JPH08219795A - Angular velocity sensor - Google Patents

Abstract

PURPOSE: To prevent the fixing from occurring when manufacturing by providing a protrusion for assuring an infinitesimal gap between the diaphragm and the board of an angular velocity sensor. CONSTITUTION: A plurality of protrusions 34 are formed at the part where a diaphragm 7 is disposed on a board 32. The diaphragm 7 is alternately vibrated in the directions indicated by arrows A1 and A2 by vibration generators 11. When an angular velocity occurs around an Y-axis, the diaphragm 7 is vibrated in the directions indicated by arrows F1 and F2 by a Coriolis' force. The velocity is detected by this displacement. An infinitesimal gap is always assured between the board 32 and the diaphragm 7 by the protrusions 34, and when manufacturing in the drying step, the diaphragm 7 is prevented from being brought into close contact with the board 32 to be fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor suitable for detecting the direction of rotation, posture, etc. of a vehicle or an aircraft.

[0002]

2. Description of the Related Art A conventional angular velocity sensor will be described with reference to FIGS.

In the figure, 1 is an angular velocity sensor according to the prior art,
Reference numerals 2 denote substrates formed in a rectangular plate shape by a single crystal silicon material having high resistance so as to form the main body of the angular velocity sensor 1, and an insulating film 3 made of silicon oxide is formed on the surface of the substrate 2. Has been done.

Reference numeral 4 denotes a movable portion formed of low-resistance polysilicon doped with P, B, Sb, etc. on the substrate 2, and the movable portion 4 is opposed to the longitudinal direction with an insulating film 3 interposed therebetween. A pair of supporting parts 5 and 5 provided and each supporting part 5
, Which extend in the longitudinal direction (Y-axis direction) from both ends to the central portion, and a diaphragm 7 supported by each of the support beams 6, and the X-axis direction. On the left and right side surfaces of the vibrating plate 7, the plurality of electrode plates 8A, 8A, ...
Movable-side comb-shaped electrodes 8 composed of (five) are formed to project. Further, only each supporting portion 5 is fixed to the substrate 2,
The support beams 6 and the diaphragm 7 are held in a state of being floated from the substrate 2, and the diaphragm 7 is indicated by an arrow A1 so as to be parallel to the substrate 2.
, A2 lateral vibration is generated.

Reference numerals 9 and 9 denote a pair of fixed portions provided on the substrate 2 so as to sandwich the vibrating plate 7 with the insulating film 3 interposed therebetween. Each fixed portion 9 has the movable side comb-shaped electrodes 8 and 8. The fixed-side comb-shaped electrode 10 having the electrode plates 10A, 10A, ... (Five) is formed on the surface facing.

Reference numerals 11 and 11 denote vibration generators serving as vibration generators. Each of the vibration generators 11 is composed of a movable side comb-shaped electrode 8 and a fixed side comb-shaped electrode 10.
A gap is formed between the electrode plates 8A and 10A. Here, when a vibration drive signal of frequency f is applied between the movable side comb-shaped electrode 8 and each fixed side comb-shaped electrode 10, an electrostatic force is generated between the electrode plates 8A and 10A, and this electrostatic force causes The vibrating plate 7 alternately vibrates in the horizontal direction with the substrate 2 with the same magnitude in the directions A1 and A2.

Reference numeral 12 denotes a cover for covering the movable portion 4, the fixed portion 9 and the like from the upper side. The cover 12 is made of an insulating material such as glass material, ceramics, resin, etc., and foreign matter and liquid enter from the outside. It is designed to prevent
Further, the inner center of the cover 12 is formed in a concave shape, and the movable portion 4, the fixed portion 9 and the like are accommodated inside thereof. Further, a detection electrode plate 13 made of platinum-gold-chromium or chrome-gold is formed on the center of the recess of the cover 12 as a film.

Reference numeral 14 denotes a displacement detecting section which serves as a displacement detecting means. The displacement detecting section 14 is composed of a vibrating plate 7 and a detecting electrode plate 13, and a distance between the vibrating plate 7 and the detecting electrode plate 13 is separated. Is detected as a change in capacitance between the detection electrode plate 13 and the vibration plate 7.

In the angular velocity sensor 1 constructed as described above, when a vibration drive signal is applied to each of the vibration generators 11, the vibrating plate 7 has the same size in the directions A1 and A2 shown by the arrows and is alternately arranged on the substrate 2. When the angular velocity Ω is applied around the Y-axis in this state by vibrating in the horizontal direction, Coriolis forces (inertial forces) F1 and F2 are alternately generated in the height directions opposite to each other.

Here, the vibration plate 7 formed by each vibration generating unit 11
The horizontal displacement x and the velocity V of are as in the following equation 1.

[0011]

X = Asin ((2πf) t) V = A (2πf) cos ((2πf) t) where A: amplitude f: frequency of vibration drive signal

Further, the Coriolis forces F1 and F2 are given by the equation (2).

[0013]

[Formula 2] F1 = F2 = 2 mΩ V = 2 mΩ × A (2πf)
cos ((2πf) t) where m: mass of diaphragm 7

Then, as shown in FIGS. 16 and 18, the diaphragm 7 vibrates up and down by the force of the equation 2,
The vibration displacement due to is detected as a change in capacitance between the detection electrode plate 13 and the vibration plate 7, and the angular velocity Ω is detected.

Next, a method of manufacturing the angular velocity sensor 1 described above will be described with reference to FIGS.

First, in the insulating film manufacturing process, a high resistance silicon substrate 21 as shown in FIG. 20 is used, and an insulating film 2 made of an oxide film or a nitride film is formed on the surface of the silicon substrate 21.
2 is deposited (see FIG. 21). The silicon substrate 21 usually has a diameter of about 7.5 to 15.5 cm,
A silicon wafer having a thickness of about 300 μm is used, and when manufacturing the angular velocity sensor 1, a plurality of angular velocity sensors 1 are manufactured at one time from one silicon wafer.

Next, in the sacrifice layer forming step, as shown in FIG. 22, phosphorus-doped SiO ₂ is formed by means of CVD or the like.
The sacrificial layer 23 made of a film is used as the insulating film 22 of the silicon substrate 21.
Form on top.

In the step of forming the silicon layer, as shown in FIG. 23, the polysilicon layer 24 is formed on the silicon substrate 21 by the insulating film 22 or the sacrificial layer 2 by means such as CVD.
3 on top. The polysilicon layer 24 is formed to have a low resistance by diffusing phosphorus or the like. Also, patterning is performed by etching to separately form the movable portion 4, the fixed portion 9 and the like on the polysilicon layer 24.

Further, in the sacrifice layer removing step, as shown in FIG. 24, after the sacrifice layer 23 is removed by means such as wet etching, the sacrifice layer 23 is washed and dried.

Through the above-described manufacturing process, the movable portion 4 formed of the polysilicon layer 24 on the substrate 21 via the insulating film 22.
The fixed portion 8 is formed. Furthermore, as shown in FIG.
In the cover bonding step, the cover 12 is bonded onto the silicon substrate 21 by anodic bonding or an adhesive agent, so that the angular velocity sensor 1 is completed.

In the angular velocity sensor 1 thus formed, as shown in FIGS. 16 and 18, the vibrating plate 7 vibrates up and down by the Coriolis force of the equation 2, and the vibration displacement by the vibrating plate 7 is caused. The angular velocity Ω is detected by detecting the change in the electrostatic capacitance between the detection electrode plate 13 and the vibration plate 7.

[0022]

In the method of manufacturing the angular velocity sensor 1 described above, the silicon substrate 21 is used at a high speed as a method usually used in the method of manufacturing silicon in the drying step after the sacrifice layer removing step shown in FIG. The method of rotating water to scatter water (spin dry) is used.

This method is used for manufacturing the silicon substrate 21,
This method is often used in a photolithography process or the like. With this method, there is a surface tension of the liquid that has entered the portion where the sacrificial layer 23 was present, so that the vibration of the silicon substrate 21 and the silicon substrate 21 occurs in the process of splashing water. There is a risk that the water between the plate 7 and the plate 7 will evaporate and bond without being scattered.

If the silicon substrate 21 and the vibration plate 7 adhere to each other, the vibration plate 7 does not move and the angular velocity sensor 1
However, there is a problem that the yield is reduced.

Therefore, in order to eliminate the above-mentioned problems due to the spin dry method, for example, after washing, pure water is replaced with a suitable solvent having a high melting point (for example, 2-methyl-2-propanol), and this solvent is replaced with this solvent. There is also a method called freeze-drying in which a solid is frozen and then placed in a vacuum device to sublimate the solid.

However, in this method, the silicon substrate 21
The space between the vibrating plate 7 and the vibrating plate 7 becomes solid, and the surface tension to be removed by sublimation does not work, so that adhesion can be prevented.

Further, a method of drying by utilizing the supercritical state of carbon dioxide is also known (Gregory T. Mullem
Others' Supercritical Carbon Dioxide Drying of Microst
ruc-tures', Senser and Actuators (1993)).

However, in the freeze-drying described above, in the step of substituting the solvent (2-methyl-2-propanol) after washing the element, the most important space between the element vibrating plate 7 and the silicon substrate 21 is several .mu.m which is very narrow. Therefore, it will take considerable time to be completely replaced. For example, the space is 1μ
If the size of the diaphragm 7 is about 500 μm square in m, it may take several hours. If the replacement of the solvent is insufficient, it is conceivable that the remaining water does not freeze and the surface tension of the water causes the diaphragm 7 to adhere to the silicon substrate 21. As described above, the number of working procedures increases and it takes time and labor. There is.

Further, the drying method utilizing a state exceeding the critical point has a problem that the number of working steps is increased and a dedicated device is required, resulting in high cost.

On the other hand, even in the completed angular velocity sensor 1, since the space between the substrate 2 and the diaphragm 7 is about several μm, there is a problem in that the sensor 2 may adhere due to external vibration or the like depending on the usage environment of the sensor. .

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can prevent the generation of defective products in the cleaning process and the drying process, improve the yield, and improve the reliability of finished products. It is an object of the present invention to provide an improved angular velocity sensor.

[0032]

An angular velocity sensor according to the present invention comprises a substrate, and a diaphragm supported by the substrate via a support beam and vibrating in a horizontal direction and a vertical direction with respect to the substrate. , A vibration generating means for vibrating the diaphragm horizontally with respect to the substrate, and a vertical direction of the diaphragm due to Coriolis force in a state in which the vibration generating means is vibrating the diaphragm in the horizontal direction. And a displacement detecting means for detecting the displacement.

Then, in order to solve the above-mentioned problems,
A feature of the configuration adopted by the invention of claim 1 is that between the substrate and the diaphragm facing each other, at least one protrudes toward the other, and a minute gap is secured between the substrate and the diaphragm. This is due to the formation of the protruding portion.

According to a second aspect of the present invention, the protrusion is formed by etching an insulating film formed on the surface of the substrate.

According to a third aspect of the present invention, the substrate is provided with a cover for covering the diaphragm so as to accommodate the diaphragm inside, and the displacement detecting means is provided on the cover.

According to a fourth aspect of the present invention, the substrate is made of a single crystal silicon material, and the support beam and the diaphragm are made of a polysilicon material.

According to a fifth aspect of the present invention, a sacrificial layer is formed on the substrate so as to cover the protrusions, and reflow is performed.

[0038]

According to the structure of the first aspect, the vibration is applied to the diaphragm in the horizontal direction by the vibration generating means, and the diaphragm vibrating horizontally with respect to the substrate is rotated about the vibration axis of the diaphragm. When an angular velocity is applied, the diaphragm vibrates in the vertical direction due to the Coriolis force. On the other hand, since the diaphragm detects the displacement of the diaphragm by the displacement detecting means, the angular velocity applied to the diaphragm can be detected. further,
Even if water is present between the diaphragm and the substrate in the drying process, the protrusions ensure a minute gap between the members,
It is possible to prevent the vibrating plate from sticking to the substrate and from adhering to the substrate due to evaporation of water in the drying process.

According to the second aspect, the protrusion can be easily formed by etching the insulating film on the surface of the substrate to form the protrusion.

According to a third aspect of the present invention, the cover is provided on the substrate so as to accommodate the diaphragm inside, and the displacement detecting means is provided on the cover, so that the movable portion and the fixed portion are sealed. It can be accommodated in a space, dust and the like can be prevented from entering, and displacement detecting means can be easily formed.

As described in claim 4, by forming a film of a polysilicon material on the substrate using a silicon material and etching the polysilicon film, a support beam, a diaphragm, etc. can be easily formed.

According to a fifth aspect of the present invention, a sacrificial layer is formed on the substrate so as to cover the protrusions, and reflowing is performed, so that the surface of the sacrificial layer becomes smooth, and the protrusions are formed when the diaphragm is formed. Since the shape of the portion is not transferred to the back surface, the effect of preventing the connection of the protruding portion is further improved.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

First, FIGS. 1 to 11 show a first embodiment of the present invention.

In the figure, reference numeral 31 denotes an angular velocity sensor according to this embodiment. The angular velocity sensor 31 is similar to the angular velocity sensor 1 according to the prior art, and a pair of supports formed on a substrate 32 having an insulating film 33 described later. Parts 5, 5, support beams 6, 6
A movable portion 4 having a diaphragm 7 supported via a diaphragm, and a pair of fixed portions 9 and 9 provided so as to sandwich the diaphragm 7 of the movable portion 4, and vibrates the diaphragm. The generators 11 and 11 include a plurality of electrode plates 8 formed on the vibration plate 7.
A movable side comb-shaped electrode 8 made of A, 8A, ... And a fixed side comb-shaped electrode 10 made of a plurality of electrode plates 10A, 10A ,. Further, the cover 1 having the detection electrode plate 13 on the substrate 32
2 is provided so as to cover the movable portion 4, the fixed portion 9 and the like from above, and the displacement detecting portion 14 (see FIGS. 2 and 3) is configured by the detection electrode plate 13 and the vibration plate 7. It has become.

Here, reference numeral 32 denotes a substrate according to this embodiment, and the substrate 32 is formed in a rectangular plate shape from a single crystal silicon material having high resistance.

Reference numeral 33 denotes an insulating film. The insulating film 33 is a film of silicon oxide formed on the surface of the substrate 32, and a space 33A is formed in the center of the substrate 32 without the insulating film 33. There is.

A plurality of 34, 34, ... (For example, 5)
The protrusions 34 are located in the space 33A of the substrate 32, and are formed so as to project from the substrate 32 toward the diaphragm 7 at predetermined positions as shown in FIG. In addition, each protrusion 34 is configured to form a space 33A and each protrusion 34 by performing a process of etching an insulating film 33 described later.

Next, the manufacturing method will be described with reference to FIGS.
The manufacturing method of the angular velocity sensor 31 described above will be described based on 1.

First, in the insulating film forming step, a high resistance silicon substrate 41 as shown in FIG. 4 is used, and an insulating film 42 made of an oxide film or a nitride film is formed on the surface of the silicon substrate 41.
To form a film (see FIG. 5). The silicon substrate 4
Since a silicon wafer is used for 1, a plurality of angular velocity sensors 31 can be manufactured in one manufacturing process.

Next, in the insulating film patterning step, a resist (not shown) formed on the insulating film 42 is patterned using a photolithography technique, and at this time, at least a portion corresponding to the vibrating portion 7 is formed. After patterning so that the space 33A and the plurality of protrusions 34 are formed, the insulating film 42 is subjected to etching treatment (see FIG. 6).

Next, in the sacrifice layer forming step, as shown in FIG.
Sea urchin, by means of CVD or the like, phosphorus-doped SiO ₂ 
The sacrificial layer 43 made of a film is formed on the protruding portion 34 of the silicon substrate 41.
Is formed so as to cover.

Further, by reflowing at around 950 °, the sacrificial layer 43 which is made uneven by the protrusions 34.
The surface of is melted to form a smooth surface (see FIG. 8).

In the silicon layer forming step, as shown in FIG. 9, the polysilicon layer 4 is formed by means of CVD or the like.
4 is formed on the insulating film 42 or the reflow layer 44 on the silicon substrate 41. The polysilicon layer 44 is formed to have a low resistance by diffusing phosphorus or the like. Also, patterning is performed by etching to separately form the movable portion 4, the fixed portion 9 and the like on the polysilicon layer 44.

Further, in the sacrifice layer removing step, as shown in FIG. 10, an HF aqueous solution (concentration: H ₂ O: HF = 50:
After removing the sacrificial layer 43 by means such as wet etching using 1), a cleaning / drying process is performed.

Through the above-described manufacturing process, the movable portion 4 formed by the polysilicon layer 44 on the substrate 41 with the insulating film 42 interposed therebetween.
The fixed portion 9 is formed. Further, as shown in FIG.
In the cover joining step, the angular velocity sensor 31 is completed by joining the cover 12 onto the silicon substrate 41 by anodic bonding or an adhesive.

In the angular velocity sensor 31 formed in this way, the diaphragm 7 has the same formula 2 as in the prior art.
It vibrates up and down by the Coriolis force, and the vibration displacement by the vibrating plate 7 is detected as a change in the capacitance between the detecting electrode plate 13 and the vibrating plate 7 to detect the angular velocity Ω. There is.

However, in this embodiment, since the plurality of protrusions 34 are formed by etching the insulating film 42, the sacrifice layer 43 is removed by performing wet etching with an HF aqueous solution and then vibrated in a drying process. Board 7 and board 3
Even if water intervenes between the diaphragm 7 and the substrate 2, the tips of the protrusions 34 can abut the diaphragm 7 to secure a minute gap, and by letting water escape from the minute gap, the diaphragm 7 and the substrate 32 sticks together or approaches as water evaporates in the drying process,
It is possible to reliably prevent these from being fixed inseparably.

As a result, according to the present embodiment, the defective products of the angular velocity sensor 31 can be remarkably reduced and the yield can be remarkably improved.

Further, the angular velocity sensor 31 as in this embodiment is used.
By adopting the structure of, in the drying process, it is possible to adopt the spin dry method, which is the most inexpensive and easy to work as compared with the method of drying using freeze drying or the supercritical state of carbon dioxide, The cost of the angular velocity sensor 31 can be reduced.

Further, between the sacrificial layer forming step of forming the sacrificial layer 43 on the silicon substrate 41 and the silicon layer forming step of forming the polysilicon layer 44, the sacrificial layer 43 is reflowed so that the surface becomes smooth. By performing the process, the contact surface between the polysilicon 44 formed on the sacrificial layer 43 and the sacrificial layer 43 can be made substantially flat, and the polysilicon 44, that is, the lower surface of the vibration plate 7 can be made substantially horizontal. The contact area with the protrusion 34 can be reduced only at the tip portion, and a minute gap can be reliably formed between the diaphragm 7 and the substrate 32.

On the other hand, when this reflow process is not performed, the shape of the protrusion 34 is also formed on the lower surface of the polysilicon 44, and the contact area between the vibrating plate 7 and the protrusion 34 becomes the tip portion and the side surface. There is a risk that the protrusion 34 and the diaphragm 7 may be fixed to each other, and this can be reliably avoided by the reflow process.

Next, FIG. 12 shows a second embodiment according to the present invention. The characteristics of the angular velocity sensor 51 according to this embodiment are as follows.
The protrusion 52 is formed so as to protrude from the diaphragm 7 toward the substrate 32 side. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Therefore, the angular velocity sensor 51 according to this embodiment is
Also in the above, it is possible to obtain the same effect as that of the first embodiment described above.

Further, FIG. 13 shows a third embodiment according to the present invention. The characteristics of the angular velocity sensor 61 according to the present embodiment are that a projection portion 62 formed to project from the substrate 32 toward the diaphragm 7 and a vibration This is to form the protrusions 63 protruding from the plate 7 toward the substrate 32 and arrange the protrusions 62, 63 alternately. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Therefore, the angular velocity sensor 61 according to this embodiment is
Also in the above, it is possible to obtain the same effect as that of the first embodiment described above.

Next, FIGS. 14 and 15 show a fourth embodiment. The feature of this embodiment is that it has a pair of diaphragms, and each diaphragm is an angular velocity sensor that vibrates a tuning fork. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 71 denotes an angular velocity sensor according to this embodiment. The angular velocity sensor 71 is formed of a silicon material having high resistance, and a substrate 72 on which an insulating film 73 is formed, and on the substrate 72. In general, the tuning fork vibrator 77 and the fixing portions 83, 84, 84, which will be described later, are formed by processing a polysilicon material using a semiconductor fine processing technique.

Reference numeral 74 denotes a movable portion formed of low-resistance polysilicon, and the movable portion 74 is provided with a pair of support portions 75, 75, which will be described later, that are opposed to each other in the longitudinal direction with an insulating film 73 interposed therebetween. A frame-shaped tuning fork vibrator 7 that is supported by each of the support portions 75 via a support beam 76 and that has vibration plates 78, 78.
It is roughly composed of 7, 77.

Reference numerals 75 and 75 denote supporting portions, and the respective supporting portions 7
5 are spaced apart in the front-rear direction on the substrate 72 via an insulating film 73, and four support beams 76, 76, ... ing.

Reference numeral 77 denotes a frame-shaped tuning fork vibrator supported through each support beam 76. The tuning fork vibrator 77 includes a pair of vibrating plates 78, 78 which are spaced apart from each other in the left-right direction. Vibration side comb-shaped portions 79, 79 formed on both left and right side surfaces of each diaphragm 78 and extending in the left-right direction, respectively, and eight first comb-shaped portions extending from the respective diaphragm plates 78 in the front-rear direction. , And second arm portions 81, 81 extending in the left-right direction by connecting the distal end side of each first arm portion 80 and the distal end side of the support beam 76. In addition, each diaphragm 7
8 is provided with through-holes 82, 82, ... Penetrating in the vertical direction to reduce air resistance when the respective vibration plates 78 are displaced in the vertical direction.

83, 84, 84 are insulating films 7 on the substrate 72.
3 shows a fixed portion fixed through 3, the fixed portion 83 is provided between the vibrating plates 78 (that is, the central portion of the substrate 72), and the fixed portions 84 are located on both left and right sides of the substrate 72. Is provided. In addition, the fixed portion 8 located in the central portion
Fixed side comb-shaped portions 85, 85 are formed on the left and right side surfaces of the third member 3 so as to face the vibration-side comb-shaped portions 79 of the respective vibration plates 78 and engage with the vibration-side comb-shaped portions 79 through a gap. Has been done.
On the other hand, on the inner side surface of each of the fixed portions 84, a fixed-side comb-shaped portion 86 that faces the vibrating-side comb-shaped portion 79 of each of the vibration plates 78 and that meshes with the vibrating-side comb-shaped portion 79 via a gap, 86 are formed respectively.

Reference numerals 87 and 87 denote vibration generating portions as vibration generating means provided between the left and right vibrating plates 78 and 78 with the fixed portion 83 interposed therebetween, and each vibration generating portion 87 has a comb shape on each vibration side. It is composed of a portion 79 and each fixed side comb-like portion 85. When a vibration drive signal is applied to each of the vibration side comb-shaped portions 79 and each of the fixed side comb-shaped portions 85, each vibrating plate 78 vibrates in the arrow A1 and A2 directions by the electrostatic force generated therebetween. To do.

On the other hand, reference numerals 88 and 88 denote vibration generating portions as vibration generating means provided between the vibrating plates 78 and 78 and the fixed portions 84 and 84, respectively, and each of the vibration generating portions 88 has a comb shape on the vibration side. It is composed of a portion 79 and a fixed side comb-shaped portion 86. When a vibration drive signal is applied to the vibrating-side comb-shaped portion 79 and the fixed-side comb-shaped portion 86, the respective vibrating plates 78 cause the arrows A1 and A2 to be generated by the electrostatic force generated therebetween.
Vibrates in the direction.

Reference numerals 89 and 89 denote the vibrating plates 7 of the tuning fork vibrator 77.
8 shows a pair of vibrating side electrode plates respectively provided on 8
Each of the vibrating electrode plates 89 is formed on each of the vibrating plates 78 via an insulating film. An external signal processing circuit (neither is shown) is connected to each of the vibrating electrode plates 89 via a lead wire.
The vibration-side electrode plate 89 is adapted to detect a capacitance between the vibration-side electrode plate 89 and a detection electrode plate 91 described later.
The lead wire connected to each of the vibrating electrode plates 89 is
Each second arm portion 81, each first arm portion 80 and support beam 76.
Etc. are patterned on the upper surface of each supporting portion 75.
Is connected to an external signal processing circuit via.

Reference numeral 90 denotes a cover provided so as to cover the substrate 72 from the upper side, and the cover 90 accommodates the tuning fork vibrator 77, the fixing portions 83, 84, 84 and the like inside, and foreign matter from the outside. And prevent liquids from entering.

Reference numerals 91 and 91 are covers 9 as shown in FIG.
0 is a detection electrode plate located on the inner side of 0 and arranged at a position facing each of the vibration-side electrode plates 89. The detection electrode plates 91 serve as displacement detection means by the vibration-side electrode plate 89. The displacement detection unit 92 is configured to be connected to the above-described signal processing circuit, and detects the capacitance between the vibration side electrode plate 89 and the detection electrode plate 91. There is.

Reference numerals 93, 93, ... Denote projections according to the present embodiment. A plurality of projections 93 are formed so as to project from the substrate 72 toward the vibrating plates 78, and the vibrating plates 78 are in close contact with the substrate 72. Is being prevented.

In the angular velocity sensor 71 of the present embodiment constructed as described above, the support beams 75 and the tuning fork vibrators 77 are formed by integrally forming the support parts 75, the support beams 76 and the tuning fork vibrator 77. Since the child 77 is supported in a floating state on the substrate 72, the support beam 7
By virtue of the tension of 6 and the arm portions 80, 81, the vibration plates 78
Can vibrate in the left-right direction (horizontal direction with respect to the substrate 72) and in the up-down direction (vertical direction).

Next, the angular velocity detecting operation of the angular velocity sensor 71 according to the present embodiment will be described. First, when a vibration drive signal is applied to each of the vibration generating parts 87 and 88, each vibrating side comb-shaped part 79 and each fixed side comb. Electrostatic force is generated between the vibrating side comb-shaped portion 79 and the fixed side comb-shaped portion 86 between the vibrating plate 78 and each of the vibrating plates 78 in opposite directions as indicated by arrows A1 and A2 in the figure. The tuning fork vibrates in the same size. In this state, when the tuning fork axis Y-Y is rotated at an angular velocity Ω about the axis, the Coriolis force F1 is applied to each diaphragm 78 in the direction orthogonal to the tuning fork axis Y-Y.
, F2 (inertial force) is generated. Further, the Coriolis forces F1 and F2 cause leakage vibrations on the vibration plate 78, so that each detection electrode plate 91 facing each vibration side electrode plate 89.
The separation distance between and changes, which changes the capacitance between the two. This is output as an angular velocity detection signal to an external signal processing circuit.

Then, the angular velocity sensor 71 according to the present embodiment.
In the same manner as in the first embodiment described above, it is possible to obtain operational effects such as prevention of sticking between the vibration plate 78 and the substrate 72 in the manufacturing process.

In the fourth embodiment as well, as in the second and third embodiments, the position of the protrusion 93 is formed on the diaphragm 78 side or the diaphragm 78 and the substrate 72 side. Of course, you can do that.

Further, in each of the above-described embodiments, the vibration generating means and the displacement detecting means utilize electrostatic force, but the present invention is not limited to this, and the vibration generating and displacement detection may be performed using a piezoelectric body or the like. You may

Furthermore, in each of the above embodiments, the insulating film 33 is used.
The case where (73) is formed of an oxide film has been described, but the present invention is not limited to this, and may be formed of a nitride film or an oxide film + nitride film.

In each of the above embodiments, the protrusion 34 (5
2, 62, 63, 93) were formed,
1, 2, 3, 4, 6, ... May be used, but in the present invention, when the number of protrusions having a large tip area is increased, the contact area is almost the same as that of the prior art. Occasionally, the protrusions and the vibration plate 7 are fixed to each other to reduce the effect of the present invention. On the other hand, when the number of the protrusions having a small tip area is reduced, the vibration plate 7 may be inclined and fixed to the substrate 32. Therefore, it is necessary to set it by the area of the vibration plate 7 and the distance from the substrate 32 from the relationship between the number of protrusions and the area of the tip.

[0086]

As described in detail above, according to the first aspect of the invention, the vibrating shaft of the vibrating plate is rotated on the vibrating plate which is vibrated by the vibration generating means and vibrates horizontally with respect to the substrate. When an angular velocity about the center is applied, the diaphragm vibrates in the vertical direction due to Coriolis force, and the displacement of the diaphragm is detected by the displacement detecting means. Therefore, the angular velocity applied to the diaphragm can be detected. Furthermore, in the manufacturing method of the angular velocity sensor, even when water is present between the diaphragm and the substrate in the drying step, the protrusion is formed from at least one of the diaphragm and the substrate toward the other. , The protrusion allows a minute gap to be secured between each member, and the vibration plate can be prevented from sticking to the substrate or being adhered to the substrate due to evaporation of water in the drying process, thereby reducing defective products. In addition, the yield can be improved.

According to the second aspect, the protrusion is formed by etching the insulating film on the surface of the substrate, so that the protrusion can be easily formed during the manufacturing process.

According to the third aspect of the present invention, the cover is provided on the substrate so as to house the diaphragm inside, and the displacement detecting means is provided on the cover. Therefore, the movable portion and the fixed portion are enclosed in a closed space. In addition, it is possible to prevent the entry of dust and the like and to easily form the displacement detecting means.

According to a fourth aspect of the present invention, a polysilicon material film is formed on a substrate by using a silicon material, and the polysilicon film is etched to easily support silicon beams by using a silicon etching technique (micromachining technique). It is possible to form a diaphragm or the like.

According to the present invention, since the sacrificial layer is formed on the substrate so as to cover the projecting portion and the reflow process is performed, the surface of the sacrificial layer becomes smooth, and the shape of the projecting portion is formed when the diaphragm is formed. Is not transferred to the back surface, so that the effect of preventing the protrusions from adhering can be further improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an angular velocity sensor according to a first embodiment of the present invention with a part of a cover cut away.

FIG. 2 is a vertical sectional view as seen from the direction of arrows II-II in FIG.

FIG. 3 is a vertical cross-sectional view as seen from the direction of arrows III-III in FIG.

FIG. 4 is a vertical cross-sectional view showing a silicon substrate used in the manufacturing process of the angular velocity sensor.

FIG. 5 is a vertical cross-sectional view showing an insulating film forming step of forming an insulating film on a silicon substrate.

FIG. 6 is a vertical cross-sectional view showing an insulating film patterning process following the insulating film forming process.

FIG. 7 is a vertical cross-sectional view showing a sacrifice layer forming step following the insulating film patterning step.

FIG. 8 is a vertical sectional view showing a reflow step following the sacrificial layer forming step.

FIG. 9 is a vertical cross-sectional view showing a silicon layer forming step following the reflow step.

FIG. 10 is a vertical cross-sectional view showing a sacrifice layer removing step following the silicon layer forming step.

FIG. 11 is a vertical cross-sectional view showing a state before the cover is joined to the silicon substrate.

FIG. 12 is a vertical sectional view showing an angular velocity sensor according to a second embodiment of the present invention.

FIG. 13 is a vertical sectional view showing an angular velocity sensor according to a third embodiment of the present invention.

FIG. 14 is a perspective view showing an angular velocity sensor according to a fourth embodiment of the present invention with a part of the cover cut away.

15 is a vertical cross-sectional view as seen from the direction of arrows XV-XV in FIG.

FIG. 16 is a perspective view showing an angular velocity sensor according to a conventional technique with a part of a cover cut away.

FIG. 17 is a plan view of the angular velocity sensor in FIG. 16 seen from above.

FIG. 18 is a vertical cross-sectional view as seen from the direction of arrows XVIII-XVIII in FIG.

FIG. 19 is a vertical cross-sectional view as seen from the arrow XIX-XIX direction in FIG.

FIG. 20 is a vertical cross-sectional view showing a silicon substrate used in the manufacturing process of the angular velocity sensor.

FIG. 21 is a vertical cross-sectional view showing an insulating film forming step of forming an insulating film on a silicon substrate.

FIG. 22 is a vertical cross-sectional view showing a sacrifice layer forming step following the insulating film forming step.

FIG. 23 is a vertical cross-sectional view showing a silicon layer forming step following the sacrificial layer forming step.

FIG. 24 is a vertical cross-sectional view showing a sacrifice layer removing step following the silicon layer forming step.

FIG. 25 is a vertical cross-sectional view showing a state before the cover is joined to the silicon substrate.

[Explanation of symbols]

 31, 51, 61, 71 Angular velocity sensor 32, 72 Substrate 33, 73 Insulating film 6, 76 Support beam 7, 78 Vibration plate 11, 87, 88 Vibration generating part (vibration generating means) 12, 90 Cover 14, 92 Displacement detection Part (displacement detecting means) 34, 52, 62, 63, 93 Projection part

Front page continued (72) Inventor Kenichi Atsuchi 2-10-10 Tenjin, Nagaokakyo, Kyoto Prefecture Murata Manufacturing Co., Ltd. (72) Inventor Katsuhiko Tanaka 2-10-10 Tenjin, Nagaokakyo, Kyoto Murata Manufacturing Co., Ltd.

Claims (5)

[Claims] 1. A substrate, a vibrating plate supported by the substrate via a supporting beam and provided so as to be vibrable in a horizontal direction and a vertical direction with respect to the substrate, and the vibrating plate is provided in a horizontal direction with respect to the substrate. Angular velocity composed of a vibration generating means for vibrating the diaphragm and a displacement detecting means for detecting a vertical displacement of the diaphragm due to a Coriolis force in a state where the diaphragm is vibrating in the horizontal direction. In the sensor, between the substrate and the vibrating plate facing each other, at least one projecting portion is formed to project toward the other, and a protrusion is formed between the substrate and the vibrating plate to secure a minute gap. Angular velocity sensor. 2. The angular velocity sensor according to claim 1, wherein the protrusion is formed by etching an insulating film formed on the surface of the substrate. 3. The angular velocity sensor according to claim 1, wherein the substrate is provided with a cover that covers the diaphragm so as to be housed therein, and the displacement detecting means is provided on the cover. 4. The angular velocity sensor according to claim 1, wherein the substrate is made of a single crystal silicon material, and the support beam and the diaphragm are made of a polysilicon material. 5. The angular velocity sensor according to claim 1, 2, 3, or 4, wherein a sacrificial layer is formed on the substrate so as to cover the protrusion, and reflow is performed.