JP5373262B2 - Cap fixing method of semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an adhesive agent from overflowing from the specified adhesion area as much as possible when a cap is adhered to a semiconductor substrate having a movable part, and to reduce residual stress during curing of the adhesive agent. <P>SOLUTION: When forming an adhesive layer A in the adhesion area 9 of a cap 6, the adhesive layer A is intermittently formed. Thus, the adhesive layer A is separated by a slit B, so that, when the cap 6 is overlapped over the semiconductor substrate and both are heated and pressed, the expanded adhesive layer A is extended to the slit B to effectively prevent the adhesive agent from overflowing from the adhesion area 9. Furthermore, when the adhesive layer A is cured, the adhesive layer A is separated by the slit B, so that the quantity of shrinkage can be suppressed and residual stress be also reduced. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention relates to a cap fixing method for a semiconductor substrate, in which a cap that is put on a semiconductor substrate provided with a movable portion for protecting the movable portion is fixed with an adhesive.

There is a semiconductor device called a micro electro mechanical system (MEMS) device. This is a structure in which a movable portion is formed on a surface portion of a semiconductor substrate by employing a micromachining technique.
A semiconductor angular velocity sensor (gyro sensor) and a semiconductor acceleration sensor (G sensor) are also a kind of MEMS device. In these sensors, when an angular velocity and an acceleration are applied, a movable portion provided on the surface portion of the substrate generates a distortion corresponding to the applied angular velocity and acceleration. If fine dust or the like adheres to such a movable part, accurate angular velocity and acceleration cannot be measured. Therefore, the movable part is protected by covering the semiconductor substrate with a cap (see, for example, Patent Documents 1 and 2). ).
Japanese Examined Patent Publication No. 6-70643 JP-A-10-209471

  The cap is fixed to the substrate by adhesion. That is, the cap is provided with an adhesive margin around the surface overlapped with the substrate, and the inner portion surrounded by the adhesive margin is a shallow concave portion. A gap is formed between the cap and the cap.

In Patent Document 2, a glass tape is used for forming an adhesive layer, and this glass tape is attached to the entire surface of the cap bonding allowance, and then the glass tape is softened by applying pressure while heating the cap overlaid on the semiconductor substrate. It is melted and bonded. However, in this method of fixing the cap, when the pressure is applied while heating, the softened and melted glass tape (adhesive) may protrude from the bonding allowance. In particular, if the adhesive protrudes toward the inside where the movable part of the semiconductor substrate is located, the function as an acceleration sensor may be impaired. In addition, the adhesive shrinks when it is cured, and during this shrinkage, the adhesive of each part is pulled while being cured, which causes a residual stress in the adhesive. This residual stress will cause cracking of the adhesive later, which may impair the adhesive strength.
As a method of reducing this residual stress, there is a method of bonding at a low temperature as disclosed in Patent Document 1. However, in the case of this low-temperature bonding, there is a problem that there are many restrictions such that it is impossible to perform this in a subsequent process when it is necessary to heat to a temperature higher than that at the time of bonding.

  The present invention has been made in view of the above circumstances, and its purpose is to prevent the adhesive from protruding from the portion determined as the bonding allowance as much as possible and to reduce residual stress remaining when the adhesive is cured. An object of the present invention is to provide a cap fixing method for a semiconductor substrate.

  In the method of fixing a cap of a semiconductor substrate according to claim 1, since the adhesive layer is divided by the slit, the adhesive moves so as to spread toward the slit when pressed while being heated, and the direction protruding from the bonding margin to the outside The spread to is less. For this reason, it can prevent as much as possible that an adhesive protrudes outside from the adhesion allowance. Further, when the adhesive layer is cured, even if the adhesive layer shrinks, the presence of the slits reduces the range of pulling on each other, thereby reducing the residual stress.

As the shape of the adhesive layer, various forms such as a donut shape, a convex shape, or a cross shape are conceivable.

In the cap fixing method according to the sixth aspect of the present invention, since the groove is formed in the bonding margin, the excess adhesive enters the groove. For this reason, it is possible to more reliably prevent the adhesive from protruding from the bonding allowance.

If adhesion margins is rectangular, as in claim 6, it is preferable to increase the internal volume of the grooves at the corner portion of the adhesion margins. If it does in this way, even if an adhesive agent turns around from a both sides toward a corner part, the adhesive agent can be absorbed with a groove | channel and the protrusion of an adhesive agent can be prevented further more reliably.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 3 shows a MEMS device, for example a semiconductor angular velocity sensor 1. The semiconductor angular velocity sensor 1 includes a movable portion 4 that is opposed to a semiconductor substrate 2 via a gap (not shown) and supported by a needle-like body 3, and a pair disposed on both sides of the movable portion 4. The fixed part 5 is composed. Further, the semiconductor substrate 2 is provided with a detection electrode portion (not shown) that faces the movable portion 4 with a gap portion interposed therebetween. The movable part 4 and the detection electrode part constitute a capacitor.

  The movable part 4 has a part between the needle-like bodies 3 as a weight part 4a, and integrally has comb-like movable electrode parts 4b on both left and right sides of the weight part 4a. On the other hand, the fixed portions 5 on both the left and right sides also have a comb-like fixed electrode portion 5a that protrudes so as to mesh with the movable electrode portion 4b of the movable portion 4.

  And the movable part 4 is always horizontal (parallel to the plate surface of the semiconductor substrate 2) by a voltage periodically applied between its movable electrode part 4b and the fixed electrode part 5a of the fixed part 5. Direction). When an angular velocity is applied to the semiconductor angular velocity sensor 1 in this state, vibration in the vertical direction (direction perpendicular to the plate surface of the semiconductor substrate 2) is generated in the movable portion 4. Since the distance between the movable portion 4 and the detection electrode portion changes due to the vertical vibration, a current that flows into the detection electrode portion by applying a constant voltage to the detection electrode portion. The angular velocity applied to the semiconductor angular velocity sensor 1 can be detected from the detected value.

  In such a semiconductor angular velocity sensor 1, if fine dust or the like adheres to the gap between the movable part 4 and the semiconductor substrate 2, it may cause a malfunction. A cap 6 as shown in FIG. The cap 6 is made of, for example, resin. The cap 6 is attached to the semiconductor substrate 2 by bonding. A shallow rectangular recess 7 is formed on the surface to be bonded to the semiconductor substrate 2, and the cap 6 is attached to the semiconductor substrate 2. A recess 8 forms a space 8 between the semiconductor substrate 2 and the semiconductor substrate 2 when bonded.

The semiconductor substrate 2 and the cap 6 of the semiconductor angular velocity sensor 1 have a rectangular shape with the same size. Then, on the surface of the cap 6 on the side to be bonded to the semiconductor substrate 2, the peripheral portion of the recess 7 has a rectangular frame-shaped bonding allowance 9, and an adhesive such as a photosensitive adhesive is thin. A layer (adhesive layer A) is formed. The bonding margin 10 of the semiconductor substrate 2 corresponding to the bonding margin 9 of the cap 6 is an outer portion of the two-dot chain line shown in FIG.
In this embodiment, as shown in FIG. 1, the adhesive layer A is formed discontinuously (intermittently) so as to form a thin strip in the width direction center of the adhesive allowance 9 or a position slightly offset outward. Has been. In this case, the broken portion of the adhesive layer A is a slit B that communicates the inside and outside of the recess 7. In this embodiment, a total of four slits B are provided at the corner portion of the bonding allowance 9.

  In the adhesive forming step, the photosensitive adhesive is initially thinly formed on the entire bonding allowance 9. Thereafter, a portion other than the portion desired to be left as the adhesive layer A is masked and exposed in this state. After the exposure, development is performed to remove portions other than the photosensitive portion from the bonding allowance 9. Thereby, the adhesive layer A is formed in a state where it is divided by the slit B as shown in FIG.

  The cap 6 on which the adhesive layer A is formed is overlaid on the semiconductor substrate 2 and pressed while being heated. By this heating and pressing, the adhesive softens and is crushed and spread. At this time, since the slits B are present in places on the adhesive layer A, a part of the adhesive spreads toward the slits B. For this reason, the amount of the adhesive spreading in the direction protruding from the bonding allowance 9 is reduced, and the protruding of the adhesive from the bonding allowances 9 and 10 is prevented as much as possible. In this case, since it is only necessary to prevent the adhesive from protruding to the movable portion 4 side, the adhesive layer A is provided slightly offset from the center in the width direction of the bonding allowance 9 so that it can be moved. The effect of preventing protrusion to the portion 4 side is further enhanced.

  In particular, the adhesive spreads from the adhesive layer A on two sides that intersect at the corner portion of the bonding portion 9. In consideration of this, in this embodiment, since the slit B is provided in the corner portion of the bonding allowance 9, the adhesive spreading from both sides toward the corner portion can be absorbed by the corner portion. Can be prevented from protruding from the bonding allowance 9 as much as possible.

  The heat-pressed adhesive is eventually cured. At the time of curing, the adhesive shrinks, but the adhesive layer A is divided due to the presence of the slit B, so the length of the continuous adhesive layer A is shortened, and the generation of internal stress due to the shrinkage is suppressed. . As a result, a large residual stress is prevented from remaining in the adhesive layer A.

(Second Embodiment)
FIG. 4 shows a second embodiment of the present invention. The difference from the first embodiment is that the adhesive layer A is formed in a dot shape such as a circle, an ellipse, or a rectangle, and this dot-like adhesion is shown. The layer A is intermittently formed so as to be arranged in a line through the slits B (positioned between the center portions in the width direction of the bonding allowance 9 or slightly outside).
If the adhesive layer A is formed in a dot shape in this way, the adhesive can spread in all directions, so that it is possible to more reliably prevent the adhesive margins 9 and 10 from protruding.

(Third embodiment)
FIG. 5 shows a third embodiment of the present invention. The difference from the first embodiment is that the formation shape of the adhesive layer A is a donut shape. Are formed intermittently so as to be aligned in a row with the slit B in between at the center in the width direction or at a position slightly deviated outward. In this case, at the time of heating and pressurizing, the adhesive spreads to the adhesive non-formation part (blank part) in the center of the doughnut-shaped adhesive layer A. The protrusion from 10 can be prevented.

(Fourth embodiment)
FIG. 6 shows a fourth embodiment of the present invention. The difference from the first embodiment is that the formation shape of the adhesive layer A is changed to a plurality of parallel two lines extending along the adhesive allowance 9. A ladder connected by a wire, and this ladder-like adhesive layer A is formed intermittently so as to be lined up in a row via a slit B at a position that is slightly offset in the center in the width direction of the bonding margin 9 or slightly outward. It is.

(Fifth embodiment)
FIG. 7 shows a fifth embodiment of the present invention. The difference from the first embodiment is that the adhesive layer A is formed in a convex shape, and the convex adhesive layer A is bonded. The slits B are formed in a row so as to engage with each other in opposite directions so that the slits B are in a crank shape (bent shape) at a position slightly deviated to the center in the width direction of the margin 9.
In this embodiment, since the slits B between the convex adhesive layers A have a maze shape (crank shape), it is possible to more effectively prevent dust and the like from entering the recesses 7 through the slits B.

(Sixth embodiment)
FIG. 8 shows a sixth embodiment of the present invention. The difference from the first embodiment is that the formation shape of the adhesive layer A is a cross shape, and this cross-shaped adhesive layer A is bonded to an adhesive allowance 9. The slits B are arranged in a line so as to mesh with each other at the center in the width direction or at a position slightly deviated outward.

(Seventh embodiment)
FIG. 9 shows a seventh embodiment of the present invention. The difference from the first embodiment is that the formation shape of the adhesive layer A is composed of two lines (double line shape) arranged in parallel. The double-lined adhesive layer A is formed intermittently through the slit B at a position biased slightly to the center in the width direction of the bonding allowance 9 or slightly outside.

(Eighth embodiment)
FIG. 10 shows an eighth embodiment of the present invention. The difference from the first embodiment is that the formation shape of the adhesive layer A is a triple line (triple line) arranged in parallel. The adhesive layer A is formed intermittently through the slits B at a position that is biased slightly to the center in the width direction of the adhesive allowance 9 or slightly outside.

(Ninth embodiment)
FIG. 11 shows a ninth embodiment of the present invention. In this embodiment, the formation shape of the adhesive layer A is based on the double line shown in FIG. 9, and the adjacent line between the two lines is shown in FIG. In this configuration, a single line is inserted so as to straddle two lines. In such a case, the slit B is further formed into a labyrinth, so that the intrusion of dust into the concave portion 7 can be more reliably prevented.

(Tenth embodiment)
FIG. 12 shows a tenth embodiment of the present invention. The difference from the first embodiment is that the formation shape of the adhesive layer A is substantially S-shaped, and a part of the adhesive is bonded via the slit B. 9 in the width direction.

(Eleventh embodiment)
FIG. 13 shows an eleventh embodiment of the present invention. The difference from the first embodiment is that the formation shape of the adhesive layer A is substantially square-shaped, and a part of the adhesive is bonded via the slit B. 9 in the width direction.

(Twelfth embodiment)
14 to 16 show a twelfth embodiment of the present invention. The difference from the first embodiment is that an adhesive layer A is formed on the cap 6 and bonded to the cap 6 of the semiconductor substrate 2. The groove 11 is formed in the periphery of the surface. As shown in FIG. 15, the corner portion of the groove 11 (the portion corresponding to the corner portion of the bonding allowance 10) is expanded, for example, in an elliptical shape in order to increase the internal volume of the portion.
If the groove 11 is provided in this way, the adhesive enters the groove 11 as shown in FIG. 16 at the time of heating and pressurization, so that the protrusion from the bonding margins 9 and 10 can be more reliably prevented. it can. In particular, the adhesive spreads from both sides to the corner portion of the bonding allowance 9, but since the inner volume of the corner portion of the groove 11 is large, the adhesive coming from both sides can be sufficiently absorbed.

(13th Embodiment)
FIG. 17 shows a thirteenth embodiment of the present invention. In this embodiment, the groove 11 is provided as in the twelfth embodiment. In order to increase the internal volume of the groove 11 at the corner portion of the semiconductor substrate 2, one side and the other side intersecting at the corner portion are arranged. The groove 11 is extended so as to cross the cross.

(Fourteenth embodiment)
FIG. 18 shows a fourteenth embodiment of the present invention. In this embodiment, the groove 11 is provided in the same manner as the twelfth and thirteenth embodiments. However, the adhesive layer A is formed in the bonding margin 10 of the semiconductor substrate 2, and the groove 11 is bonded to the bonding margin 9 of the cap 6. This is different from the twelfth and thirteenth embodiments.

(Other embodiments)
In the first embodiment shown in FIGS. 1 to 3, the slit B may be provided only in the middle part of the four sides instead of the corner part of the bonding allowance 9. The position and number of the slits B may be determined as appropriate in consideration of prevention of the adhesive layer A from protruding and the degree of residual stress.
The adhesive may be formed by screen printing, may be formed by a transfer method, may be formed by an ink jet method, and various other formation methods are conceivable.
It is not necessary to form the recess 7 in the cap 6 in particular. Even without the recess 7, the cap 6 is lifted from the semiconductor substrate 2 by the thickness of the adhesive, and as a result, a space is formed between the semiconductor substrate 2 and the cap 6.
The adhesive layer A is not limited to the one provided on the cap 6 side and the one provided on the semiconductor substrate 2 side, and may be provided on both.
The cap 6 is not limited to resin, but may be glass, silicon, ceramic, or the like.
The semiconductor substrate to which the cap 6 is fixed is not limited to the semiconductor substrate of the semiconductor angular velocity sensor, but may be a semiconductor substrate of a semiconductor sensor such as a semiconductor acceleration sensor, a semiconductor substrate of a MEMS device, or a semiconductor substrate having a movable part. Widely applicable to.

The top view which shows the formation shape of the adhesive agent in the 1st Embodiment of this invention Sectional view of a semiconductor angular velocity sensor with a cap attached Plan view of main part of semiconductor angular velocity sensor FIG. 1 equivalent diagram showing a second embodiment of the present invention FIG. 1 equivalent view showing a third embodiment of the present invention FIG. 1 equivalent view showing a fourth embodiment of the present invention FIG. 1 equivalent view showing a fifth embodiment of the present invention FIG. 1 equivalent view showing a sixth embodiment of the present invention FIG. 1 equivalent view showing a seventh embodiment of the present invention FIG. 1 equivalent view showing an eighth embodiment of the present invention FIG. 1 equivalent view showing a ninth embodiment of the present invention FIG. 1 equivalent view showing a tenth embodiment of the present invention FIG. 1 equivalent view showing an eleventh embodiment of the present invention Sectional drawing which shows the 12th Embodiment of this invention apart from a board | substrate and a cap Plan view showing the shape of the groove Cross-sectional view for explaining the action of the groove FIG. 15 equivalent diagram showing a thirteenth embodiment of the present invention FIG. 14 equivalent diagram showing the fourteenth embodiment of the present invention

Explanation of symbols

  In the figure, 1 is a semiconductor angular velocity sensor, 2 is a semiconductor substrate, 4 is a movable part, 4a is a weight part, 4b is a movable electrode part, 5 is a fixed part, 5a is a fixed electrode part, 6 is a cap, 7 is a recess, 9 , 10 is a bonding allowance, 11 is a groove, A is an adhesive layer, and B is a slit.

Claims (6)

In a semiconductor substrate cap fixing method in which a cap that covers the movable portion is fixed to a semiconductor substrate provided with a movable portion by an adhesive.
When forming the adhesive at the bonding margin of the semiconductor substrate and / or the cap, by forming the adhesive discontinuously, an adhesive layer separated by a slit is formed,
Then, the semiconductor substrate and the cap are stacked, both are heated and pressurized and fixed by the adhesive layer,
The adhesive layer is a donut-shaped dot pattern formed by developing after exposure and removing portions other than the photosensitive portion , and arranged in the adhesive margin via the slit. A method for fixing a cap of a semiconductor substrate. In a semiconductor substrate cap fixing method in which a cap that covers the movable portion is fixed to a semiconductor substrate provided with a movable portion by an adhesive.
When forming the adhesive at the bonding margin of the semiconductor substrate and / or the cap, by forming the adhesive discontinuously, an adhesive layer separated by a slit is formed,
Then, the semiconductor substrate and the cap are stacked, both are heated and pressurized and fixed by the adhesive layer,
The adhesive layer has a dot-like shape in a plan view, which is patterned by developing after light exposure and removing portions other than the photosensitive portion, and is arranged through the slits in the bonding allowance. A method for fixing a cap of a semiconductor substrate, characterized in that: 3. The method of fixing a cap of a semiconductor substrate according to claim 2, wherein the convex adhesive layers are alternately arranged in reverse directions along the adhesive margin so that the slits are crank-shaped. In a semiconductor substrate cap fixing method in which a cap that covers the movable portion is fixed to a semiconductor substrate provided with a movable portion by an adhesive.
  When forming the adhesive at the bonding margin of the semiconductor substrate and / or the cap, by forming the adhesive discontinuously, an adhesive layer separated by a slit is formed,
Then, the semiconductor substrate and the cap are stacked, both are heated and pressurized and fixed by the adhesive layer,
The adhesive layer is formed in a cross-like dot pattern formed by developing after exposure and removing portions other than the photosensitive portion, and is arranged through the slit in the bonding margin. A method for fixing a cap of a semiconductor substrate. 5. The method of fixing a cap of a semiconductor substrate according to claim 4, wherein the cross-shaped adhesive layers are arranged along the adhesive margin so that the slit has a crank shape. The adhesive layer is formed in one bonding margin of the semiconductor substrate and the cap, and a continuous groove is formed in the other bonding margin,
  The bonding margin is a form that surrounds the movable portion in a rectangular shape, and the groove has a larger inner volume than the other portion at the corner portion of the bonding margin. 6. The method for fixing a cap of a semiconductor substrate according to any one of claims 1 to 5.

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