above the first semiconductor layer. Therefore, according to the method for manufacturing a piezoelectric oscillator, the oscillation section can be formed very thin. Accordingly, in a piezoelectric oscillator that may generate a resonance frequency of an oscillator that is used for a clock module, the oscillation section can be made shorter in length. In other words, the piezoelectric oscillator can be made smaller in size, compared to a piezoelectric oscillator that uses quartz.
- It is noted that, in the descriptions concerning the invention, the term “above” may be used, for example, in a manner as “a specific element (hereafter referred to as “A”) is formed ‘above’ another specific element (hereafter referred to as “B”).” In the descriptions concerning the invention, in the case of such an example, the term “above” is used, while assuming that it include a case in which A is formed directly on B, and a case in which A is formed above B through another element.
- In the method for manufacturing a piezoelectric oscillator in accordance with an aspect of the embodiment of the invention, in the step of removing the first semiconductor layer, the etching rate of the first semiconductor layer may be greater than the etching rate of any of the substrate, the oscillation section and the supporting section.
- In the method for manufacturing a piezoelectric oscillator in accordance with an aspect of the embodiment of the invention, the first semiconductor layer may be formed from silicon germanium, and the substrate, the oscillation section and the supporting section may be formed from silicon.
- In the method for manufacturing a piezoelectric oscillator in accordance with an aspect of the embodiment of the invention, the oscillation section may be formed to have a thickness of 100 nm or less.
- In the method for manufacturing a piezoelectric oscillator in accordance with an aspect of the embodiment of the invention, the oscillation section may be formed to have a length of 100 μm or less.
- It is noted that, in the present embodiment, the length of the oscillation section is a distance between the affixed end of the oscillation section and its free end in a plan view. Also, a distance between two ends of the oscillation section in a direction perpendicular to the lengthwise direction of the oscillation section is called a width of the oscillation section. Furthermore, for example, the length of the piezoelectric layer is a length of the piezoelectric layer in the lengthwise direction of the oscillation section, and the width of the piezoelectric layer is a width of the piezoelectric layer in the widthwise direction of the oscillation section.
- In the method for manufacturing a piezoelectric oscillator in accordance with an aspect of the embodiment of the invention, the piezoelectric oscillator may be formed to have a resonance frequency at 213 Hz (8.192 kHz) or higher, and 215 Hz (32.768 kHz) or lower.
- A piezoelectric oscillator in accordance with an embodiment of the invention includes: a substrate; a supporting section formed above the substrate; an oscillation section having one end affixed to the supporting section and another free end; and a driving section that is formed above the oscillation section and generates flexing vibration in the oscillation section, wherein the driving section includes a first electrode, a piezoelectric layer formed above the first electrode, and a second electrode formed above the piezoelectric layer, and the oscillation section is composed of a material different from a material of the supporting section.
- It is noted that, in the present invention, materials having different states, such as, for example, single crystal silicon, polycrystal silicon and amorphous silicon, are treated as different materials.
- In the piezoelectric oscillator in accordance with an aspect of the embodiment of the invention, the oscillation section may be composed of semiconductor, and the supporting section may be composed of dielectric.
- In the piezoelectric oscillator in accordance with an aspect of the embodiment of the invention, the oscillation section may be composed of single crystal silicon, and the supporting section may be composed of polycrystal silicon or amorphous silicon.
-
FIG. 1 is a schematic plan view of a piezoelectric oscillator in accordance with an embodiment of the invention. -
FIG. 2 is a schematic cross-sectional view of the piezoelectric oscillator in accordance with the embodiment of the invention. -
FIG. 3 is a schematic cross-sectional view of the piezoelectric oscillator in accordance with the embodiment of the invention. -
FIG. 4 is a cross-sectional view schematically showing a step of manufacturing a piezoelectric oscillator in accordance with an embodiment of the invention. -
FIG. 5 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment. -
FIG. 6 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment. -
FIG. 7 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment. -
FIG. 8 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment. -
FIG. 9 is a plan view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment. -
FIG. 10 is a cross-sectional view schematically showing a step of manufacturing the piezoelectric oscillator in accordance with the present embodiment. -
FIG. 11 is a cross-sectional view schematically showing a piezoelectric oscillator in accordance with a modified example of the present embodiment. -
FIG. 12 is a plan view schematically showing a piezoelectric oscillator in accordance with a modified example of the present embodiment. -
FIG. 13 is a circuit diagram of the basic structure of an oscillator in accordance with an embodiment of the invention. -
FIG. 14 is a schematic plan view of an oscillator in accordance with an embodiment of the invention. -
FIG. 15 is a schematic cross-sectional view of the oscillator in accordance with the embodiment of the invention. -
FIG. 16 is a schematic flow chart of an exemplary process of manufacturing an oscillator in accordance with an embodiment of the invention. -
FIG. 17 is a schematic circuit block diagram of a real-time clock in accordance with an embodiment of the invention. -
FIG. 18 is a schematic see-through plan view of a real-time clock in accordance with an embodiment of the invention. -
FIG. 19 is a schematic see-through side view of the real-time clock in accordance with the embodiment of the invention. -
FIG. 20 is a schematic circuit block diagram of a radio clock receiver module in accordance with an embodiment of the invention. - Preferred embodiments of the invention are described below with reference to the accompanying drawings.
- 1. First, a
piezoelectric oscillator 100 in accordance with an embodiment of the invention is described.FIG. 1 is a plan view schematically showing thepiezoelectric oscillator 100 in accordance with the present embodiment, andFIG. 2 is a cross-sectional view schematically showing thepiezoelectric oscillator 100. It is noted thatFIG. 2 is a cross-sectional view taken along a line II-II inFIG. 1 . Also, inFIG. 1 , illustration of abase layer 5 and aprotection layer 6 to be described below is omitted for the sake of convenience. - The
piezoelectric oscillator 100 includes asubstrate 2, a supportingsection 4, anoscillation section 10 and adriving section 20, as shown inFIG. 1 andFIG. 2 . - As the
substrate 2, for example, a semiconductor substrate may be used. As the semiconductor substrate, for example, a single crystal silicon substrate may be enumerated. For example, various kinds of semiconductor circuits (not shown) may be formed in thesubstrate 2. The use of a silicon substrate as thesemiconductor substrate 2 may be advantageous because an ordinary semiconductor manufacturing technology can be used. - The supporting
section 4 can supports theoscillation section 10. The supportingsection 4 may be formed, for example, in a rectangular frame shape, as shown in the figure. - One end of the
oscillation section 10 is affixed to an inner side of the supportingsection 4, and the other end is a free end. Theoscillation section 10 may be formed from, for example, a single beam, and thepiezoelectric oscillator 100 may be in a unimorph type. Theoscillation section 10 may have a plane configuration that is, for example, rectangular (oblong or square), and is in an oblong shape in the illustrated example. Theoscillation section 10 is, for example, 10 nm or more but 100 nm less in thickness. The thickness of theoscillation section 10 is desirably 100 nm or less for miniaturization of thepiezoelectric oscillator 100. The length of theoscillation section 10 is, for example, 10 μm or more but 100 μm or less. - The
oscillation section 10 may be composed of, for example, the same material as that of the supportingsection 4. Theoscillation section 10 and the supportingsection 4 may be composed of, for example, semiconductor. As the semiconductor, for example, single crystal silicon may be enumerated. - Also, the
oscillation section 10 may be composed of, for example, a material different from that of the supportingsection 4. For example, as shown inFIG. 3 , theoscillation section 10 may be composed of semiconductor, and the supportingsection 4 may be composed of dielectric.FIG. 3 is a schematic cross-sectional view of thepiezoelectric oscillator 100 in this case. As the semiconductor, for example, single crystal silicon may be enumerated. As the dielectric, for example, silicon oxide (SiO2) may be enumerated. Also, for example, theoscillation section 10 may be composed of single crystal silicon, and the supportingsection 4 may be composed of polycrystal silicon or amorphous silicon. - The
oscillation section 10 is formed over acavity section 80 that is formed by removing a portion of afirst semiconductor layer 60 to be described below, as shown inFIG. 2 . Thecavity section 80 is formed on thesubstrate 2. Thecavity section 80 is surrounded by the supportingsection 4. Thecavity section 80 has a plane configuration that is, for example, rectangular, and in the illustrated example is in an oblong shape, and its longer-side direction is in the same direction as the lengthwise direction (X direction) of theoscillation section 10. - An
opening section 42 that allows vibration of theoscillation section 10 is formed around theoscillation section 10. Theopening section 42 is provided between theoscillation section 10 and the supportingsection 4. Theopening section 42 and theoscillation section 10, when viewed as one body in a plan view (FIG. 1 ), coincide with, for example, thecavity section 80. - The driving
section 20 is formed on theoscillation section 10. The drivingsection 20 generates flexing vibration of theoscillation section 10. For example, as shown inFIG. 1 , asingle driving section 20 may be provided on a single beam section. The drivingsection 20 has a plane configuration that is, for example, rectangular, and in the illustrated example is in an oblong shape, and its longer-side direction is in the same direction as the lengthwise direction (X direction) of theoscillation section 10. The drivingsection 20 has, as shown inFIG. 2 , afirst electrode 22 formed above theoscillation section 10, apiezoelectric layer 24 formed on thefirst electrode 22, and asecond electrode 26 formed on thepiezoelectric layer 24. The drivingsection 20 may further have abase layer 5 formed between theoscillation section 10 and thefirst electrode 22. The major portion of the drivingsection 20 is formed on theoscillation section 10 on the affixed end side thereof, for example, as shown inFIG. 1 andFIG. 2 . A portion of the driving section 20 (more specifically, thebase layer 5 and the first electrode 22) is also formed, for example, on the supportingsection 4. Thebase layer 5 may cover, for example, the top surface of theoscillation section 10 and the top surface of the supportingsection 4. - The
base layer 5 is a dielectric layer, such as, a silicon oxide (SiO2) layer, a silicon nitride (Si3N4) layer or the like. Thebase layer 5 may be formed from a compound layer of, for example, 2 or more layers. - As the
first electrode 22, for example, a platinum (Pt) layer may be used. Thefirst electrode 22 may have any thickness as long as it provides a sufficiently low electrical resistance value, and may be, for example, 10 nm or more but 100 nm or less. - The
piezoelectric layer 24 may be formed from piezoelectric material, such as, for example, lead zirconate titanate (Pb (Zr, Ti) O3: PZT), lead zirconate titanate solid solution or the like. As the lead zirconate titanate solid solution, for example, lead zirconate titanate niobate (Pb (Zr, Ti, Nb) O3: PZTN) and the like are enumerated. The thickness of thepiezoelectric layer 24 may preferably be about the same as the thickness of theoscillation section 10. When the thickness is in such a range, a driving force that can sufficiently vibrate the beam can be secured. For example, when the thickness of theoscillation section 10 is 10 nm or greater but 100 nm or less, the thickness of thepiezoelectric layer 24 can be 10 nm or greater but 100 nm or less. - As the
second electrode 26, for example, a platinum (Pt) layer may be used. Thesecond electrode 26 may have any thickness as long as it provides a sufficiently low electrical resistance value, and may be, for example, 10 nm or greater but 100 nm or less. - It is noted that, in the illustrated example, the driving
section 20 has only thepiezoelectric layer 24 provided between thefirst electrode 22 and thesecond electrode 26, but may have other layers in addition to thepiezoelectric layer 24 between theelectrodes piezoelectric layer 24 can be appropriately changed according to resonance conditions. - In the
piezoelectric oscillator 100 in accordance with the present embodiment, electric fields in alternately opposing directions are applied to the drivingsection 20, thereby causing flexing vibration in theoscillation section 10 in up and down directions (Z direction). - The resonance frequency of the
piezoelectric oscillator 100 in accordance with the present embodiment may be at 213 Hz (8.192 kHz) or higher, and 215 Hz (32.768 kHz) or lower. For example, the resonance frequency at 32.768 kHz (also simply referred to as “32 kHz”) is suitable for clock modules. When the resonance frequency is 215 Hz=32.768 kHz, it can be divided by a 15-stage flip-flop circuit whereby a signal with 1 Hz can be generated. Also, by setting the resonance frequency in a range between 213 Hz=8.192 kHz and 215 Hz=32.768 kHz, the flip-flop circuit can be formed not only from 15 stages, but also 14 stages or 13 stages, which can reduce the power consumption. Also, in view of power consumption, the flip-flop circuit may possibly be formed from 16 stages, and therefore the resonance frequency of thepiezoelectric oscillator 100 in accordance with the present embodiment can be 216 Hz (65.536 kHz) or lower. - 2. Next, an example of a method for manufacturing the
piezoelectric oscillator 100 in accordance with an embodiment of the invention is described with reference to the accompanying drawings.FIGS. 4-8 are cross-sectional views schematically showing a process for manufacturing thepiezoelectric oscillator 100 in accordance with the present embodiment, each of which corresponds to the cross-sectional view shown inFIG. 2 . Also,FIG. 9 is a plan view schematically showing a step of manufacturing thepiezoelectric oscillator 100 in accordance with the present embodiment, andFIG. 10 is a cross-sectional view schematically showing a step of manufacturing thepiezoelectric oscillator 100 in accordance with the present embodiment. It is noted thatFIG. 10 is a cross-sectional view taken along a line X-X ofFIG. 9 . - (1) First, as shown in
FIG. 4 , afirst semiconductor layer 60 is formed on asubstrate 2. Thefirst semiconductor layer 60 is formed from, for example, silicon germanium (SiGe). For example, by using SiGe as thefirst semiconductor layer 60, and Si as thesubstrate 2, lattice matching between thesemiconductor layer 60 and thesubstrate 2 can be obtained, and thefirst semiconductor layer 60 can be formed with good crystallinity. Thefirst semiconductor layer 60 may be formed by, for example, a CVD (Chemical Vapor Deposition) method. - (2) Next, as shown in
FIG. 4 , asecond semiconductor layer 11 is formed on thefirst semiconductor layer 60. Thesecond semiconductor layer 11 is formed from, for example, silicon (Si). For example, by using Si as thesecond semiconductor layer 11, and SiGe as thefirst semiconductor layer 60, lattice matching between thesecond semiconductor layer 11 and thefirst semiconductor layer 60 can be obtained, and thesecond semiconductor layer 11 can be formed with good crystallinity. Also, various kinds of semiconductor circuits (not shown) can be formed in thesecond semiconductor layer 11, like thesubstrate 2. The use of silicon as thesecond semiconductor layer 11 may be advantageous because an ordinary semiconductor manufacturing technology can be used. Thesecond semiconductor layer 11 may be formed by, for example, a CVD method. - (3) Next, as shown in
FIG. 4 , anoxide layer 7 may be formed on thesecond semiconductor layer 11. The oxide layer may be formed from, for example, silicon oxide (SiO2). Theoxide layer 7 may be formed by, for example, a thermal oxidation method. - (4) Next, as shown in
FIG. 5 , theoxide layer 7, thesecond semiconductor layer 11 and thefirst semiconductor layer 60 are patterned, whereby afirst opening section 40 that exposes thesubstrate 2 is formed. By this step, thesecond semiconductor layer 11 and thefirst semiconductor layer 60 in a forming region to form a supporting section 4 (seeFIG. 1 andFIG. 2 ) are removed. Theoxide layer 7, thesecond semiconductor layer 11 and thefirst semiconductor layer 60 may be patterned by, for example, photolithography technique and etching technique. - (5) Next, the supporting
section 4, that covers the exposed top surface of thesubstrate 2, the exposed side surface of thefirst semiconductor layer 60 and the exposed side surface of thesecond semiconductor layer 11, is formed inside thefirst opening section 40. For example, the supportingsection 4 can be formed in a manner that thefirst opening section 40 is embedded entirely up to the position of the top surface of thesecond semiconductor layer 11. Further, although not shown, for example, the supportingsection 4 may be thinly formed, and the supportingsection 4 may be formed in a manner that the position of a portion of the top surface of the supportingsection 4 is lower than the position of the top surface of thesecond semiconductor layer 11. The supportingsection 4 may be formed by, for example, a CVD method. - The supporting
section 4 may be formed from, for example, silicon (Si). For example, by using Si for both of the supportingsection 4 and thesubstrate 2, the supportingsection 4 can be epitaxially grown on thesubstrate 2, and the supportingsection 4 can be formed with good crystallinity. Further, for example, by using Si as the supportingsection 4, SiGe as thefirst semiconductor layer 60, and Si as thesecond semiconductor layer 11, the supportingsection 4 can be epitaxially grown from the side surface of thefirst semiconductor layer 60 and the side surface of thesecond semiconductor layer 11. By this, the supportingsection 4 can be formed with good crystallinity. - Also, for example, after forming the supporting
section 4, a covering layer (not shown) may be further formed on the supportingsection 4. The covering layer and the supportingsection 4 may be formed together in a single step. The covering layer can be formed in a manner to cover theoxide layer 7. In this case, after forming the covering layer, the covering layer may be polished by, for example, a chemical mechanical polishing (CMP) method, until theoxide layer 7 is exposed. Theoxide layer 7 can be used as a stopper layer in the CMP method. - Next, the
oxide layer 7 may be removed by, for example, a wet etching method. - (6) Then, as shown in
FIG. 7 , abase layer 5 may be formed over the entire surface of thesecond semiconductor layer 11 and the supportingsection 4. Thebase layer 5 may be formed by a thermal oxidation method, a CVD method, a sputter method or the like. - (7) Next, as shown in
FIG. 8 , a drivingsection 20 is formed above thesecond semiconductor layer 11. More specifically, on thebase layer 5 is formed afirst electrode 22, apiezoelectric layer 24 and asecond electrode 26 composing the drivingsection 20. - First, on the entire top surface of the
base layer 5, layers for thefirst electrode 22, thepiezoelectric layer 24 and thesecond electrode 26 are formed in this order. Thefirst electrode 22 may be formed by a vapor deposition method, a sputter method or the like. Thepiezoelectric layer 24 may be formed by a solution method (sol-gel method), a laser ablation method, a vapor deposition method, a sputter method, a CVD method, or the like. Thesecond electrode 26 may be formed by a vapor deposition method, a sputter method, a CVD method or the like. - Next, the
second electrode 26 and thepiezoelectric layer 24 may be patterned into a desired configuration. The patterning may be conducted by, for example, photolithography technique and etching technique. - Then, for example, the
first electrode 22 is patterned into a desired configuration. The patterning may be conducted by, for example, photolithography technique and etching technique. - (8) Next, a protection layer 6 (see
FIG. 10 ) that covers the surface of the drivingsection 20 and thebase layer 5 may be formed. Theprotection layer 6 may be formed by a CVD method or the like. - Then, the
second semiconductor layer 11 is patterned into a desired configuration, whereby anoscillation section 10 and asecond opening section 42 are formed. Theoscillation section 10 may be obtained by forming thesecond opening section 42 that cuts through thesecond semiconductor layer 11 and exposes the upper surface of thefirst semiconductor layer 60. Theoscillation section 10 is provided with the inner side of the supportingsection 4 as its base end, and in a manner that the other end of theoscillation section 10 would not contact the supportingsection 4. - More specifically, first, resist is coated on the entire surface over the
substrate 2, and then the resist is patterned by a photolithography method, whereby a resistlayer 90 that covers the surface area other than thesecond opening section 42 is formed, as shown inFIG. 9 andFIG. 10 . Next, with the resistlayer 90 being used as a mask, a portion of theprotection layer 6, a portion of thebase layer 5 and a portion of thesecond semiconductor layer 11 are removed by a dry etching method. In this etching step, thefirst semiconductor layer 60 can be used as an etching stopper layer. In other words, when etching thesecond semiconductor layer 11, the etching rate of thefirst semiconductor layer 60 is lower than the etching rate of thesecond semiconductor layer 11. - In a manner described above, the
oscillation section 10 and thesecond opening section 42 are formed. - Next, for example, the
first semiconductor layer 60 is patterned in a desired shape, whereby athird opening section 81 can be formed. More specifically, for example, with the resistlayer 90 being used as a mask, a portion of thefirst semiconductor layer 60 is removed by a dry etching method or the like, whereby thethird opening section 81 that cuts through thefirst semiconductor layer 60 and exposes thesubstrate 2 is formed. In this etching step, thesubstrate 2 can be used as an etching stopper layer. In other words, when etching thefirst semiconductor layer 60, the etching rate of thesubstrate 2 is lower than the etching rate of thefirst semiconductor layer 60. It is noted that thethird opening section 81 and thesecond opening section 42 described above can be formed altogether in a single process. - (9) Next, the
first semiconductor layer 60 is removed through the portion exposed by thesecond opening section 42 and thethird opening section 81 by an etching method, whereby acavity section 80 is formed at least below the oscillation section 10 (seeFIG. 1 andFIG. 2 ). Thecavity section 80 is formed in a manner that theoscillation section 10 can have flexing vibration in a state where thefree end 10 a of theoscillation section 10 is free from mechanical force of constraint (to be described below). Thecavity section 80 is formed, for example, below theoscillation section 10 and thesecond opening section 42. - In the step of removing the
first semiconductor layer 60, the etching rate of thefirst semiconductor layer 60 is higher than the etching rate of any of thesubstrate 2, theoscillation section 10 and the supportingsection 4. By this, etching of thesubstrate 2, theoscillation section 10 and the supportingsection 4 can be suppressed, and thefirst semiconductor layer 60 can be selectively removed. For example, when thefirst semiconductor layer 60 is composed of SiGe, and thesubstrate 2, theoscillation section 10 and the supportingsection 4 are composed of Si, thefirst semiconductor layer 60 may be selectively removed by a wet etching method, using, for example, a mixed solution of hydrofluoric acid and nitric acid (nitric-hydrofluoric acid). In this case, the etching selection ratio of Si with respect to SiGe can be set to about 1:100 to about 1:10000. Also, when thefirst semiconductor layer 60 is composed of SiGe, and thesubstrate 2, theoscillation section 10 and the supportingsection 4 are composed of Si, thefirst semiconductor layer 60 may also be selectively removed by a dry etching method, using, for example, carbon tetrafluoride (CF4) gas. - Then, the resist
layer 90 is removed by ashing. By removing the resistlayer 90, the mechanical force of constraint to thefree end 10 a of theoscillation section 10 is cancelled, whereby theoscillation section 10 can sufficiently vibrate. - (10) By the process described above, the
piezoelectric oscillator 100 in accordance with the present embodiment is formed, as shown inFIG. 1 andFIG. 2 . - 3. In the method for manufacturing the
piezoelectric oscillator 100 in accordance with the present embodiment, theoscillation section 10 can be obtained through patterning thesecond semiconductor layer 11. Thesecond semiconductor layer 11 can be very thinly formed on thefirst semiconductor layer 60, such that, according to the method for manufacturing thepiezoelectric oscillator 100 in accordance with the present embodiment, the thickness of theoscillation section 10 can be made very thin (for example, 100 nm or less). By this, in thepiezoelectric oscillator 100 that generates a resonance frequency of a resonator that may be used in a clock module, the length of the oscillation section (beam) 10 can be made shorter. In other words, for example, compared to a piezoelectric oscillator using quartz, thepiezoelectric oscillator 100 in accordance with the present embodiment can be further miniaturized. For example, when a resonance frequency at 32 kHz is used, the thickness of theoscillation section 10 can be made to 100 nm or less, the length of theoscillation section 10 can be made to 100 μm, and the package length of thepiezoelectric oscillator 100 can be made to 1 mm or less. - As a concrete example of the
piezoelectric oscillator 100 in accordance with the present embodiment, the thickness of thefirst electrode 22 is 50 nm, the thickness of thepiezoelectric layer 24 is 100 nm, the thickness of thesecond electrode 26 is 50 nm, the thickness of the drivingsection 20 is 200 nm, the thickness of theoscillation section 10 is 100 nm, the beam length of theoscillation section 10 is 80 nm, and the beam width is 40 nm. A resonance frequency of flexing vibration of thepiezoelectric oscillator 100 having the structure described above, in simulation through solving an equation of motion using a finite element method, is 32 kHz. - Also, according to the method for manufacturing the
piezoelectric oscillator 100 in accordance with the present embodiment, thepiezoelectric oscillator 100 can be fabricated by using, for example, an inexpensive Si substrate as thesubstrate 2. Accordingly, for example, a SOI substrate, which is expensive, does not have to be used, such that the manufacturing cost can be reduced. - Also, with the
piezoelectric oscillator 100 in accordance with the present embodiment in a unimorph type, the resonance frequency is proportional to the thickness of theoscillation section 10. Accordingly, by thepiezoelectric oscillator 100, the resonance frequency can be adjusted by the thickness of theoscillation section 10. For example, when the oscillation section is in a tuning fork shape, the resonance frequency is proportional to the width of the oscillation section. Accordingly, in the case of a tuning fork type piezoelectric oscillator, the width of its oscillation section may be reduced as a measure to lower its resonance frequency, but its processing technology has a limitation. In contrast, according to thepiezoelectric oscillator 100 in a unimorph type in accordance with the present embodiment, the thickness of theoscillation section 10 may be made thinner as a measure to lower the resonance frequency. Accordingly, a desired resonance frequency can be obtained without any limitation to the processing technology to be applied to theoscillation section 10. - Also, in the
piezoelectric oscillator 100 in a unimorph type in accordance with the present embodiment, one beam (oscillation section) 10 is provided with one drivingsection 20. For this reason, thepiezoelectric oscillator 100 in accordance with the present embodiment is structurally advantageous in miniaturization. - It is noted that the
piezoelectric oscillator 100 in accordance with the present embodiment may also be used as a trigger generator in asynchronous circuits such as circuits that do not essentially require a timing device. - Also, according to the
piezoelectric oscillator 100 in accordance with the present embodiment, another cavity section similar to thecavity section 80 of thepiezoelectric oscillator 100 may be formed over thesubstrate 2 in areas other than the area where thepiezoelectric oscillator 100 is formed, and a dielectric layer may be formed in the cavity section, whereby, for example, a SOI (Silicon On Insulator) structure can be formed. For example, a semiconductor integrated circuit may be formed on the dielectric layer of the SOI structure. Therefore, according to thepiezoelectric oscillator 100 in accordance with the present embodiment, the semiconductor integrated circuit using the SOI structure and thepiezoelectric oscillator 100 may be mixed and mounted on a single substrate thereby forming a piezoelectric oscillator module. As a result, the module package can be made smaller. - Moreover, for example, an oscillation circuit can be formed on the dielectric layer in the SOI structure described above. Therefore, according to the
piezoelectric oscillator 100 in accordance with the present embodiment, the oscillation circuit using the SOI structure and thepiezoelectric oscillator 100 can be mixed and mounted on a single substrate. A device with the SOI structure can be operated with a low operation voltage. Therefore, according to thepiezoelectric oscillator 100 in accordance with the present embodiment, one-chip clock modules with low power consumption can be provided. - 4. Next, piezoelectric oscillators and methods for manufacturing the same in accordance with modified examples of the present embodiment are described with reference to the accompanying drawings. It is noted that features different from those of the
piezoelectric oscillator 100 and its manufacturing method described above (hereafter referred to as an “example ofpiezoelectric oscillator 100”) are described, and description of the same features is omitted. - (1) First, a first modified example is described.
FIG. 11 is a schematic cross-sectional view of thepiezoelectric oscillator 300 in accordance with the modified example. - In the present modified example, a
substrate opening section 82 may be provided below thecavity section 80. More specifically, thecavity section 80 may be formed above thesubstrate opening section 82 formed by removing a portion of thesubstrate 2. - To obtain the
piezoelectric oscillator 300 in accordance with the present modified example, for example, first, the process up to forming anoscillation section 10 and asecond opening section 42 are conducted, in a manner similar to the example ofpiezoelectric oscillator 100. - Then, the
substrate 2 is patterned in a desired configuration, thereby forming thesubstrate opening section 82. Thesubstrate opening section 82 is formed by cutting through thesubstrate 2 so as to expose thefirst semiconductor layer 60. More concretely, first, resist is coated on the entire upper and lower surfaces of thesubstrate 2, and then the resist coated over the lower surface of thesubstrate 2 is patterned by a photolithography method, whereby a second resist layer (not shown) that covers areas other than thesubstrate opening section 82 is formed. Next, by using the second resist layer as a mask, a portion of thesubstrate 2 is removed by, for example, a dry etching method. In the step of etching thesubstrate 2, thefirst semiconductor layer 60 can be used as an etching stopper layer. In other words, when etching thesubstrate 2, the etching rate of thefirst semiconductor layer 60 is lower than the etching rate of thesubstrate 2. - Next, the
first semiconductor layer 60 is removed by, for example, a wet etching method through a portion exposed by thesubstrate opening section 82, whereby thecavity section 80 is formed at least below theoscillation section 10. In the etching step, thefirst semiconductor layer 60 can be selectively removed. Thereafter, the first resist layer 90 (seeFIG. 10 ) and the second resist layer are removed by ashing. - By the process described above, the
piezoelectric oscillator 300 in accordance with the present modified example can be formed. - (2) Next, a second modified example is described.
FIG. 12 is a schematic plan view of apiezoelectric oscillator 200 in accordance with the present modified example. - In the present modified example, the
oscillation section 210 is formed to have a tuning fork shape composed of a base section 212 and twobeam sections section 4 and thebeam sections FIG. 12 . The twobeam sections beam sections FIG. 12 . - Driving sections 220 in a pair is provided on each of the
beam sections first beam section 214 is provided afirst driving section 220 a and asecond driving section 220 b formed along the lengthwise direction of thefirst beam section 214 in parallel with each other. Similarly, on thesecond beam section 216 is provided a third driving section 220 c and afourth driving section 220 d formed along the lengthwise direction of thesecond beam section 216 in parallel with each other. Thefirst driving section 220 a disposed on the outer side of thefirst beam section 214 and thefourth driving section 220 d disposed on the outer side of thesecond beam section 216 are electrically connected together by a wiring (not shown). Thesecond driving section 220 b disposed on the inner side of thefirst beam section 214 and the third driving section 220 c disposed on the inner side of thesecond beam section 216 are electrically connected together by a wiring (not shown). - (3) It is noted that the modified examples described above are only example, and the invention is not limited to these modified examples. For example, the modified examples may be appropriately combined.
- 5. Next, an oscillator having the piezoelectric oscillator described above is described.
-
FIG. 13 is a circuit diagram of a basic structure of anoscillator 500 having thepiezoelectric oscillator 100 described above. The circuit (oscillation circuit) includes, for example, anamplifier 401 formed from a CMOS inverter and a feedback circuit connected between an input and an output of theamplifier 401. The feedback circuit includes apiezoelectric oscillator 100, aresistance 403 and twocapacitors amplifier 401. As the power supply voltage E is increased and reaches an oscillation starting voltage, the current I rapidly increases and oscillation starts. When the power supply voltage E is further increased, the current I generally proportionally increases while maintaining the oscillation state. -
FIG. 14 is a schematic plan view of theoscillator 500 in accordance with the present embodiment, andFIG. 15 is a schematic cross-sectional view of theoscillator 500. It is noted thatFIG. 15 is a cross-sectional view taken along lines XV-XV ofFIG. 14 . Also, inFIG. 14 andFIG. 15 , the illustration of thepiezoelectric oscillator 100 is simplified for the sake of convenience. - The
oscillator 500 is sealed by a sealingmaterial 502. An IC (integrated circuit) 503 is connected toexternal terminals 570 by bondingwires 504 such as gold wires. Theexternal terminals 570 are electrically connected to mountingterminals 541 through alead frame 505 and abonding material 506. The mountingterminals 541 are electrically connected to electrodes of thepiezoelectric oscillator 100 through wirings or the like (not shown). Thepiezoelectric oscillator 100 is sealed by alid member 539 and aseal member 540. -
FIG. 16 schematically shows an example of a process for manufacturing theoscillator 500 in accordance with the present embodiment. - First, tape attaching and dicing are conducted on an IC wafer. Then, a chip with the
IC 503 is mounted on thelead frame 505. Then, wire-bonding is applied to theIC 502 using thebonding wires 504. - Then, the mounting
terminals 541 of thepiezoelectric oscillator 100 are bonded to thelead frame 505, using thebonding material 506 such as solder, thereby mounting thepiezoelectric oscillator 100. Next, thepiezoelectric oscillator 100 and theIC 503 are sealed by using the sealing material (mold material) 502. Thereafter, characteristic tests, marking, taping and packing are conducted, and the product is shipped out. - Furthermore, although not illustrated, a semiconductor process may be applied to areas in the substrate 2 (see
FIG. 2 ) and the second semiconductor layer 11 (seeFIG. 4 ) other than the area where thepiezoelectric oscillator 100 is formed, whereby an IC adjacent in the plane to thepiezoelectric oscillator 100 may be formed, and thus the oscillator in accordance with the present embodiment may be formed. By this, a one-chip type oscillator can be formed, and its packaging can be omitted. - 6. Next, a real-time clock having the piezoelectric oscillator described above is described.
-
FIG. 17 is a circuit block diagram schematically showing a real-time clock 600 having the oscillator (OSC) 500 described above. An integrated circuit section of the real-time clock 600 is integrated in asingle substrate 601, and connected to a microprocessor (not shown). - The
oscillator 500 connected totiming connection terminals divider circuit 605, whereby timing pulses at 1 Hz are inputted in atiming counter 606. Thetiming counter 606 is formed from, for example, a second timing bit s, a minute timing bit m, an hour timing bit h, a day-of-week timing bit d, a day timing bit D, a month timing bit M, and a year timing bit Y. When a specified number of timing pulses is inputted in thetiming counter 606, each of the timing bits is advanced. - When rewriting the timing bit of the
timing counter 606, first, a selection signal is supplied from the microprocessor to aninput terminal 607. Then, the microprocessor supplies to adata input terminal 608 external information composed of a data bit indicating information to be rewritten, an address bit indicating an address of the timing bit, and an operation bit indicating a write operation to be applied to thetiming counter 606. As a result, the external information is stored in serially connectedshift registers shift register 610, acommand decoder 612 sends a write-enable signal to thetiming counter 606, and outputs an address signal designating the timing bit. As a result, the data bit stored in theshift register 609 is written to the timing bit of thetiming counter 606, whereby real-time data is rewritten. - Further, when reading out real-time data from the
timing counter 606, the microprocessor sends external information having an operation bit indicating a readout operation. Then, thecommand decoder 612 sets the write-enable signal to thetiming counter 606 to an inactive state. As a result, aninverter 613 supplies a write-enable signal in an active state to theshift register 609, whereby theshift register 609 is set to a read-enable state, and the content of thetiming counter 606 is read out to theshift register 609. The real-time data read out to theshift register 609 is transferred to adata output terminal 615 in synchronism with a clock signal that is applied to theclock input terminal 614, and then sent out to, for example, a register of the microprocessor. - It is noted that data, such as, for example, calculation results may be stored in a random access memory (RAM) 616.
-
FIG. 18 is a schematic see-through plan view of the real-time clock 600 in accordance with the present embodiment, andFIG. 19 is a schematic see-through side view of the real-time clock 600. It is noted thatFIG. 19 is a figure viewed in a direction of arrows XIX ofFIG. 18 . - An
IC chip 651 having an oscillation circuit or the like is affixed with adhesive such as conductive adhesive to anisland section 653 of alead frame 652.Electrode pads 654 provided on the top surface of theIC chip 651 are electrically connected to I/O lead terminals 656 disposed along a peripheral section of the package by bondingwires 655. In a plan view, anoscillator housing 657 that stores therein thepiezoelectric oscillator 100 is disposed next to theIC chip 651. For example, thepiezoelectric oscillator 100 is air-tightly sealed in theoscillator housing 657.Leads 658 that are electrically connected to the respective electrodes of thepiezoelectric oscillator 100 protrude outside from within theoscillator housing 657. The leads 658 are affixed with adhesive such as conductive adhesive toconnection pads 659 of thelead frame 652. TheIC chip 651, thelead frame 652 and theoscillator housing 657 are packaged in one piece withresin 660. - Further, although not illustrated, a semiconductor process may be applied to areas in the substrate 2 (see
FIG. 2 ) and the second semiconductor layer 11 (seeFIG. 4 ) other than the area where thepiezoelectric oscillator 100 is formed, whereby an IC adjacent in the plane to thepiezoelectric oscillator 100 may be formed, and the real-time clock in accordance with the present embodiment may be formed. By this, the packaging can be omitted, and a one-chip type real-time clock can be formed. - 7. Next, a radio clock receiver module having the piezoelectric oscillator described above is described.
-
FIG. 20 is a circuit block diagram schematically showing a radio clock receiver module in accordance with an embodiment of the invention. - A
frequency filter 805 of the radio clock receiver module has thepiezoelectric oscillator 100 described above (100A and 100B in this example). - A radio clock is a clock equipped with the function to receive a standard radio wave including time information, automatically correcting the time and displaying the time. Within Japan, there are radio stations in Fukushima Prefecture (40 kHz) and Saga Prefecture (60 kHz) that broadcast standard radio waves.
- An
antenna 801 receives a longwave standard radio wave at 40 kHz or 60 kHz. The standard radio wave is composed of an amplification-modulated (AM) 40 kHz or 60 kHz carrier wave and time information (time code) superposed thereon. - The received standard radio wave is amplified by an
amplifier 802, and filtered and tuned by thefrequency filter 805 with thepiezoelectric oscillator 100A or 100 b having a resonance frequency that is the same as the carrier frequency. The filtered signal of the predetermined frequency is detected and demodulated by a detection-rectifier circuit 806. Then, the time code is retrieved from the signal by awaveform rectifier circuit 807, and counted by a central processing unit (CPU) 808. TheCPU 808 reads information for, for example, the current year, the total days, the day of week, the time and the like. The readout information is reflected on a real-time clock (RTC) 809, whereby correct time information is displayed. - Because the carrier radio wave is 40 kHz or 60 kHz, the piezoelectric oscillators in accordance with the present embodiment of the invention are suitable for the
piezoelectric oscillators frequency filter 805. For example, in the case of 40 kHz, a piezoelectric oscillator having the following dimensions can be used. For example, the thickness of thefirst electrode 22 is 50 nm, the thickness of thepiezoelectric layer 24 is 100 nm, the thickness of thesecond electrode 26 is 50 nm, the thickness of theoscillation section 10 is 100 nm, the length of theoscillation section 10 is 92 nm, and the width of theoscillation section 10 is 40 nm. - Furthermore, although not illustrated, a semiconductor process may be applied to areas in the substrate 2 (see
FIG. 2 ) and the second semiconductor layer 11 (seeFIG. 4 ) other than the area where thepiezoelectric oscillator 100 is formed, whereby an IC adjacent in the plane to thepiezoelectric oscillator 100 may be formed, and the radio clock receiver module in accordance with the present embodiment may be formed. By this, a one-chip type radio clock receiver module can be formed, and its packaging can be omitted. - 8. The embodiments of the invention are described above in detail. However, a person having an ordinary skill in the art should readily understand that many modifications can be made without departing in substance from the novel matter and effect of the invention. Accordingly, those modified examples are also deemed included in the scope of the invention.
Claims (4)
1. A piezoelectric oscillator comprising:
a substrate;
a supporting section formed above the substrate;
an oscillation section having one end affixed to the supporting section and another free end; and
a driving section that is formed above the oscillation section and generates flexing vibration in the oscillation section,
wherein the driving section includes a first electrode, a piezoelectric layer formed above the first electrode, and a second electrode formed above the piezoelectric layer, and the oscillation section is composed of a material different from a material of the supporting section; and
wherein the oscillation section is composed of single crystal silicon, and the supporting section is composed of polycrystal silicon or amorphous silicon.
2. The piezoelectric oscillator according to claim 1 , wherein the oscillation section has a thickness of 100 nm or less.
3. The piezoelectric oscillator according to claim 1 , wherein the oscillation section has a length of 100 μm or less.
4. The piezoelectric oscillator according to claim 1 , wherein the piezoelectric oscillator has a resonance frequency at 213 Hz (8.192 kHz) or higher, and 215 Hz (32.768 kHz) or lower.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/759,060 US20100194248A1 (en) | 2007-01-25 | 2010-04-13 | Piezoelectric oscillator and method for manufacturing the same |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2007014836A JP4328981B2 (en) | 2007-01-25 | 2007-01-25 | Method for manufacturing piezoelectric vibrator |
JP2007-014836 | 2007-01-25 | ||
US12/019,244 US7830215B2 (en) | 2007-01-25 | 2008-01-24 | Piezoelectric oscillator and method for manufacturing the same |
US12/759,060 US20100194248A1 (en) | 2007-01-25 | 2010-04-13 | Piezoelectric oscillator and method for manufacturing the same |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/019,244 Division US7830215B2 (en) | 2007-01-25 | 2008-01-24 | Piezoelectric oscillator and method for manufacturing the same |
Publications (1)
Publication Number | Publication Date |
---|---|
US20100194248A1 true US20100194248A1 (en) | 2010-08-05 |
Family
ID=39667279
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/019,244 Expired - Fee Related US7830215B2 (en) | 2007-01-25 | 2008-01-24 | Piezoelectric oscillator and method for manufacturing the same |
US12/759,060 Abandoned US20100194248A1 (en) | 2007-01-25 | 2010-04-13 | Piezoelectric oscillator and method for manufacturing the same |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/019,244 Expired - Fee Related US7830215B2 (en) | 2007-01-25 | 2008-01-24 | Piezoelectric oscillator and method for manufacturing the same |
Country Status (2)
Country | Link |
---|---|
US (2) | US7830215B2 (en) |
JP (1) | JP4328981B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104079250A (en) * | 2013-03-27 | 2014-10-01 | 精工爱普生株式会社 | Method for manufacturing a vibrator, vibrator, and oscillator |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4328980B2 (en) * | 2006-12-18 | 2009-09-09 | セイコーエプソン株式会社 | Piezoelectric vibrator and manufacturing method thereof, MEMS device and manufacturing method thereof |
US8410868B2 (en) | 2009-06-04 | 2013-04-02 | Sand 9, Inc. | Methods and apparatus for temperature control of devices and mechanical resonating structures |
US8476809B2 (en) | 2008-04-29 | 2013-07-02 | Sand 9, Inc. | Microelectromechanical systems (MEMS) resonators and related apparatus and methods |
JP5367612B2 (en) * | 2009-02-17 | 2013-12-11 | 日本碍子株式会社 | Lamb wave device |
US9048811B2 (en) | 2009-03-31 | 2015-06-02 | Sand 9, Inc. | Integration of piezoelectric materials with substrates |
WO2010114602A1 (en) * | 2009-03-31 | 2010-10-07 | Sand9, Inc. | Integration of piezoelectric materials with substrates |
JP5466537B2 (en) * | 2009-09-30 | 2014-04-09 | エスアイアイ・クリスタルテクノロジー株式会社 | Piezoelectric vibrator, oscillator and oscillator package |
WO2011132532A1 (en) * | 2010-04-23 | 2011-10-27 | 株式会社村田製作所 | Piezoelectric actuator and manufacturing method for piezoelectric actuator |
JP2022128670A (en) * | 2021-02-24 | 2022-09-05 | セイコーエプソン株式会社 | Oscillation unit and communication method |
Citations (21)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4672849A (en) * | 1985-04-10 | 1987-06-16 | Nissan Motor Co., Ltd. | Semiconductor vibration detecting structure |
US5023503A (en) * | 1990-01-03 | 1991-06-11 | Motorola, Inc. | Super high frequency oscillator/resonator |
US5589084A (en) * | 1994-02-23 | 1996-12-31 | Daewoo Electronics Co. Ltd. | Thin film actuated mirror array |
US5723775A (en) * | 1995-07-05 | 1998-03-03 | Nikon Corporation | Atomic force microscope under high speed feedback control |
US5796000A (en) * | 1993-09-14 | 1998-08-18 | Nikon Corporation | Vibration angular-velocity sensor and process for producing it |
US5877889A (en) * | 1996-08-30 | 1999-03-02 | Daewoo Electronics Co., Ltd. | Method for the manufacture of a thin film actuated mirror array |
US5914507A (en) * | 1994-05-11 | 1999-06-22 | Regents Of The University Of Minnesota | PZT microdevice |
US20030119220A1 (en) * | 2000-02-08 | 2003-06-26 | Boston Microsystems, Inc. | Micromechanical piezoelectric device |
US20040147132A1 (en) * | 2002-09-26 | 2004-07-29 | Yun-Woo Nam | Flexible MEMS transducer manufacturing method |
US6842088B2 (en) * | 2001-05-11 | 2005-01-11 | Ube Industries, Ltd. | Thin film acoustic resonator and method of producing the same |
US6849861B2 (en) * | 2001-03-28 | 2005-02-01 | Seiko Epson Corporation | Electronic device and electronic apparatus |
US20050051515A1 (en) * | 2003-09-08 | 2005-03-10 | Lg Electronics Inc. | Cantilever microstructure and fabrication method thereof |
US20050099236A1 (en) * | 2003-09-19 | 2005-05-12 | Takashi Kawakubo | Voltage controlled oscillator |
US20050210988A1 (en) * | 2004-03-05 | 2005-09-29 | Jun Amano | Method of making piezoelectric cantilever pressure sensor array |
US7002437B2 (en) * | 2002-06-11 | 2006-02-21 | Murata Manufacturing Co., Ltd. | Piezoelectric thin-film resonator, piezoelectric filter, and electronic component including the piezoelectric filter |
US20060186762A1 (en) * | 2005-02-21 | 2006-08-24 | Denso Corporation | Ultrasonic element |
US7220995B2 (en) * | 2003-08-07 | 2007-05-22 | Tdk Corporation | Substrate for electronic device, electronic device and methods of manufacturing same |
US20070158552A1 (en) * | 2006-01-10 | 2007-07-12 | Samsung Electronics Co., Ltd. | Two-axis micro optical scanner |
US20080143450A1 (en) * | 2006-12-18 | 2008-06-19 | Seiko Epson Corporation | Piezoelectric oscillator and method for manufacturing the same, and mems device and method for manufacturing the same |
US7420320B2 (en) * | 2004-01-28 | 2008-09-02 | Kabushiki Kaisha Toshiba | Piezoelectric thin film device and method for manufacturing the same |
US7427797B2 (en) * | 2004-11-11 | 2008-09-23 | Kabushiki Kaisha Toshiba | Semiconductor device having actuator |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH07113643A (en) | 1993-10-15 | 1995-05-02 | Nikon Corp | Piezoelectric vibrational angular velocity meter |
JPH07298394A (en) * | 1994-04-22 | 1995-11-10 | Res Dev Corp Of Japan | Vibration detector and its manufacture |
JP2003258589A (en) * | 2002-02-26 | 2003-09-12 | Seiko Epson Corp | Piezoelectric device, radio watch utilizing the piezoelectric device, mobile phone utilizing the piezoelectric device, and electronic device utilizing the piezoelectric device |
JP4356479B2 (en) | 2004-03-01 | 2009-11-04 | パナソニック株式会社 | Angular velocity sensor |
JP4478495B2 (en) | 2004-03-31 | 2010-06-09 | ソニー株式会社 | Vibrating gyro sensor element and manufacturing method thereof |
-
2007
- 2007-01-25 JP JP2007014836A patent/JP4328981B2/en not_active Expired - Fee Related
-
2008
- 2008-01-24 US US12/019,244 patent/US7830215B2/en not_active Expired - Fee Related
-
2010
- 2010-04-13 US US12/759,060 patent/US20100194248A1/en not_active Abandoned
Patent Citations (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4672849A (en) * | 1985-04-10 | 1987-06-16 | Nissan Motor Co., Ltd. | Semiconductor vibration detecting structure |
US5023503A (en) * | 1990-01-03 | 1991-06-11 | Motorola, Inc. | Super high frequency oscillator/resonator |
US5796000A (en) * | 1993-09-14 | 1998-08-18 | Nikon Corporation | Vibration angular-velocity sensor and process for producing it |
US5802684A (en) * | 1993-09-14 | 1998-09-08 | Nikon Corporation | Process for producing a vibration angular-velocity sensor |
US5589084A (en) * | 1994-02-23 | 1996-12-31 | Daewoo Electronics Co. Ltd. | Thin film actuated mirror array |
US5914507A (en) * | 1994-05-11 | 1999-06-22 | Regents Of The University Of Minnesota | PZT microdevice |
US5723775A (en) * | 1995-07-05 | 1998-03-03 | Nikon Corporation | Atomic force microscope under high speed feedback control |
US5877889A (en) * | 1996-08-30 | 1999-03-02 | Daewoo Electronics Co., Ltd. | Method for the manufacture of a thin film actuated mirror array |
US20030119220A1 (en) * | 2000-02-08 | 2003-06-26 | Boston Microsystems, Inc. | Micromechanical piezoelectric device |
US6849861B2 (en) * | 2001-03-28 | 2005-02-01 | Seiko Epson Corporation | Electronic device and electronic apparatus |
US6842088B2 (en) * | 2001-05-11 | 2005-01-11 | Ube Industries, Ltd. | Thin film acoustic resonator and method of producing the same |
US7002437B2 (en) * | 2002-06-11 | 2006-02-21 | Murata Manufacturing Co., Ltd. | Piezoelectric thin-film resonator, piezoelectric filter, and electronic component including the piezoelectric filter |
US20040147132A1 (en) * | 2002-09-26 | 2004-07-29 | Yun-Woo Nam | Flexible MEMS transducer manufacturing method |
US7220995B2 (en) * | 2003-08-07 | 2007-05-22 | Tdk Corporation | Substrate for electronic device, electronic device and methods of manufacturing same |
US20050051515A1 (en) * | 2003-09-08 | 2005-03-10 | Lg Electronics Inc. | Cantilever microstructure and fabrication method thereof |
US20050099236A1 (en) * | 2003-09-19 | 2005-05-12 | Takashi Kawakubo | Voltage controlled oscillator |
US7420320B2 (en) * | 2004-01-28 | 2008-09-02 | Kabushiki Kaisha Toshiba | Piezoelectric thin film device and method for manufacturing the same |
US20050210988A1 (en) * | 2004-03-05 | 2005-09-29 | Jun Amano | Method of making piezoelectric cantilever pressure sensor array |
US7427797B2 (en) * | 2004-11-11 | 2008-09-23 | Kabushiki Kaisha Toshiba | Semiconductor device having actuator |
US20060186762A1 (en) * | 2005-02-21 | 2006-08-24 | Denso Corporation | Ultrasonic element |
US20070158552A1 (en) * | 2006-01-10 | 2007-07-12 | Samsung Electronics Co., Ltd. | Two-axis micro optical scanner |
US20080143450A1 (en) * | 2006-12-18 | 2008-06-19 | Seiko Epson Corporation | Piezoelectric oscillator and method for manufacturing the same, and mems device and method for manufacturing the same |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104079250A (en) * | 2013-03-27 | 2014-10-01 | 精工爱普生株式会社 | Method for manufacturing a vibrator, vibrator, and oscillator |
US9331668B2 (en) | 2013-03-27 | 2016-05-03 | Seiko Epson Corporation | Vibrator with a beam-shaped portion above a recess in a substrate, and oscillator using same |
Also Published As
Publication number | Publication date |
---|---|
JP2008182526A (en) | 2008-08-07 |
US7830215B2 (en) | 2010-11-09 |
JP4328981B2 (en) | 2009-09-09 |
US20080180186A1 (en) | 2008-07-31 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7830215B2 (en) | Piezoelectric oscillator and method for manufacturing the same | |
US7339309B2 (en) | Surface mount crystal oscillator | |
CN1921299B (en) | Piezoelectric vibrator, manufacture method thereof, and electronic components and method of fabricating electronic part | |
US9030078B2 (en) | Vibrating element, vibrator, oscillator, and electronic device | |
JP2011004035A (en) | Flexural vibration piece, and method for manufacturing flexural vibration piece | |
US8102102B2 (en) | Thin film tuning-fork type inflection resonator and electric signal processing element | |
JP3754913B2 (en) | Surface mount crystal oscillator | |
JP5668392B2 (en) | Piezoelectric vibration element, piezoelectric vibrator and piezoelectric oscillator | |
JP5019040B2 (en) | Piezoelectric vibrator and oscillator | |
US20090115005A1 (en) | Semiconductor IC and manufacturing method of the same | |
JP2008211352A (en) | Piezoelectric vibrator, oscillator, real time clock and radio-controlled timepiece reception module | |
JP2008244552A (en) | Piezoelectric vibrator, manufacturing method thereof and electronic apparatus | |
JP2001320240A (en) | Piezoelectric oscillator | |
JP4363859B2 (en) | Manufacturing method of crystal oscillator | |
JP2007173906A (en) | Method of manufacturing piezoelectric resonator chip and piezoelectric device | |
JP2008283529A (en) | Tuning fork oscillator and electronic equipment | |
JP2022032563A (en) | Vibration device | |
JP5364185B2 (en) | Method for manufacturing piezoelectric vibrating piece | |
JP2008199276A (en) | Piezoelectric vibrator and manufacturing method thereof, oscillator, real-time clock, and radio-controlled timepiece reception module | |
JP2005033294A (en) | Crystal oscillation element | |
JP2006279777A (en) | Surface acoustic wave device and electronic device | |
US20230208388A1 (en) | Vibrator device and method for manufacturing vibrator device | |
JP2008236363A (en) | Piezoelectric vibrator, manufacturing method thereof and electronic equipment | |
US20220182033A1 (en) | Resonator Device | |
JP2607199B2 (en) | Hybrid integrated circuit and manufacturing method thereof |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |