JP2005049208A - Acceleration sensor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acceleration sensor small in size and low in cost, and to provide a method of manufacturing the same. <P>SOLUTION: Between the sensor main part 1 composed of an overlapping part 12 arranged inside the frame part 11 and supported by the frame part 11 via the 4 bending parts 13, and the bottom wall 3a of the boxy package 3 to store the sensor main part 1 therein, a sheetlike stopper 2 is interposed. The stopper 2 is formed from a thermosetting adhesive film by thermosetting. The sensor main body 1 constitutes the semiconductor acceleration sensor main body, and the package 3 constitutes the base member. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an acceleration sensor used in various fields such as consumer electronics such as home appliances and entertainment products, and a manufacturing method thereof.

  In recent years, semiconductor sensors such as semiconductor acceleration sensors and semiconductor pressure sensors have been widely used in various fields such as consumer electronics such as home appliances and entertainment products, and in particular, they have sensitivity to accelerations in multiple directions. The demand for semiconductor multi-axis acceleration sensors is increasing rapidly. As a general semiconductor acceleration sensor, a so-called cantilever type semiconductor acceleration sensor and a so-called doubly-supported type semiconductor acceleration sensor are known. As a detection method, mechanical strain is measured by electric resistance. There are known a method for detecting a change and a method for detecting a displacement of a weight part as a change in capacitance.

  Here, as a doubly supported semiconductor multi-axis acceleration sensor for detecting mechanical strain as a change in electrical resistance, for example, a sensor having a configuration shown in FIG. 14 has been proposed (see, for example, Patent Document 1). . The semiconductor multi-axis acceleration sensor having the configuration shown in FIG. 14 has a glass on the back surface of a sensor body (semiconductor acceleration sensor body) 1 ′ formed using a so-called epi substrate 200 in which a silicon epitaxial layer 202 is grown on a silicon substrate 201. A stopper 2 'made of a substrate is bonded by anodic bonding.

  The sensor body 1 ′ includes a frame portion 11 ′ having a rectangular frame shape, and a weight portion 12 ′ disposed on the inner side of the frame portion 11 ′ via four flexible portions 13 ′ that are thinner than the frame portion 11 ′. It has a structure that is continuously and integrally connected to the frame portion 11 '. The four bent portions 13 'are arranged in a cross shape.

  Two piezoresistors R are formed in each bent portion 13 'as resistors for detecting strain. The piezoresistors R are connected by wiring (not shown) so as to form two bridge circuits. Further, pads 16 serving as terminals of the bridge circuit are formed on the frame portion 11 '.

  Here, as shown on the left side of FIG. 14, the thickness direction of the sensor body 1 ′ is the z-axis direction, and the direction along one side of the frame portion 11 ′ in the plane orthogonal to the z-axis direction is the x-axis direction. If the direction along the side orthogonal to the y-axis direction is defined as the y-axis direction, the weight portion 12 'is extended in the y-axis direction with a pair of bent portions 13' and 13 'extended in the x-axis direction. In addition, it is supported by the frame portion 11 ′ via a pair of bending portions 13 ′ and 13 ′, and is formed in two bending portions 13 ′ and 13 ′ extended in the x-axis direction. A total of four piezoresistors R are electrically connected by wiring so as to form a bridge circuit for detecting acceleration in the x-axis direction, and are formed in two flexures 13 ′ and 13 ′ extended in the y-axis direction. A total of four piezoresistors R are used to detect acceleration in the y-axis direction. It is electrically connected by a wiring so as to constitute a bridge circuit.

  The stopper 2 ′ has a rectangular outer shape, and a peripheral portion is joined to the back surface of the sensor body 1 ′ by anodic bonding, and the movement range of the weight portion 12 ′ is set on the surface facing the weight portion 12 ′. A recess 2a ′ for securing is formed. The stopper 2 'has a function of limiting the amount of displacement of the weight portion 12'.

  In the semiconductor multi-axis acceleration sensor having the configuration shown in FIG. 14 described above, when an external force (that is, acceleration) including a component in the x-axis direction or the y-axis direction acts on the sensor body 1 ′, the inertia of the weight portion 12 ′. The weight portion 12 ′ is displaced with respect to the frame portion 11 ′. As a result, the bent portion 13 ′ is bent, and the resistance value of the piezoresistor R formed in the bent portion 13 ′ is changed. That is, by detecting a change in the resistance value of the piezoresistor R, the acceleration in the x-axis direction or the y-axis direction that has acted on the sensor body 1 ′ can be detected.

  Incidentally, in the sensor main body 1 ′ in FIG. 14, etching is performed from the back side of the epitaxial substrate 200 using an alkaline solution such as a potassium hydroxide aqueous solution (KOH) in order to separate the frame portion 11 ′ and the weight portion 12 ′. Since anisotropic etching by wet etching is performed using the crystal orientation dependence of speed, a mask formed on the back surface of the epitaxial substrate 200 when the sensor body 1 ′ is miniaturized to perform the anisotropic etching. Therefore, the length of the bent portion 13 'is shortened and it is difficult to achieve high sensitivity. Therefore, in the sensor body 1 ′ in FIG. 14, the sensitivity is increased by increasing the length of the bent portion 13 ′ by forming the cut groove 203 after performing the anisotropic etching.

The semiconductor multi-axis acceleration sensor having the configuration shown in FIG. 14 is housed in a package (not shown) or mounted on a substrate (not shown).
JP-A-9-289327 (pages 3 to 4, FIGS. 1 and 2)

  By the way, in each of the semiconductor multi-axis acceleration sensors described above, the displacement of the weight portion 12 ′ can be limited by the stopper 2 ′ made of a glass substrate. Therefore, when excessive acceleration is applied in the z-axis direction, the bending portion 13 ′. Etc. can be prevented from being damaged.

  However, in each of the semiconductor multi-axis acceleration sensors described above, the sensor body 1 ′, which is the semiconductor acceleration sensor body, and the stopper 2 ′ are fixed by anodic bonding. In the dicing process of separating into the main body 1 ′, the cutting margin of the chip has to be relatively large, the number of chips obtained from one wafer is reduced, the manufacturing cost is increased, and the sensor main body 1 ′ is increased. It gets bigger.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide an acceleration sensor that can be reduced in size and reduced in cost and a method for manufacturing the same.

  According to the first aspect of the present invention, the weight portion disposed inside the frame-shaped frame portion is supported by the frame portion via at least one set of bending portions disposed with the weight portion interposed therebetween, and the displacement of the weight portion relative to the frame portion is achieved. The semiconductor acceleration sensor main body in which the resistor whose resistivity is changed by the strain generated in the bending portion is formed in the bending portion, the base member for fixing the semiconductor acceleration sensor main body, and the semiconductor acceleration sensor main body and the base member interposed A stopper for limiting the displacement of the weight part, and the stopper is formed by thermosetting a thermosetting adhesive film. Examples of the base member include a package and a substrate.

  According to the present invention, in the dicing process of separating a wafer formed with a large number of semiconductor acceleration sensor main bodies into individual semiconductor acceleration sensor main bodies, the cutting margin of the chip (semiconductor acceleration sensor main body) can be reduced as in the prior art. Since the number of chips obtained from one wafer can be increased, the size of the semiconductor acceleration sensor body can be reduced, and the size and cost can be reduced. Can be easily achieved. Note that there is a correlation between the cutting margin and the thickness of the chip, and the cutting margin tends to increase as the thickness of the chip increases. The reason for this tendency is that as the thickness of the chip increases, the power required for cutting increases, and a dicing saw that can withstand it must be used, and a thicker dicing saw must be used. It is.

  According to a second aspect of the present invention, in the first aspect of the invention, the frame portion opens the stopper side and the weight portion side over the entire circumference of the end portion on the weight portion side on the surface facing the stopper. A recess is formed, and the distance between the surface facing the stopper in the recess and the stopper is set so as not to be less than the distance between the weight and the stopper.

  According to this invention, it can prevent that the said thermosetting adhesive film and the said weight part adhere | attach at the time of the thermosetting of the said thermosetting adhesive film.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the thermosetting adhesive film has an adhesion preventing recess that prevents the thermosetting adhesive film from adhering to the weight portion during thermosetting. It is formed on the opposing surface.

  According to this invention, it is possible to prevent the thermosetting adhesive film and the weight part from adhering at the time of thermosetting the thermosetting adhesive film, and it is possible to reduce the cost by improving the production yield.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the thermosetting adhesive film is formed such that a portion facing the weight portion is cured in advance before being overlapped with the semiconductor acceleration sensor main body. Features.

  According to this invention, it is possible to prevent the thermosetting adhesive film and the weight part from being bonded at the time of manufacturing, and cost reduction can be achieved by improving the manufacturing yield.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the invention, the base member is provided with a support protrusion that holds the peripheral portion of the stopper between the frame portion and the central portion of the stopper. A gap is formed between the two.

  According to this invention, it is possible to prevent the thermosetting adhesive film and the weight part from being bonded at the time of manufacturing, and cost reduction can be achieved by improving the manufacturing yield.

  The invention of claim 6 is characterized in that, in the inventions of claims 1 to 5, the thermosetting adhesive film is made of a material having a smaller elastic modulus than the material of the base member.

  According to this invention, compared with the case where the stopper is made of a material having a larger elastic modulus than the base member, the bending portion breaks when the weight portion collides with the stopper due to excessive acceleration. This reduces the possibility of doing so and improves reliability.

  The invention of claim 7 is characterized in that, in the inventions of claims 1 to 6, the thermosetting adhesive film is formed of an epoxy resin.

  According to this invention, compared with the case where the thermosetting adhesive film is formed of another thermosetting resin such as a ferrule resin or an unsaturated polyester resin, the adhesive force between the stopper and the semiconductor acceleration sensor main body is increased. In addition, the adhesive force between the stopper and the base member can be increased, and the chemical and electrical stability of the stopper is increased.

  The invention of claim 8 is characterized in that, in the inventions of claims 1 to 7, the thermosetting adhesive film contains a filler.

  According to the present invention, it is possible to prevent a phenomenon in which the frame portion of the semiconductor acceleration sensor body sinks into the stopper due to temporary softening of the thermosetting adhesive film when the thermosetting adhesive film is heated. Therefore, when the thermosetting adhesive film is heated, the thermosetting adhesive film and the weight portion of the semiconductor acceleration sensor main body can be prevented from adhering to each other, and the stopper and the weight portion can be prevented. Can be prevented from becoming shorter than the design value.

  The invention according to claim 9 is the method of manufacturing the acceleration sensor according to claim 1, wherein a thermosetting adhesive film having a size corresponding to a large number of semiconductor acceleration sensor bodies is laminated on a wafer on which a large number of semiconductor acceleration sensor bodies are formed. Thereafter, dicing is performed to form a sensor chip composed of the semiconductor acceleration sensor main body and the thermosetting adhesive film, and then the sensor chip is disposed at a predetermined position of the base member to heat the thermosetting adhesive film. It adheres to a base member by this.

  According to the present invention, in a dicing process in which a wafer formed with a large number of semiconductor acceleration sensor bodies is separated into individual semiconductor acceleration sensor bodies, the chip acceleration margin is bonded to the semiconductor acceleration sensor body and the stopper by conventional anodic bonding. The size of the semiconductor acceleration sensor body can be reduced while the number of chips obtained from one wafer can be increased and the size of the semiconductor acceleration sensor body can be reduced. A sensor can be provided.

  A tenth aspect of the present invention is the method of manufacturing the acceleration sensor according to the first aspect, wherein a thermosetting adhesive film serving as a stopper and a semiconductor acceleration sensor main body are disposed in a predetermined position on the base member so as to overlap each other. The adhesive film is heated to adhere to the base member.

  According to the present invention, in a dicing process in which a wafer formed with a large number of semiconductor acceleration sensor bodies is separated into individual semiconductor acceleration sensor bodies, the chip acceleration margin is bonded to the semiconductor acceleration sensor body and the stopper by conventional anodic bonding. The size of the semiconductor acceleration sensor body can be reduced while the number of chips obtained from one wafer can be increased and the size of the semiconductor acceleration sensor body can be reduced. A sensor can be provided.

  The invention according to claim 11 is the method for manufacturing the acceleration sensor according to claim 3, wherein an adhesion preventing recess is formed in the thermosetting adhesive film before the semiconductor acceleration sensor main body and the thermosetting adhesive film for stopper are overlapped. When the thermosetting adhesive film is heated after the semiconductor acceleration sensor body and the thermosetting adhesive film are overlaid and the recess for preventing adhesion is formed, the thermosetting adhesive film It is characterized in that the region where the adhesion preventing recess is to be formed is etched with an organic solvent.

  According to the present invention, in a dicing process in which a wafer formed with a large number of semiconductor acceleration sensor bodies is separated into individual semiconductor acceleration sensor bodies, the chip acceleration margin is bonded to the semiconductor acceleration sensor body and the stopper by conventional anodic bonding. The size of the semiconductor acceleration sensor main body can be reduced while the number of chips obtained from one wafer can be increased, and the thermosetting adhesive film and the weight portion can be reduced. Therefore, it is possible to provide an acceleration sensor that can be easily downsized and reduced in cost.

  The invention of claim 12 is the method of manufacturing the acceleration sensor according to claim 3, wherein the recess for preventing adhesion is formed in the thermosetting adhesive film before the semiconductor acceleration sensor main body and the thermosetting adhesive film for stopper are overlapped. When the thermosetting adhesive film is heated after the semiconductor acceleration sensor body and the thermosetting adhesive film are overlaid and the recess for preventing adhesion is formed, the thermosetting adhesive film Insert cut grooves with a depth corresponding to the depth dimension of the adhesion prevention recess in a plurality of areas where the adhesion prevention recess is to be formed, and then correspond to the adhesion prevention recess in the thermosetting adhesive film. It is characterized by removing parts.

  According to the present invention, in a dicing process in which a wafer formed with a large number of semiconductor acceleration sensor bodies is separated into individual semiconductor acceleration sensor bodies, the chip acceleration margin is bonded to the semiconductor acceleration sensor body and the stopper by conventional anodic bonding. The size of the semiconductor acceleration sensor main body can be reduced while the number of chips obtained from one wafer can be increased, and the thermosetting adhesive film and the weight portion can be reduced. Therefore, it is possible to provide an acceleration sensor that can be easily downsized and reduced in cost.

  According to the first to eighth aspects of the present invention, in the dicing process of separating a wafer on which a plurality of semiconductor acceleration sensor bodies are formed into individual semiconductor acceleration sensor bodies, the cutting margin of the chip (semiconductor acceleration sensor body) is reduced as in the prior art. Since the sensor body and the stopper can be made smaller than those bonded by anodic bonding, the number of chips obtained from one wafer can be increased and the size of the semiconductor acceleration sensor body can be reduced. There exists an effect that size reduction and cost reduction can be achieved easily.

  According to the ninth aspect of the present invention, in the dicing process of separating a wafer formed with a large number of semiconductor acceleration sensor bodies into individual semiconductor acceleration sensor bodies, the semiconductor acceleration sensor body and the stopper are anodic bonded to each other as in the prior art. Compared to the bonded ones, the number of chips obtained from one wafer can be increased and the size of the semiconductor acceleration sensor body can be reduced, so that it is easy to reduce the size and cost. There is an effect that an acceleration sensor can be provided.

  According to the tenth aspect of the present invention, in a dicing process of separating a wafer formed with a large number of semiconductor acceleration sensor bodies into individual semiconductor acceleration sensor bodies, the semiconductor acceleration sensor body and the stopper are anodic bonded to each other as in the prior art. Compared to the bonded ones, the number of chips obtained from one wafer can be increased and the size of the semiconductor acceleration sensor body can be reduced, so that it is easy to reduce the size and cost. There is an effect that an acceleration sensor can be provided.

  According to the eleventh aspect of the present invention, in the dicing process of separating a wafer formed with a large number of semiconductor acceleration sensor bodies into individual semiconductor acceleration sensor bodies, the semiconductor acceleration sensor body and the stopper are anodic bonded to each other as in the prior art. Compared to what is bonded, the number of chips obtained from a single wafer can be increased, the size of the semiconductor acceleration sensor body can be reduced, and the weight of the thermosetting adhesive film can be reduced during manufacturing. Since the recess for preventing adhesion for preventing the adhesion to the portion can be easily formed, there is an effect that it is possible to provide an acceleration sensor that can be reduced in size and easily reduced in cost.

  In the twelfth aspect of the present invention, in the dicing process of separating a wafer formed with a large number of semiconductor acceleration sensor bodies into individual semiconductor acceleration sensor bodies, the semiconductor acceleration sensor body and the stopper are anodic bonded to each other as in the prior art. Compared to what is bonded, the number of chips obtained from a single wafer can be increased, the size of the semiconductor acceleration sensor body can be reduced, and the weight of the thermosetting adhesive film can be reduced during manufacturing. Since the recess for preventing adhesion for preventing the adhesion to the portion can be easily formed, there is an effect that it is possible to provide an acceleration sensor that can be reduced in size and easily reduced in cost.

  The semiconductor acceleration sensor of the present embodiment includes a sensor body 1 as shown in FIGS. As shown in FIG. 3A, the sensor body 1 is formed using an SOI (Silicon on Insulator) substrate 100 having a buried oxide film 102 made of a silicon oxide film in the middle in the thickness direction. Here, the SOI substrate 100 is a part of a so-called SOI wafer in which a buried oxide film 102 as an insulating layer is formed between a support substrate 101 made of a silicon substrate and an n-type silicon layer (silicon active layer) 103. Consists of. As for the SOI substrate 100, the thickness of the support substrate 101 is set to about 400 to 600 μm, the thickness of the buried oxide film 102 is set to about 0.5 to 3 μm, and the thickness of the silicon layer 103 is set to about 4 to 10 μm. However, these numerical values are not particularly limited. Moreover, as the SOI substrate 100, a substrate whose surface (the surface of the silicon layer 103) has a (100) plane is used.

  The sensor body 1 includes a frame portion 11 having a rectangular frame shape, and a weight portion 12 disposed inside the frame portion 11 is continuously integrated with the frame portion 11 via four flexure portions 13 that are thinner than the frame portion 11. It has the structure connected to. Here, in the sensor body 1, the thickness of the back surface side of the weight portion 12 relative to the buried oxide film 102 is thinner than the thickness of the back surface side of the frame portion 11 relative to the buried oxide film 102. The back surface of the frame portion 11 is fixed to the peripheral portion of the rectangular stopper 2 over the entire periphery. Therefore, a gap is formed between the back surface of the weight portion 12 and the stopper 2 so that the weight portion 12 can be displaced in the thickness direction of the weight portion 12.

  Further, the frame portion 11 is formed with a recess 11a that opens the stopper 2 side and the weight portion 12 side over the entire circumference of the end portion on the weight portion 12 side on the surface facing the stopper 2, and the stopper 2 in the recess portion 11a is formed. The distance between the facing surface and the stopper 2 is set to the same value as the distance between the weight portion 12 and the stopper 2. Although the function of the recess 11a will be described later, it is desirable that the distance between the surface of the recess 11a facing the stopper 2 and the stopper 2 is set so as not to be less than the distance between the weight 12 and the stopper 2. .

  The weight portion 12 has a rectangular planar shape, and is supported by the frame portion 11 via the four bending portions 13 described above. Therefore, a slit 14 is formed in a space surrounded by the frame portion 11 and the weight portion 12 and the two bent portions 13 and 13 extended in a direction orthogonal to each other. In other words, four L-shaped slits 14 are formed around the weight portion 12 except for the four bent portions 13.

  By the way, as shown on the left side of FIG. 2A, the thickness direction of the sensor body 1 is the z-axis direction, and the direction along one side of the rectangular frame-shaped frame portion 11 in the plane orthogonal to the z-axis direction is the x-axis. If the direction along the direction perpendicular to the one side is defined as the y-axis direction, the weight portion 12 is extended in the x-axis direction to sandwich the weight portion 12, and a set of two bent portions 13 and 13; The frame portion 11 is supported via a pair of bending portions 13 and 13 extending in the y-axis direction and sandwiching the weight portion 12.

  In this case, two piezoresistors (not shown) for detecting acceleration in the x-axis direction are formed in the vicinity of the weight portion 12 in the two bent portions 13 and 13 having the longitudinal direction in the x-axis direction. (These four piezoresistors have the longitudinal direction aligned with the longitudinal direction of the bending portion 13), and a first bridge circuit (not shown) is provided via a wiring (not shown) such as a metal wiring or a diffusion layer wiring. Connected) to constitute.

  Similarly, two piezoresistors (not shown) for detecting acceleration in the y-axis direction are formed in the vicinity of the weight portion 12 in the two bent portions 13 and 13 having the longitudinal direction in the y-axis direction. (These four piezoresistors have the longitudinal direction coincided with the longitudinal direction of the bending portion 13), and a second bridge circuit (not shown) via a wiring (not shown) such as a metal wiring or a diffusion layer wiring. Connected) to constitute.

  Further, one piezoresistor for detecting acceleration in the z-axis direction is formed in the vicinity of the frame portion 11 in the longitudinal direction of each of the four flexures 13 described above, and wiring such as metal wiring and diffusion layer wiring A third bridge circuit (not shown) is connected via a (not shown). However, each of the piezoresistors formed in the vicinity of the frame portion 11 in the two bent portions 13 and 13 having the longitudinal direction in the x-axis direction is matched with the bent portion 13 in the longitudinal direction. Each of the piezoresistors formed in the vicinity of the frame portion 11 in the two bending portions 13, 13 having the longitudinal direction as the axial direction has the longitudinal direction matched with the width direction (short direction) of the bending portion 13.

  Also, the frame unit 11 is provided with eight pads (not shown), and the pad serving as the output terminal of each bridge circuit described above is provided for each bridge circuit. The pads serving as terminals are shared by the three bridge circuits (that is, only two pads are provided as input terminals for the three bridge circuits). As is clear from the above description, the semiconductor acceleration sensor of the present embodiment can detect accelerations in a plurality of directions (x-axis direction, y-axis direction, z-axis direction). The acceleration detection principle is well known and will not be described. Further, in the present embodiment, each piezoresistor constitutes a resistor whose resistivity changes due to strain generated in the bending portion 13 due to the displacement of the weight portion 12 with respect to the frame portion 11.

  By the way, as shown in FIG. 1, the semiconductor acceleration sensor of the present embodiment has a sheet-like stopper 2 between the sensor main body 1 and the bottom wall 3 a of the box-shaped package 3 that is open on one side for housing the sensor main body 1. However, the stopper 2 is formed by thermosetting a thermosetting adhesive film. In the present embodiment, the sensor main body 1 constitutes a semiconductor acceleration sensor main body, and the package 3 constitutes a base member. However, the base member is not limited to the package 3, but a circuit board (for example, a printed board). ) May be used.

  Hereinafter, although the manufacturing method of the acceleration sensor of this embodiment is demonstrated, the manufacturing method of the above-mentioned sensor main body 1 is demonstrated easily first.

  Each of the piezoresistors and each diffusion layer wiring described above may be formed by injecting a p-type impurity such as boron into the silicon layer 103 using an ion implantation apparatus and performing heat treatment, or a p-type impurity such as boron. It may be formed by performing drive-in after performing the predeposition. Each piezoresistor and each diffusion layer wiring are covered with a protective film (not shown) made of a silicon oxide film formed on the surface side of the silicon layer 103 or a laminated film of a silicon oxide film and a silicon nitride film. . In this embodiment, since the conductivity type of the silicon layer 103 is n-type, the conductivity type of each piezoresistor is p-type. However, when the conductivity type of the silicon layer 103 is p-type, The conductivity type may be n-type.

  Further, in order to form the frame portion 11, the bending portion 13, the weight portion 12, the slit 14, and the like, for example, the silicon oxide film 18b and the silicon nitride film 19b are sequentially formed on the back surface side of the SOI substrate 100, and then the photo A first resist layer (not shown) patterned to form a recess 100a (see FIG. 3B) is formed on the back surface side of the SOI substrate 100 using a lithography technique, Using the first resist layer as a mask, the silicon nitride film 19b and the silicon oxide film 18b on the back surface side of the SOI substrate 100 are etched, and the first resist layer is removed to obtain a structure as shown in FIG. . Subsequently, using the patterned silicon nitride film 19b on the back side of the SOI substrate 100 as a mask, the SOI substrate 100 is set to a predetermined depth from the back side (this predetermined depth is a gap formed between the weight portion 12 and the stopper 2). The recess 100a is formed by etching until the silicon nitride film 19b and the silicon oxide film 18b are removed, and then silicon oxide is formed on the back surface side of the SOI substrate. The film 28b and the silicon nitride film 29b are sequentially formed, and then patterned to form the weight portion 12, the bent portion 13, the slit 14, and the frame portion 11 on the back surface side of the SOI substrate 100 using a photolithography technique. Forming a second resist layer, and using the second resist layer as a mask, a silicon nitride film on the back side of the SOI substrate 100 Etching the 9b and the silicon oxide film 28b, by removing the second resist layer to obtain a structure shown in FIG. 3 (b). After that, in the SOI substrate 100, the buried oxide film 102 is used as an etching stopper layer so that the portions corresponding to the frame portion 11 and the respective bending portions 13 and the weight portion 12 remain, and the portions corresponding to the slits 14 and the bending portion 13 are on the back side. After performing a back surface side patterning process in which dry etching is performed perpendicularly to a depth reaching the buried oxide film 102, the silicon nitride film 29b and the silicon oxide film 28b are removed, and then the frame portion 11 and each deflection in the SOI substrate 100 are removed. A surface-side patterning process is performed to etch the SOI substrate 100 from the surface side to a depth reaching the buried oxide film 102 using the buried oxide film 102 as an etching stopper layer so that a portion corresponding to the portion 13 and the weight portion 12 remains. The buried oxide film 102 is exposed after the side patterning process. By removing the weight by etching with hydrofluoric acid or the like and performing a separate etching step to form the slit 14, the weight portion 12 is separated from the frame portion 11 and is supported by the four flexible portions 13. The structure shown in FIG.

  In the etching step for forming the recess 100a, wet etching using an alkaline solution such as KOH (potassium hydroxide aqueous solution) or TMAH (tetramethylammonium aqueous solution) may be performed. Dry etching such as RIE (reactive ion etching) may be performed. Further, in the above-described back side patterning step, for example, an inductively coupled plasma type dry etching apparatus may be used as an etching apparatus. Here, by performing the back surface side patterning step, the concave portion 11a formed of a part of the recess 100a is formed on the back surface side of the portion corresponding to the frame portion 11. In the surface side patterning step, for example, dry etching using an inductively coupled plasma type dry etching apparatus may be performed as an etching apparatus, but wet etching may be performed. Moreover, you may make it perform a back surface side patterning process and a surface side patterning process simultaneously, and you may make it perform a surface side patterning process before a back surface side patterning process. Further, in the manufacturing method of the sensor body 1 described above, when the weight portion 12 is formed, the portion corresponding to the slit 14 and the bent portion 13 in the SOI substrate 100 is embedded and oxidized by an inductively coupled plasma type dry etching apparatus from the back side. Although the etching is performed vertically until reaching the film 102, the weight 12 may be formed by using anisotropic etching of silicon using an alkaline solution such as KOH. 3 (a), (b), and (c) in the process are as shown in FIGS. 7 (a), (b), and (c), and the sensor body 1 having the structure shown in FIG. 6 is obtained. It is done. However, in the back surface side patterning process, it is more preferable to perform the vertical etching until the buried oxide film 102 is reached by a dry etching apparatus capable of vertical deep digging such as an inductively coupled plasma type dry etching apparatus. Since the distance between the outer peripheral surface and the inner peripheral surface of the frame portion 11 can be reduced, the sensor main body 1 can be reduced in size, and the sensor chip A including the sensor main body 1 and the stopper 2 can be reduced in size. Can do.

  By the way, in the method for manufacturing the acceleration sensor according to the present embodiment, after a large number of the above-described sensor bodies 1 are formed on the wafer (the above-described SOI wafer), that is, after the wafer process is finished, the wafer (in short, the previous process is finished). Wafer) A sheet-like thermosetting adhesive film 20 made of epoxy resin on the back surface of the wafer 10 (the thermosetting adhesive film 20 here is formed in a size corresponding to all the sensor bodies 1 of the wafer 10). Is laminated while heating and pressing (see FIG. 4A). Here, as a condition of the laminating process for laminating the thermosetting adhesive film 20 on the wafer 10, the temperature may be set to about 80 ° C. to 100 ° C. and the pressure may be set to about 1 MPa, for example. As the thermosetting adhesive film 20, an epoxy tape or the like may be used. For example, “Die Attachment Film (trade name)” manufactured by Nippon Steel Chemical Co., Ltd. can be used. Further, the wafer 10 in FIG. 4A schematically shows only a portion where the sensor body 1 is formed. Further, since the thermosetting adhesive film 20 is formed of an epoxy resin, the stopper 2 and the sensor main body 1 are compared with the case where the thermosetting adhesive film 20 is formed of another thermosetting resin such as a ferrule resin or an unsaturated polyester resin. The adhesive strength between the stopper 2 and the package 3 can be increased, and the chemical and electrical stability of the stopper 2 is increased.

  Thereafter, the wafer 10 to which the above-mentioned thermosetting adhesive film 20 is attached is attached to an adhesive sheet (called a dicing sheet or dicing tape) 4 made of a plastic film with an adhesive (FIG. 4B). )reference).

  Thereafter, the dicing saw (blade) 5 is rotated at a high speed to cut the wafer 10 along a scribe line (dicing line) L, whereby a thermosetting adhesive film 20a having the same size as the sensor body 1 is formed on the back surface of the sensor body 1. A dicing process is performed to separate the individual sensor chips A attached with (see FIG. 4C), and the sensor chip A is picked up (see FIG. 4D). Here, when picking up the sensor chip A, as shown in FIG. 5A, after the push-up pin 6 is disposed on the surface of the adhesive sheet 4 opposite to the sensor chip A side, the sensor chip is moved by the push-up pin 6. A is pushed up one by one and picked up as shown in FIG. 5B using a collet 7, and the bottom of the package 3 in which the sensor chip A picked up by the collet 7 is heated to a predetermined temperature (for example, about 100 ° C.) in advance. The sensor chip A and the package 3 are bonded to each other and the thermosetting adhesive film 20a is heated by performing predetermined heating processing for mounting the thermosetting adhesive film 20a on the predetermined portion of the wall 3a. It hardens | cures and the stopper 2 is formed (refer FIG.4 (e)). Note that the heat treatment condition may be, for example, a heating temperature of 150 ° C. and a heating time of 1 hour. Here, when the heat treatment is performed, the stickiness of the exposed surface of the thermosetting adhesive film 20a is lost. Therefore, even if the weight portion 12 of the sensor main body 1 comes into contact with the stopper 2 after the heat treatment, it does not adhere.

  According to the acceleration sensor manufacturing method of the present embodiment described above, in the dicing process of separating the wafer 10 on which a large number of sensor bodies 1 are formed into individual sensor bodies 1, the chip margins are conventionally changed to the sensor body 1. Since 'and the stopper 2' can be made smaller than those joined by anodic bonding, the number of chips obtained from one wafer 10 can be increased and the size of the sensor body 1 can be reduced. Thus, it is possible to provide an acceleration sensor that can be easily reduced in size and cost as compared with the conventional case. Here, in the acceleration sensor of the present embodiment, the displacement amount of the weight portion 12 can be limited by the stopper 2, and the displacement of the weight portion 12 is limited by the stopper 2 when excessive acceleration is applied in the z-axis direction. Therefore, it is possible to prevent the bending portion 13 from being broken, and since the stopper 2 is made of a material having a smaller elastic modulus than the material of the package 3, it is bent when an excessive acceleration is applied in the z-axis direction. The possibility that the portion 13 is broken is reduced, and the reliability is improved. In the above-described manufacturing method, the dicing process is performed after laminating the thermosetting adhesive film 20 on the back side of the wafer 10, but after the wafer 10 is directly attached to the adhesive sheet 4 and dicing is performed, On the predetermined part of the bottom wall 3a of the package 3, a thermosetting adhesive film 20a separately formed in the same size as the sensor body 1 and the sensor body 1 are arranged so as to overlap each other, and the thermosetting adhesive film 20a is heated. You may make it form the stopper 2 by thermosetting the thermosetting adhesive film 20a by performing the predetermined heat processing for making it harden | cure.

  By the way, since the epoxy tape used as the thermosetting adhesive film 20 has adhesiveness until the curing is completely completed, in the process after the thermosetting adhesive film 20 is attached to the wafer 10, the thermosetting is performed. It is desirable to take measures to prevent the adhesive film 20a and the weight portion 12 of the sensor body 1 from adhering. Therefore, as an example of this type of countermeasure, the frame portion 11 of the sensor body 1 of the present embodiment includes a stopper 2 side and a weight portion over the entire circumference of the end portion on the weight portion 12 side on the surface facing the stopper 2. The concave portion 11a having the 12 side opened is formed. By providing such a recess 11a, it is possible to prevent the thermosetting adhesive film 20a and the weight portion 12 from adhering when the thermosetting adhesive film 20a is thermally cured.

  As another example of the above-described countermeasure, as shown in FIG. 8, a recess 22 for preventing adhesion is formed in advance on the surface facing the weight portion 12 of the thermosetting adhesive film 20a that becomes the stopper 2 by thermosetting. In this case, it is possible to prevent the thermosetting adhesive film 20a and the weight portion 12 from being bonded at the time of heating when the thermosetting adhesive film 20a is bonded to the package 3, and to reduce the manufacturing yield. Cost can be reduced. Here, in forming the adhesion preventing recess 22, the region where the adhesion preventing recess 22 is to be formed in the thermosetting adhesive film 20 a for stopper may be etched with an organic solvent such as acetone ( Etching conditions in this case are, for example, that the temperature of the organic solvent is normal temperature and the etching time is about several minutes), and half-cut dicing is performed on the thermosetting adhesive film 20 for stopper by a dicing saw. Thus, as shown in FIG. 9, after forming the cut grooves 23 in a lattice shape, the portion corresponding to the adhesion preventing recess 22 may be hooked and removed with a jig such as a pin. In addition, when forming the recess 22 for preventing adhesion by performing half-cut dicing, for example, as shown in FIG. 10, it is processed so that the convex portions 26 remain at the four corners of the thermosetting adhesive film 20a, or FIG. 11, if processing is performed so that the convex portions 26 remain at the central portions of the four sides constituting the peripheral portion of the thermosetting adhesive film 20 a, the bottom surface of the weight portion 12 and the adhesion preventing recess 22 Since the distance between the bottom surface can be increased, it is possible to more reliably prevent the weight portion 12 from being adhered to the thermosetting adhesive film 20a.

  As another example of the above-mentioned countermeasure, as shown in FIG. 12, the thermosetting adhesive film 20 a that becomes the stopper 2 by thermosetting is weighted on the thermosetting adhesive film 20 a before being overlapped with the sensor body 1. The region to be opposed to the portion 12 may be cured in advance using a heat source such as a laser to provide the thermosetting portion 25, and the thermosetting portion 25 in the thermosetting adhesive film 20a is compared with other portions. Therefore, even when such measures are taken, the thermosetting adhesive film 20a and the weight portion 12 are bonded during heating when the thermosetting adhesive film 20a is bonded to the package 3. Can be prevented, and the cost can be reduced by improving the manufacturing yield. Of course, the above-described recess 11a may be provided in the frame portion 11 in the structure of FIGS.

  As still another example of the above-described countermeasure, as shown in FIG. 13, the frame portion 11 extends around the entire periphery of the stopper 2 at a portion of the package 3 facing the frame portion 11 via the stopper 2. If a structure in which a rectangular annular support projection 3c is provided between the center portion of the thermosetting adhesive film 20a serving as the stopper 2 and the bottom wall 3a of the package 3 is formed, a gap is formed. Since the thermosetting adhesive film 20a is warped in a convex shape toward the package 3, it can be prevented that the thermosetting adhesive film 20a and the weight portion 12 are bonded during manufacturing. The cost can be reduced by improving the yield.

  By the way, since the epoxy tape used as the above-mentioned thermosetting adhesive film 20a is temporarily softened during the curing heat treatment, the frame portion 11 in the bonding partner (a wafer on which a large number of sensor bodies 1 are formed or the sensor body 1 alone) is formed. A phenomenon of sinking into the thermosetting adhesive film 20a occurs (the amount of sinking is about several μm to several tens of μm although it depends on conditions). When this kind of subsidence occurs, the distance between the stopper 2 and the weight 12 becomes shorter than the design value. In order to solve this problem, a filler such as silica may be contained in the thermosetting adhesive film 20a, and the thermosetting adhesive film 20a is temporarily softened during the curing heat treatment of the thermosetting adhesive film 20a. Thus, the phenomenon that the frame portion 11 of the sensor body 1 sinks into the stopper 2 can be prevented. Here, the size of the filler is desirably several μm or more.

  Needless to say, the stopper 2 in the present embodiment may be applied in place of the stopper 2 'in the conventional configuration shown in FIG.

It is a schematic sectional drawing which shows embodiment. The sensor main body in the same as above is shown, (a) is a plan view, (b) is a sectional view, and (c) is a bottom view. It is explanatory drawing of a manufacturing method same as the above. It is explanatory drawing of a manufacturing method same as the above. It is explanatory drawing of a manufacturing method same as the above. The other example of the sensor main body same as the above is shown, (a) is a plan view, (b) is a sectional view, and (c) is a bottom view. It is explanatory drawing of the manufacturing method of the sensor main body in another example same as the above. It is explanatory drawing of the other structural example same as the above. It is explanatory drawing of a manufacturing method same as the above. It is explanatory drawing of the other example of the manufacturing method same as the above. It is explanatory drawing of another example of the manufacturing method same as the above. It is explanatory drawing of another structural example same as the above. It is explanatory drawing of another structural example same as the above. It is a schematic perspective view partly broken showing the conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor main body 2 Stopper 3 Package 3a Bottom wall 4 Adhesive sheet 5 Dicing saw 6 Push-up pin 7 Collet 10 Wafer 11 Frame part 12 Weight part 13 Deflection part 20 Thermosetting adhesive film 20a Thermosetting adhesive film A Centimeter chip

Claims (12)

  The weight portion arranged inside the frame-shaped frame portion is supported by the frame portion via at least one set of bending portions arranged with the weight portion interposed therebetween, and is caused by strain generated in the bending portion due to the displacement of the weight portion with respect to the frame portion. A semiconductor acceleration sensor main body in which a resistor having a variable resistivity is formed at a bending portion, a base member for fixing the semiconductor acceleration sensor main body, and a displacement between the semiconductor acceleration sensor main body and the base member and limiting the displacement of the weight portion. An acceleration sensor, wherein the stopper is formed by thermosetting a thermosetting adhesive film.   The frame portion is formed with a concave portion that opens the stopper side and the weight portion side over the entire circumference of the end portion on the weight portion side on the surface facing the stopper, and the surface facing the stopper in the concave portion. The acceleration sensor according to claim 1, wherein a distance between the stopper and the stopper is set so as not to be less than a distance between the weight portion and the stopper.   2. The thermosetting adhesive film according to claim 1, wherein an adhesion preventing recess for preventing the thermosetting adhesive film from adhering to the weight portion at the time of thermosetting is formed on a surface facing the weight portion. 2. The acceleration sensor according to 2.   3. The acceleration sensor according to claim 1, wherein the thermosetting adhesive film is precured at a portion facing the weight portion before being overlapped with the semiconductor acceleration sensor main body.   2. The base member according to claim 1, wherein a support protrusion is provided to hold the peripheral portion of the stopper between the frame portion and a gap is formed between the base member and the central portion of the stopper. The acceleration sensor according to claim 4.   6. The acceleration sensor according to claim 1, wherein the thermosetting adhesive film is formed of a material having a smaller elastic modulus than a material of the base member.   The acceleration sensor according to claim 1, wherein the thermosetting adhesive film is formed of an epoxy resin.   The acceleration sensor according to any one of claims 1 to 7, wherein the thermosetting adhesive film contains a filler.   2. The method of manufacturing an acceleration sensor according to claim 1, wherein dicing is performed after a thermosetting adhesive film having a size corresponding to a large number of semiconductor acceleration sensor bodies is laminated on a wafer on which a large number of semiconductor acceleration sensor bodies are formed. Forming a sensor chip composed of a semiconductor acceleration sensor body and a thermosetting adhesive film, and then placing the sensor chip at a predetermined position on the base member and heating the thermosetting adhesive film to adhere to the base member A method of manufacturing an acceleration sensor.   2. The method of manufacturing an acceleration sensor according to claim 1, wherein a thermosetting adhesive film serving as a stopper and a semiconductor acceleration sensor main body are placed in a predetermined position on the base member, and the thermosetting adhesive film is heated. A method of manufacturing an acceleration sensor, characterized by bonding to a base member.   4. The method of manufacturing an acceleration sensor according to claim 3, wherein an adhesion preventing recess is formed in the thermosetting adhesive film before the semiconductor acceleration sensor main body and the thermosetting adhesive film for stopper are stacked. When the thermosetting adhesive film is heated after the acceleration sensor body and the thermosetting adhesive film are overlaid to form the adhesion preventing recess, formation of the adhesion preventing recess in the thermosetting adhesive film is performed. A method for manufacturing an acceleration sensor, wherein a predetermined region is etched with an organic solvent.   4. The method of manufacturing an acceleration sensor according to claim 3, wherein an adhesion preventing recess is formed in the thermosetting adhesive film before the semiconductor acceleration sensor main body and the thermosetting adhesive film for stopper are stacked. When the thermosetting adhesive film is heated after the acceleration sensor body and the thermosetting adhesive film are overlaid to form the adhesion preventing recess, formation of the adhesion preventing recess in the thermosetting adhesive film is performed. It is characterized in that a cut groove having a depth corresponding to the depth of the recess for preventing adhesion is put in a plurality of locations in the planned area, and then a portion corresponding to the recess for preventing adhesion in the thermosetting adhesive film is removed. A method for manufacturing an acceleration sensor.

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