WO2019181087A1 - 圧電性材料基板と支持基板との接合体 - Google Patents
圧電性材料基板と支持基板との接合体 Download PDFInfo
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- WO2019181087A1 WO2019181087A1 PCT/JP2018/044864 JP2018044864W WO2019181087A1 WO 2019181087 A1 WO2019181087 A1 WO 2019181087A1 JP 2018044864 W JP2018044864 W JP 2018044864W WO 2019181087 A1 WO2019181087 A1 WO 2019181087A1
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- piezoelectric material
- bonding layer
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- support substrate
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- 239000000758 substrate Substances 0.000 title claims abstract description 110
- 239000000463 material Substances 0.000 title claims abstract description 51
- 230000007847 structural defect Effects 0.000 claims abstract description 35
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 32
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 claims abstract description 14
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims abstract description 10
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 5
- 238000000926 separation method Methods 0.000 abstract 1
- 238000000034 method Methods 0.000 description 10
- 238000010897 surface acoustic wave method Methods 0.000 description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 238000001994 activation Methods 0.000 description 7
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
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- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 229910000838 Al alloy Inorganic materials 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
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- 238000010586 diagram Methods 0.000 description 3
- 238000005468 ion implantation Methods 0.000 description 3
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- 229910052757 nitrogen Inorganic materials 0.000 description 3
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- 230000001133 acceleration Effects 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
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- 238000005488 sandblasting Methods 0.000 description 2
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- 238000004544 sputter deposition Methods 0.000 description 2
- 238000004506 ultrasonic cleaning Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 235000019687 Lamb Nutrition 0.000 description 1
- 229910002808 Si–O–Si Inorganic materials 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 239000006061 abrasive grain Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
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- 238000000151 deposition Methods 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000010419 fine particle 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
- 238000010438 heat treatment Methods 0.000 description 1
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- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 238000009832 plasma treatment Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- -1 sialon Chemical compound 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
- H10N30/072—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies
- H10N30/073—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies by fusion of metals or by adhesives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/04—Interconnection of layers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
- B32B9/02—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising animal or vegetable substances, e.g. cork, bamboo, starch
- B32B9/025—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising animal or vegetable substances, e.g. cork, bamboo, starch comprising leather
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
-
- 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
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02559—Characteristics of substrate, e.g. cutting angles of lithium niobate or lithium-tantalate substrates
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
-
- 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
- H03H3/08—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 resonators or networks using surface acoustic waves
-
- 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
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
Definitions
- the present invention relates to a joined body of a piezoelectric material substrate and a support substrate.
- an SOI substrate composed of a high resistance Si / SiO 2 thin film / Si thin film is widely used.
- Plasma activation is used to realize an SOI substrate. This is because bonding can be performed at a relatively low temperature (400 ° C.).
- a composite substrate composed of a similar Si / SiO 2 thin film / piezoelectric thin film has been proposed to improve the characteristics of the piezoelectric device (Patent Document 1).
- Patent Document 1 a piezoelectric material substrate made of lithium niobate or lithium tantalate is bonded to a silicon substrate provided with a silicon oxide layer after activation by an ion implantation method.
- Patent Document 2 describes that lithium tantalate and sapphire or ceramics are joined by a plasma activation method through a silicon oxide layer.
- Non-Patent Document 1 a lithium tantalate substrate and a silicon substrate provided with a silicon oxide layer are irradiated with O 2 RIE (13.56 MHz) plasma and N 2 microwave (2.45 GHz) plasma in succession. Joining is described.
- O 2 RIE 13.56 MHz
- N 2 microwave 2.45 GHz
- Non-patent Document 2 In plasma activated bonding between Si and SiO 2 / Si, a sufficient bonding strength is obtained by forming a Si—O—Si bond at the bonding interface. At the same time, Si is oxidized to SiO 2 to improve the smoothness and promote the above-mentioned joining at the outermost surface (Non-patent Document 2).
- An object of the present invention is to provide a piezoelectric material substrate made of a material selected from the group consisting of lithium niobate, lithium tantalate, and lithium niobate-lithium tantalate and a support substrate through a bonding layer made of silicon oxide. In bonding, it is to suppress peeling at the interface between the silicon oxide constituting the bonding layer and the support substrate.
- the present invention Support substrate, A bonding layer provided on a surface of the support substrate, the bonding layer made of silicon oxide; and A joined body comprising a piezoelectric material substrate made of a material selected from the group consisting of lithium niobate, lithium tantalate and lithium niobate-lithium tantalate, A concave portion is provided on the surface of the support substrate, and the bonding layer includes a structural defect portion extending on the concave portion.
- the present inventor has tried to increase the adhesion between the support substrate and the bonding layer in order to suppress the occurrence of fine peeling at the interface between the silicon oxide constituting the bonding layer and the support substrate. For this reason, the surface of the support substrate was roughened, but it alone could not suppress the peeling at the interface of the bonded body.
- the present inventor devised a processing method for the surface of the support substrate, provided on the surface a smooth portion and a concave portion recessed from the smooth portion, and formed a bonding layer made of silicon oxide thereon. Tried. As a result, it was confirmed that a structural defect portion having a lower density than other portions of the bonding layer was formed on the concave portion. A silicon oxide matrix exists on both sides of the structural defect portion, and silicon oxide is fractionated by the structural defect portion. Such a structural defect part and the silicon oxide matrix of the both sides can be confirmed with a transmission electron microscope (TEM).
- TEM transmission electron microscope
- a bonded body having such a microstructure does not easily peel along the interface between the bonding layer and the support substrate even when pressure is applied to the piezoelectric material substrate by polishing or the like.
- the reason for this is not clear, but the structural defect portion on the recess is slightly lower in density than the silicon oxide matrix on both sides, and the structural defect portion is elastically deformed when the bonded body is polished to absorb the processing load. Therefore, it seems that peeling along the interface is less likely to occur.
- (A) shows the piezoelectric material substrate 1, and (b) shows a state where the activation surface 5 is generated by irradiating the bonding surface of the piezoelectric material substrate 1 with plasma A.
- (A) shows a state where the processing B is performed on the surface of the support substrate 3,
- (b) shows a state where the bonding layer 4 is provided on the processed surface 3b of the support substrate 3, and
- FIG. 1 shows the joined body 8 of the piezoelectric material substrate 1 and the support substrate 3
- FIG. 3 shows a state in which the piezoelectric material substrate 1 of the joined body 8A is thinned by processing
- FIG. 3 shows a state in which the piezoelectric material substrate 1 of the joined body 8A is thinned by processing
- FIG. 4 shows elasticity.
- the wave element 11 is shown.
- (A) is an enlarged view showing the surface 3 a of the support substrate 3
- (b) is an enlarged view showing the surface 3 b of the support substrate 3 after surface processing
- (c) is a structure on the recess 12.
- the state in which the defect part 13 was provided is shown.
- 4 is a transmission electron microscope (TEM) photograph showing the vicinity of the interface between the surface of the support substrate and the bonding layer in the bonded body according to the embodiment of the present invention. It is a schematic diagram corresponding to the photograph of FIG. It is the elements on larger scale of the photograph of FIG. It is
- FIG. 1A a piezoelectric material substrate 1 having a pair of main surfaces 1a and 1b is prepared.
- the bonding surface 1a of the piezoelectric material substrate 1 is irradiated with plasma as indicated by an arrow A to obtain a surface activated bonding surface 5.
- the surface 3a of the support substrate 3 is subjected to surface processing as indicated by an arrow B to form a processed surface 3b as shown in FIG. 2 (b).
- the bonding layer 4 made of silicon oxide is formed on the surface 3 b of the support substrate 3.
- surface activation is performed by irradiating the surface 4a of the bonding layer 4 with plasma as indicated by an arrow C, thereby forming an activated bonding surface 6.
- the activated bonding surface 5 on the piezoelectric material substrate 1 and the activated bonding surface 6 of the bonding layer 4 on the support substrate 3 are brought into contact with each other and directly bonded, as shown in FIG.
- the joined body 8 can be obtained.
- an electrode may be provided on the piezoelectric material substrate 1.
- the main surface 1b of the piezoelectric material substrate 1 is processed to make the substrate 1 thin, and a joined body 8A including the thinned piezoelectric material substrate 1A is formed. obtain. 9 is a processing surface.
- a predetermined electrode 10 is formed on the processed surface 9 of the piezoelectric material substrate 1A of the joined body 8A, and the acoustic wave element 11 can be obtained.
- a smooth surface and a recess are provided on the surface of the support substrate, and the bonding layer includes a structural defect portion extending on the recess.
- the processed surface 3 b is formed by processing the surface 3 a of the support substrate 3.
- the surface 3 b has a smooth surface 14 and a recess 12 that is recessed from the smooth surface 14 toward the inside of the support substrate 3.
- the structural defect portion 13 can be provided in the bonding layer 4 as shown in FIG. 4C. .
- Each structural defect portion 13 is formed on the recess 12.
- the concave portion 12 present on the surface 3 b means a portion that is recessed from the smooth surface 14 of the surface toward the inside of the support substrate 3.
- the planar shape of the recess 12 is not limited, and may be a circle, an ellipse, a polygon, or an indefinite shape.
- the depth d of the recess 12 is preferably 80 nm or more and 250 nm or less from the viewpoint of causing the structural defect portion 13 in the silicon oxide 4. From this viewpoint, the depth d of the recess 12 is more preferably 100 nm or more, and further preferably 230 nm or less.
- the width w of the recess 12 is preferably 140 nm or more and preferably 500 nm or less from the viewpoint of causing the structural defect portion 13 in the silicon oxide 4.
- the bonding layer 4 of the present invention is made of silicon oxide.
- the structural defect portion 13 means a portion made of silicon oxide and having a lower density than the silicon oxide matrix constituting the bonding layer 4.
- the structural defect 13 is identified as follows. That is, observation is performed with a transmission electron microscope at an acceleration voltage of 200 kV, a magnification of 100,000 times, and a field of view of 1.9 ⁇ 2.1 ⁇ m. Then, the contrast of the observation field is adjusted on the analysis software.
- the structural defect portion 13 is provided on the recess 12 and extends between the recess 12 and the activation surface 6 of the bonding layer 4. However, it is not necessary that the entire structural defect portion 13 exists on the recess 12, and it is sufficient that a part of the structural defect portion 13 exists on the recess 12.
- the depths, widths, and shapes of the recesses 12 do not need to match each other and may be different from each other. Further, it is not necessary that the structural defect portions 13 exist on all the concave portions 12, and it is sufficient if the structural defect portions 13 exist on a part of the concave portions 12.
- the surface 3b of the support substrate 3 is provided with recesses 12A, 12B, and 12C, and the dimensions, particularly the depth d, of the recesses 12A, 12B, and 12C are different from each other.
- the depth d of the recess 12A is 110 nm
- the depth d of the recess 12B is 70 nm
- the depth d of the recess 12C is 190 nm.
- the structural defect part 13 was producing
- FIG. 7 is an enlarged photograph showing another concave portion 12 and a structural defect portion 13 thereon
- FIG. 8 is a schematic diagram of FIG.
- the depth d of the recess 12 is 125 nm in this example.
- a structural defect portion 13 is provided on the recess 12, and the silicon oxide matrix 15 is fractionated by the structural defect portion 13.
- the brightness of the silicon oxide matrix 15 is relatively low, and the structural defect portion 13 is relatively whitish.
- the structural defect portion 13 when the bonded body 8 is polished, the structural defect portion 13 can be elastically deformed to absorb the processing load. It is considered that peeling along the interface between the bonding surface 5 of the conductive material substrate 1A and the bonding surface 6 of the bonding layer 4 is less likely to occur.
- the material of the support substrate 3 is not particularly limited, but is preferably made of a material selected from the group consisting of silicon, quartz, sialon, mullite, sapphire, and translucent alumina. Thereby, the temperature characteristic of the frequency of the acoustic wave element 11 can be further improved.
- the method for forming the bonding layer 4 is not limited, and examples thereof include sputtering, chemical vapor deposition (CVD), and vapor deposition.
- the structural defect portion 13 is easily generated on the concave portion 12.
- the following is preferable.
- the surface treatment by machining can realize the recess 12 most easily.
- a blasting method in which fine particles collide with the surface at a high speed and a grinding process with fixed abrasive grains can be mentioned.
- the blasting process is most preferable as a method for realizing the present invention, by selecting a seed material, a particle diameter, a processing time, and the like of particles used for processing so that appropriate processing conditions can be selected from a wide range of conditions.
- the grinding process can be easily adjusted in the same manner by selecting the processing conditions such as the grindstone count, spindle rotation speed, and feed rate.
- the thickness of the bonding layer 4 made of silicon oxide is preferably 0.05 ⁇ m or more, more preferably 0.1 ⁇ m or more, and more preferably 0.2 ⁇ m from the viewpoint of promoting the generation of the structural defect portion 13. The above is particularly preferable. From the viewpoint of bonding strength, the thickness of the bonding layer 4 is preferably 3 ⁇ m or less, preferably 2.5 ⁇ m or less, and more preferably 2.0 ⁇ m or less.
- the piezoelectric material substrate 1 is a lithium tantalate (LT) single crystal, a lithium niobate (LN) single crystal, or a lithium niobate-lithium tantalate solid solution. Since these have a high propagation speed of elastic waves and a large electromechanical coupling coefficient, they are suitable as surface acoustic wave devices for high frequencies and wideband frequencies.
- the normal direction of the principal surface of the piezoelectric material substrate 1 is not particularly limited.
- the piezoelectric material substrate 1 is made of LT
- the Y axis is centered on the X axis, which is the propagation direction of the surface acoustic wave. It is preferable to use the one rotated in the direction of 32 to 55 ° from the Z axis to the Z axis and with the Euler angle display (180 °, 58 to 35 °, 180 °) because of small propagation loss.
- the piezoelectric material substrate 1 is made of LN
- (a) a surface rotated by 37.8 ° from the Z axis to the -Y axis around the X axis, which is the propagation direction of the surface acoustic wave, and displayed as Euler angle display (0 ° , 37.8 °, 0 °) is preferable because the electromechanical coupling coefficient is large, or (b) 40 to 65 from the Y axis to the Z axis centering on the X axis that is the propagation direction of the surface acoustic wave. It is preferable to use (180 °, 50 to 25 °, 180 °) in the rotated direction and Euler angle display because high sound speed can be obtained.
- the size of the piezoelectric material substrate 1 is not particularly limited.
- the piezoelectric material substrate 1 has a diameter of 100 to 200 mm and a thickness of 0.15 to 1 ⁇ m.
- plasma is applied to the bonding surface 1a of the piezoelectric material substrate 1 and the bonding surface 4a of the bonding layer 4 on the support substrate 3 at 150 ° C. or lower to activate the bonding surfaces 1a and 4a.
- the pressure at the time of surface activation is preferably 100 Pa or less, and more preferably 80 Pa or less.
- the atmosphere may be only nitrogen and may be only oxygen, but may be a mixture of nitrogen and oxygen.
- the temperature during plasma irradiation is 150 ° C or less. As a result, it is possible to obtain the bonded bodies 8 and 8A having high bonding strength and no deterioration in crystallinity. From this point of view, the temperature during plasma irradiation is set to 150 ° C. or lower, more preferably 100 ° C. or lower.
- the energy during plasma irradiation is preferably 30 to 150 W. Further, the product of the energy at the time of plasma irradiation and the irradiation time is preferably 0.12 to 1.0 Wh.
- the bonding surfaces 5 and 6 of the plasma-treated substrate are brought into contact with each other at room temperature. At this time, the treatment may be performed in a vacuum, but more preferably, the contact is performed in the air.
- the bonding surface 1a of the piezoelectric material substrate 1 and the bonding surface 4a of the bonding layer 4 are planarized before the plasma treatment.
- a method for flattening the bonding surfaces 1a and 4a there are lap polishing, chemical mechanical polishing (CMP), and the like.
- the flat surface is preferably Ra ⁇ 1 nm, more preferably 0.3 nm or less.
- the bonding surface 5 of the piezoelectric material substrate 1 and the bonding surface 6 of the bonding layer 4 on the support substrate 3 are brought into contact with each other and bonded. Thereafter, it is preferable to improve the bonding strength by performing an annealing treatment.
- the annealing temperature is preferably 100 ° C. or higher and 300 ° C. or lower.
- the joined bodies 8 and 8A of the present invention can be suitably used for the acoustic wave element 11.
- a surface acoustic wave device As the acoustic wave element 11, a surface acoustic wave device, a Lamb wave element, a thin film resonator (FBAR), and the like are known.
- a surface acoustic wave device has an IDT (Interdigital Transducer) electrode (also referred to as a comb-shaped electrode or a comb-shaped electrode) for exciting surface acoustic waves on the surface of a piezoelectric material substrate and an output side for receiving surface acoustic waves. IDT electrodes are provided.
- IDT Interdigital Transducer
- the material constituting the electrode 10 on the piezoelectric material substrate 1A is preferably aluminum, aluminum alloy, copper, or gold, and more preferably aluminum or aluminum alloy.
- As the aluminum alloy it is preferable to use Al mixed with 0.3 to 5% by weight of Cu.
- Ti, Mg, Ni, Mo, Ta may be used instead of Cu.
- a joined body 8A was produced as described with reference to FIGS. Specifically, a 42Y cut X-propagation LiTaO 3 substrate (piezoelectric material substrate) 1 having a thickness of 200 ⁇ m and polished on both sides to a mirror surface, and a high resistance (> 2 k ⁇ ⁇ cm) Si (100) having a thickness of 675 ⁇ m A substrate (support substrate) 3 was prepared. The substrate size is 150 mm for all.
- the surface 3a of the support substrate 3 was sandblasted.
- # 6000 alumina particles were used as the blasting agent.
- the average particle diameter of the alumina particles was 2 um.
- the blast gun was moved in parallel with the wafer so that the entire wafer surface was processed and processed with an automatic machine.
- Ra of the surface of the support substrate 3 after processing was 1.2 nm.
- the bonding layer 4 made of silicon oxide was formed by a sputtering apparatus. At this time, the thickness of the bonding layer 4 was 540 nm.
- the surface of the formed silicon oxide was subjected to CMP processing so that Ra was 0.3 nm, thereby forming a bonding surface 4a.
- the bonding surface 1a of the piezoelectric material substrate 1 and the bonding surface 4a of the bonding layer 4 on the support substrate 3 were cleaned and surface activated, respectively. Specifically, ultrasonic cleaning using pure water was performed, and the substrate surface was dried by spin drying. Next, the washed support substrate 3 was introduced into a plasma activation chamber, and the bonding surface 4a was activated at 30 ° C. with nitrogen gas plasma. Similarly, the piezoelectric material substrate 1 was introduced into a plasma activation chamber, and the bonding surface 1a was surface activated at 30 ° C. with nitrogen gas plasma. The surface activation time was 40 seconds and the energy was 100W. In order to remove particles adhering during the surface activation, the same ultrasonic cleaning and spin drying as described above were performed again.
- the substrates 1 and 3 were aligned, and the activated bonding surfaces 5 and 6 of the substrates 1 and 3 were brought into contact with each other at room temperature. Contact was made with the piezoelectric material substrate 1 side up. As a result, it was confirmed that the adhesion between the substrates spread (so-called bonding wave), and that the preliminary bonding was performed well.
- the bonded body was put into an oven in a nitrogen atmosphere and held at 150 ° C. for 10 hours.
- the surface 1b of the piezoelectric material substrate 1 of the bonded body 8 after the heating was subjected to grinding, lapping, and CMP so that the thickness of the piezoelectric material substrate 1A was 1 ⁇ m.
- the polished joined chip was put in an oven and left in an atmosphere at 320 ° C. for 2 hours. When it was taken out from the oven, it was confirmed that no damage or peeling was observed.
- Example 2 In Example 1, instead of sandblasting, the surface 3a of the support substrate 3 was processed with a # 8000 grinding wheel to a depth of about 2 ⁇ m. Except for this, a joined body chip was produced in the same manner as in Example 1.
- the polished joined chip was put in an oven and left in an atmosphere at 320 ° C. for 2 hours. When it was taken out from the oven, it was confirmed that no damage or peeling was observed.
- Example 1 (Comparative Example 1) In Example 1, the sandblasting of the surface 3a of the support substrate 3 was not performed. Ra of the surface 3a of the support substrate 3 is 0.2 nm. Otherwise, the joined body chip was produced in the same manner as in Example 1.
- the polished bonded chip was put in an oven and left in an atmosphere at 260 ° C. for 2 hours. When it was taken out from the oven, it peeled along the interface between the bonding surface 5 of the piezoelectric material substrate 1A and the bonding surface 6 of the bonding layer 4, and voids were generated.
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Abstract
Description
支持基板、
前記支持基板の表面上に設けられた接合層であって、酸化珪素からなる接合層、および、
ニオブ酸リチウム、タンタル酸リチウムおよびニオブ酸リチウム-タンタル酸リチウムからなる群より選ばれた材質からなる圧電性材料基板
を備えている接合体であって、
前記支持基板の前記表面に凹部が設けられており、前記接合層が、前記凹部上に延びる構造欠陥部を備えていることを特徴とする。
まず、図1(a)に示すように、一対の主面1a、1bを有する圧電性材料基板1を準備する。次いで、図1(b)に示すように、圧電性材料基板1の接合面1aに対して矢印Aのようにプラズマを照射し、表面活性化された接合面5を得る。
支持基板3の材質は特に限定されないが、好ましくは、シリコン、水晶、サイアロン、ムライト、サファイアおよび透光性アルミナからなる群より選ばれた材質からなる。これによって、弾性波素子11の周波数の温度特性を一層改善することができる。
表面活性化時の圧力は、100Pa以下が好ましく、80Pa以下が更に好ましい。また、雰囲気は窒素のみであって良く、酸素のみであってよいが、窒素、酸素の混合物であってもよい。
プラズマ処理した基板の接合面5と接合面6同士を室温で互いに接触させる。このとき真空中で処理してもよいが、より好ましくは大気中で接触させる。
弾性波素子11としては、弾性表面波デバイスやラム波素子、薄膜共振子(FBAR)などが知られている。例えば、弾性表面波デバイスは、圧電性材料基板の表面に、弾性表面波を励振する入力側のIDT(Interdigital Transducer)電極(櫛形電極、すだれ状電極ともいう)と弾性表面波を受信する出力側のIDT電極とを設けたものである。入力側のIDT電極に高周波信号を印加すると、電極間に電界が発生し、弾性表面波が励振されて圧電性材料基板上を伝搬していく。そして、伝搬方向に設けられた出力側のIDT電極から、伝搬された弾性表面波を電気信号として取り出すことができる。
図1~図4を参照しつつ説明したようにして、接合体8Aを作製した。
具体的には、厚さが200μmで両面が鏡面に研磨されている42YカットX伝搬LiTaO3基板(圧電性材料基板)1と、厚みが675μmの高抵抗(>2kΩ・cm)Si(100)基板(支持基板)3を用意した。基板サイズはいずれも150mmである。
支持基板3の表面3aを洗浄した後、スパッタ装置で酸化珪素からなる接合層4を成膜した。この時の接合層4の厚みは540nmであった。成膜した酸化珪素の表面をRaが0.3nmになるようCMP加工し接合面4aとした。次いで、圧電性材料基板1の接合面1aおよび支持基板3上の接合層4の接合面4aをそれぞれ洗浄および表面活性化した。具体的には、純水を用いた超音波洗浄を実施し、スピンドライにより基板表面を乾燥させた。次いで、洗浄後の支持基板3をプラズマ活性化チャンバーに導入し、窒素ガスプラズマで30℃で接合面4aを活性化した。また、圧電性材料基板1を同様にプラズマ活性化チャンバーに導入し、窒素ガスプラズマで30℃で接合面1aを表面活性化した。表面活性化時間は40秒とし、エネルギーは100Wとした。表面活性化中に付着したパーティクルを除去する目的で、上述と同じ超音波洗浄、スピンドライを再度実施した。
測定条件:加速電圧200kV
装置:日立ハイテクノロジーズ製 H-9500
倍率:10万倍
測定結果:
図7、図8に示すような形態の断面写真が得られた。具体的な形態は以下のとおりである。
凹部12の深さd: 125nm
凹部12の幅w :340nm
構造欠陥部13の長さT:430nm
実施例1において、サンドブラスト加工の代わりに、支持基板3の表面3aを#8000の研削砥石で深さ2μmほど加工した。これ以外は実施例1と同様にして接合体チップを作製した。
測定結果:
図5、図6に示すような形態の断面写真が得られた。具体的な形態は以下のとおりである。
凹部12の深さd: 70~190nm
凹部12の幅w: 90~350nm
構造欠陥部13の長さT: 170~380nm
ただし、凹部12の深さが70nmの凹部12上には構造欠陥部13は見られなかった。
実施例1において、支持基板3の表面3aのサンドブラスト加工を行わなかった。支持基板3の表面3aのRaは、0.2nmである。他は実施例1と同様にして接合体チップを作製した。
Claims (3)
- 支持基板、
前記支持基板の表面上に設けられた接合層であって、酸化珪素からなる接合層、および、
ニオブ酸リチウム、タンタル酸リチウムおよびニオブ酸リチウム-タンタル酸リチウムからなる群より選ばれた材質からなる圧電性材料基板
を備えている接合体であって、
前記支持基板の前記表面に凹部が設けられており、前記接合層が、前記凹部上に延びる構造欠陥部を備えていることを特徴とする、接合体。 - 前記凹部の深さが80~250nmであることを特徴とする、請求項1記載の接合体。
- 前記圧電性材料基板の厚さが4.0μm以下であることを特徴とする、請求項1または2記載の接合体。
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CN201880089853.3A CN111869105B (zh) | 2018-03-20 | 2018-12-06 | 压电性材料基板与支撑基板的接合体 |
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WO2022190465A1 (ja) * | 2021-03-10 | 2022-09-15 | 日本碍子株式会社 | 接合体 |
EP4068624A4 (en) * | 2019-11-29 | 2023-05-24 | NGK Insulators, Ltd. | CONNECTED BODY WITH A SUBSTRATE OF PIEZOELECTRIC MATERIAL AND SUPPORT SUBSTRATE |
EP4068625A4 (en) * | 2019-11-29 | 2023-05-24 | NGK Insulators, Ltd. | COMPOSITE BODY MADE OF PIEZOELECTRIC MATERIAL SUBSTRATE AND CARRIER SUBSTRATE |
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