JP4502125B2 - Mechanical quantity sensor, electronic device, and manufacturing method of mechanical quantity sensor - Google Patents

Description

  The present invention relates to a mechanical quantity sensor such as an acceleration sensor or an angular velocity sensor in which a sealed chamber is formed using a glass substrate and a silicon substrate, and a detection unit for detecting various mechanical quantities such as acceleration and angular velocity is accommodated in the sealed chamber. The present invention also relates to an electronic device having the mechanical quantity sensor and a method for manufacturing the mechanical quantity sensor.

  Conventionally, a mechanical quantity sensor that detects acceleration or angular velocity applied to an electronic device has been provided. In this type of mechanical quantity sensor, a sensor obtained by anodically bonding a glass substrate and a silicon substrate in a vacuum state is widely used. On the other hand, this type of mechanical quantity sensor is built in an electronic device, and is configured to be ultra-small so that a detection signal is very small. Therefore, the noise that obscures the detection signal that has been made minute is a great enemy for this type of mechanical quantity sensor. One cause of such noise is leakage current.

  In order to manufacture this kind of mechanical quantity sensor, when the glass substrate and the silicon substrate are anodically bonded as described above, the layer near the surface of the glass substrate opposite to the bonded side (hereinafter, surface layer) Alkali metals (for example, sodium, potassium, etc.) contained in the glass substrate were segregated. Since the segregated alkali metal has conductivity, it generates a leakage current that causes the noise described above. If this leakage current is, for example, several hundred pA to several tens of nA when the detection signal is several nA or less, the detection signal is buried in the noise caused by the leakage current, and an appropriate detection signal is obtained. It was a bad thing that can not be obtained.

Therefore, in order to solve such a problem, an anodic bonding method shown in FIG. 11 is provided (see Patent Document 1). That is, as shown in FIG. 11, when anodically bonding a glass substrate 102 provided with a through-hole 101 to a silicon substrate 103, first, it is opposite to the bonding surface of the glass substrate 104 that is previously bonded to the silicon substrate 103. The electrode pin 106 is brought into close contact with the side surface through the conductive plate 105. Then, a positive voltage is applied to the conductive plate 105 by the electrode pins 106, and a negative voltage is applied to the conductive plate 107 that is in close contact with the surface opposite to the bonding surface of the glass substrate 102. Reference numeral 108 denotes a heater for heating the glass substrate 102. According to this anodic bonding method, when the glass substrate 102 is bonded to the silicon substrate 103, the segregated alkali metal is drawn into the conductive plate 107 to which a negative voltage is applied. Thereby, segregation of alkali metal has been reduced.
JP 2001-158672 A

  However, in the anodic bonding method described above, it has been inconvenient to remove all alkali metals segregated on the surface layer of the glass substrate. That is, at least a small amount of alkali metal remains on the surface layer of the glass substrate, and although this is reduced by the remaining alkali metal, there is still a problem that leakage current occurs. It was left.

  The present invention has been made in view of such circumstances, and the purpose thereof is a leakage current that is generated by an alkali metal segregated on the surface layer of the glass substrate when anodically bonding the glass substrate and the silicon substrate. Is to provide a mechanical quantity sensor and an electronic device, and a method for manufacturing the mechanical quantity sensor, in which the ratio of a detection signal to noise is improved.

The present invention provides the following means in order to solve the above problems.
The mechanical quantity sensor of the present invention includes a glass substrate, a silicon substrate bonded to the glass substrate by anodic bonding, and a surface that is electrically connected to the silicon substrate and opposite to the surface on which the silicon substrate is bonded. A plurality of thin film terminals formed on the surface of the glass substrate, and a surface notch portion formed between each of the plurality of thin film terminals on the surface on which the plurality of thin film terminals are formed, To do. In addition, this glass substrate may be comprised of a pair that is anodically bonded so as to sandwich a silicon substrate. That is, a pair of glass substrates, a silicon substrate bonded by anodic bonding while being sandwiched between the pair of glass substrates, and a surface electrically connected to the silicon substrate and bonded to the silicon substrate A plurality of thin film terminals formed on the surfaces of the pair of one or both glass substrates opposite to each other, and surfaces formed between the plurality of thin film terminals on the surface on which the plurality of thin film terminals are formed You may comprise so that a notch part may be provided.

As described above, in a glass substrate that is anodically bonded to a silicon substrate, alkali metal is segregated on the surface layer on the surface opposite to the bonding surface with the silicon substrate. This alkali metal causes a leak current.
In the mechanical quantity sensor of the present invention, the surface notch is provided between the thin film terminals provided for applying the voltage and so as to cut out a part of the surface layer of the glass substrate. That is, a part of the conductive alkali metal segregated on the surface layer of the glass substrate as if it is connected is removed, and a part of the surface layer of the glass substrate is removed as if it is disconnected. Therefore, even if a voltage is applied to the thin film terminal provided on the surface side where the alkali metal is segregated, the conductive alkali metal is partially removed as if it were disconnected. Therefore, it is difficult for the current to flow through the alkali metal. That is, a leak current that causes noise is unlikely to occur.

  Even when the glass substrate is bonded to only one surface of the silicon substrate, or even when a pair of two glass substrates are bonded to both surfaces of the silicon substrate so as to sandwich the silicon substrate. When the surface notch is provided so as to remove the surface layer of the glass substrate containing alkali metal segregated between the thin film terminals, the connection between the alkali metals is disconnected, and the current is It becomes difficult to flow through the alkali metal. That is, a leak current that causes noise is unlikely to occur.

The mechanical quantity sensor of the present invention is characterized in that the surface notch is configured to have a depth of at least 0.1 μm.
As will be described in detail later, among the anodically bonded glass substrates, the alkali metal described above is most often segregated on the surface layer having a depth of 0.1 μm from the surface opposite to the bonded side. Therefore, as in the case of the mechanical quantity sensor of the present invention, when the surface notch portion is configured to remove the surface layer containing the most segregated alkali metal, the above-described desired action can be obtained. it can. In other words, the conductive alkali metal is partially cut away and removed as if it were disconnected, so a voltage is applied to the thin-film terminal provided on the surface side where the alkali metal is segregated. Even then, the current is less likely to leak due to conduction with the alkali metal. That is, a leak current that causes noise is unlikely to occur.

  Furthermore, when the surface notch is formed at a depth of 0.5 to 1.0 μm from the surface opposite to the bonded side, the surface layer containing the most segregated alkali metal is formed. The surface notch is configured to be preferably removed, and the desired action as described above can be obtained more effectively. Furthermore, the rigidity of glass substrate itself will be suitably maintained by the depth of the surface notch part being 1.0 micrometer or less.

The mechanical quantity sensor of the present invention is characterized in that the surface notch portion is configured to have a depth of 0.125 to 0.25% with respect to the thickness of the glass substrate.
Of the anodically bonded glass substrate, the surface notch portion was formed at a depth of 0.125% or more with respect to the thickness of the glass substrate from the surface opposite to the bonded side. Thus, the location where the segregated alkali metal is segregated is suitably removed, and the desired action as described above can be effectively obtained. Furthermore, the rigidity of the glass substrate itself is maintained by setting the depth of the surface notch to 0.25% or less. For example, when this glass substrate is made of 400 μm having a thickness of 300 to 800 μm, the depth of the surface notch portion is made of 0.5 μm or more, so that the alkali metal is segregated. The removed part is preferably removed. Furthermore, since the depth of this surface notch part is comprised at 1.0 micrometer or less, the rigidity of glass substrate itself is also suitably maintained.

An electronic apparatus according to the present invention includes the above-described mechanical quantity sensor.
In the case where an electronic device is configured with the mechanical quantity sensor configured as described above, the mechanical quantity sensor, which is configured to prevent the occurrence of a leak current that causes noise, is applied to the acceleration of the electronic apparatus. Or angular velocity is detected. As described above, since the noise is suitably suppressed in this mechanical quantity sensor, the detection signal is appropriately recognized without being buried in the noise, and the acceleration or angular velocity applied to the electronic device Can be suitably detected.

  The method of manufacturing a mechanical quantity sensor according to the present invention includes an anodic bonding step of bonding a glass substrate provided with a plurality of through holes to a silicon substrate by anodic bonding, and the surface opposite to the surface on which the silicon substrate is bonded. A metal thin film forming step for forming a metal thin film on the surface of the glass substrate, the inner peripheral surface of the through hole, and the silicon substrate so as to be electrically conductive with each other; the metal thin film positioned between the plurality of through holes; A notch step of notching the glass substrate to form a thin film terminal and a face notch.

  The method of manufacturing a mechanical quantity sensor of the present invention includes an anodic bonding step, a metal thin film forming step, and a notch step. In the anodic bonding step, the glass substrate and the silicon substrate are suitably bonded. The In the metal thin film forming step, the surface of the glass substrate opposite to the surface to which the silicon substrate is bonded, the inner peripheral surface of the through hole, and the silicon substrate are integrated with each other so as to be electrically conductive. Is deposited. Next, in the notch step, the metal thin film and the glass substrate positioned between the plurality of through holes are notched to form the thin film terminals and the face notch portions.

  Therefore, the thin film terminal and the surface notch are preferably formed, and as described above, one of the conductive alkali metals segregated on the surface layer of the glass substrate as if they were connected. A part of the surface of the glass substrate is removed as if the part is disconnected, and a thin film terminal to which a voltage can be applied is also formed. As a result, as described above, it is possible to obtain a mechanical quantity sensor in which a current is made difficult to flow through an alkali metal, that is, a leak current that causes noise is hardly generated. In the method of manufacturing the mechanical quantity sensor, an appropriate process may be included in the above-described process, or a new process may be appropriately provided.

  Further, the notch process may include a blade notch process in which the metal thin film and the glass substrate are notched together by a blade (blade). When configured in this manner, the metal thin film and the glass substrate positioned between the plurality of through holes are cut out by the blade to form the thin film terminals and the surface cut-out portions. That is, it is possible to easily and quickly form the thin film terminal and the face notch. In addition, in the blade (blade) used in this blade notch process, an appropriate blade (blade) that can be cut so as to form the thin film terminal and the face notch can be used. For example, an appropriate draining blade or the like can be employed without being limited to a metal blade.

  Furthermore, in the notch step, the method includes a resist film forming step for forming a resist film on the metal thin film before the blade notch step, and removing the resist film after the blade notch step. You may comprise so that a resist film removal process may be included. In such a configuration, since a resist film is formed on the metal thin film in the resist film forming process, chips generated by cutting out the metal thin film and the glass substrate in the blade notch process are formed. The resist film does not affect the metal thin film. In addition, since the resist film is removed after the thin film terminal and the surface notch are formed in the blade notch process, the thin film terminal and the surface notch are preferably formed. Therefore, as described above, it is possible to obtain a mechanical quantity sensor in which a current is made difficult to flow through an alkali metal, that is, a leak current causing noise is hardly generated.

  In this way, the notch process is not constituted by a blade notch process in which the metal thin film and the glass substrate are notched together by a blade (blade), but a so-called etching process is performed between a plurality of through holes. The metal thin film and the glass substrate that are positioned may be cut out to form the thin film terminal and the surface cutout portion. That is, in the notch step, a resist film forming step for forming a resist film on the metal thin film, an etching processing step for etching the metal thin film and the glass substrate, and a resist film after the etching processing step It may be configured to include a removing step of removing the. In such a configuration, the thin film terminal and the surface notch formed by cutting out the metal thin film and the glass substrate are neatly formed, and the current is made difficult to flow through the alkali metal. That is, it is possible to obtain a mechanical quantity sensor that hardly generates a leak current that causes noise. As the etching process, either a wet etching process or a dry etching process can be employed.

  Moreover, it replaces with the manufacturing method of the above mechanical quantity sensors, and you may manufacture a mechanical quantity sensor as follows. That is, the manufacturing method of the mechanical quantity sensor includes an anodic bonding step of bonding a glass substrate provided with a plurality of through holes to a silicon substrate by anodic bonding, and the glass substrate on the side opposite to the surface on which the silicon substrate is bonded. You may comprise so that the polishing process which grind | polishes the surface of this, and the thin film terminal formation process which provides a thin film terminal in the surface of the grinding | polishing side may be included.

  When the manufacturing method of the mechanical quantity sensor is configured as described above, in the anodic bonding step, the glass substrate provided with a plurality of through holes is bonded to the silicon substrate by anodic bonding. In the polishing step, the surface of the glass substrate opposite to the surface to which the silicon substrate is bonded is polished. That is, a part of the conductive alkali metal segregated on the surface layer of the glass substrate as if it is connected is removed, and a part of the surface layer of the glass substrate is removed as if it is disconnected. Next, in the thin film terminal forming step, a thin film terminal is provided on the polished surface.

  Therefore, the thin film terminal and the surface notch are preferably formed, and as described above, one of the conductive alkali metals segregated on the surface layer of the glass substrate as if they were connected. A part of the surface layer of the glass substrate is removed as if the part is disconnected, and a thin film terminal to which a voltage can be applied is also formed. . As a result, as described above, it is possible to obtain a mechanical quantity sensor in which a current is made difficult to flow through an alkali metal, that is, a leak current that causes noise is hardly generated. In the method of manufacturing the mechanical quantity sensor, an appropriate process may be included in the above-described process, or a new process may be appropriately provided.

  According to the mechanical quantity sensor and the manufacturing method of the mechanical quantity sensor according to the present invention, when anodically bonding a glass substrate and a silicon substrate, there is a problem of leakage current that is generated by an alkali metal segregated on the surface layer of the glass substrate. An object of the present invention is to provide a mechanical quantity sensor, an electronic device, and a manufacturing method of the mechanical quantity sensor, in which the ratio of the detection signal to the noise is improved by the suppression.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a mechanical quantity sensor, an electronic apparatus, and a manufacturing method of a mechanical quantity sensor according to the invention will be described with reference to FIGS.
In the present embodiment, the electronic device will be described as an electronic device 1 having a camera mechanism such as a digital camera or a mobile phone, and the mechanical quantity sensor will be described as a gyro sensor 2 that detects angular velocity.
As shown in FIG. 1, the electronic apparatus 1 includes a camera module 3 and a sensor unit 4 having the gyro sensor 2. The camera module 3 includes a lens correction amount calculation circuit 5 that calculates a correction amount of a camera lens (not shown) based on the angular velocity sent from the sensor unit 4, and a correction amount calculated by the lens correction amount calculation circuit 5. And a lens driving circuit 8 for driving the X-axis lens actuator 6 and the Y-axis lens actuator 7. The lens actuators 6 and 7 can perform camera shake correction and the like by displacing the camera lens in the X and Y directions as appropriate.

  The sensor unit 4 includes the gyro sensor 2, a CV conversion circuit 9 that converts a capacitance according to the angular velocity detected by the gyro sensor 2 into a voltage, and an angular velocity that calculates an angular velocity from the converted voltage. And a calculation circuit 10. Further, the angular velocity calculation circuit 10 outputs the calculated angular velocity to the lens correction amount calculation circuit 5.

As shown in FIGS. 2A and 2B, the gyro sensor 2 includes a pair of glass substrates 20 and a silicon substrate bonded by anodic bonding while being sandwiched between the pair of glass substrates 20. 21, a sealed chamber 22 surrounded by the silicon substrate 21 and the pair of glass substrates 20, and a detection unit 23 that detects an angular velocity (mechanical quantity) that is housed in the sealed chamber 22 and acts from the outside. Yes. In the present embodiment, as the silicon substrate 21, a silicon (Si) support substrate 25 (for example, 400 μm having a thickness of 300 to 800 μm) and silicon dioxide (SiO ₂ ) formed on the Si support substrate 25 are used. ) BOX layer (Buried Oxide) 26 and an Si active layer 27 (for example, a thickness of 5 to 100 μm) formed on the BOX layer 26, an SOI (Silicon On Insulator) substrate (hereinafter referred to as a silicon substrate) 21. An example using this will be described.

  The sealed chamber 22 is formed by a space surrounded by a recess 30 formed in the silicon substrate 21 and the pair of glass substrates 20. Further, as shown in FIGS. 2A and 2B, the silicon substrate 21 is not in contact with the glass substrate 20 by four beams (beam portions) 31 in the sealed chamber 22 (in a hollow state). ) A suspended proof mass 32 is formed. The four beams 31 are supported on the base end side by a frame 33 surrounded by a quadrangular shape, and extend inward from intermediate positions of the four sides of the frame 33. Further, around the frame 33, as shown in FIG. 2A, a post 34 is provided between the pair of glass substrates 20 with a predetermined interval therebetween.

  A first electrode 35 a is provided on the glass substrate 20 (first glass substrate 20 a) on the Si active layer 27 side at a position facing the proof mass 32. The first electrode 35a is connected to the first glass pad 20a provided between the second glass substrate 20b and the post 34, the first post 34a, and the wiring 38a, and the wiring 38b. And the second post 34b are electrically connected to the third electrode pad 37a. When a voltage is applied to the first electrode pad 36a, an electrostatic attractive force acts on the upper portion of the proof mass 32 from the first electrode 35a. A second electrode 35 b is provided on the glass substrate 20 (second glass substrate 20 b) on the Si support substrate 25 side at a position facing the proof mass 32. The second electrode 35b is electrically connected to a second electrode pad 36b and a fourth electrode pad 37b provided between the second glass substrate 20b and the frame 33 by wiring (not shown). When a voltage is applied to the second electrode pad 36b, an electrostatic attractive force acts on the lower portion of the proof mass 32 from the second electrode 35b.

  As shown in FIGS. 2A and 2B, the proof mass 32 is excited with a predetermined input waveform by electrostatic attraction by the first electrode 35a and the second electrode 35b. When the proof mass 32 receives an angular velocity from the outside in this excited state, the proof mass 32 is twisted and displaced about the four beams 31 around the X or Y direction. Here, on the glass substrate 20 on the Si active layer 27 side, a detection electrode (not shown) for measuring the distance from the proof mass 32 is provided at a position facing the proof mass 32. This detection electrode detects a change in distance from the proof mass 32 as a change in capacitance. As a result, the displacement of the proof mass 32 can be detected as a capacitance corresponding to the displacement, and the detected capacitance can be detected by the fourth electrode pad 37b provided between the second glass substrate 20b and the post 34, and The signal is output to the CV conversion circuit 9 via the third electrode pad 37a. That is, the proof mass 32, the first electrode 35 a, the second electrode 35 b, and the detection electrode function as the detection unit 23 accommodated in the sealed chamber 22.

  The second glass substrate 20b is provided with four through holes 40 (40a, 40b, 40c, 40d) at predetermined intervals, and the first to fourth through holes 40a, 40b, 40c, An electrode pad is formed on each of 40d, so that it can be electrically connected to an external device. The first to fourth electrode pads 36a, 36b, 37a, and 37b correspond to thin film terminals in the present invention, and are the surfaces where the silicon substrate 21 is bonded to the second glass substrate 20b. It is formed on a surface (hereinafter referred to as “surface”) 51 that is the opposite side. Of the first to fourth electrode pads 36a, 36b, 37a, 37b, the first electrode pad 36a will be described as an example. The first electrode pad 36a is an inner peripheral surface 41a of the through hole 40a. The metal thin film is formed on the silicon substrate 21 and on the surface 51 of the second glass substrate 20b around the through hole 40 so as to be conductive.

  And between each of the 1st-4th electrode pad 36a, 36b, 37a, 37b, the surface notch part 60 (60a) formed so that the surface 51 of the said 2nd glass substrate 20b was notched. , 60b, 60c). Next, of the gyro sensor 2, the second glass substrate 20b constituting the main part of the present invention, the first to fourth electrode pads 36a, 36b, 37a, 37b serving as thin film terminals, and the face cutting. The notch 60 (60a, 60b, 60c) will be described in detail together with the manufacturing method thereof.

  The gyro sensors (dynamic quantity sensors) 2a, 2b, 2c shown in FIGS. 4, 6, and 8 are various embodiments of the gyro sensor 2 described above. These gyro sensors 2a, 2b, and 2c are formed by anodically bonding a pair of glass substrates 20 (first and second glass substrates 20a and 20b) so as to sandwich the silicon substrate 21 as shown in FIG. The first glass substrate 20a is anodically bonded to the silicon substrate 21 in advance. Therefore, in FIG. 3, the second glass substrate 20 b is anodically bonded to the silicon substrate 21. In the following embodiments, only the portions constituting the main part of the present invention are denoted by reference numerals, described above, and the reference numerals for the portions that are configured identically are omitted. In addition, the drawings of the manufacturing process of the gyro sensor 2 shown in FIGS. 5, 7, and 9 are schematically shown, and the BOX layer 26 and the like are not shown.

  That is, the second glass substrate 20b is anodically bonded to the second surface 21a of the silicon substrate 21, and the first and second glass substrates 20a and 20b are sandwiched between the first glass substrate 20b and the second glass substrate 20b. A conductive plate 91 and a second conductive plate 92 are disposed in close contact with the first and second glass substrates 20a and 20b. An electrode 93 applied with a high voltage is brought into close contact with the first conductive plate 20a that is in close contact with the first glass substrate 20a, and the second glass substrate 20b is anodically bonded to the silicon substrate 21. Note that the second conductive plate 92 has a built-in heater capable of heating the second glass substrate 20b to a predetermined temperature.

  Then, the first conductive plate 20a is applied by the electrode 93 applied with the high voltage, and the heater of the second conductive plate 92 is also heated to bring the second glass substrate 20b to a predetermined temperature. heat. Then, the second glass substrate 20b and the silicon substrate 21 are bonded. The step of bonding the second glass substrate 20b and the silicon substrate 21 is the anodic bonding step in the present invention. In this way, the second glass substrate 20b is anodically bonded to the silicon substrate 21 to be integrated. At this time, alkali metal (for example, sodium, potassium, etc.) is segregated on the surface layer 52 of the surface 51 of the second glass substrate 20b. The second glass substrate 20b is provided with four through holes 40 (40a, 40b, 40c, 40d) at predetermined intervals in advance. The silicon substrate 21 and the second glass substrate 20b including the first glass substrate 20a that are anodically bonded in this way have first to fourth electrode pads (thin film terminals) 36a, 36b, 37a, 37b and the surface notch 60 (60a, 60b, 60c) are provided.

(First embodiment)
Reference numeral 2 a (2) shown in FIG. 4 indicates the gyro sensor of the first embodiment. In the gyro sensor 2a, first to fourth electrode pads 36a, 36b, 37a, and 37b serving as thin film terminals are provided in the first to fourth through holes 40a, 40b, 40c, and 40d, respectively. Yes. As described above, the first to fourth electrode pads 36a, 36b, 37a, and 37b are the surface 51 of the second glass substrate 20b and the first to fourth through holes 40a, 40b, and 40c. , 40d and the inner peripheral surface 41 (41a, 41b, 41c, 41d) of the first to fourth through holes 40a, 40b, 40c, 40d, and are provided in close contact with the silicon substrate 21. Connected. Then, a first surface notch 60a is formed between the first electrode pad 36a and the third electrode pad 36b, and a second surface is formed between the second electrode pad 36b and the fourth electrode pad 37b. The surface notch 60b is formed, and the third surface notch 60c is formed between the fourth electrode pad 37b and the third electrode pad 37a. These surface notches 60 (60a, 60b, 60c) are formed so as to cut out the surface layer 52 of the surface 51 of the second glass substrate 20b at a depth D1. The depth D1 is a depth of 0.5 to 1.0 μm, which is 0.1 μm or more, and is 0.125 to 0.00 with respect to the thickness T (for example, 400 μm) of the glass substrate. It is set at 25%. The thickness T of the second glass substrate 20b can be appropriately selected from 300 to 800 μm. However, in the second glass substrate 20b, 400 μm is selected as the thickness T. It has become.

  The gyro sensor 2a is manufactured as follows. That is, as described above, first, in the anodic bonding step, the second glass substrate 20b is bonded to the silicon substrate 21. Then, the second glass substrate 20b joined and integrated with the silicon substrate 21 is then transferred to a metal thin film forming step for forming a metal thin film M on the surface 51 so as to be conductive. As shown in FIG. 5A, the metal thin film forming step includes a surface 51 of the glass substrate 20b and an inner peripheral surface 41 (41a, 41b, 41d) of the through hole 40 (40a, 40b, 40c, 40d). 41c, 41d) and the metal thin film M is formed over the portion where the through hole 40 is penetrated and the silicon substrate 21 appears. The metal thin film M is formed by vapor-depositing a conductive metal such as aluminum or by using an appropriate film forming method such as a sputtering method or a CVD (Chemical Vapor Deposition) method. Any film can be used.

  Thus, after the metal thin film M is formed, the metal thin film M positioned between the plurality of through holes 40 (40a, 40b, 40c, 40d) and the surface layer 52 of the glass substrate 20b are cut. Move to the notch process. This notch process is a process in which the first to fourth electrode pads 36a, 36b, 37a, 37b, which are thin film terminals, and the surface notch 60 (60a, 60b, 60c) are formed. ing.

  In the notch process of the first embodiment, a resist film forming process for forming a resist film R1 on the metal thin film M, and an etching process for etching the metal thin film M and the surface layer 52 of the glass substrate 20b. It includes a processing step and a removal step of removing the resist film R1 after the etching processing step.

  In the resist film forming step, as shown in FIG. 5B, for each of the through holes 40 (40a, 40b, 40c, 40d), a resist film R1 slightly larger than the hole diameter is formed. In forming the resist film R1, for example, the resist film R1 may be formed by an appropriate resist film forming method such as a known positive photoresist method.

  Next, the process proceeds to an etching process for etching the metal thin film M and the surface layer 52 of the glass substrate 20b. In this etching process, a first etching process (FIG. 5C) for etching the metal thin film M and a second etching process (FIG. 5 (FIG. 5) for etching the surface layer 52 of the second glass substrate 20b are performed. d)). In the first etching process, as shown in FIG. 5C, the remaining portion of the metal thin film M other than the portion where the resist film R1 is formed is removed. Specifically, the resist film R1 is not affected at all, and the metal thin film M is immersed in a chemical solution capable of dissolving, so that the resist film R1 of the metal thin film M other than the part where the resist film R1 is formed. Remove the rest. This etching process is not limited to adopting such a wet etching method, and any etching process may be used as long as an appropriate etching process method such as a dry etching method is used. In this way, the first to fourth electrode pads 36a, 36b, 37a, 37b serving as thin film terminals are formed.

  Then, after an appropriate cleaning process is performed, a second etching process is performed next. In this second etching process, as shown in FIG. 5D, the remaining portion of the surface layer 52 of the second glass substrate 20b other than the portion where the resist film R1 is formed is removed. Specifically, the surface layer 52 of the second glass substrate 20b is immersed in a chemical solution that does not affect the resist film R1 and has no effect on the surface layer 52 of the second glass substrate 20b. The remaining portions other than the portions where the resist film R1 is formed are removed. The thickness of the surface layer 52 removed at this time is the depth D1 described above. Accordingly, the processing is performed so as to have a thickness of 0.5 to 1.0 μm which is 0.1 μm or more from the surface 51 of the original second glass substrate 20b as described above. Specifically, the thickness of the surface layer 52 to be removed is adjusted to a depth of 0.5 to 1.0 μm by appropriately adjusting the concentration of the chemical solution and the immersion time. Note that this etching process is not limited to adopting such a wet etching method, and any etching process may be used as long as an appropriate etching process method such as a dry etching method is used. Thus, the said surface notch part 60 (60a, 60b, 60c) is formed in the said 2nd glass substrate 20b.

  Then, after an appropriate cleaning process is performed, the process proceeds to a removing step for removing the resist film R1. In this removing step, as shown in FIG. 5E, the resist film R1 is removed by immersing the resist film R1 in a removable chemical solution. After the resist film R1 is sufficiently removed, it is sufficiently washed with water and dried. In this way, the gyro sensor 2a (2) shown in FIG. 4 and described in the first embodiment is obtained.

(Second Embodiment)
Next, a second embodiment different from the above-described first embodiment will be described.
Reference numeral 2b (2) shown in FIG. 6 indicates the gyro sensor of the second embodiment. The gyro sensor 2b is provided with the first to fourth electrode pads 36a, 36b, 37a, 37b, which are thin film terminals, different from the gyro sensor of the first embodiment described above, and the chamfer cutting. Notch portions 60 (60a, 60b, 60c) are formed.

  First, the surface notch 60 (60a, 60b, 60c) according to the second embodiment will be described. The first through hole 40a and the second through hole 40b will be described later in the manufacturing process. The first surface notch 60a is formed between the second through hole 40b and the third through hole 40c, and the second surface notch 60b is formed between the second through hole 40c and the third through hole. A third surface notch 60a is formed between 40c and the fourth through hole 40d. These surface notches 60 (60a, 60b, 60c) are formed with a width of several tens to several hundreds of μm in the length direction of the second glass substrate 20b, and the second glass substrate 20b has a width. The surface layer 52 of the surface 51 is formed so as to be cut out at a depth D2. The depth D2 is set in the same manner as the depth D1 described above. Therefore, the depth to be cut is a depth obtained by adding the thickness of the metal thin film M to the depth D1. These surface notches 60 (60a, 60b, 60c) are formed, and the metal thin film M is disconnected to form the first to fourth electrode pads 36a, 36b, 37a, 37b at the same time.

  The gyro sensor 2b is manufactured as follows. That is, as described above, first, in the anodic bonding step, the second glass substrate 20b is bonded to the silicon substrate 21. Then, the second glass substrate 20b joined and integrated with the silicon substrate 21 is then transferred to a metal thin film forming step for forming a metal thin film M on the surface 51 so as to be conductive. This metal thin film forming step is the same metal thin film forming step as that of the first embodiment described above. That is, in this metal thin film forming step, as shown in FIG. 7A, the surface 51 of the glass substrate 20b and the inner peripheral surface 41 (41a, 41a, 40d) of the through holes 40 (40a, 40b, 40c, 40d). 41b, 41c, 41d) and a portion where the through hole 40 is penetrated and the silicon substrate 21 appears, the metal thin film M is formed. The metal thin film M is formed by depositing a conductive metal such as aluminum or by using an appropriate film forming method such as a sputtering method or a CVD method. I just need it.

  Thus, after the metal thin film M is formed, the metal thin film M positioned between the plurality of through holes 40 (40a, 40b, 40c, 40d) and the surface layer 52 of the glass substrate 20b are cut. Move to the notch process. In this notch process, the first to fourth electrode pads 36a, 36b, 37a, 37b, which are thin film terminals, and the surface notch 60 (60a, 60b, 60c).

  In the notch process of the second embodiment, a resist film film forming process for forming a resist film R2 on the metal thin film M, and the metal thin film M and the surface layer 52 of the glass substrate 20b are collectively bladed. And a removal step of removing the resist film R2 after the blade notch step.

  In the resist film formation step, a resist film R2 is formed over the metal thin film M. The resist film R2 is formed by cutting the metal thin film M and the second glass substrate 20b in the blade notch process to be transferred later, and the first to fourth electrode pads 36a, It is provided so as not to affect 36b, 37a, 37b. In forming the resist film R2, for example, the resist film R2 may be formed by an appropriate resist film forming method such as a known positive photoresist method.

  Next, the metal thin film M and the surface layer 52 of the glass substrate 20b are moved to a blade notch process in which the blades are notched together. In this step, the first thin hole M and the surface layer 52 of the glass substrate 20b are collectively cut out between the first through hole 40a and the second through hole 40b by a blade (blade), The surface notch 60a is formed. Further, at the same time when the first surface notch 60a is formed, the metal thin film M is separated into the first electrode pad 36a and the second electrode pad 36b. In this way, the first surface notch 60a is formed, and the first electrode pad 36a is also formed.

  In this way, the second surface notch portion is formed by collectively cutting the metal thin film M and the surface layer 52 of the glass substrate 20b between the second through hole 40b and the third through hole 40c. 60b is formed. Similarly, the second surface notch 60b is formed, and at the same time, the metal thin film M is separated into the second electrode pad 36b and the fourth electrode pad 37b. In this way, the second surface notch 60b is formed, and the second electrode pad 36b is also formed.

  Similarly, the third surface notch 60c is formed by collectively cutting the metal thin film M and the surface layer 52 of the glass substrate 20b between the third through hole 40c and the fourth through hole 40c. Form. Similarly, the third surface notch 60c is formed, and at the same time, the metal thin film M is separated into the fourth electrode pad 37b and the fourth electrode pad 37a. Yes. In this way, the third surface notch 60c is formed, and the fourth electrode pad 37b and the third electrode pad 37a are also formed.

  Then, after an appropriate cleaning process is performed, the process proceeds to a removing step for removing the resist film R2. In this removing step, as shown in FIG. 7C, the resist film R2 is removed by immersing the resist film R2 in a removable chemical solution. After the resist film R2 is sufficiently removed, it is sufficiently washed with water and dried. In this way, the gyro sensor 2b (2) shown in FIG. 6 and the above-described second embodiment is obtained. In the second embodiment, since the gyro sensor 2b (2) can be obtained by reducing the number of steps, it can be said to be the most advantageous embodiment from the viewpoint of workability.

(Third embodiment)
Next, a third embodiment different from the first and second embodiments described above will be described.
Reference numeral 2c (2) shown in FIG. 8 indicates the gyro sensor of the third embodiment. The gyro sensor 2c is provided with the first to fourth electrode pads 36a, 36b, 37a, 37b, which are thin film terminals, which are different from the gyro sensor of the third embodiment described above, and the chamfer cutting. Notch portions 60 (60a, 60b, 60c) are formed. Note that the gyro sensor 2c of the third embodiment is configured in the same manner as the first embodiment described above in terms of appearance, although the manufacturing method is different, the gyro sensor shown in FIG. The sensor 2c is assigned the same reference numeral as that of the configuration of the gyro sensor 2a of the first embodiment, and the description of each part is omitted.

  The gyro sensor 2c is manufactured as follows. That is, as described above, first, in the anodic bonding step, the second glass substrate 20b is bonded to the silicon substrate 21. Then, the second glass substrate 20b bonded and integrated with the silicon substrate 21 is then transferred to a polishing step for polishing the surface 51 of the second glass substrate 20b. As shown in FIG. 9A, this polishing step is a step of polishing so as to scrape off the surface layer 52 of the surface 51 of the glass substrate 20b, using an appropriate polishing tool or polishing apparatus (sand blasting etc.) or the like. The surface 51 of the glass substrate 20b is polished. The broken line in FIG. 9A shows the surface 51 before polishing, and the solid line shows the surface 51a after polishing.

And in this 3rd Embodiment, the surface 51 of the said glass substrate 20b is grind | polished so that the space | interval of the surface 51a before this grinding | polishing and the surface 51a after grinding | polishing may become D3. That means
These surface notches 60 (60a, 60b, 60c) are formed so as to cut out the surface layer 52 of the surface 51 of the second glass substrate 20b at a depth D3 similar to the depth D1. It has become. After the polishing, the surface 51a is appropriately cleaned. The distance D3 has a depth of 0.5 to 1.0 μm which is set to 0.1 μm or more, and is 0.125 to 0.00 with respect to the thickness T (for example, 400 μm) of the glass substrate 20b. It is set at 25%. Thus, in this polishing step, the surface layer 52 on which the alkali metal is segregated is removed in advance.

  After this polishing step, the process then proceeds to a metal thin film deposition step for depositing a metal thin film M on the surface 51a so as to be conductive. This metal thin film forming step is the same metal thin film forming step as that in the first and second embodiments described above. That is, in this metal thin film forming step, as shown in FIG. 9B, the surface 51 of the glass substrate 20b and the inner peripheral surface 41 (41a, 41d) of the through holes 40 (40a, 40b, 40c, 40d). 41b, 41c, 41d) and a portion where the through hole 40 is penetrated and the silicon substrate 21 appears, the metal thin film M is formed. The metal thin film M is formed by depositing a conductive metal such as aluminum or by using an appropriate film forming method such as a sputtering method or a CVD method. I just need it.

  After the metal thin film M is formed in this way, the process proceeds to a notch process in which the metal thin film M positioned between the plurality of through holes 40 (40a, 40b, 40c, 40d) is cut out. This notch process is a process in which the first to fourth electrode pads 36a, 36b, 37a, 37b to be thin film terminals are formed. Further, in the notch process of the third embodiment, a resist film forming process for forming a resist film R3 on the metal thin film M, an etching process process for etching the metal thin film M, and the etching And a removal step of removing the resist film R3 after the treatment step.

  In the resist film forming step, as shown in FIG. 9C, a resist film R3 slightly larger than the hole diameter is formed for each of the through holes 40 (40a, 40b, 40c, 40d). In forming the resist film R3, for example, the resist film R3 may be formed by an appropriate resist film forming method such as a known positive photoresist method.

  Next, the process proceeds to an etching process for etching the metal thin film M. In this etching process, as shown in FIG. 9D, the remaining portions of the metal thin film M other than the portion where the resist film R3 is formed are removed. Specifically, the metal thin film M is immersed in a chemical solution that does not affect the resist film R3 and has no influence on the resist film R3 other than the portion where the resist film R3 is formed. The part of is removed. This etching process is not limited to adopting such a wet etching method, and any etching process may be used as long as an appropriate etching process method such as a dry etching method is used. In this way, the first to fourth electrode pads 36a, 36b, 37a, 37b to be thin film terminals are formed.

  Then, after an appropriate cleaning process is performed, the process proceeds to a removing step for removing the resist film R3. In this removing step, as shown in FIG. 9E, the resist film R3 is removed by immersing the resist film R3 in a removable chemical solution. After the resist film R3 is sufficiently removed, the resist film R3 is sufficiently washed with water and dried. In this way, the gyro sensor 2c (2) according to the third embodiment shown in FIG. 8 is obtained.

  When the second glass substrate 20b is anodically bonded to the silicon substrate 21, the surface notch 60 formed in the first to third embodiments described above is included in the second glass substrate 20b. It is formed by cutting out the surface layer 52 on which an alkali metal (for example, sodium, potassium, etc.) is segregated. FIG. 10A is a graph showing the concentration of alkali metal segregated according to the depth from the surface 51 of the second glass substrate 20b when the second glass substrate 20b is anodically bonded to the silicon substrate 21. FIG. is there. In order to compare the concentration of the alkali metal segregated on the second glass substrate 20b after anodic bonding, the concentration of the alkali metal is shown using the second glass substrate 20b before anodic bonding as a reference glass. Yes.

  As can be seen from the graph shown in FIG. 10A, the alkali metal is segregated from the surface 51 of the second glass substrate 20b to a depth of 0.5 μm, and the depth of 0.1 μm from the surface 51 is obtained. By the way, alkali metals are most segregated. That is, if a depth of 0.5 μm is removed from the surface 51 where the alkali metal is segregated in the second glass substrate 20b, it becomes close to a normal reference glass. Therefore, when the surface notch 60 (60a, 60b, 60c) formed in the first to third embodiments described above is provided, 0.5 to 1.0 μm which is set to 0.1 μm or more. Therefore, it is close to a normal reference glass. Further, the depth of the surface notch 60 (60a, 60b, 60c) is set to 0.125 to 0.25% with respect to the thickness T (for example, 400 μm) of the glass substrate 20b. Therefore, since the depth is 0.5 to 1.0 μm, which is 0.1 μm or more, the surface layer 52 containing the most segregated alkali metal is removed. It will be close to the reference glass.

  Therefore, since the alkali metal having conductivity is removed by cutting out part as if it was disconnected, the thin film terminal provided on the surface 51 on the surface layer 52 side where the alkali metal is segregated Even if a voltage is applied to the first to fourth electrode pads 36a, 36b, 37a, and 37b, the current is less likely to leak due to conduction to the alkali metal. That is, a leak current that causes noise is unlikely to occur. Furthermore, the rigidity of the 2nd glass substrate 20b itself will be suitably maintained because the depth of the surface notch part 60 (60a, 60b, 60c) shall be 1.0 micrometer or less.

  FIG. 10B is a graph showing a leakage current value generated according to the depth of the surface notch 60 (60a, 60b, 60c). As can be seen from the graph shown in FIG. 10A, when the depth of the surface notch 60 (60a, 60b, 60c) is 1.0 μm, the generated leakage current value is It is suppressed to a few pA. On the other hand, when the surface notch 60 (60a, 60b, 60c) is not formed, the leakage current value is several tens to several hundreds nA.

  Therefore, when the glass substrate 20 and the silicon substrate 21 are anodically bonded, the leakage current generated by the alkali metal segregated on the surface layer 52 of the glass substrate 21 is preferably suppressed. As a result, it is possible to obtain a mechanical quantity sensor in which the ratio of the detection signal to noise is improved. Furthermore, when an electronic device is configured using this mechanical quantity sensor, the electronic device can obtain a detection signal suitably.

The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in the present embodiment, the gyro sensor 2 has been described as an example of the mechanical quantity sensor. However, the gyro sensor 2 is not limited to the gyro sensor 2. For example, the gyro sensor 2 may be configured as an acceleration sensor that detects acceleration. No problem. In this case, the proof mass 32 may not be configured to be forcibly excited.

It is a block diagram which shows one Embodiment of the electronic device which has a gyro sensor which concerns on this invention. It is sectional drawing of the gyro sensor shown in FIG. 1, and a perspective view which shows the internal structure of a proof mass periphery. It is sectional drawing which shows the anodic bonding process of anodically bonding a 2nd glass substrate to a silicon substrate. It is sectional drawing which shows 1st Embodiment of a gyro sensor. It is process drawing which showed the manufacturing method of the gyro sensor shown in FIG. It is sectional drawing which shows 2nd Embodiment of a gyro sensor. It is process drawing which showed the manufacturing method of the gyro sensor shown in FIG. It is sectional drawing which shows 3rd Embodiment of a gyro sensor. It is process drawing which showed the manufacturing method of the gyro sensor shown in FIG. It is a graph which shows the density | concentration of the alkali metal segregated according to the depth from the surface of a 2nd glass substrate, and the graph which shows the leakage current value generate | occur | produced according to the depth of a surface notch part. It is a figure which shows a prior art example.

Explanation of symbols

1 Electronic equipment 2 Gyro sensor (mechanical quantity sensor)
20 Glass substrate 21 SOI substrate (silicon substrate)
36a, 36b, 37a, 37b Thin film terminal 51 Glass substrate surface 60 surface notch

Claims (10)

A glass substrate;
A silicon substrate bonded to the glass substrate by anodic bonding;
A plurality of thin film terminals electrically connected to the silicon substrate and formed on the surface of the glass substrate opposite to the surface to which the silicon substrate is bonded;
A mechanical quantity sensor comprising: a surface notch portion formed between each of the plurality of thin film terminals on a surface on which the plurality of thin film terminals are formed. A pair of glass substrates;
A silicon substrate bonded by anodic bonding in a state sandwiched between the pair of glass substrates;
A plurality of thin film terminals electrically connected to the silicon substrate and formed on the surface of the pair of one or both glass substrates opposite to the surface to which the silicon substrate is bonded;
A mechanical quantity sensor comprising: a surface notch portion formed between each of the plurality of thin film terminals on a surface on which the plurality of thin film terminals are formed. The mechanical quantity sensor according to claim 1 or 2,
The mechanical quantity sensor, wherein the surface notch is configured to have a depth of at least 0.1 μm. The mechanical quantity sensor according to claim 3,
A mechanical quantity sensor characterized in that the surface notch is configured with a depth of 0.5 to 1.0 μm. The mechanical quantity sensor according to claim 1 or 2,
A mechanical quantity sensor characterized in that the surface notch portion is configured with a depth of 0.125 to 0.25% with respect to the thickness of the glass substrate. An electronic apparatus comprising the mechanical quantity sensor according to any one of claims 1 to 5. An anodic bonding step of bonding a glass substrate provided with a plurality of through holes to the silicon substrate by anodic bonding;
A metal thin film forming step of forming a metal thin film on the surface of the glass substrate opposite to the surface on which the silicon substrate is bonded, the inner peripheral surface of the through hole, and the silicon substrate so as to be electrically conductive with each other;
And a notch step of notching the metal thin film and the glass substrate positioned between the plurality of through holes to form a thin film terminal and a face notch, and a method of manufacturing a mechanical quantity sensor . In the manufacturing method of the mechanical quantity sensor according to claim 7,
The method of manufacturing a mechanical quantity sensor characterized in that the notch step includes a blade notch step of notching the metal thin film and the glass substrate all together with a blade. In the manufacturing method of the mechanical quantity sensor according to claim 8,
Of the notch steps, a resist film forming step of forming a resist film on the metal thin film before the blade notch step and a removing step of removing the resist film after the blade notch step The manufacturing method of the mechanical quantity sensor characterized by including. In the manufacturing method of the mechanical quantity sensor according to claim 7,
A resist film forming step of forming a resist film on the metal thin film in the notch step;
The manufacturing method of the mechanical quantity sensor characterized by including the etching process process which etches the said metal thin film and the said glass substrate, and the removal process which removes the said resist film after the said etching process process.

Images