CN101542296A - Acceleration sensor and method for manufacturing the same - Google Patents

Acceleration sensor and method for manufacturing the same Download PDF

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Publication number
CN101542296A
CN101542296A CNA2008800006320A CN200880000632A CN101542296A CN 101542296 A CN101542296 A CN 101542296A CN A2008800006320 A CNA2008800006320 A CN A2008800006320A CN 200880000632 A CN200880000632 A CN 200880000632A CN 101542296 A CN101542296 A CN 101542296A
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electrode
dielectric layer
acceleration transducer
ceramic substrate
layer
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吉川泰弘
田尻浩之
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Rohm Co Ltd
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Rohm Co Ltd
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Abstract

Provided is an acceleration sensor which has high detection sensitivity and can be manufactured with improved manufacturing efficiency. An acceleration sensor (50) is provided with a ceramic substrate (1) composed of Al2O3; a ferroelectric layer (2), which is formed of BaTiO3 in a prescribed region on the ceramic substrate (1) by screen printing; a proof mass (4), which is arranged to face the ferroelectric layer (2) at a prescribed distance (d) from the ferroelectric layer (2); and first electrode (7) and a second electrode (8) which are fixed on the proof mass (4) on the side of the ferroelectric layer (2). The first electrode (7) and the second electrode (8) are interdigitally formed, and interdigital sections (7a, 8a) of the electrodes are alternately arranged.

Description

Acceleration transducer and manufacture method thereof
Technical field
The present invention relates to acceleration transducer and manufacture method thereof, relate to capacitor type acceleration transducer and manufacture method thereof particularly.
Background technology
The capacitor type acceleration transducer that uses MEMS (MEMS (micro electro mechanical system)) technology to form is known.This capacitor type acceleration transducer has such structure usually, wherein, is provided in the sensor and has the detection quality (pouring weight: moveable part) by the supporting of crossbeam or analog of predetermined quality.Therefore, when acceleration transducer stood acceleration, the detection quality that is provided in the sensor moved because of inertial force.For this reason, be considered as being equal to by variation with amount of movement and capacitance, just can sense acceleration.
By the way, about above-mentioned capacitor type acceleration transducer, know all that generally acceleration transducer has broach in the side of detecting quality.
Figure 47 is the planimetric map of an example of conventional acceleration transducer.With reference to Figure 47, in conventional acceleration transducer 100,, on silicon substrate 101, form and detect quality 102, header portion 103, supporting part 104, fixed electorde 105 or analog by the surface micromachined technology.And, detect quality 102 and have broach 102a in its side.In addition, each fixed electorde 105 all is made up of first fixed electorde 106 and second fixed electorde 107, first fixed electorde 106 is made up of fixed electorde supporting part 106a and the comb teeth shape fixed electorde 106b that forms in the side of fixed electorde supporting part 106a, and comb teeth shape fixed electorde 106b and the broach 102a that detects quality 102 arrange alternately.In addition, second fixed electorde 107 forms and is parallel to comb teeth shape fixed electorde 106b extension, as seeing in the planimetric map.At least a portion of second fixed electorde 107 is arranged between the broach 102a and comb teeth shape fixed electorde 106b that detects quality 102.In addition, detect quality 102 and generally make, and be configured such that the broach 102a that detects quality 102 serves as travelling electrode 102a by polysilicon (conductor).As a result, the side of broach (travelling electrode) 102a that forms in detecting quality 102 and the side of fixed electorde 105 (the comb teeth shape fixed electorde 106b and second fixed electorde 107) form capacitor.
In the above-mentioned conventional acceleration transducer 100 shown in Figure 47, when sensor stood acceleration, inertial force acted on and detects on the quality 102, therefore detected quality 102 and moved on (direction that arrow X or Y are indicated) in the horizontal direction.The variable in distance that this causes between travelling electrode 102a and the fixed electorde 105 (the comb teeth shape fixed electorde 106b and second fixed electorde 107) causes the variation of capacitance thus.By the variation of detection capacitance, but the acceleration that detecting sensor stood.
But, in the above-mentioned conventional acceleration transducer 100 shown in Figure 47, in order to increase electric capacity, must increase the lateralarea of broach 102a and the lateralarea of fixed electorde 105 (the comb teeth shape fixed electorde 106b and second fixed electorde 107) by the formed capacitor in side of the side of broach (travelling electrode) 102a that detects quality 102 and fixed electorde 105 (the comb teeth shape fixed electorde 106b and second fixed electorde 107).This makes must increase the thickness that detects quality 102 and fixed electorde 105, when causing in detecting quality 102, forming broach 102a or when forming fixed electorde 105, and the trouble that adopts DRIE (dark active-ion-etch) technology to bring of having to.This can reduce production efficiency, is undesirable.
For this reason, in routine techniques, proposed to prevent the capacitor type acceleration transducer (for example referring to non-patent document 1) of production efficiency reduction.
Figure 48 is the schematic sectional view of the conventional acceleration sensor structure of proposition in the above-mentioned non-patent document 1.With reference to Figure 48, in the conventional acceleration transducer 200 that in above-mentioned non-patent document 1, proposes, make it adjacent one another are at upper surface two electrodes of configuration (first electrode 202 and second electrode 203) of silicon substrate 201.Here, in the acceleration transducer 200 that in above-mentioned non-patent document 1, proposes, owing between electrode, be applied with voltage, between first electrode 202 and second electrode 203, produce fringing field 204 (fringe field) (electric field that the next door, space between electrode produces).In addition, above-mentioned first electrode 202 and second electrode 203 and by parylene (relative dielectric constant: the detection quality of 3.15) making 205 is in the fringing field 204 thereby supported by header portion 206.By the way, detecting quality 205 is constructed to be permeable to go up in the vertical direction (direction that arrow Z is indicated) with respect to the upper surface of silicon substrate 201 and moves.
In the conventional acceleration transducer 200 of structure as mentioned above, stand acceleration because of sensor on the indicated direction of arrow Z when mobile when detecting quality 205, detect the volume ratio of quality 205 (dielectric) in fringing field 204 and change, cause the variation of capacitance.Therefore, by the variation of detection capacitance, but the acceleration that detecting sensor stood.
In addition, different in the above-mentioned acceleration transducer 200 that in non-patent document 1, proposes with the above-mentioned acceleration transducer 100 shown in Figure 47 with broach 102a, in manufacture process, do not need to adopt DRIE technology.This helps to prevent the reduction of production efficiency.
Non-patent document 1:the Collection of the Lecture Treatises Presented at theSymposium held by Kansai University Organization for Research andDevelopment of Innovative Science and Technology, the 8th volume, 153-156 page or leaf (2004.01.10)
Summary of the invention
The problem to be solved in the present invention
But the above-mentioned conventional acceleration transducer 200 that proposes in the non-patent document 1 has a shortcoming: because made by parylene as dielectric detection quality 205, so dielectric relative dielectric constant is relatively little.This feasible detection sensitivity that is difficult to improve acceleration is undesirable.
In view of above-mentioned problem of running into usually, an object of the present invention is to provide a kind of acceleration transducer that has high detection sensitivity and can enhance productivity, and manufacture method.
The method of dealing with problems
In order to achieve the above object, according to a first aspect of the invention, acceleration transducer provides: ceramic substrate; By the dielectric layer that forms in the presumptive area of serigraphy on ceramic substrate, dielectric layer is made by metal oxide; Be arranged to the moveable part in the face of dielectric layer, movable part separates dielectric layer preset distance; And first electrode and second electrode that form in that side of moveable part in the face of dielectric layer.
In acceleration transducer according to first aspect, as mentioned above, form first electrode and second electrode by that side in the face of dielectric layer at moveable part, can between first electrode and second electrode, produce fringing field.In addition, by forming the dielectric layer made from metal oxide in the presumptive area on ceramic substrate, utilization have relative dielectric constant for example be 1000 or higher metal oxide situation as the metal oxide that forms dielectric layer under, (relative dielectric constant: 3.15) compare, the relative dielectric constant that can make dielectric layer is even as big as gratifying degree with parylene.This makes it possible to the variation with the caused capacitance of variation of the volume ratio of high Precision Detection dielectric layer in fringing field, thus the acceleration that can be stood with the high-sensitivity detection sensor.
And, in first aspect,, can form dielectric layer in the presumptive area on ceramic substrate easily by forming dielectric layer in the presumptive area of serigraphy on ceramic substrate.This with for example on ceramic substrate, compare during additional tabular dielectric layer, make it possible to enhance productivity.In said structure, and compare by using sputter, sol-gel process or similar approach to form dielectric layer, can increase dielectric layer thickness.This helps avoid such possibility, promptly makes the variation with the high Precision Detection capacitance become difficult owing to dielectric layer thickness is little.Therefore, can when enhancing productivity, improve the detection sensitivity of acceleration.In addition, adopt ceramic substrate, electrical isolation higher when adopting silicon substrate or analog as substrate and the physical strength of Geng Gao can be provided as substrate.This makes it possible to improve detection sensitivity when enhancing productivity, and improves reliability.
According to a second aspect of the invention, acceleration transducer provides: ceramic substrate; By the dielectric layer that forms in the presumptive area of serigraphy on ceramic substrate, dielectric layer is made by metal oxide; Be arranged to the moveable part in the face of dielectric layer, movable part separates dielectric layer preset distance; And first electrode and second electrode that form in that side of moveable part in the face of dielectric layer.Here, the presumptive area on the upper surface of dielectric layer has metal level to form.
In acceleration transducer according to second aspect, as mentioned above, form first electrode and second electrode by that side in the face of dielectric layer at moveable part, can between first electrode and second electrode, produce fringing field.And, by forming metal level in the presumptive area on the upper surface of dielectric layer, in addition when moveable part when the predetermined party that is parallel to the first type surface of ceramic substrate (upper surface) moves up, also can change the appearance of fringing field line of electric force.That is to say, though the line of electric force of the fringing field that produces between first electrode and second electrode can pass dielectric layer, but they can not pass metal level, therefore, by forming metal level in the presumptive area on the upper surface of dielectric layer, the appearance that can cause the fringing field line of electric force is along with the moveable part that is fixed with first electrode and second electrode moving and change on the predetermined direction of the first type surface that is parallel to ceramic substrate (dielectric layer) (upper surface).The result, capacitance changes with the variation of the appearance of line of electric force, make it possible to detect acceleration on the predetermined direction of the first type surface that is parallel to ceramic substrate (dielectric layer) (upper surface) by the variation that detects capacitance, and the acceleration that can be stood with the high-sensitivity detection sensor.
In addition, in second aspect,, can form dielectric layer in the presumptive area on ceramic substrate easily by forming dielectric layer in the presumptive area of serigraphy on ceramic substrate.This compares during with the additional tabular dielectric layer of the presumptive area on ceramic substrate for example, makes it possible to enhance productivity.By the way, in the acceleration transducer of structure as mentioned above, do not use DRIE technology can make yet.In addition, by using ceramic substrate, can provide electrical isolation higher when adopting silicon substrate or analog and the physical strength of Geng Gao as substrate as substrate.This helps to improve the detection sensitivity when the acceleration on the predetermined direction that detects the first type surface (upper surface) that is parallel to ceramic substrate (dielectric layer), and the reliability that improves acceleration transducer.
In acceleration transducer, preferably, form metal level and make it not outstanding from the upper surface of dielectric layer according to second aspect.Adopt this structure,, also can proceed the manufacture process of back by the technology identical with the situation that does not form metal level even when metal level is formed on the upper surface of dielectric layer.This helps avoid such possibility, promptly owing to metal level becomes complicated from the outstanding subsequent manufacturing processes that makes of the upper surface of dielectric layer.This makes it possible to easily enhance productivity.And, adopt this structure, can prevent along with the predetermined party of moveable part at the first type surface that is parallel to ceramic substrate (dielectric layer) (upper surface) moves up the joint between metal level and the moveable part (first electrode, second electrode).This helps avoid such possibility, and promptly engaging between metal level and the moveable part (first electrode and second electrode) hinders moveable part to move up in the predetermined party of the first type surface that is parallel to ceramic substrate (dielectric layer) (upper surface).As a result, can easily detect acceleration on the predetermined direction of the first type surface (upper surface) that is parallel to ceramic substrate (dielectric layer).
In acceleration transducer, preferably, further provide the header portion of supporting moveable part, and header portion is long at Width at the thickness direction ratio according to second aspect.Adopt this structure, can prevent that moveable part from moving on respect to the vertical direction of the first type surface (upper surface) of ceramic substrate (dielectric layer), thereby making it possible to prevent is comprised in the acceleration that is detected with respect to the component of acceleration on the vertical direction of the first type surface (upper surface) of ceramic substrate (dielectric layer).This makes it possible to easily detect the acceleration on the predetermined direction of the first type surface that is parallel to ceramic substrate (dielectric layer) (upper surface), and can improve accuracy of detection easily.
In according to the acceleration transducer aspect first and second, preferably, dielectric layer is by BaTiO 3Make.Adopt this structure, because BaTiO 3Be that to have relative dielectric constant be 1000 or higher metal oxide (ferroelectric material), (relative dielectric constant: 3.15) compare, the relative dielectric constant that can make dielectric layer is even as big as gratifying degree with parylene.This makes it possible to easily the variation with the high Precision Detection capacitance.In addition, even the distance between increase dielectric layer and the moveable part can prevent that also the detection sensitivity of capacitance from reducing.As a result, by increasing the distance between dielectric layer and the moveable part, can prevent the generation of static friction (adhesion between dielectric layer and the moveable part).This makes it possible to improve easily acceleration when enhancing productivity detection sensitivity also can prevent to reduce reliability because static friction takes place.By the way, because BaTiO 3Be the ferroelectric material that does not contain Pb (lead), so pass through by BaTiO 3Make dielectric layer, can reduce environmental pressure that waste products causes and the mankind's deleterious effect.
In according to the acceleration transducer aspect first and second, preferably, ceramic substrate Al 2O 3Make.Adopt this structure, the physical strength of higher electrical isolation and Geng Gao can be provided easily.This makes it possible to improve the detection sensitivity of acceleration when enhancing productivity, and improves reliability.
In according to the acceleration transducer aspect first and second, preferably, each all forms the broach shape with a plurality of broach part first electrode and second electrode, and from planimetric map, their broach part with interlace mode by predetermined being spaced.Adopt this structure, can produce uniform fringing field at the reverse side (lower surface) of moveable part.This makes it possible to detect the variation by the caused capacitance of variation of the volume ratio of dielectric layer in fringing field.This makes it possible to the easier detection sensitivity of improving when enhancing productivity.
In according to the acceleration transducer aspect first and second, preferably, dielectric layer has 5 μ m or thicker thickness.Adopt this structure, can avoid such possibility, promptly owing to dielectric layer thickness makes the variation with the high Precision Detection capacitance become difficult less than 5 μ m.As a result, can be when enhancing productivity the easier detection sensitivity of improving acceleration.
In according to the acceleration transducer aspect first and second, between ceramic substrate and dielectric layer, can further form glaze layer (glaze layer).By the way, glaze layer of the present invention is the layer that adopts for the smooth surface that obtains being suitable for forming dielectric layer or analog.
According to a third aspect of the invention we, a kind of method of making acceleration transducer comprises: by forming the step of the dielectric layer made from metal oxide in the presumptive area of serigraphy on ceramic substrate; Forming first electrode and second electrode makes it be in the step of dielectric layer top; And the formation moveable part makes its step of facing dielectric layer above dielectric layer, and described first electrode and second electrode are fixed in the described moveable part.
In acceleration transducer manufacture method according to the third aspect, as mentioned above, by forming the dielectric layer made from metal oxide in the presumptive area on ceramic substrate, for example have relative dielectric constant be 1000 or higher metal oxide be used as under the situation of the metal oxide that forms dielectric layer, (relative dielectric constant: 3.15) compare, the relative dielectric constant that can make dielectric layer is even as big as gratifying degree with parylene.This makes it possible to the high Precision Detection capacitance variations, thus the acceleration that can be stood with the high-sensitivity detection sensor.In addition, by forming dielectric layer in the presumptive area of serigraphy on ceramic substrate, can form dielectric layer in the presumptive area on ceramic substrate easily.This with for example on ceramic substrate, compare during additional tabular dielectric layer, can enhance productivity.
In addition,, form dielectric layer, and form dielectric layer by sputter, melten gel-gel method or similar approach and compare, can increase dielectric layer thickness easily by serigraphy in the third aspect.This helps avoid such possibility, promptly makes the variation with the high Precision Detection capacitance become difficult owing to dielectric layer thickness is little.Therefore, can when enhancing productivity, make and have highly sensitive acceleration transducer.In addition, adopt ceramic substrate, electrical isolation higher when adopting silicon substrate or analog as substrate and the physical strength of Geng Gao can be provided as substrate.This makes it possible to improve detection sensitivity when enhancing productivity, and improves reliability.By the way, said structure saves in the manufacture process of acceleration transducer the needs to DRIE technology.
In the acceleration transducer manufacture method according to the third aspect, preferably, the step that forms dielectric layer comprises by BaTiO 3Make the step of dielectric layer.Adopt this structure, because BaTiO 3Be that to have relative dielectric constant be 1000 or higher metal oxide (ferroelectric material), so (relative dielectric constant: 3.15) compare, the relative dielectric constant that can make dielectric layer is even as big as gratifying degree with parylene.This makes it possible to easily the variation with the high Precision Detection capacitance.In addition, even the distance between increase dielectric layer and the moveable part also can prevent the reduction of the detection sensitivity of capacitance.As a result, can prevent the generation of static friction by the distance between increase dielectric layer and the moveable part.This makes it possible to easily improve the detection sensitivity of acceleration when enhancing productivity, also can prevent from owing to static friction takes place reliability to be reduced.By the way, because BaTiO 3Be the ferroelectric material that does not contain Pb (lead), so pass through by BaTiO 3Make dielectric layer, can reduce environmental pressure that waste products causes and the mankind's deleterious effect.
In acceleration transducer manufacture method according to the third aspect, preferably, the step that forms first electrode and second electrode comprises: each all forms the broach shape with a plurality of broach parts to make first electrode and second electrode, and from planimetric map, their broach part is pressed predetermined spaced step with interlace mode.Adopt this structure, can produce uniform fringing field at the reverse side (lower surface) of moveable part.This makes it possible to detect the variation by the caused capacitance of variation of the volume ratio of dielectric layer in fringing field.This makes it possible to the easier detection sensitivity of improving when enhancing productivity.
In acceleration transducer manufacture method, preferably, further provide the step that on the surface of ceramic substrate, forms wiring layer by serigraphy according to the third aspect.Adopt this structure, can form wiring layer easily.This also helps to enhance productivity.
Advantage of the present invention
As mentioned above,, can obtain to have the acceleration transducer that high detection sensitivity also can be enhanced productivity easily according to the present invention, and manufacture method.
Description of drawings
Fig. 1 is the structure skeleton view according to the acceleration transducer of first embodiment of the invention.
Fig. 2 is along the obtained cut-open view of the A1-A1 line of Fig. 1.
Fig. 3 is the planimetric map according to the acceleration transducer of first embodiment of the invention.
Fig. 4 is the structure skeleton view according to the ferroelectric layer of the acceleration transducer of first embodiment of the invention.
Fig. 5 is according to the detection quality of the acceleration transducer of the first embodiment of the invention planimetric map from its verso view.
Fig. 6 is along the obtained cut-open view of the B1-B1 line of Fig. 3.
Fig. 7 is the skeleton view according to the part of the acceleration transducer of first embodiment of the invention.
Fig. 8 is the schematic sectional view that is used to illustrate according to the acceleration transducer operation of first embodiment of the invention.
Fig. 9 is the thickness of ferroelectric layer and the graph of a relation between the coverage rate.
Figure 10 is the cut-open view that is used to illustrate according to the manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 11 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 12 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 13 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 14 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 15 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 16 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 17 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 18 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of first embodiment of the invention.
Figure 19 is the structure skeleton view according to the acceleration transducer of second embodiment of the invention.
Figure 20 is the cut-open view that the A2-A2 line along Figure 19 is obtained.
Figure 21 is the planimetric map according to the acceleration transducer of second embodiment of the invention.
Figure 22 is the structure skeleton view according to the ferroelectric layer of the acceleration transducer of second embodiment of the invention.
Figure 23 is according to the detection quality of the acceleration transducer of the second embodiment of the invention planimetric map from its verso view.
Figure 24 is at the structure enlarged perspective according to the header portion in the acceleration transducer of second embodiment of the invention.
Figure 25 is along the obtained cut-open view of the B2-B2 line of Figure 21.
Figure 26 is the skeleton view that is used to illustrate according to the acceleration transducer operation of second embodiment of the invention.
Figure 27 is forming pattern (formation pattern) cut-open view according to first of the metal level in the acceleration transducer of second embodiment of the invention.
Figure 28 is the amount of movement of the detection quality in the first formation pattern shown in Figure 27 and the graph of a relation between the capacitance C.
Figure 29 is forming the pattern cut-open view according to second of the metal level in the acceleration transducer of second embodiment of the invention.
Figure 30 is the amount of movement of the detection quality in the second formation pattern shown in Figure 29 and the graph of a relation between the capacitance C.
Figure 31 is forming the pattern cut-open view according to the 3rd of the metal level in the acceleration transducer of second embodiment of the invention.
Figure 32 is the amount of movement of the detection quality in the 3rd formation pattern shown in Figure 31 and the graph of a relation between the capacitance C.
Figure 33 is the thickness of ferroelectric layer and the graph of a relation between the coverage rate.
Figure 34 is the cut-open view that is used to illustrate according to the manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 35 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 36 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 37 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 38 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 39 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 40 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 41 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 42 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 43 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 44 is the cut-open view that is used to illustrate according to this manufacture method of the acceleration transducer of second embodiment of the invention.
Figure 45 is according to the detection quality of the acceleration transducer of modification 1 of the present invention and the structure skeleton view of header portion.
Figure 46 is the structural plan figure according to the acceleration transducer of modification 2 of the present invention.
Figure 47 is the planimetric map of conventional acceleration transducer example.
Figure 48 is the structural representation cut-open view of the conventional acceleration transducer of non-patent document 1 proposition.
The reference symbol table
1 ceramic substrate
2,22 ferroelectric layers (dielectric layer)
3,23 frame parts
3a, the 23a opening
4,24 detect quality (moveable part)
5 glaze layers
6 wiring layers
7,27 first electrodes
7a, 8a, 27a, 28a broach part
7b, 8b, 27b, 28b coupling part
7c, 8c, 27c, 28c pad electrode
8,28 second electrodes
9,29 header portions
10 fringing fields
11,31 sacrifice layers
Embodiment
Below, will be described embodiments of the invention with reference to the accompanying drawings.
(first embodiment)
Fig. 1 is the structure skeleton view according to the acceleration transducer of first embodiment of the invention.Fig. 2 is along the obtained cut-open view of Figure 1A 1-A1 line.Fig. 3 is the planimetric map of the acceleration transducer according to first embodiment of the invention shown in Figure 1.Fig. 4 to 7 is the figure that are used to illustrate according to the acceleration sensor structure of first embodiment of the invention.At first, referring to figs. 1 to 7 structures of describing according to the acceleration transducer 50 of first embodiment of the invention.
As shown in Figure 1, acceleration transducer 50 according to first embodiment of the invention comprises: ceramic substrate 1, be formed on the ferroelectric layer 2 on the ceramic substrate 1, thereby be formed on the frame part 3 that centers on ferroelectric layer 2 on the ceramic substrate 1, and be configured in the detection quality 4 in the frame part 3.Ferroelectric layer 2 is examples of " dielectric layer " of the present invention, and detecting quality 4 is examples of " moveable part " of the present invention.
Ceramic substrate 1 is by Al 2O 3Make and have the thickness of about 1mm.Upper surface at ceramic substrate 1 is formed with glaze layer 5.Forming glaze layer 5 is in order to obtain being suitable for forming the smooth surface of ferroelectric layer 2 or analog.In addition, provide the wiring layer 6 that forms by serigraphy in the presumptive area of the upper surface of ceramic substrate 1 (glaze layer 5), this presumptive area is in frame part 3 outsides.Wiring layer 6 is made by for example Au (gold) or analog.
Here, in first embodiment, ferroelectric layer 2 is by BaTiO 3(relative dielectric constant is 1000 or higher) makes.In addition, as shown in Fig. 2 and 4, by forming ferroelectric layer 2 in the presumptive area of serigraphy on ceramic substrate 1 (glaze layer 5).Ferroelectric layer 2 has and is essentially tetragonal shape, as seeing in the planimetric map.
In addition, in first embodiment, ferroelectric layer 2 forms has 5 μ m or thicker thickness.Particularly, ferroelectric layer 2 forms thickness t 1 (see figure 6) with 5 to 20 μ m.
And in first embodiment, the upper surface of ferroelectric layer 2 has the surfaceness (not shown) of 0.1 to 0.2 μ m magnitude, and it is by control BaTiO 3Grain size form.Contact with the upper surface of ferroelectric layer 2 even detect quality 4, also may reduce to detect the contact area between quality 4 and the ferroelectric layer 2.Therefore, can prevent the quiet control that rubs (adhesion between ferroelectric layer 2 and the detection quality 4) effectively.
In addition, detect quality 4 by parylene (P-xylene base resin: parylene) make, and form thickness t 2 (see figure 6)s, shown in Fig. 2 and 6 with about 5 μ m.And, as shown in Figure 3, detect quality 4 formation and be essentially tetragonal shape (the about 1000 μ m in every limit), as seeing in the planimetric map.
Here, in first embodiment, as shown in Figure 5, at the reverse side (lower surface) that detects quality 4, two electrodes made of aluminum (first electrode 7 and second electrode 8) form in same plane, thereby are in state adjacent one another are.Particularly, from planimetric map, first electrode 7 and second electrode 8 form the shape of broach, thereby the broach part 8a of the broach part 7a of first electrode 7 and second electrode 8 arranges with interlace mode.In addition, as shown in Fig. 6 and 7, the width w of the width w of each broach part 7a of first electrode 7 and each broach part 8a of second electrode 8 is approximately 5 μ m, and the length g from each broach part 7a of first electrode 7 to the broach part 8a of the second adjacent electrode 8 is approximately 5 μ m.Should be noted that in acceleration transducer 50 according to first embodiment, as shown in Figure 5, almost whole reverse side (lower surface) top of detecting quality 4 that is formed on of first electrode 7 and second electrode 8.
In addition, as shown in Fig. 1 and 3, detect quality 4 and comprise and its whole four header portions 9 that are connected.These four header portions 9 provide one for each of four angles detecting quality 4, and form radial extension, as seeing in the planimetric map.And four header portions 9 integrally are connected to frame part 3 at their end.This makes detection quality 4 be supported in the top of ferroelectric layer 2 and faces ferroelectric layer 2, as shown in figs. 1 and 2.By the way, be approximately 1 μ m to what detect quality 4 (first electrode 7 and second electrode 8) apart from d (seeing Fig. 2 and 6) from the upper surface of ferroelectric layer 2.
And each all has the thickness of about 5 μ m and the width of about 50 μ m four header portions 9.That is to say that header portion 9 is formed in Width than long at thickness direction, thereby make them can be than being easier to elastic deformation on respect to the vertical direction (direction that arrow Z is indicated) of the upper surface of ceramic substrate 1.As a result, when the detection quality 4 that is supported when four header portions 9 stood acceleration, inertial force made and detects quality 4 and can go up in the vertical direction (the indicated direction of arrow Z) with respect to the upper surface of ceramic substrate 1 and move.
In addition, as shown in Figure 5, above-mentioned first electrode 7 is electrically connected to pad electrode 7c by coupling part 7b, and above-mentioned second electrode 8 is electrically connected to pad electrode 8c by coupling part 8b.
In addition, as shown in Figure 2, the thickness that frame part 3 has is greater than the thickness that detects quality 4, and as Fig. 1 to 3 as shown in, has the function that keeps detection quality 4 by header portion 9.By the way, frame part 3 is mainly made by parylene.And, in the presumptive area of frame part 3, be formed for the opening 3a on exposed pad electrode 7c and 8c surface.
Fig. 8 is the schematic sectional view that is used to illustrate according to the acceleration transducer operation of first embodiment of the invention.Below, will be with reference to the operation of figure 5 to 8 descriptions according to the acceleration transducer 50 of first embodiment of the invention.
In acceleration transducer 50 according to first embodiment of the invention, by between pad electrode 7c (see figure 5) and pad electrode 8c (see figure 5), applying voltage, as shown in Fig. 6 and 7, produce fringing field 10 (electric field that the next door, space between electrode produces) between the broach part 8a of the broach part 7a of first electrode 7 and second electrode 8.Here, as shown in Figure 5, each all is that shape with broach forms because produce first electrode 7 of fringing field 10 and second electrode 8, and the broach part 8a of the broach part 7a of first electrode 7 and second electrode 8 arranges with interlace mode, produces equably in reverse side (lower surface) top of detecting quality 4 so fringing field 10 is almost whole.On the other hand, as shown in Fig. 6 to 8, in the face of the ferroelectric layer 2 that detects quality 4 is in the fringing field 10 of such generation.
If acceleration transducer 50 stands acceleration in this state, just have inertial force and act on detection quality 4.As a result, as shown in Figure 8, detect quality 4 and on the indicated direction of arrow Z, move.This causes the variation of the volume ratio of ferroelectric layer 2 in fringing field 10, thereby causes the variation of capacitance.Therefore, but the acceleration that is stood by the variation sense acceleration sensor 50 that detects capacitance.
Below, will be described as estimating the computer simulation results of doing according to the usefulness of the acceleration transducer 50 of first embodiment.In this computer simulation, obtain coverage rate by the thickness t 1 that changes ferroelectric layer 2.
Fig. 9 is the graph of a relation between ferroelectric layer thickness and the coverage rate.The Z-axis of Fig. 9 is represented coverage rate (%), and the transverse axis of Fig. 9 is represented the thickness t 1 (μ m) of ferroelectric layer 2.That is to say that Fig. 9 is illustrated in the structure of above-mentioned acceleration transducer 50 according to first embodiment, the variation of observed coverage rate when the thickness t 1 of ferroelectric layer 2 changes.Here, provide coverage rate by following formula (1).
Coverage rate (%)=(X1-X2)/X1 * 100 (1)
Wherein, X1 is the number of the line of electric force of fringing field 10, and these line of electric force enter the zone of ferroelectric layer 2, and
X2 can not walk around in the zone of ferroelectric layer 2 and the number of the line of electric force that penetrates from the zone bottom of ferroelectric layer 2.
That is to say that coverage rate is indication line of electric force number of walking around and the proportional numerical value that enters the line of electric force number of ferroelectric layer 2 in the zone of ferroelectric layer 2.Numerical value is high more, and the sensitivity that detects capacitance variation is just high more.By the way, 0V voltage is applied to one of electrode (first electrode 7 or second electrode 8), simultaneously 5V voltage has been applied to another electrode (second electrode 8 or first electrode 7).
As shown in Figure 9, have been found that making ferroelectric layer 2 have 5 μ m or thicker thickness t 1 can obtain 99% or higher coverage rate.Also have been found that to make ferroelectric layer 2 have 10 μ m or thicker thickness t 1 can obtain the almost coverage rate of 100% (99.8% or higher), make ferroelectric layer 2 have 20 μ m or thicker thickness t 1 then can obtain 100% coverage rate.By the way, thickness t 1 at ferroelectric layer 2 is under the situation of 10 μ m, the thickness t 1 of ferroelectric layer 2 equal first electrode 7 and second electrode 8 both one of the width w (being about 5 μ m) and total length (w+g: be approximately 10 μ m) of broach part 7a (or 8a) from each broach part 7a of first electrode 7 to length g (the being approximately 5 μ m) addition of the broach part 8a of the second adjacent electrode 8.Thickness t 1 at ferroelectric layer 2 is under the situation of 20 μ m, and the thickness t 1 of ferroelectric layer 2 equals the twice (2 (w+g)) of above-mentioned total length (w+g: be approximately 10 μ m).
As mentioned above, confirmed by making ferroelectric layer 2 have 5 μ m or thicker thickness t 1 can obtain enough coverage rates, so can be with the variation of high Precision Detection capacitance.Therefore, confirmed to improve the detection sensitivity of acceleration.
In first embodiment, as mentioned above,, can between first electrode 7 and second electrode 8, produce fringing field 10 by forming first electrode 7 and second electrode 8 in that side of detecting quality 4 in the face of ferroelectric layer 2.In addition, by in the presumptive area of ceramic substrate 1, forming by BaTiO 3The ferroelectric layer of making 2, the relative dielectric constant that can make ferroelectric layer 2 is even as big as gratifying degree, because BaTiO 3Be to have 1000 or the metal oxide of high relative dielectric constant (ferroelectric material) more.This makes it possible to the variation of high Precision Detection by the caused capacitance of variation of the volume ratio of ferroelectric layer 2 in fringing field 10, thereby makes it possible to the acceleration that stood with the high-sensitivity detection sensor.
In addition, in first embodiment, by by BaTiO 3Make ferroelectric layer 2, even increasing apart from d between ferroelectric layer 2 and the detection quality 4 can prevent that also the detection sensitivity of capacitance from reducing.As a result, may prevent static friction apart from d between ferroelectric layer 2 and the detection quality 4 by increasing.This helps to prevent owing to static friction takes place reliability to be reduced.By the way, because BaTiO 3Be the ferroelectric material that does not contain Pb (lead), so pass through by BaTiO 3Make ferroelectric layer 2, can reduce environmental pressure that waste products causes and the mankind's deleterious effect.
In addition, in first embodiment, by adopting by Al 2O 3The ceramic substrate of making 1 is as substrate, and electrical isolation higher when adopting silicon substrate or analog as substrate and the physical strength of Geng Gao can be provided.This makes it possible to improve detection sensitivity when enhancing productivity, and improves reliability.And, by adopting ceramic substrate 1, can obtain to compare production cost lower when adopting silicon substrate as substrate.
And, in first embodiment, have 5 μ m or thicker thickness t 1 by making ferroelectric layer 2, can obtain 99% or higher coverage rate.As a result, can be with the variation of high Precision Detection capacitance.This makes it possible to the easier detection sensitivity of improving acceleration when enhancing productivity.Preferably, the thickness t 1 of ferroelectric layer 2 is 10 μ m or thicker, is preferably 20 μ m or thicker.
In addition, in first embodiment,, can improve the smoothness of the upper surface of ferroelectric layer 2 by between ceramic substrate 1 and ferroelectric layer 2, forming glaze layer 5.As a result, by control BaTiO 3Grain size, can form the surfaceness of 0.1 to 0.2 μ m magnitude at the upper surface of ferroelectric layer 2.
Figure 10 to 18 is the figure that are used to illustrate according to the manufacture method of the acceleration transducer of first embodiment of the invention.Below, will be with reference to figure 1,5,6 and 10 to 18 manufacture methods of describing according to the acceleration transducer 50 of first embodiment of the invention.By the way, the acceleration transducer 50 according to first embodiment mainly is to use the surface micromachined technology to make.
At first, as shown in Figure 10, has about 1mm thickness and by Al 2O 3The upper surface of the ceramic substrate of making 1 forms glaze layer 5.The method that forms glaze layer 5 is for example to print the liquid that contains glass ingredient on ceramic substrate 1, fires with predetermined temperature then.
Then, on glaze layer 5, form the wiring layer 6 shown in Fig. 1 by serigraphy.Then as shown in Figure 10, form ferroelectric layer 2 in the presumptive area on ceramic substrate 1 (glaze layer 5).
Here, in first embodiment, form ferroelectric layer 2 by serigraphy.Particularly, will contain BaTiO 3Paste be printed onto after the presumptive area of glaze layer 5, the product that obtains is thus fired with the firing temperature of 800 to 1200 ℃ of magnitudes.Like this, just, form by BaTiO 3The ferroelectric layer of making 2.
In addition, in first embodiment, ferroelectric layer 2 forms thickness t 1 (see figure 6) with 5 to 20 μ m, and by control BaTiO 3Grain size, the surfaceness (not shown) that makes its surface have 0.1 to 0.2 μ m magnitude.
Then, as shown in Figure 11,, cover ferroelectric layer 2 thereby on glaze layer 5, form the sacrifice layer made from amorphous silicon 11 by plasma CVD.Here, sacrifice layer 11 is based on the imagination that will remove in the subsequent treatment and the layer that forms.
Then, as shown in Figure 12, by photoetching technique with utilize SF 6The dry ecthing of plasma gas forms long narrow slot part (slit) 11a in sacrifice layer 11.Then, as shown in Figure 13, at the upper surface vapour deposition first parylene layer 12 of sacrifice layer 11.In this case, the first parylene layer 12 of vapour deposition in narrow slot part 11a is just as the anchor portion that keeps detecting quality 4.
Then, as shown in Figure 14, by photoetching technique with utilize O 2The etching of plasma gas, the presumptive area of removing the first parylene layer 12.
After this, at sacrifice layer 11 with above the first parylene layer 12, by sputter or gas phase deposition technology, the deposition aluminium lamination, and, as shown in Figure 15, use photoetching technique and wet etching to carry out composition to the aluminium lamination that deposits.The result forms comb teeth shape first electrode 7 and comb teeth shape second electrode 8 as shown in Figure 5, and forms pad electrode 7C and the 8C that is electrically connected to first electrode 7 and second electrode 8 respectively.By the way, be connected the coupling part 7b (see figure 5) between first electrode 7 and the pad electrode 7C and be connected coupling part 8b (see figure 5) between second electrode 8 and the pad electrode 8C, form simultaneously with composition to aluminium lamination.
Then, as shown in Figure 16, the vapour deposition second parylene layer 13 on the sacrifice layer 11 and the first parylene layer 12, thus first electrode 7, second electrode 8, pad electrode 7C and 8C and coupling part 7b and 8b (see figure 5) covered.Then, the second parylene layer 13 is carried out composition handle, make it have as shown in Figure 17 shape.As a result, form detection quality 4 (see figure 1)s, header portion 9 (see figure 1)s and frame part 3 (see figure 1)s of all making by parylene.About this point, as shown in Figure 17 and 18, in the presumptive area of frame part 3, be formed for the opening 3a on exposed pad electrode 7C and 8C surface.By the way, the first parylene layer 12 and the second parylene layer 13 can form (vapour deposition) at ambient temperature.
At last, pass through XeF 2The dry ecthing of gas is removed the presumptive area of sacrifice layer 11 and is being detected leaving space between quality 4 and the ferroelectric layer 2.Like this, just, form the acceleration transducer 50 shown in Fig. 1 according to first embodiment of the invention.
In this manufacture method of first embodiment, as mentioned above, by forming by BaTiO in the presumptive area of serigraphy on ceramic substrate 1 3The ferroelectric layer of making 2 can form ferroelectric layer 2 easily in presumptive area.This compares with the situation of for example adding tabular ferroelectric layer on substrate, can enhance productivity.By the way, in acceleration transducer 50, can make without DRIE technology according to first embodiment.
In addition, in first embodiment, form by BaTiO by serigraphy 3The ferroelectric layer of making 2 is compared with the situation that adopts sputter, sol-gel process or similar approach to form ferroelectric layer 2, thickness t 1 that can easier increase ferroelectric layer 2.This helps avoid such possibility, promptly makes variation with the high Precision Detection capacitance difficulty that becomes owing to the thickness t 1 of ferroelectric layer 2 is little.This makes it possible to obtain to have highly sensitive acceleration transducer 50 when enhancing productivity.
In addition, in first embodiment, form wiring layer 6 at the upper surface of ceramic substrate 1 (glaze layer 5), can form wiring layer 6 easily by serigraphy.This also helps to enhance productivity.
(second embodiment)
Figure 19 is the structure skeleton view according to the acceleration transducer of second embodiment of the invention.Figure 20 is along the obtained cut-open view of the A2-A2 line of Figure 19.Figure 21 is the planimetric map according to the acceleration transducer of second embodiment of the invention shown in Figure 19.Figure 22 to 25 is the figure that are used to illustrate according to the acceleration sensor structure of second embodiment of the invention.At first, will be referring to figures 19 through 25 structures of describing according to the acceleration transducer 60 of second embodiment of the invention.
As shown in Figure 19 and 20, acceleration transducer 60 according to second embodiment of the invention comprises: ceramic substrate 1, be formed on the ferroelectric layer 22 on the ceramic substrate 1, thereby be formed on the frame part 23 that centers on ferroelectric layer 22 on the ceramic substrate 1, and be configured in the detection quality 24 in the frame part 23.By the way, ferroelectric layer 22 is examples of " dielectric layer " of the present invention, and detecting quality 24 is examples of " moveable part " of the present invention.
Ceramic substrate 1 is by Al 2O 3Make and have about 1mm thickness.Identical with above-mentioned first embodiment, be formed with glaze layer 5 at the upper surface of ceramic substrate 1.By the way, forming glaze layer 5 is in order to obtain being suitable for forming the smooth surface of ferroelectric layer 22 or analog.In addition, as shown in Figure 19, in the presumptive area of the upper surface of ceramic substrate 1 (glaze layer 5), provide the wiring layer 6 that forms by serigraphy, this presumptive area is in frame part 23 outsides.Wiring layer 6 is made by the material of for example Au (gold) or analog.
Here, in a second embodiment, as in above-mentioned first embodiment, ferroelectric layer 22 is by BaTiO 3(relative dielectric constant is 1000 or higher) makes.In addition, as shown in Figure 20 and 22, by forming ferroelectric layer 22 in the presumptive area of serigraphy on ceramic substrate 1 (glaze layer 5).Ferroelectric layer 22 has and is essentially tetragonal shape, as seeing in the planimetric map.
In addition, ferroelectric layer 22 forms and has 5 μ m or thicker thickness.Particularly, ferroelectric layer 22 forms the thickness t 1 (seeing Figure 25) with 5 to 20 μ m.
And the upper surface of ferroelectric layer 22 has the surfaceness (not shown) of 0.1 to 0.2 μ m magnitude, and it is by control BaTiO 3Grain size form.Like this, contact with the upper surface of ferroelectric layer 22, also can reduce to detect the contact area between quality 24 and the ferroelectric layer 22 even detect quality 24.Therefore, can prevent static friction (adhesion between ferroelectric layer 22 and the detection quality 24) effectively.This helps to prevent to reduce because of static friction causes the reliability of acceleration transducer 60.
In addition, in a second embodiment, as shown in Figure 20 and 22,, form the metal level of making by aluminium (Al) 40 in the presumptive area of the upper surface of ferroelectric layer 22.Metal level 40 has predetermined pattern, and forms not outstanding from the upper surface of ferroelectric layer 22.Particularly, from planimetric map, broach part 27a and 28a that metal level 40 forms respectively with first electrode 27 and second electrode 28 extend abreast, and this will be described later.And, metal level 40 form its upper surface basically with the upper surface flush of ferroelectric layer 22.
In addition, as shown in Figure 20 and 25, detect quality 24 by parylene (P-xylene base resin: parylene) make, and form thickness t 12 (seeing Figure 24) with about 5 μ m.And, as shown in Figure 21, detect quality 24 formation and be essentially tetragonal shape (the about 1000 μ m in every limit), as seeing in the planimetric map.
And in a second embodiment, as shown in Figure 23, at the reverse side (lower surface) that detects quality 24, two electrodes made of aluminum (first electrode 27 and second electrode 28) form in same plane, thereby are in state adjacent one another are.Particularly, from planimetric map, first electrode 27 and second electrode 28 form the shape of broach, and the broach part 27a of the electrode 27 of winning and the broach part 28a of second electrode 28 are arranged with interlace mode.And, as shown in Figure 25, the width w1 of the width w1 of each broach part 27a of first electrode 27 and each broach part 28a of second electrode 28 is approximately 5 μ m, and the length g1 from each broach part 27a of first electrode 27 to the broach part 28a of the second adjacent electrode 28 is approximately 5 μ m.Should be noted that in acceleration transducer 60 according to second embodiment, as shown in Figure 23, almost whole reverse side (lower surface) top of detecting quality 24 that is formed on of first electrode 27 and second electrode 28.
In addition, shown in Figure 19 and 21, detect quality 24 and comprise and its whole four header portions 29 that are connected.These four header portions 29 are provided at and detect 24 two opposite sides of quality, and each side provides two header portions 29, and form on same direction and extend, as seeing in the planimetric map.And four header portions 29 integrally are connected to frame part 23 at their end.This makes detection quality 24 can be supported in the top of ferroelectric layer 22 and faces ferroelectric layer 22, as shown in Figure 19 and 20.By the way, be approximately 1 μ m to what detect quality 24 (first electrode 27 and second electrode 28) apart from d1 (seeing Figure 20 and 25) from the upper surface of ferroelectric layer 22.
And in a second embodiment, as shown in Figure 24, header portion 29 has the thickness t 12 of about 5 μ m and the width w11 of about 3 μ m.That is to say that header portion 29 is formed in thickness direction than long at Width, thereby make the header portion 29 can be than being easier to, promptly be parallel to elastic deformation (seeing Figure 19) on the direction of upper surface (first type surface) of ceramic substrate 1 in the direction shown in the arrow X.Therefore, when the detection quality 24 that is supported when four header portions 29 stood acceleration, inertial force made and detects quality 24 and can move by the upper surface (first type surface) with respect to ceramic substrate 1 on the indicated horizontal direction of arrow X.
In addition, as shown in Figure 23, above-mentioned first electrode 27 is electrically connected to pad electrode 27c by coupling part 27b, and above-mentioned second electrode 28 is electrically connected to pad electrode 28c by coupling part 28b.
In addition, as shown in Figure 20, the thickness that frame part 23 has is greater than the thickness that detects quality 24, and as Figure 19 and 21 as shown in, has the function that keeps detection quality 24 by header portion 29.By the way, frame part 23 is mainly made by parylene.And, in the presumptive area of frame part 23, be formed for the opening 23a on exposed pad electrode 27c and 28c surface.
Those of other structures of second embodiment and above-mentioned first embodiment are identical.
Figure 26 to 32 is the figure that are used to illustrate according to the acceleration transducer operation of second embodiment of the invention.Below, will operation according to the acceleration transducer 60 of second embodiment of the invention be described with reference to Figure 23 and Figure 25 to 32.
In acceleration transducer 60 according to second embodiment, by between pad electrode 27c (seeing Figure 23) and pad electrode 28c (seeing Figure 23), applying voltage, as shown in Figure 25 and 26, between the broach part 28a of the broach part 27a of first electrode 27 and second electrode 28, produce fringing field 10 (electric field that the next door, space between electrode produces).Here, as shown in Figure 23, each all is that shape with broach forms because produce first electrode 27 of fringing field 10 and second electrode 28, and the broach part 28a of the broach part 27a of first electrode 27 and second electrode 28 arranges with interlace mode, produces equably in reverse side (lower surface) top of detecting quality 24 so fringing field 10 is almost whole.On the other hand, be in the fringing field 10 of such generation in the face of the ferroelectric layer 22 that detects quality 24.
If acceleration transducer 60 stands acceleration in this state, just have inertial force and act on detection quality 24.As a result, detecting quality 24 upper surface with respect to ceramic substrate 1 on the indicated horizontal direction of arrow X moves.In this case, though the line of electric force of the fringing field 10 that produces between first electrode 27 and second electrode 28 can pass ferroelectric layer 22, but they can not pass metal level 40, move on the indicated direction of arrow X along with detecting quality 24, will cause that the appearance of line of electric force changes.This changes with the variation of line of electric force appearance with regard to causing capacitance.Therefore, by detecting the variation of capacitance, but the acceleration that on the indicated direction of arrow X, is subjected to of sense acceleration sensor 60 just.
By the way, the changing pattern of capacitance is considered to change with the formation pattern of metal level 40.For example, as shown in Figure 27, just in time be in forming metal level 40 under the situation below the broach part 28a of the broach part 27a of first electrode 27 and adjacent second electrode 28 (first forms pattern), be easy to expect capacitance C such variation as shown in Figure 28.Other direction, as shown in Figure 29, just in time be not in forming metal level 40 under the situation below the broach part 28a of the broach part 27a of first electrode 27 and second electrode 28 (second forms pattern), be easy to expect capacitance C such variation as shown in Figure 30.In addition, as shown in Figure 31, just in time be in forming wide relatively metal level 40 under the broach part 27a and the situation below one of second electrode 28 and broach part 28a of first electrode 27 (the 3rd forms pattern), be easy to expect capacitance C such variation as shown in Figure 32.Therefore, by changing the formation pattern of metal level 40 by different way, can adjust the detection sensitivity of acceleration.
Below, carry out computer simulation in order to estimate usefulness, adopted the method that is similar to described in first embodiment according to the acceleration transducer 60 of second embodiment.The result is illustrated among Figure 33.
As shown in Figure 33, have been found that making ferroelectric layer 22 have 5 μ m or thicker thickness or thicker thickness t 11 can obtain 99% or higher coverage rate.Also have been found that to make ferroelectric layer 22 have 10 μ m or thicker thickness t 11 can obtain the almost coverage rate of 100% (99.8% or higher), and make ferroelectric layer 22 have 20 μ m or thicker thickness t 11 can obtain 100% coverage rate.By the way, thickness t 11 at ferroelectric layer 22 is under the situation of 10 μ m, the thickness t 11 of ferroelectric layer 22 equal first electrode 27 and second electrode 28 both one of the width w1 (about 5 μ m) and total length (w1+g1: about 10 μ m) of broach part 27a (or 28a) from each broach part 27a of first electrode 27 to the length g1 addition of the broach part 28a of the second adjacent electrode 28.Thickness t 11 at ferroelectric layer 22 is under the situation of 20 μ m, and the thickness t 11 of ferroelectric layer 22 equals above-mentioned total length (w1+g1: twice about 10 μ m) (2 (w1+g1)).
As mentioned above, confirmed to make ferroelectric layer 22 to have 5 μ m or thicker thickness t 11 can obtain enough coverage rates, so can be with the variation of high Precision Detection capacitance.As a result, confirmed to improve the detection sensitivity of acceleration.
In a second embodiment, as mentioned above, by forming first electrode 27 and second electrode 28 in that side of detecting quality 24 in the face of ferroelectric layer 22, can be between the broach part 28a of the broach part 27a of first electrode 27 and second electrode 28 generation fringing field 10.In addition, by in the presumptive area of the upper surface of ferroelectric layer 22, forming metal level 40, even promptly be parallel on the direction of upper surface (first type surface) of ceramic substrate 1 when mobile in the indicated direction of arrow X when detecting quality 24, also can change the appearance of the line of electric force of fringing field 10.That is to say, though the line of electric force of the fringing field 10 that produces between the broach part 28a of the broach part 27a of first electrode 27 and second electrode 28 can pass ferroelectric layer 22, but they can not pass metal level 40, so by form metal level 40 in the presumptive area of the upper surface of ferroelectric layer 22, the line of electric force appearance that can make fringing field 10 changes with detecting quality 24 moving on the indicated direction of arrow X.As a result, capacitance changes with the variation of line of electric force appearance, makes it possible to detect in the indicated direction of arrow X by the variation that detects capacitance promptly be parallel to acceleration on the direction of ceramic substrate 1 (ferroelectric layer 22) upper surface (first type surface).
In addition, in a second embodiment, make it not outstanding by forming metal level 40,, also can proceed the manufacture process of back on the upper surface of ferroelectric layer 22 by the technology identical with the situation that does not form metal level 40 even when metal level 40 forms from the upper surface of ferroelectric layer 22.This helps avoid such possibility, and promptly subsequent manufacturing processes is because metal level 40 is outstanding and become complicated from the upper surface of ferroelectric layer 22.This makes it possible to easily enhance productivity.
And, in a second embodiment, make it not outstanding by forming metal level from the upper surface of ferroelectric layer 22, can prevent from promptly to be parallel on the direction of upper surface (first type surface) of ceramic substrate 1 (ferroelectric layer 22) when mobile in the indicated direction of arrow X engaging between metal level 40 and the detection quality 24 (first electrode 27, second electrode 28) when detecting quality 24.This helps avoid such possibility, promptly metal level 40 with detect engages between the quality 24 (first electrode 27, second electrode 28) hinder detect on quality 24 promptly is parallel to ceramic substrate 1 (ferroelectric layer 22) in the indicated direction of arrow X the direction of upper surface (first type surface) mobile.As a result, can easily detect acceleration on the direction of upper surface (first type surface) that the indicated direction of arrow X promptly is parallel to ceramic substrate 1 (ferroelectric layer 22).
In addition, in a second embodiment, by by BaTiO 3Make ferroelectric layer 22, the relative dielectric constant that can make ferroelectric layer 22 is even as big as gratifying degree, because BaTiO 3Be that to have relative dielectric constant be 1000 or higher metal oxide (ferroelectric material).This just makes it possible to the variation with the high Precision Detection capacitance, thereby makes it possible to easily promptly to be parallel to acceleration on the direction of upper surface (first type surface) of ceramic substrate 1 (ferroelectric layer 22) with the indicated direction of high Precision Detection arrow X.By the way, because BaTiO 3Be the ferroelectric material that does not contain Pb (lead), so pass through by BaTiO 3Make ferroelectric layer 22, can reduce environmental pressure that waste products causes and influential to the mankind thereof.
In addition, in a second embodiment, long at Width by the header portion 29 that makes supporting detection quality 24 at the thickness direction ratio, can prevent to detect quality 24 and go up in the vertical direction (direction that arrow Z is indicated) with respect to the upper surface (first type surface) of ceramic substrate 1 (ferroelectric layer 22) and move, this can prevent that the component of acceleration on the indicated direction of arrow Z is comprised in the acceleration that is detected.This makes it possible to easily to detect the acceleration on the direction of upper surface (first type surface) that the indicated direction of arrow X promptly is parallel to ceramic substrate 1 (ferroelectric layer 22), and improves the precision that detects easily.
In addition, in a second embodiment,, have 5 μ m or thicker thickness t 11, can obtain 99% or higher coverage rate by making ferroelectric layer 22 as in above-mentioned first embodiment.This makes it possible to the variation with the high Precision Detection capacitance.As a result, can promptly be parallel to acceleration on the direction of upper surface (first type surface) of ceramic substrate 1 (ferroelectric layer 22) with the indicated direction of higher accuracy detection arrow X.
And, in a second embodiment,, can improve the smoothness of the upper surface of ferroelectric layer 22 by between ceramic substrate 1 and ferroelectric layer 22, forming glaze layer 5.As a result, by control BaTiO 3Grain size, can form the surfaceness of 0.1 to 0.2 μ m magnitude at the upper surface of ferroelectric layer 22.
Other effects that should be noted that second embodiment are identical with above-mentioned first embodiment's.
Figure 34 to 44 is the figure that are used to illustrate according to the acceleration transducer manufacture method of second embodiment of the invention.Below with reference to Figure 19, Figure 23 to 25 and Figure 34 to 44, the manufacture method according to the acceleration transducer 60 of second embodiment of the invention is described.By the way, the acceleration transducer 60 according to second embodiment mainly is to use the manufacturing of surface micromachined technology.
At first, as shown in Figure 34, has about 1mm thickness and by Al 2O 3The upper surface of the ceramic substrate of making 1 forms glaze layer 5.The method that forms glaze layer 5 is for example to print the liquid that contains glass ingredient on ceramic substrate 1, fires with predetermined temperature then.
Then, on glaze layer 5, form the wiring layer 6 shown in Figure 19 by serigraphy.By the way, form wiring layer 6, can form wiring layer 6 easily by serigraphy.This also helps to enhance productivity.
Then, as shown in Figure 34, form ferroelectric layer 22 by serigraphy in the presumptive area of ceramic substrate 1 (glaze layer 5).Particularly, will contain BaTiO 3Paste be printed onto after the presumptive area of glaze layer 5, products obtained therefrom is fired with the firing temperature of 800 to 1200 ℃ of magnitudes.Like this, just, form by BaTiO 3The ferroelectric layer of making 22.
In addition, ferroelectric layer 22 forms the thickness t 11 (seeing Figure 25) with 5 μ m to 20 μ m, and is by control BaTiO 3The grain size surfaceness (not shown) that makes their upper surface have 0.1 to 0.2 magnitude form.
Then, as shown in Figure 35, utilize gas phase deposition technology or similar approach, at the pattern formation metal level 40 of presumptive area to be scheduled to of ferroelectric layer 22.Then, it is softening that the firing temperature (for example about 50 ℃) that temperature is increased to a little higher than ferroelectric layer 22 makes ferroelectric layer 22.This causes the metal level 40 downward depressions that are formed on the ferroelectric layer 22.Therefore, as shown in Figure 36, metal level 40 is formed not outstanding from the upper surface of ferroelectric layer 22.
Then, as shown in Figure 37, utilize plasma CVD, cover ferroelectric layer 22 thereby on glaze layer 5, form the sacrifice layer made from amorphous silicon 31.Here, sacrifice layer 31 is based on the imagination that will remove in the subsequent treatment and the layer that forms.
Then, as shown in Figure 38, by photoetching technique and use SF 6The dry ecthing of plasma gas forms long narrow slot part (slit) 31a in sacrifice layer 31.Then, as shown in Figure 39, at the upper surface vapour deposition first parylene layer 32 of sacrifice layer 31.In this case, the first parylene layer 32 that is deposited among the narrow slot part 31a just is used as the anchor portion that keeps detecting quality 24.
Then, as shown in Figure 40, by photoetching technique and use O 2The etching of plasma gas, the presumptive area of removing the first parylene layer 32.
After this, on the sacrifice layer 31 and the first parylene layer 32,, deposit aluminium lamination, and as shown in Figure 41, utilize photoetching technique and wet etching to carry out composition the aluminium lamination that deposits by sputter or gas phase deposition technology.The result forms comb teeth shape first electrode 27 and comb teeth shape second electrode 28 as shown in Figure 23, and forms pad electrode 27c and the 28c that is electrically connected to first electrode 27 and second electrode 28 respectively.By the way, be connected the coupling part 27b (seeing Figure 23) between first electrode 27 and the pad electrode 27c and be connected coupling part 28b (seeing Figure 23) between second electrode 28 and the pad electrode 28c, form simultaneously with composition to aluminium lamination.
Then, as shown in Figure 42, the vapour deposition second parylene layer 33 on the sacrifice layer 31 and the first parylene layer 32, thus first electrode 27, second electrode 28, pad electrode 27c and 28c (seeing Figure 23) covered, and coupling part 27b and 28b (seeing Figure 23).Then, the second parylene layer 33 is carried out composition to have shape as shown in Figure 43.About this point, as shown in Figure 24, each all is formed in thickness direction than long at Width four header portions 29.As a result, form detection quality 24 (seeing Figure 19), header portion 29 (seeing Figure 19) and the frame part of all making 23 (seeing Figure 19) by parylene.About this point, in the presumptive area of frame part 23, be formed for the opening 23a on exposed pad electrode 27c and 28c surface.By the way, the first parylene layer 32 and the second parylene layer 33 can form (vapour deposition) at ambient temperature.
At last, by using XeF 2The dry ecthing of gas is removed the presumptive area of sacrifice layer 31 and is being detected leaving space between quality 24 and the ferroelectric layer 22 from the state shown in Figure 44.Like this, just, form the acceleration transducer 60 shown in Figure 19 according to second embodiment of the invention.
In a second embodiment, as mentioned above, in the presumptive area of ceramic substrate 1, form ferroelectric layer 22, form ferroelectric layer 22 in the presumptive area on ceramic substrate 1 easily by serigraphy.This compares with the situation that for example presumptive area on ceramic substrate 1 is added tabular ferroelectric layer 22, makes it possible to enhance productivity.By the way, in acceleration transducer 60, can not use DRIE technology to make according to second embodiment.
Should be appreciated that the foregoing description is graphic extension and example, rather than as restriction.Scope of the present invention is not to be limited to the content that had specifically described, but states in accompanying Claim, and comprise any with claim in the meaning of those set forth equivalence on and modification and the modification made in the scope.
For example, above-mentioned first and second embodiment relate to wherein ferroelectric layer by BaTiO 3The example of making.But, the invention is not restricted to these examples, but can be achieved like this, promptly ferroelectric layer can be with removing BaTiO 3Metal oxide is in addition made, as long as this metal oxide has 1000 or higher relative dielectric constant, and applicable serigraphy.In this case, preferably use the metal oxide that does not contain Pb (lead).
In addition, above-mentioned first and second embodiment relate to wherein that ferroelectric layer forms the example with 5 μ m to 20 μ m thickness.But, the invention is not restricted to these examples, but can be achieved like this, promptly ferroelectric layer forms and has 20 μ m or thicker thickness.By the way, as mentioned above, because the formation of ferroelectric layer finishes by serigraphy, thus can form easily, even ferroelectric bed thickness to 20 μ m or thicker.
In addition, above-mentioned first and second embodiment relate to the example that wherein forms ferroelectric layer on the ceramic substrate that is formed with the glaze layer by serigraphy.But, the invention is not restricted to these examples, but can be achieved like this, promptly on the ceramic substrate that does not have the glaze layer, form ferroelectric layer by serigraphy.
In addition, above-mentioned first and second embodiment relate to ferroelectric layer wherein and fire and the example that forms through the firing temperature of 800 to 1200 ℃ of magnitudes.But, the invention is not restricted to these examples, but can be achieved like this, promptly ferroelectric layer can form by firing with the temperature that is different from above-mentioned firing temperature.For example fire, perhaps fire with 700 ℃ or lower low relatively firing temperature with the high relatively firing temperature of 1200 to 1500 ℃ of magnitudes.By the way, under situation about firing to the firing temperature of 1500 ℃ of magnitudes with 1200 ℃, above embodiment described in acceleration transducer, can be by on the ceramic substrate that does not have the glaze layer, forming ferroelectric layer, and make forming the method that ferroelectric layer forms wiring layer later on.In addition, under situation about firing, preferably, form ferroelectric layer and be unlikely and only have 1000 or littler relative dielectric constant with 700 ℃ firing temperature.
In addition, above-mentioned first and second embodiment relate to wherein and adopting by Al 2O 3The example of the ceramic substrate of making.But, the invention is not restricted to these examples, but can be achieved like this, promptly adopt by Al 2O 3The ceramic substrate that stupalith is in addition made is made acceleration transducer.
In addition, above-mentioned first and second embodiment relate to the example that wherein adopts frame section to assign to keep detecting quality.But, the invention is not restricted to these examples, but can be achieved like this, promptly adopt the parts different to keep detecting quality with frame part.
By the way, in above-mentioned first and second embodiment, detect quality and can provide a plurality of through holes, these through holes form from the upper surface that detects quality and are through to its lower surface.This structure makes it possible to than being easier to remove sacrifice layer, and can reduce air resistance.
In addition, above-mentioned second embodiment relates to and wherein forms metal level and make it not from the outstanding example of ferroelectric layer upper surface.But, the invention is not restricted to this example, but can be achieved like this, promptly form metal level and make its upper surface outstanding from ferroelectric layer.
In addition, as the example of metal level formation pattern, above-mentioned second embodiment relates to three kinds and forms patterns: first forms pattern, and second forms pattern and the 3rd forms pattern.But, the invention is not restricted to these examples.The formation pattern of metal level can be to form pattern and the 3rd with the above-mentioned first formation pattern, second to form the different formation pattern of pattern.And metal level can make up and adopt two or more to form pattern.As mentioned above, adopt two or more metal levels to form under the situation of pattern, can adjust the detection sensitivity of acceleration and improve detection sensitivity in combination.
In addition, above-mentioned second embodiment relates to wherein metal level example made of aluminum.But, the invention is not restricted to this example, but can be achieved like this, promptly metal level is made by the metal except that aluminium.
In addition, above-mentioned first embodiment relates to and wherein detects the structure of quality with the supporting of four header portions.But, the invention is not restricted to this structure.Supporting detect quality header portion can with constitute as the different any method of the above-mentioned specific descriptions method of embodiment, allow to detect quality on the direction of upper surface of ceramic substrate and move as long as can promptly be parallel in predetermined direction.For example, as shown in Figure 45, the header portion 39 that supporting detects quality 34 can constitute can be crooked on the indicated direction of arrow X.
In addition, above-mentioned second embodiment relates to wherein acceleration transducer and constitutes and can detect the indicated direction of arrow X, promptly is parallel to the example of the acceleration on the direction of upper surface of ceramic substrate.But, the invention is not restricted to this example, but can be achieved like this, promptly, can detect the acceleration on a plurality of directions simultaneously by on single ceramic substrate, forming a plurality of acceleration transducers.For example, as shown in Figure 46, on single ceramic substrate, at least can form two acceleration transducers 60 and be used to detect acceleration on the different directions of upper surface that arrow X and the indicated different directions of Y promptly be parallel to ceramic substrate 1, and acceleration transducer 50 is used to detect with respect to the acceleration on the vertical direction of the upper surface of ceramic substrate 1, can detect three acceleration on axially so simultaneously.In addition, as shown in Figure 46, can further provide have not the detection quality that moves acceleration transducer 70 as a reference.This structure makes it possible to further improve the accuracy of detection of acceleration.

Claims (13)

1. acceleration transducer comprises:
Ceramic substrate;
Dielectric layer is formed in the presumptive area on the ceramic substrate by serigraphy, and dielectric layer is made by metal oxide;
Moveable part is arranged in the face of dielectric layer, and moveable part is formed on apart from the position of dielectric layer preset distance; And
First electrode and second electrode are formed on facing on the side of dielectric layer of moveable part.
2. acceleration transducer comprises:
Ceramic substrate;
Dielectric layer is formed in the presumptive area on the ceramic substrate by serigraphy, and dielectric layer is made by metal oxide;
Moveable part is arranged in the face of dielectric layer, and moveable part is formed on apart from the position of dielectric layer preset distance; And
First electrode and second electrode are formed on facing on the side of dielectric layer of moveable part,
Wherein, form metal level in the presumptive area on the upper surface of dielectric layer.
3. acceleration transducer according to claim 2, wherein,
Metal level forms and makes this metal level not outstanding from the upper surface of dielectric layer.
4. according to claim 2 or 3 described acceleration transducers, further comprise:
Header portion, the supporting moveable part,
Wherein, header portion is longer at Width at the thickness direction ratio.
5. according to any one the described acceleration transducer in the claim 1 to 3, wherein,
Dielectric layer is by BaTiO 3Make.
6. according to any one the described acceleration transducer in the claim 1 to 3, wherein,
Ceramic substrate is by Al 2O 3Make.
7. according to any one the described acceleration transducer in the claim 1 to 3, wherein,
First electrode and second electrode form according to the broach shape with a plurality of broach part separately, and, from planimetric map, the broach of first electrode and second electrode part with interlace mode by predetermined being spaced.
8. according to any one the described acceleration transducer in the claim 1 to 3, wherein,
Dielectric layer has 5 μ m or thicker thickness.
9. according to any one the described acceleration transducer in the claim 1 to 3, wherein,
Between ceramic substrate and dielectric layer, further form the glaze layer.
10. method of making acceleration transducer comprises:
Utilize the step that forms the dielectric layer of making by metal oxide in the presumptive area of serigraphy on ceramic substrate;
Forming first electrode and second electrode makes win electrode and second electrode be positioned at the step of the top of dielectric layer; And
Form moveable part and make moveable part face the step of dielectric layer above dielectric layer, first electrode and second electrode are fixed in moveable part.
11. the method for manufacturing acceleration transducer according to claim 10,
Wherein, the step of formation dielectric layer comprises by BaTiO 3Form the step of dielectric layer.
12. according to the method for claim 10 or 11 described manufacturing acceleration transducers,
Wherein, the step that forms first electrode and second electrode comprises according to the broach shape with a plurality of broach parts and forms each step in first electrode and second electrode, and from planimetric map, the broach of first electrode and second electrode part with interlace mode by predetermined being spaced.
13. the method according to claim 10 or 11 described manufacturing acceleration transducers further comprises:
On the surface of ceramic substrate, form the step of wiring layer by serigraphy.
CNA2008800006320A 2007-05-30 2008-05-16 Acceleration sensor and method for manufacturing the same Pending CN101542296A (en)

Applications Claiming Priority (3)

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JP143571/2007 2007-05-30
JP143576/2007 2007-05-30
JP2007143571 2007-05-30

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102589762A (en) * 2012-03-08 2012-07-18 西安交通大学 Micro-voltage high-overload sensor chip of beam membrane single island structure
CN102955045A (en) * 2011-08-17 2013-03-06 精工爱普生株式会社 Physical quantity sensor and electronic apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102955045A (en) * 2011-08-17 2013-03-06 精工爱普生株式会社 Physical quantity sensor and electronic apparatus
CN102589762A (en) * 2012-03-08 2012-07-18 西安交通大学 Micro-voltage high-overload sensor chip of beam membrane single island structure
CN102589762B (en) * 2012-03-08 2014-01-15 西安交通大学 Micro-voltage high-overload sensor chip of beam membrane single island structure

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