JP2010060398A - Gyroscope sensor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gyroscope sensor which is excellent in the detection accuracy of an angular velocity, and especially enables its vibrator to be mounted to a package having a flat basal plane, and to provide a method for manufacturing the gyroscope sensor which enables an operation test to be carried out in such a multiple string state that a base of the vibrator is connected. <P>SOLUTION: The gyroscope sensor includes: the vibrator 25 formed of an SOI substrate 33; and a package 40 for containing the vibrator 25. The vibrator 25 is configured to include: the base 17 and arms 15, 16 which are formed on an upper silicon substrate 13; and a pedestal 34 formed of a lower silicon substrate 11 below the base 17 through an insulating layer 12. The pedestal 34 is bonded to a package basal plane 40a, and an allowance space 41 for coping with the downward displacement of the arms is formed between the basal plane 40a and the arms 15, 16. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gyro sensor including a vibrator formed of an SOI substrate and a manufacturing method thereof.

FIG. 6 shows a cross-sectional view of a conventional gyro sensor.
As shown in FIG. 6, the vibrator 1 constituting the gyro sensor is formed of a silicon substrate. The vibrator 1 includes a base portion 2 and an arm portion 3 formed to extend from the base portion 2. Although not shown, a piezoelectric functional element in which a lower electrode, a piezoelectric film, and an upper electrode are stacked in this order is provided on the vibrator 1.

  As shown in FIG. 6, the vibrator 1 is housed in the package 5, and at this time, the arm 3 is moved downward between the arm 3 of the vibrator 1 and the bottom surface 5 a of the package 5. In order to form an allowable space 6 for displacement, a projecting portion 7 projecting upward is formed on the bottom surface 5 a of the package 5. Then, die bonding is performed between the protrusion 7 and the base 2 of the vibrator 1.

  However, the conventional gyro sensor has the following problems. First, the package 5 having a flat bottom surface 5a cannot be used, and it is necessary to process the projecting portion 7 on the bottom surface 5a of the package 5.

  Further, in order to obtain a predetermined detection accuracy, it is necessary to position the base 2 with respect to the protruding portion 7 with high accuracy.

  Further, since the adhesive layer 8 by die bonding is provided directly below the base portion 2 formed of the silicon substrate, the stress generated in the adhesive layer 8 is likely to affect the arm portion 3. Therefore, the accuracy of angular velocity detection is likely to be lowered.

Further, the vibrator 1 is formed in a multiple state in which the base 2 is connected, and is finally divided into individual vibrators 1 and each vibrator 1 is accommodated in each package 5. Conventionally, in the above-described multiple state, the strength of the connected bases 2 is very weak, so that the bases 2 are in an unstable state. Therefore, it is difficult to stably move the vibrator 1 in the multiple state to the operation test apparatus and to set the operation test for the vibrator 1 in the multiple state. Further, in the vibrator 1 in a multiple state, there is a high possibility that the weak base portion 2 may be damaged during movement or setting. Therefore, it was necessary to perform an operation test after dividing the vibrator 1. Further, in order to perform the operation test, it is necessary to position and fix each vibrator 1 on an installation surface in which the protruding portion 7 is formed on the bottom surface 5a as shown in FIG. Further, when an operation test is performed after the vibrator 1 is incorporated in the package 5, when it is determined as a defective product, the entire package must be disposed of, resulting in a reduction in productivity.
JP 2008-58066 A JP-A-8-233852 JP 2007-316090 A

  Therefore, the present invention is to solve the above-described conventional problems, and in particular, to provide a gyro sensor in which a vibrator can be installed in a package having a flat bottom surface and excellent in angular velocity detection accuracy and a method for manufacturing the same. It is aimed.

  It is another object of the present invention to provide a method for manufacturing a gyro sensor capable of performing an operation test in a multiple state in which the bases of vibrators are connected.

The gyro sensor in the present invention is
A vibrator formed of an SOI substrate including an upper silicon substrate, a lower silicon substrate, and an insulating layer interposed between the upper silicon substrate and the lower silicon substrate; and a package for housing the vibrator. Have
The vibrator includes a base portion formed on the upper silicon substrate and an arm portion extending from the base portion, and a pedestal portion formed by the lower silicon substrate via the insulating layer below the base portion. And
The pedestal portion is bonded to the bottom surface of the package, and an allowable space for downward displacement of the arm portion is formed between the bottom surface of the package and the arm portion. .

  In the present invention, it is possible to use a package in which a region facing the vibrator on the bottom surface is formed as a flat surface.

  As described above, according to the present invention, even when a package having a flat bottom surface is used, an allowable space for the downward displacement of the arm portion can be appropriately and easily formed between the arm portion and the bottom surface of the package. Moreover, the influence with respect to the arm part of the stress which arose in the joining area | region between a base part and a package bottom face can be suppressed effectively.

Moreover, the manufacturing method of the gyro sensor in the present invention is as follows.
(A) a base portion on the upper silicon substrate of an SOI substrate including an upper silicon substrate, a lower silicon substrate, and an insulating layer interposed between the upper silicon substrate and the lower silicon substrate, and an arm portion extending from the base portion Forming a plurality of arm portions corresponding to a plurality of the vibrators, and connecting the base parts of the vibrators,
(B) forming a mask layer at a position facing the base on the back surface of the lower silicon substrate;
(C) removing the other lower silicon substrate so that the lower silicon substrate with the mask layer formed on the back surface remains as a pedestal;
(D) leaving the insulating layer between the pedestal part and the base part and removing the other insulating layer;
(E) removing the mask layer;
(F) cutting the base and dividing it into each vibrator;
(G) joining the pedestal portion of the vibrator to a bottom surface of a package to form an allowable space for downward displacement of the arm portion between the bottom surface of the package and the arm portion;
It is characterized by having.

  As described above, a plurality of vibrators having a pedestal portion can be simultaneously formed by a simple manufacturing method. In addition, a package having a flat bottom surface can be used, and when the pedestal part is joined to the bottom surface of the package, an allowable space for downward displacement of the arm part is appropriately formed between the bottom surface of the package and the arm part. It is possible.

  Further, in the present invention, it is preferable that an operation test is performed on each vibrator in a multiple state in which the base is connected between the step (e) and the step (f). In the present invention, a pedestal portion made of a lower silicon substrate is formed at a position facing the base portion. Therefore, the strength of the connected base portions can be kept high. Accordingly, movement to the operation test process, setting, and the like can be smoothly performed in a stable state. Moreover, at this time, it can suppress effectively that the part of the connected base part receives damage, such as bending. In addition, by temporarily joining the pedestal part to the installation surface of the motion test apparatus or holding the pedestal part, the allowable space for the downward displacement of the arm part can be easily and appropriately placed under the arm part. Can be formed. Therefore, in the present invention, the operation test can be appropriately performed in a multiple state in which the bases are connected. If there is a defective product in the operation test, the vibrator can be discarded before the vibrator is incorporated into the package, and productivity can be improved.

  According to the present invention, a vibrator can be installed in a package having a flat bottom surface, and a gyro sensor excellent in angular velocity detection accuracy can be formed.

  In addition, it is possible to appropriately perform an operation test in a multiple state where the bases of the vibrators are connected.

  FIG. 1A is a plan view of a vibration type gyro sensor according to the present embodiment, and FIG. 1B is a cross sectional view taken along line AA in FIG. FIG.

  The X-axis direction and the Y-axis direction in each figure indicate two orthogonal directions in the substrate plane. The Z-axis direction indicates a height direction (vertical direction) orthogonal to the X-axis direction and the Y-axis direction.

  As shown in FIG. 1, the vibration type gyro sensor 10 includes a vibrator 25 and a package 40 for housing the vibrator 25.

The vibrator 25 is an SOI having a laminated structure of a lower silicon substrate 11, an upper silicon substrate 13, and an insulating layer (specifically, SiO ₂ ) 12 formed between the lower silicon substrate 11 and the upper silicon substrate 13. The substrate 33 is formed by processing.

  In the form shown in FIG. 1, the vibrator 25 is a tuning fork vibrator, but is not particularly limited. As shown in FIGS. 1 (a) and 1 (b), the upper silicon substrate 13 constituting the vibrator 25 has a plurality of arm portions 15 and 16 (first) extending long in the Y-axis direction with a predetermined interval in the X-axis direction. 1 arm part 15 and 2nd arm part 16), and the base 17 which connects the one end part side of these arm parts 15 and 16 are formed. The number of arms 15 and 16 is not limited to the two shown in FIG.

  As shown in FIG. 1B, a pedestal 34 formed of the lower silicon substrate 11 is formed under the base 17 with the insulating layer 12 interposed. The insulating layer 12 is interposed between the base portion 17 and the pedestal portion 34. However, the insulating layer 12 may be such that the outer peripheral portion in the facing region between the base portion 17 and the pedestal portion 34 is removed, and the planar area of the insulating layer 12 is smaller than the area of the facing region.

  The lower surface 34a of the pedestal 34 is joined to the bottom surface 40a of the package 40 by die bonding or the like. Reference numeral 35 denotes an adhesive layer. Although not shown, the upper surface of the package 40 is closed by a lid, and the interior surrounded by the package 40 and the lid is hermetically sealed.

  As shown in FIGS. 1A and 1B, the piezoelectric functional element 14 is formed on the vibrator 25. The piezoelectric functional element 14 is formed on the upper surface of the upper silicon substrate 13 extending from the arm portions 15 and 16 to the base portion 17. Hereinafter, the form of the piezoelectric functional element 14 will be described.

  As shown in FIG. 1A, a first drive unit 18 and a second drive unit 19 provided on the upper silicon substrate 13 constituting the first arm unit 15 so as to be separated from each other in the X-axis direction, and a drive A detection unit 20 provided between the units 18 and 19 is provided.

  As shown in FIG. 1B, the first driving unit 18 and the second driving unit 19 are composed of a lower electrode 28 from the bottom, for example, a piezoelectric film 29 made of PZT and polarized in the vertical direction (Z-axis direction), and The upper electrode (drive electrode) 31 is laminated in this order.

  The detection unit 20 is also laminated in order of a lower electrode 28 from the bottom, for example, a piezoelectric film 29 made of PZT and polarized in the vertical direction (Z-axis direction), and an upper electrode (detection electrode) 31.

  The detection unit 20 is provided along the Y-axis direction at a substantially central position in the X-axis direction (width direction) of the arm unit 15, and each drive unit 18, 19 is moved from the detection unit 20 in the X-axis direction (width direction). ) At substantially equal intervals along the Y-axis direction.

  As shown in FIG. 1A, the same piezoelectric functional element 14 as the first arm portion 15 is also formed on the second arm portion 16 side. The piezoelectric functional element 14 formed on the first arm portion 15 and the piezoelectric functional element 14 formed on the second arm portion 16 are in the Y-axis direction between the first arm portion 15 and the second arm portion 16. It is formed in a line symmetrical relationship with the center line as the axis of symmetry.

  The lower electrode 28 functions as a common ground, and a part of the lower electrode 28 is exposed as an electrode pad from a hole 29a formed in the piezoelectric film 29 as shown in FIG.

  As shown in FIG. 1A, the upper electrode 31 of the first driving unit 18 formed on the first arm unit 15 and the upper electrode 31 of the first driving unit 18 formed on the second arm unit 16 are A wiring pattern and a common electrode pad 21 connected to both the wiring patterns and formed on the piezoelectric film 29 of the base portion 17 are configured.

  As shown in FIG. 1A, the upper electrode 31 of the second driving unit 19 formed on the first arm unit 15 and the upper electrode 31 of the second driving unit 19 formed on the second arm unit 16 are And a wiring pattern and a common electrode pad 22 connected to both wiring patterns and formed on the piezoelectric film 29 of the base portion 17.

  Further, as shown in FIG. 1A, the upper electrode 31 of the detection unit 20 formed on the first arm unit 15 and the upper electrode 31 of the detection unit 20 formed on the second arm unit 16 are connected to the wiring pattern. The electrode pads 23 and 24 are connected to each wiring pattern and formed on the piezoelectric film 29 of the base portion 17.

  Wire bonding is performed on each electrode pad to electrically connect to an integrated circuit (IC) (not shown). Driving vibrations whose phases are opposite to each other are supplied to the electrode pads 21 and 22 from the integrated circuit. At this time, for example, when the piezoelectric film 29 of the first drive unit 18 contracts in the Y-axis direction due to the piezoelectric effect, the piezoelectric film 29 of the second drive unit 19 extends in the Y-axis direction. As a result, the arm portions 15 and 16 are bent in the X-axis direction in the opposite phase to cause tuning fork vibration.

  As described above, when the vibrator 25 is tuning fork vibrated in the X-axis direction, when the angular velocity Ω around the Y-axis is applied to the vibration-type gyro sensor 10, the arm portions 15 and 16 are moved in the Z-axis direction by Coriolis force. Displaces in the opposite phase. The displacement amount of each arm part 15 and 16 at this time is detected by the upper electrode 31 of the detection part 20 provided in each arm part 15 and 16. The charges detected by the upper electrodes 31 of the arm portions 15 and 16 have opposite polarities, and these charges are guided to the electrode pads 23 and 24, respectively. Then, signal processing is performed by an integrated circuit electrically connected to the electrode pads 23 and 24 through wire bonding, and an angular velocity signal is output.

  As shown in FIG. 1, in the present embodiment, a pedestal portion 34 formed of the lower silicon substrate 11 is formed below the base portion 17 formed of the upper silicon substrate 13 with the insulating layer 12 interposed therebetween. The pedestal portion 34 is joined to the bottom surface 40 a of the package 40. Thus, even when the package 40 having the flat bottom surface 40a is used, the arm portions 15 and 16 are allowed to be displaced downwardly between the arm portions 15 and 16 formed of the upper silicon substrate 13 and the bottom surface 40a of the package 40. The space 41 can be appropriately formed.

  Further, by joining the pedestal portion 34 and the bottom surface 40 a of the package 40, it is possible to effectively suppress the influence of the stress generated in the adhesive layer 35 on the arm portions 15 and 16.

  Thus, in this embodiment, no special processing is required for the bottom surface 40a of the package 40 in order to form the allowable space 41, and the package structure can be simplified.

  Or the freedom degree of a process of the bottom face 40a can be raised. The thickness of the pedestal portion 34 is about 250 to 350 μm and the downward displacement of the arm portions 15 and 16 is about 1 μm at the maximum. That's enough. Therefore, in this embodiment, the bottom surface 40a of the region facing the vibrator 25 can be formed as a flat surface. However, if the displacement of the arm portions 15 and 16 can be ensured, it may not be a flat surface. Therefore, in the configuration of the present embodiment, the degree of freedom in processing the bottom surface 40a can be increased. The region other than the region facing the vibrator 25 can be arbitrarily set, whether it is formed with a flat surface or an uneven surface.

  Further, since the bonding to the bottom surface 40a of the package 40 is the lower surface 34a of the pedestal 34 in the vibrator 25, a slight positional deviation can be allowed. That is, in this embodiment, since the extension length of the arm parts 15 and 16 from the base part 34 is constant irrespective of the installation position with respect to the package 40 of the base part 34, the installation position of the base part 34 shifts a little. Does not significantly affect the characteristics.

  Moreover, since the influence with respect to the arm parts 15 and 16 which arises in the joining area | region can be suppressed, it becomes possible to improve the detection accuracy of angular velocity.

  A method for manufacturing the gyro sensor of this embodiment will be described with reference to FIGS. 3 to 5 are cross-sectional views of the vibrator 25 during the manufacturing process cut from the same portion as FIG. FIG. 2 is a plan view of the vibrator 25 during the manufacturing process.

As shown in FIG. 2, the lower silicon substrate 11, the insulating layer (specifically, SiO ₂ layer) 12 and the upper silicon substrate 13 are stacked in this order from the bottom to the upper silicon substrate 13 of the SOI substrate 33. The extending arm portions 15 and 16 are formed by deep RIE or the like.

  As shown in FIG. 2, a plurality of sets of arm portions 15 and 16 (total of six in FIG. 2) corresponding to a plurality of vibrators 25 (three in FIG. 2) are formed, and the vibrators 25 are connected. A base 50 is formed.

  As shown in FIG. 2, it is assumed that a piezoelectric functional element 14 including a lower electrode, a piezoelectric film, and an upper electrode is already formed for each vibrator 25.

  Next, as shown in FIG. 3, a mask layer 51 made of, for example, a resist is formed on the back surface 11 a of the lower silicon substrate 11 facing the base portion 50 formed on the upper silicon substrate 13. The mask layer 51 is formed on the entire region facing the base 50 by using, for example, a photolithography technique.

  Subsequently, in the step shown in FIG. 4, all the lower silicon substrate 11 exposed on the other back surface is removed so that the lower silicon substrate 11 having the mask layer 51 formed on the back surface 11 a remains as the pedestal portion 52. At this time, the lower silicon substrate 11 is removed by RIE or the like.

  The pedestal portion 52 formed in the above-described process is formed in the same size as the base portion 50. That is, a pedestal 52 is formed on the entire surface under the base 50.

  Next, in the step shown in FIG. 5, the insulating layer 12 is left between the pedestal portion 52 and the base portion 50, and the insulating layer 12 exposed on the other back surface is removed. At this time, a selective etching agent is used so that only the insulating layer 12 can be etched without etching the silicon substrates 11 and 13. In the process of FIG. 5, the insulating layer 12 near the outer periphery between the pedestal 52 and the base 50 may be partially removed due to the penetration of the etching agent.

Then, the mask layer 51 is removed.
In the manufacturing method described above, a plurality of vibrators 25 are formed in a multiple state in which the vibrators 25 are connected at the base 50 portion. In the portion of the base portion 50 formed of the upper silicon substrate 13 shown in FIG. 2, a pedestal portion 52 formed of the lower silicon substrate 11 is formed thereunder via the insulating layer 12. Therefore, the strength of the connected base 50 can be effectively increased.

  In the present embodiment, an operation test can be performed on each transducer 25 before dividing the transducers 25 in a multiple state into individual transducers 25. That is, in the present embodiment, the strength of the connected base portions 50 can be kept high, so that the movement of the multi-state vibrator 25 to the operation test apparatus and the setting for the operation test can be smoothly performed in a stable state. Can be done. In addition, at this time, it is possible to suppress damage such as bending of the connected base portion 50. Further, by temporarily joining the pedestal portion 52 to the installation surface of the operation test apparatus or sandwiching the pedestal portion 50, the arm portions 15, 16 can be moved downwardly and easily under the arm portions 15, 16. An allowable space for displacement can be formed. Therefore, in this embodiment, an operation test can be appropriately performed in a multiple state where the base 50 is connected. If there is a defective product in the operation test, the vibrator 25 can be discarded before the vibrator 25 is incorporated into the package, and productivity can be improved.

  Subsequently, the base 50 is cut to divide the vibrators 25 in a multiple state individually. Thereby, the vibrator 25 shown in FIG. 1 is completed. And the base part 34 is joined to the bottom face 40a of the package 40 by die bonding. At this time, an allowable space 41 for the downward displacement of the arm portions 15, 16 is formed between the bottom surface 40 a of the package 40 and the arm portions 15, 16.

  According to the manufacturing method described above, the plurality of vibrators 25 including the pedestal portion 34 can be simultaneously formed by a simple manufacturing method. Further, the package 40 having a flat bottom surface 40a can be used, and when the pedestal 34 is joined to the bottom surface 40a of the package 40, the arm portion 15 is simply and appropriately interposed between the bottom surface 40a and the arm portions 15 and 16. , 16 is allowed to form a permissible space 41 for downward displacement. Further, when the vibrator 25 is joined to the bottom surface 40a of the package 40, a slight positional deviation can be allowed.

(A) is a plan view of the vibration-type gyro sensor in the present embodiment, (b) is a cross-sectional view of the vibration-type gyro sensor taken along the line AA in FIG. A plan view of the vibrator 25 during the manufacturing process; Sectional drawing of the vibrator | oscillator 25 in the manufacturing process cut | disconnected from the same part as Fig.1 (a), Sectional drawing which shows the process performed after FIG. Sectional drawing which shows the process performed after FIG. Partial sectional view of a conventional vibration type gyro sensor,

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vibration type gyro sensor 11 Lower silicon substrate 12 Insulating layer 13 Upper silicon substrate 14 Piezoelectric functional element 15, 16 Arm part 17, 50 Base part 25 Vibrator 34, 52 Base part 40 Package 40a (of package) bottom surface 41 Allowable space 51 Mask layer

Claims (4)

A vibrator formed of an SOI substrate including an upper silicon substrate, a lower silicon substrate, and an insulating layer interposed between the upper silicon substrate and the lower silicon substrate; and a package for housing the vibrator. Have
The vibrator includes a base portion formed on the upper silicon substrate and an arm portion extending from the base portion, and a pedestal portion formed by the lower silicon substrate via the insulating layer below the base portion. And
The gyro sensor according to claim 1, wherein the pedestal portion is joined to a bottom surface of the package, and an allowable space for downward displacement of the arm portion is formed between the bottom surface of the package and the arm portion.   The gyro sensor according to claim 1, wherein a region of the bottom surface facing the vibrator is a flat surface. (A) a base portion on the upper silicon substrate of an SOI substrate including an upper silicon substrate, a lower silicon substrate, and an insulating layer interposed between the upper silicon substrate and the lower silicon substrate, and an arm portion extending from the base portion Forming a plurality of arm portions corresponding to a plurality of the vibrators, and connecting the base parts of the vibrators,
(B) forming a mask layer at a position facing the base on the back surface of the lower silicon substrate;
(C) removing the other lower silicon substrate so that the lower silicon substrate with the mask layer formed on the back surface remains as a pedestal;
(D) leaving the insulating layer between the pedestal part and the base part and removing the other insulating layer;
(E) removing the mask layer;
(F) cutting the base and dividing it into each vibrator;
(G) joining the pedestal portion of the vibrator to a bottom surface of a package to form an allowable space for downward displacement of the arm portion between the bottom surface of the package and the arm portion;
A method for manufacturing a gyro sensor, comprising:   4. The method for manufacturing a gyro sensor according to claim 3, wherein an operation test is performed on each of the vibrators in a multiple state in which the base is connected between the step (e) and the step (f).

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