JP2006047300A - Glass substrate and electrostatic capacity type pressure sensor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass substrate for electrostatic capacity type pressure sensor capable of accurately detecting pressure changes. <P>SOLUTION: This glass substrate 11 has a pair of main faces 11a, 11b that face each other. The glass substrate 11 is embedded with island-like bodies 12a, 12b formed of silicon. The island-like bodies 12a, 12b are respectively exposed in both the main faces of the glass substrate 11. On the main face 11a of the glass substrate 11, an electrode 13a is formed, such that the electrode 13a is electrically connected to one exposure portion of the island-like body 12a, and an electrode 13b is formed such that the electrode 13b is electrically connected to one exposure portion of the island-like body 12b. An electrode 14 is formed on the main face 11b of the glass substrate 11, such that the electrode 14 is electrically connected to the other exposure portion of the island-like body 12a, and a silicon substrate 15, having a pressure-sensitive diaphragm 15a, is jointed on the main face 11b of the glass substrate 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a capacitance pressure sensor having a glass substrate and a silicon diaphragm as a pressure sensitive part on the glass substrate.

  As such a pressure sensor, there are a differential pressure sensor that measures relative pressure and an absolute pressure sensor that measures absolute pressure.

  FIG. 10 is a cross-sectional view showing a schematic configuration of a conventional capacitive pressure sensor. A capacitive pressure sensor 1 shown in FIG. 10 is configured by bonding a silicon substrate 3 having a pressure-sensitive diaphragm 2 that is a movable electrode that receives a pressure to be measured, and a glass substrate 4. An electrode 5 is provided on the surface of the silicon substrate 3 on the glass substrate 4 side. A predetermined interval is provided between the pressure-sensitive diaphragm 2 and the glass substrate 4, and a space 6 is formed. A fixed electrode 7 is provided on the glass substrate 4 in the space 6. The glass substrate 4 is provided with a through hole 4 a, and a connection electrode 8 is formed on the bottom surface and side surface of the through hole 4 a so as to be electrically connected to the fixed electrode 7.

Japanese Patent No. 2772111

  The conventional capacitive pressure sensor shown in FIG. 10 is manufactured as follows. First, a through-hole 4a is formed in the glass substrate 4 by sandblasting, the glass substrate on which the through-hole 4a is formed and the silicon substrate are joined, and silicon is left only in the through-hole 4a portion so as to cover the through-hole 4a. To remove other silicon. Next, the fixed electrode 7 and the connection electrode 8 are formed so as to be electrically connected to the remaining silicon, and then the silicon substrate having the pressure-sensitive diaphragm 2 and having the electrode 5 on the glass substrate 4 side is formed into a space. It joins to the glass substrate 4 so that the part 6 may be formed.

  However, in the conventional capacitive pressure sensor, the through hole 4a is formed by sandblasting as described above, and then the connection electrode 8 is formed on the side surface of the through hole 4a. Usually, when sandblasting is performed, the processed surface becomes very rough, and thus the connection electrode 8a cannot be satisfactorily deposited on the processed surface. For this reason, there is a problem that the connection electrode 8a is disconnected. Moreover, in such a structure, since the processing surface is in a rough state, the coverage of the connection electrode is not sufficient, and thus the airtightness is inferior. When the airtightness is lowered, the pressure sensitive diaphragm does not operate well, and the pressure change cannot be detected accurately.

  This invention is made | formed in view of this point, and it aims at providing the glass substrate for electrostatic capacitance type pressure sensors which can detect a pressure change correctly.

  The glass substrate of the present invention includes a glass substrate body having a pair of main surfaces opposed to each other, and a silicon island body embedded in the glass substrate body so that at least a part thereof is exposed on both of the pair of main surfaces. It is characterized by comprising.

  According to this configuration, it is possible to form the wiring from the fixed electrode while exhibiting high adhesion at the interface between the glass substrate and the island-shaped body and the interface between the glass substrate and the silicon substrate. For this reason, the glass substrate for electrostatic capacitance type pressure sensors which can detect a pressure change correctly can be obtained.

  In the glass substrate of the present invention, it is preferable that the silicon islands are electrically connected to each other by a silicon layer formed on the one main surface of the glass substrate body.

  In the glass substrate of the present invention, it is preferable that the silicon island has a metal layer embedded so as to be exposed on at least one main surface of the glass substrate body. According to this configuration, it is possible to reduce the resistance at the conduction part of the island-like body, and to reduce the power consumption of the device to be used.

  In the glass substrate of this invention, it is preferable to have a Si-Si bond or a Si-O bond in the interface of the said glass substrate main body and the said silicon island. According to this configuration, since the Si-Si bond or the Si-O bond is present at the interface between the glass substrate body and the silicon island body, the glass substrate body and the silicon island body are firmly bonded to each other. Adhesion is improved.

  The capacitance-type pressure sensor of the present invention includes the glass substrate, an electrode provided on the main surface where the silicon island is exposed, and the electrode electrically connected to the silicon island, and the electrode is formed. A silicon substrate provided on the principal surface, the silicon substrate having a pressure-sensitive diaphragm that is located at a predetermined interval from the electrode and is displaced by a pressure to be measured; and A change in capacitance between the pressure-sensitive diaphragm and the pressure-sensitive diaphragm is detected as a pressure change.

  According to this configuration, since high adhesion is exhibited at the interface between the glass substrate and the island-shaped body and the interface between the glass substrate and the silicon substrate, it can be considered that the displacement of the pressure sensitive diaphragm accurately reflects the pressure to be measured. it can. Therefore, it is possible to accurately detect the capacitance between the pressure-sensitive diaphragm and the fixed electrode, and it is possible to accurately detect the pressure change corresponding to the change in the capacitance.

  The method for producing a glass substrate of the present invention includes a step of forming an island-shaped body on the surface of a silicon substrate, a step of pressing the island-shaped body into the glass substrate under heating, and bonding the silicon substrate and the glass substrate. And polishing the surface of the glass substrate to expose the islands from the surface of the glass substrate.

  According to this method, the glass substrate and the island-shaped body and the glass substrate and the silicon substrate can be bonded with high adhesion. Therefore, it is possible to obtain a glass substrate for a capacitive pressure sensor that can accurately detect a pressure change.

  In the manufacturing method of the glass substrate of this invention, it is preferable to form the said island-like body by carrying out the wet etching of the said silicon substrate, after carrying out the half dicing of the surface of the said silicon substrate.

  According to this method, half dicing can be performed using a narrow blade, and island-like objects can be prevented from being chipped. Moreover, even if a narrow blade is used, the island can be made smaller by wet etching, that is, the base angle in the cross section of the island can be made relatively large. The interval can be narrowed. For this reason, when using an island-like body as an extraction electrode of a device, the freedom degree of device design can be enlarged.

  In the method for producing a glass substrate of the present invention, a mask is formed on the silicon substrate, and after the region surface of the silicon substrate other than the region where the mask is formed is half-diced, the silicon substrate is wet etched, It is preferable to form the islands by removing the mask.

  According to this method, the islands in the region where the mask is formed are relatively high, and the islands in the region other than the region where the mask is formed are relatively low. That is, an island-like body having a height difference can be formed. When such an island is pushed into the glass substrate and the surface is polished, the island having a high height is exposed from the surface, and the island having a low height is embedded in the glass substrate. Therefore, since the island-shaped body having a low height enhances the adhesion between the glass substrate and the silicon substrate, even in a relatively low strength portion such as an end portion of the substrate, the substrate is formed in the subsequent process. It is possible to secure strength that can counter the applied force. In addition, since an island-like body having a high height can be formed in an arbitrary portion depending on the mask pattern, a mark such as an alignment mark can be formed using an island-like body.

  The method of manufacturing a capacitive pressure sensor according to the present invention includes a step of manufacturing a glass substrate by the above method, and the glass substrate is electrically connected to the islands exposed from the surface of the glass substrate. A step of forming an electrode, and a step of bonding a silicon substrate having a pressure-sensitive diaphragm displaced by a pressure to be measured on the glass substrate so that the pressure-sensitive diaphragm is positioned at a predetermined distance from the electrode; It is characterized by comprising.

  According to this method, the glass substrate and the island-shaped body and the glass substrate and the silicon substrate can be bonded with high adhesion. Therefore, it is possible to obtain a capacitance-type pressure sensor that can accurately detect a change in capacitance between the pressure-sensitive diaphragm and the fixed electrode, and can accurately detect a change in pressure.

  According to the present invention, since the adhesion of the interface between the glass substrate and the silicon substrate is improved, the airtightness of the space between the fixed electrode and the movable electrode in the capacitive pressure sensor can be increased. It is possible to accurately detect the capacitance corresponding to the pressure to be measured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(Embodiment 1)
FIG. 1 is a cross-sectional view showing a schematic configuration of a capacitive pressure sensor including a glass substrate according to Embodiment 1 of the present invention.

  In the figure, 11 indicates a glass substrate. The glass substrate 11 has a pair of main surfaces 11a and 11b facing each other. In the glass substrate 11, islands 12a and 12b made of silicon are embedded. The island-shaped body 12a is a connection member with a fixed electrode, and the island-shaped body 12b is a connection member with a movable electrode. The islands 12a and 12b are exposed on both main surfaces of the glass substrate 11, respectively. The formation of the islands 12a and 12b will be described later.

  An electrode 13a is formed on the main surface 11a of the glass substrate 11 so as to be electrically connected to one exposed portion of the island 12a, and is electrically connected to one exposed portion of the island 12b. Thus, an electrode 13b is formed. Since the electrodes 13a and 13b are thus provided on the same main surface 11a, connection to an external device is facilitated. An electrode 14 is formed on the main surface 11b of the glass substrate 11 so as to be electrically connected to the other exposed portion of the island 12a.

  On the main surface 11 b of the glass substrate 11, a silicon substrate 15 having a pressure-sensitive diaphragm 15 a (movable electrode) is bonded. The pressure-sensitive diaphragm 15a is provided by forming recesses from both sides of the silicon substrate 15 by etching or the like. The concave portion on the glass substrate bonding surface side of the silicon substrate 15 has a size that can accommodate at least the electrode 14. By bonding the silicon substrate 15 to the glass substrate 11, a space (gap) 15 c is formed. That is, the space 15c is constituted by the side surface 15b of the concave portion of the silicon substrate 15 and the pressure-sensitive diaphragm 15a. As a result, a predetermined interval is provided between the pressure-sensitive diaphragm 15 a and the electrode 14, and an electrostatic capacity is generated between the pressure-sensitive diaphragm 15 a and the electrode 14.

  The interface 11c between the glass substrate 11 and the islands 12a and 12b preferably has high adhesion. As will be described later, the interface 11c is formed by pushing the islands 12a and 12b into the glass substrate 11 under heating. Although high adhesion can be exhibited even at the interface 11c obtained by such a method, the adhesion can be further improved by performing anodic bonding treatment after the islands 12a and 12b are pushed into the glass substrate 11. it can. Anodic bonding treatment is applied at a predetermined temperature (for example, 400 ° C. or lower) at a predetermined voltage (for example, 300 V to 1 kV), thereby generating a large electrostatic attraction between silicon and glass and sharing at the interface. A process that causes a bond to occur. The covalent bond at this interface is a Si—Si bond or a Si—O bond between the Si atom of silicon and the Si atom contained in the glass. Therefore, silicon and glass are firmly bonded by this Si—Si bond or Si—O bond, and very high adhesion is exhibited at the interface between the two. In order to perform such anodic bonding efficiently, the glass material of the glass substrate 11 is preferably a glass material containing an alkali metal such as sodium (for example, Pyrex (registered trademark) glass).

  The same applies to the interface between the main surface 11 b of the glass substrate 11 and the silicon substrate 15. That is, the adhesion can be enhanced by mounting the silicon substrate 15 on the main surface 11b of the glass substrate 11 and performing an anodic bonding process. Thus, by exhibiting high adhesiveness at the interface 11c between the glass substrate 11 and the island-like body 12a and the interface 11d between the glass substrate 11 and the silicon substrate 15, the pressure sensitive diaphragm 15a and the main surface of the glass substrate 11 The airtightness in the space part 15c comprised between 11b can be kept high.

  The capacitance type pressure sensor having such a configuration has a predetermined capacitance between the pressure sensitive diaphragm 15 a and the electrode 14 on the glass substrate 11. When pressure is applied to the capacitance type pressure sensor, the pressure sensitive diaphragm 15a moves according to the pressure. Thereby, the pressure sensitive diaphragm 15a is displaced. At this time, the capacitance between the pressure sensitive diaphragm 15a and the electrode 14 on the glass substrate 11 changes. Therefore, the change can be a pressure change using the capacitance as a parameter. As described above, since the high adhesion is exhibited at the interface 11c between the glass substrate 11 and the island 12a and the interface 11d between the glass substrate 11 and the silicon substrate 15, the displacement of the pressure-sensitive diaphragm 15a is a pressure to be measured. Can be considered only. Therefore, it is possible to accurately detect the capacitance between the pressure sensitive diaphragm 15a and the electrode 14, and it is possible to accurately detect a pressure change corresponding to the change in the capacitance.

  Next, a method for manufacturing a capacitive sensor using the glass substrate of the present embodiment will be described. 2 (a) to 2 (e) are cross-sectional views for explaining the glass substrate manufacturing method according to Embodiment 1 of the present invention.

  First, a silicon substrate 12 having a low resistance by doping impurities is prepared. The impurity may be an n-type impurity or a p-type impurity. The concentration is, for example, about 0.01 Ω · cm. This silicon substrate is etched to form islands 12a and 12b as shown in FIG. Etching may be dry etching or wet etching. However, in the case of wet etching, it is preferable to perform anisotropic etching by defining the crystal plane of the surface of the silicon substrate 12 so that the etching rate is different. In addition, it is preferable that the corner | angular part 12c of the island-like bodies 12a and 12b is as curved as possible for joining with the glass substrate mentioned later.

  Next, as shown in FIG. 2B, a glass substrate 11 is placed on the silicon substrate 12 on which the islands 12a and 12b are formed. Further, the silicon substrate 12 and the glass substrate 11 are heated, and as shown in FIG. 2C, the silicon substrate 12 is pressed against the glass substrate 11 so that the islands 12a and 12b are applied to the main surface 11a of the glass substrate 11. The silicon substrate 12 and the glass substrate 11 are bonded by pressing. The temperature at this time is preferably a temperature below the melting point of silicon and capable of deforming the glass. For example, the heating temperature is about 600 ° C.

  Further, in order to further improve the adhesion at the interface 11c between the islands 12a, 12b of the silicon substrate 12 and the glass substrate 11, it is preferable to perform an anodic bonding treatment. In this case, an electrode is attached to each of the silicon substrate 12 and the glass substrate 11 and a voltage of about 300 V to 1 kV is applied under heating at about 400 ° C. or lower. Thereby, the adhesiveness in the interface 11c becomes higher, and the airtightness of the space portion 15c of the capacitive sensor can be improved.

  Next, as shown in FIG. 2D, the islands 12a and 12b are partially exposed at the main surface 11b by polishing the main surface 11b side of the glass substrate 11. As a result, the islands 12a and 12b are embedded in the glass substrate 11. Further, as shown in FIG. 2E, the islands 12a and 12b are partially exposed from both surfaces of the glass substrate 11 by polishing the silicon substrate 12. Thus, the glass substrate (FIGS. 2D and 2E) of the present invention is produced.

  Here, the manufacturing process of the glass substrate according to the present invention will be described. 3A and 3B are views for explaining a method of forming islands 12a and 12b on the silicon substrate 11 as shown in FIG. First, as shown in FIG. 3A, the surface of the silicon substrate 21 is half-diced (grooved) using a dicing blade to form an island 21a. At this time, it is desirable that the width of the island-shaped body 21a is wider than the width of the groove 21b formed by half dicing. Thereby, it can prevent that the island-shaped body 21a is missing in the case of half dicing. Further, by forming the islands 21a by half dicing as described above, the verticality of the sidewalls of the islands 21a can be increased, and the arrangement density of the islands 21a can be increased. In addition, the half dicing does not require expensive equipment such as a dry etching apparatus, and can reduce the cost.

  Next, as shown in FIG. 3B, wet etching is performed on the silicon substrate 21 on which the islands 21a are formed to form islands 21c. In this way, by performing wet etching on the silicon substrate 21 shown in FIG. 3A, the upper surface and the side surface of the island-shaped body 21a are etched, and the width of the island-shaped body 21a is narrowed. Therefore, the space between the islands 21c is increased. Further, the island-shaped body 21c is formed by half dicing, has high verticality, and can make the base angle in the cross section of the island-shaped body relatively large, so that the interval between the island-shaped bodies can be narrowed. . For this reason, when using an island-like body as an extraction electrode of a device, the freedom degree of device design can be enlarged. As an etchant used for wet etching, a TMAH (tetramethylammonium hydroxide) aqueous solution, a KOH solution, or the like can be used. In order to use these etchants, it is preferable that the surface of the silicon substrate 21 be a (100) plane in advance.

  FIGS. 4A to 4E are views for explaining another example of a method of forming islands 12a and 12b on both surfaces of the silicon substrate 11 as shown in FIG. 4A. First, an oxide film 22 is formed on the silicon substrate 21. As the oxide film 22, a thermal oxide film formed by heat treatment, an oxide film formed by CVD treatment, or the like can be used. Next, as shown in FIG. 4B, one oxide film 22 is patterned to form a mask 22a. This patterning is performed by ordinary photolithography and etching. The mask 22a is preferably shaped and sized in consideration of side etching that occurs during alkali etching. For this reason, it is desirable to form with the width | variety narrower than the width | variety of the island-shaped body formed by the half dicing mentioned later.

  Next, as shown in FIG. 4C, the surface of the silicon substrate 21 is half-diced (grooved) using a dicing blade to form islands 21a. At this time, it is desirable that the width of the island-shaped body 21a is wider than the width of the groove 21b formed by half dicing. Thereby, it can prevent that the island-shaped body 21a is missing in the case of half dicing. Further, by forming the islands 21a by half dicing as described above, the verticality of the sidewalls of the islands 21a can be increased, and the arrangement density of the islands 21a can be increased. In addition, the half dicing does not require expensive equipment such as a dry etching apparatus, and can reduce the cost.

  Next, as shown in FIG. 4D, wet etching is performed on the silicon substrate 21 on which the islands 21a are formed to form islands 21d and 21e. When wet etching is performed, the etching is limited in the region having the mask 22a, so that the island-shaped body 21d having a relatively high height is formed. A low island 21e is formed. In this way, two types of islands 21d and 21e with different heights are formed. As an etchant used for wet etching, a TMAH (tetramethylammonium hydroxide) aqueous solution, a KOH solution, or the like can be used. In order to use these etchants, it is preferable that the surface of the silicon substrate 21 be a (100) plane in advance. Thereafter, as shown in FIG. 4E, the mask 22a is removed.

  Since islands with different heights can be formed as described above, when the islands 21d and 21e are pushed into the glass substrate 23 and the surface is polished as shown in FIG. As shown in FIG. 3, the island-shaped body 21d having a high height is exposed from the surface, and the island-shaped body 21e having a low height is embedded in the glass substrate 23. Therefore, the island-like body 21e having a low height increases the adhesion between the glass substrate 23 and the silicon substrate 21. That is, since the upper surface of the island-shaped body 21e is not exposed on the surface but exists in the glass substrate 23, the contact area between the island-shaped body 21e and the glass substrate 23 is large, and both are firmly adhered. For this reason, even in a relatively low strength portion such as an end portion of the substrate, it is possible to secure a strength that can resist the force applied to the substrate in the subsequent process.

  For example, as shown in FIG. 6A, the strength of the outer peripheral portion is improved by forming the island-shaped body 21d around the inside and providing the island-shaped body 21e at the outer peripheral portion (end) in the wafer W. Therefore, even when wafer level processing is performed, chipping of the outer peripheral portion of the wafer W can be prevented.

  Further, since the island-shaped body 21d having a high height can be formed in an arbitrary portion by the pattern of the mask 22a, it is possible to form a mark such as an alignment mark with the island-shaped body 21d. For example, as shown in FIG. 6B, the island 21d 'can be used as an alignment mark by disposing the island 21d' at the center of the rectangular frame of the island 21d.

  Further, as described above, since the wet etching is performed after the half dicing, the upper surfaces and the side surfaces of the islands 21d and 21e are etched to narrow the width of the islands. Accordingly, the distance between the islands 21d and 21e is increased. Therefore, the islands 21d and 21e have high verticality, and the base angle in the cross section of the islands can be made relatively large, so that the distance between the islands can be reduced. For this reason, when using an island-like body as an extraction electrode of a device, the freedom degree of device design can be enlarged. For example, as shown in FIG. 6C, since the interval between the islands 21d can be narrowed, many (here, six) islands 21d are provided in a specific region on the wafer W. And can be used as an extraction electrode.

  A capacitance type pressure sensor is manufactured using the glass substrate manufactured as described above. As shown in FIG. 7, the electrode 14 is formed on the main surface 11b of the glass substrate 11 so as to be electrically connected to the island-shaped body 12a. In this case, first, an electrode material is deposited on the main surface 11b of the glass substrate 11, a resist film is formed thereon, and the resist film is patterned so that the resist film remains in the electrode formation region (photolithography). Then, the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed.

  Next, as shown in FIG. 1, the silicon substrate 15 having the pressure-sensitive diaphragm 15a that is displaced by the pressure to be measured is placed on the main substrate of the glass substrate 11 so that the pressure-sensitive diaphragm 15a is positioned at a predetermined distance from the electrode 14. It joins on the surface 11b. In this case, first, the silicon substrate 15 is etched from both main surface sides to provide recesses to form the pressure sensitive diaphragm 15a. Etching may be dry etching or wet etching. However, in the case of wet etching, it is preferable to perform anisotropic etching by defining the crystal plane of the surface of the silicon substrate 15 so that the etching rate is different. In particular, since the tapered surface 15d is formed in the concave portion that does not constitute the space portion 15c of the silicon substrate 15, the concave portion is formed by anisotropic etching.

  The recess on the space 15c side of the silicon substrate 15 is formed larger than the electrode 14 to the extent that the electrode 14 on the glass substrate 11 can be surrounded. The depth of the recess is determined in consideration of the distance between the pressure sensitive diaphragm 15a and the electrode 14, the thickness of the electrode 14, and the like. The silicon substrate 15 having the recesses on both sides thus produced is formed so that the recess having the tapered surface 15d faces upward, that is, the recess having no tapered surface faces the glass substrate 11. It is placed on the main surface 11b and subjected to anodic bonding. At this time, it is performed by applying a voltage of about 500 V to the silicon substrate 15 and the glass substrate 11 under heating at about 400 ° C. or lower. Thereby, the adhesiveness in the interface between the silicon substrate 15 and the glass substrate 11 becomes higher, and the airtightness of the space 15c can be improved.

  Next, electrodes 13a and 13b are formed on the main surface 11a of the glass substrate 11 so as to be electrically connected to the islands 12a and 12b, respectively. In this case, first, an electrode material is deposited on the main surface 11a of the glass substrate 11, a resist film is formed thereon, and the resist film is patterned so that the resist film remains in the electrode formation region (photolithography). Then, the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed.

  In the capacitive pressure sensor thus obtained, the electrode 14 that is a fixed electrode is electrically connected to the electrode 13a via the island 12a, and the pressure-sensitive diaphragm 15a that is a movable electrode is connected to the island. It is electrically connected to the electrode 13b through the shaped body 12b. Therefore, the change signal of the electrostatic capacitance detected between the pressure sensitive diaphragm 15a and the electrode 14 can be acquired from the electrode 13a via the island 12b. The measured pressure can be calculated based on this signal.

(Embodiment 2)
FIG. 8 is a cross-sectional view showing a schematic configuration of a capacitive pressure sensor including a glass substrate according to Embodiment 2 of the present invention. In FIG. 8, the same parts as those in FIG. 1 are denoted by the same reference numerals as those in FIG.

  The glass substrate 11 and the silicon substrate 12 are joined. At this time, island-like bodies 12 a and 12 b made of silicon are embedded in the glass substrate 11. Further, the islands 12 a and 12 b are partially exposed at the main surface 11 b of the glass substrate 11. Therefore, the islands 12a and 12b are electrically connected to each other by the silicon layer formed on the main surface 11a.

  An electrode 16a is formed on the main surface 11a of the glass substrate 11 so as to be electrically connected to the exposed portion of the island-shaped body 12a, and the electrode 16a is electrically connected to the exposed portion of the island-shaped body 12b. 16b is formed.

  On the main surface 11 b of the glass substrate 11, a silicon substrate 15 having a pressure-sensitive diaphragm 15 a (movable electrode) is bonded. The pressure sensitive diaphragm 15a has the same configuration as that of the first embodiment. As a result, a predetermined interval is provided between the pressure-sensitive diaphragm 15 a and the electrode 14, and an electrostatic capacity is generated between the pressure-sensitive diaphragm 15 a and the electrode 14. Further, an electrode 17 for a movable electrode is provided on the surface of the silicon substrate 15 opposite to the bonding surface with the glass substrate 11.

  As in the first embodiment, the interface 11c between the glass substrate 11 and the island-shaped body 12a and the interface 11d between the glass substrate 11 and the silicon substrate 15 exhibit high adhesion. For this reason, the airtightness in the space part 15c comprised between the pressure-sensitive diaphragm 15a and the main surface 11b of the glass substrate 11 can be kept high.

  The capacitance type pressure sensor having such a configuration has a predetermined capacitance between the pressure-sensitive diaphragm 15a and the electrode 14 on the glass substrate 11 as in the first embodiment. When pressure is applied to the capacitance type pressure sensor, the pressure sensitive diaphragm 15a moves according to the pressure. Thereby, the pressure-sensitive diaphragm 15a is displaced, and the electrostatic capacitance between the pressure-sensitive diaphragm 15a and the electrode 14 on the glass substrate 11 changes. Therefore, this change in capacitance can be a change in pressure. As described above, since the high adhesion is exhibited at the interface 11c between the glass substrate 11 and the island 12a and the interface 11d between the glass substrate 11 and the silicon substrate 15, the displacement of the pressure-sensitive diaphragm 15a is a pressure to be measured. Can be considered only. Therefore, the change in capacitance between the pressure-sensitive diaphragm 15a and the electrode 14 due to the displacement of the pressure-sensitive diaphragm 15a is accurately reflected in the change in pressure, and the change in pressure can be accurately detected.

  Next, a method for manufacturing a capacitive sensor using the glass substrate of the present embodiment will be described. FIG. 9 is a cross-sectional view for explaining a method for manufacturing a capacitive pressure sensor using the glass substrate obtained in FIG.

  The method for manufacturing the glass substrate is the same as in the first embodiment. In this embodiment, a glass substrate having a structure shown in FIG. As shown in FIG. 9A, electrodes 16a and 16b are formed on the main surface 11b of the glass substrate 11 so as to be electrically connected to the islands 12a and 12b, respectively. In this case, first, an electrode material is deposited on the main surface 11b of the glass substrate 11, a resist film is formed thereon, and the resist film is patterned so that the resist film remains in the electrode formation region (photolithography). Then, the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed.

  Next, as shown in FIG. 9 (b), a silicon substrate 15 having a pressure-sensitive diaphragm 15a that is displaced by the pressure to be measured is placed on a glass substrate so that the pressure-sensitive diaphragm 15a is positioned at a predetermined interval from the electrode 16a. 11 on the main surface 11b. The method for forming the pressure-sensitive diaphragm 15a is the same as in the first embodiment.

  Thereafter, an electrode 17 is formed on the surface 15e opposite to the bonding surface of the silicon substrate 15 to the glass substrate 11. In this case, first, an electrode material is deposited on the surface 15e of the silicon substrate 15, a resist film is formed thereon, and the resist film is patterned (photolithography) so that the resist film remains in the electrode formation region. The electrode material is etched using the resist film as a mask, and then the remaining resist film is removed. Here, the electrode 17 is provided on the surface 15e of the silicon substrate 15, but the electrode 17 is on the main surface 11b of the glass substrate 11 and is not electrically joined to the islands 12a and 12b. 15 may be provided in a region that is electrically connected to the electrode 15. In this case, since the electrode 17 is formed on the same surface as the electrode 16b, the degree of freedom in wiring layout increases.

  The silicon substrate 15 having the recesses on both sides thus produced is formed so that the recess having the tapered surface 15d faces upward, that is, the recess having no tapered surface faces the glass substrate 11. It is placed on the main surface 11b and subjected to anodic bonding. The anodic bonding process is performed in the same manner as in the first embodiment. Thereby, the adhesiveness in the interface between the silicon substrate 15 and the glass substrate 11 becomes higher, and the airtightness of the space 15c can be improved.

  In the capacitive pressure sensor thus obtained, the electrode 16a, which is a fixed electrode, is electrically connected to the electrode 16b via the islands 12a, 12b, and the pressure-sensitive diaphragm 15a, which is a movable electrode. Is electrically connected to the electrode 17. Therefore, the capacitance change signal detected between the pressure-sensitive diaphragm 15a and the electrode 16a can be acquired from the electrode 16b via the islands 12a and 12b. The measured pressure can be calculated based on this signal.

Next, examples performed for clarifying the effects of the present invention will be described.
The airtightness of the capacitive pressure sensor of the present invention shown in FIGS. 1 and 8 and the conventional capacitive pressure sensor was examined. Specifically, the capacitance type pressure sensor shown in FIGS. 1 and 8 and a conventional capacitance type pressure sensor prepared by embedding a metal in the hole after making a hole in the glass substrate are prepared. , Each was placed in a pressure chamber and the internal pressure was increased. We investigated whether the pressure-sensitive diaphragm was movable at that time. As a result, in the capacitive pressure sensor shown in FIGS. 1 and 8, the pressure-sensitive diaphragm was actuated by pressurization, and the state was maintained. Therefore, high adhesion is exhibited at the interface 11c between the glass substrate 11 and the island 12a and the interface 11d between the glass substrate 11 and the silicon substrate 15, and the airtightness of the space 15c is excellent. I understood. On the other hand, in the conventional capacitive pressure sensor, when the pressure is applied, the pressure-sensitive diaphragm is once actuated to bend toward the glass substrate 11, but after a short time, the pressure-sensitive diaphragm has returned to the original position. From this, it was found that the adhesion between the glass substrate and the island was poor and the airtightness of the space was poor.

  In the first and second embodiments, the case where the silicon substrate 15 is bonded to the glass substrate 11 after the concave portions are formed on both surfaces of the silicon substrate 15 has been described. A concave portion is formed on one surface, and after bonding the silicon substrate 15 to the glass substrate 11 so as to form a space portion 15c with the concave portion facing the glass substrate 11, the other surface of the silicon substrate 15 is etched. The diaphragm 15a may be formed. By manufacturing in this way, it is possible to prevent the diaphragm from being bent more than necessary due to electrostatic attraction during the anodic bonding of the silicon substrate 15 and the glass substrate 11.

  The present invention is not limited to Embodiments 1 and 2 above, and can be implemented with various modifications. For example, the numerical values and materials described in the first and second embodiments are not particularly limited, and can be appropriately changed without departing from the scope of the object of the present invention.

It is sectional drawing which shows schematic structure of the electrostatic capacitance type pressure sensor provided with the glass substrate which concerns on Embodiment 1 of this invention. (A)-(e) is sectional drawing for demonstrating the manufacturing method of the glass substrate which concerns on Embodiment 1, 2 of this invention. (A), (b) is a figure explaining the method of forming an island-like body on a silicon substrate. (A)-(e) is a figure explaining the other example of the method of forming an island-like body on a silicon substrate. (A), (b) is a figure for demonstrating the process which pushes the silicon substrate which has an island-like body into a glass substrate, and grind | polishes. (A)-(c) is a figure for demonstrating arrangement | positioning of the island-like body on a wafer. It is sectional drawing for demonstrating the manufacturing method of the electrostatic capacitance type pressure sensor using the glass substrate obtained by FIG.2 (e). It is sectional drawing which shows schematic structure of the electrostatic capacitance type pressure sensor provided with the glass substrate which concerns on Embodiment 2 of this invention. (A), (b) is sectional drawing for demonstrating the manufacturing method of the capacitance-type pressure sensor using the glass substrate obtained by FIG.2 (d). It is sectional drawing which shows schematic structure of the conventional electrostatic capacitance type pressure sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11, 23 Glass substrate 11a, 11b Main surface 11c, 11d Interface 12, 15, 21 Silicon substrate 12a, 12b, 21a, 21c-21e Island-like body 12c Corner | angular part 13a, 13b, 14, 16a, 16b, 17 Electrode 15a Pressure diaphragm 15b Side surface 15c Space 15d Tapered surface 15e Surface 21b Groove 22 Oxide film 22a Mask W Wafer

Claims (9)

  A glass substrate body having a pair of main surfaces opposed to each other, and a silicon island body embedded in the glass substrate body so that at least a part thereof is exposed on both of the pair of main surfaces. Characteristic glass substrate.   2. The glass substrate according to claim 1, wherein the silicon islands are electrically connected to each other by a silicon layer formed on the one main surface of the glass substrate body.   The glass substrate according to claim 1, wherein the silicon island has a metal layer embedded so as to be exposed on at least one main surface of the glass substrate body.   The glass substrate according to claim 1, wherein the glass substrate has a Si-Si bond or a Si-O bond at an interface between the glass substrate body and the silicon island.   The glass substrate according to claim 1, provided on the main surface where the silicon island is exposed, and electrically connected to the silicon island, and provided on the main surface where the electrode is formed. A silicon substrate having a pressure-sensitive diaphragm that is located at a predetermined distance from the electrode and that is displaced by a pressure to be measured, between the electrode and the pressure-sensitive diaphragm. A capacitance-type pressure sensor that detects a change in capacitance as a pressure change.   A step of forming islands on the surface of the silicon substrate, a step of pressing the islands into the glass substrate under heating to bond the silicon substrate and the glass substrate, and polishing the surface of the glass substrate. Exposing the islands from the surface of the glass substrate. A method for producing a glass substrate, comprising:   The method for manufacturing a glass substrate according to claim 6, wherein the island-shaped body is formed by wet-etching the silicon substrate after half-dicing the surface of the silicon substrate.   The island-shaped body is formed by forming a mask on the silicon substrate, half-dicing the region surface of the silicon substrate other than the region where the mask is formed, then wet-etching the silicon substrate, and then removing the mask The method for producing a glass substrate according to claim 6, wherein:   A step of manufacturing a glass substrate by the method according to any one of claims 6 to 8, and an electrode on the glass substrate so as to be electrically connected to the islands exposed from the surface of the glass substrate. And a step of bonding a silicon substrate having a pressure-sensitive diaphragm that is displaced by a pressure to be measured on the glass substrate so that the pressure-sensitive diaphragm is positioned at a predetermined distance from the electrode. A method for manufacturing a capacitive pressure sensor comprising:

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