JP2010169535A - Physical quantity sensor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve positive electrode junction by suppressing fixation of movable and fixed electrodes by a simple procedure. <P>SOLUTION: The physical quantity sensor includes: a pair of insulating substrates 7A, 7B including through-holes each; a center substrate that includes a movable electrode 1 that is supported in a cantilever form by a beam section 4, includes a gap at an area to the pair of insulating substrates, and can be rocked by elasticity of the beam section, is joined to the inner surface of the pair of insulating substrates, and includes conductivity higher than that of the insulating substrates; an outer substrate that is joined to an outer surface of the pair of insulating substrates and includes a conductivity higher than the insulating substrates; and a metal layer including an electrode film formed on inner surfaces that oppose the respective movable electrodes of the pair of insulating substrates and a conducting path extended to the outer substrate on the outer surface of the pair of insulating substrates via through-holes from the electrode film. In the physical quantity sensor, outer substrates 8A, 8B include a plurality of groove-like gaps formed at the depth reaching at least the insulating substrates in a position for sandwiching the through-holes at an interval wider than the width of the through-holes, a first beltlike section abutting on the conductive path while being sandwiched by the intervals, and a second beltlike section insulated from the first beltlike section by the gaps. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a physical quantity sensor produced by anodic bonding.

  The capacitance type physical quantity sensor has a movable electrode (diaphragm) that is displaced by acceleration or vibration, and a fixed electrode that faces the movable electrode with a gap. The movable electrode is formed on a substrate such as silicon. The fixed electrode is usually formed by forming a metal film on an insulating material. In a capacitance type physical quantity sensor, an element is formed by anodically bonding a substrate on which a movable electrode is formed and an insulator on which a metal thin film of a fixed electrode is formed.

  In anodic bonding, a voltage is applied across a bonding portion in a state where a substrate on which a movable electrode is formed and an insulator on which a metal thin film of a fixed electrode is formed are heated to a predetermined temperature. In that case, depending on the voltage distribution or the like, an electrostatic attractive force is generated between the movable electrode and the fixed electrode, and the movable electrode that should maintain the movable state may adhere to the fixed electrode.

  On the other hand, conventionally, in order to prevent discharge between the fixed electrode and the movable electrode, it has been proposed to short-circuit the fixed electrode and the movable electrode with a short-circuit wire so that they have the same potential (for example, See Patent Document 1 below).

JP 2006-194771 A

  Therefore, if this technique is applied and the fixed electrode and the movable electrode are set to the same potential, the electrostatic attractive force between the movable electrode and the fixed electrode can be suppressed, and the movable electrode is fixed to the fixed electrode. There is a possibility that the occurrence of the occurrence can be reduced. However, in the above conventional technique, it is necessary to cut and remove the short-circuit line obtained by short-circuiting the fixed electrode and the movable electrode after the anodic bonding, which complicates the process. An object of the present invention is to realize anodic bonding after suppressing sticking of a movable electrode and a fixed electrode by a simple procedure.

The present invention employs the following means in order to solve the above problems. That is, the present invention includes a pair of insulating substrates each having a through hole,
A pair of insulations including a movable electrode that is cantilevered and supported by a beam portion in an inner space sandwiched between a pair of insulating substrates and has a gap between the pair of insulating substrates and can be swung by elasticity of the beam portions A central substrate bonded to the inner surface of the conductive substrate and having higher conductivity than the insulating substrate;
An outer substrate bonded to the outer surfaces of the pair of insulating substrates and having higher conductivity than the insulating substrate;
A metal layer including an electrode film formed on an inner surface facing each movable electrode of the pair of insulating substrates, and a conductive path extending from the electrode film through the through hole to an outer substrate on the outer surface of the pair of insulating substrates; With
Each of the outer substrates has a plurality of groove-like gaps formed at a depth reaching at least the insulating substrate at positions sandwiching the through holes at intervals wider than the width of the through holes,
A first strip that is sandwiched between the gaps and in contact with the conductive path;
A first belt-like portion and a second belt-like portion insulated by a gap;

The present invention also includes a pair of insulating substrates,
A central substrate sandwiched between a pair of insulating substrates and having higher conductivity than the insulating substrate;
A method of manufacturing a physical quantity sensor comprising an outer substrate having higher conductivity than an insulating substrate on an outer surface of a pair of insulating substrates,
Forming a beam portion in a hole-like space penetrating the central substrate and a movable electrode that is cantilevered by the beam portion and can be swung by the elasticity of the beam portion and thinner than the thickness of the central substrate;
Forming a through hole in each of the pair of insulating substrates;
Forming an electrode film on each inner surface of the pair of insulating substrates and a conductive path extending from the electrode film through the through hole to the outer surface of the insulating substrate;
Bonding the outer substrate to each outer surface of the pair of insulating substrates to form a pair of bonded substrates;
A plurality of groove-like gaps at least deep enough to reach the insulating substrate are formed on the outer substrates of the pair of bonding substrates at positions where the through holes are sandwiched at intervals wider than the width of the through holes of the insulating substrate. Forming a first strip that is sandwiched and in contact with the conductive path and a second strip that is insulated from the first strip by a gap;
The central substrate and the insulating substrate side of the pair of bonded substrates are overlapped so that the movable electrode and the electrode film face each other and the through hole is located in the vicinity of the beam portion of the central substrate, and insulation on the back side of the second belt-shaped portion Contacting the conductive substrate and a portion of the central substrate surrounding the movable electrode;
The first strip and the central substrate are grounded, a junction voltage is applied to the second strip that is insulated from the first strip by the gap, and the insulating substrate on the back side of the second strip and the movable electrode of the central substrate Joining the surrounding portions of the substrate. The physical quantity sensor of the present invention has a gap on the outer substrate, so that when the first strip and the central substrate sandwiched between the gaps are grounded, the metal layer and the movable electrode that are in contact with the first strip are the same. Can be a potential. Even when the metal layer (metal film) and the movable electrode are set to the same potential, even when the junction voltage is applied to the second strip portion and the central substrate and the insulating substrate on the back side of the second strip portion are joined, the metal Occurrence of the phenomenon that the movable electrode adheres to the layer (metal film) can be suppressed. After joining, the physical quantity sensor element may be cut out as it is. That is, there is no need for a further additional process associated with setting the metal film and the movable electrode to the same potential during anodic bonding. In the physical quantity sensor manufacturing method of the present invention, a movable electrode and a metal layer (metal film) are formed in a simple procedure by forming a groove-like gap on the outer substrate and insulating the first and second strips. The physical quantity sensor can be manufactured without fixing.

  According to the present invention, anodic bonding can be realized with a simple procedure while suppressing the sticking of the movable electrode and the fixed electrode.

It is an example of the perspective view of a physical quantity sensor. It is an example of a sectional view of a physical quantity sensor. It is a figure which illustrates typically a top view of a diagram board which constituted a plurality of movable electrodes. It is the example of the top view which looked at the base of processing object from the outside. It is FIG. (1) explaining the example of the manufacturing process of a physical quantity sensor. It is FIG. (2) explaining the example of the manufacturing process of a physical quantity sensor. It is a figure which illustrates the concept of an anodic bonding process. It is an example of the perspective view of a processing apparatus. It is an enlarged view which illustrates the contact state of a joining base and a terminal. It is a perspective view which shows the state which the terminal attached to the bridge | crosslinking part contacted the strip | belt-shaped part of the silicon substrate. It is an external view of a spring built-in protrusion screw. It is a front view of a spring built-in protrusion screw. It is sectional drawing of a spring built-in protrusion screw. It is a figure which shows the state which the projection part extended longest from the outer shell part. It is a figure which shows the state by which the projection part was pushed in in the outer shell part. It is the side view which abbreviate | omitted some bridge | crosslinking parts from the processing apparatus. It is the side view which abbreviate | omitted some bridge | crosslinking parts from the processing apparatus.

  Hereinafter, a processing device for a capacitance type physical quantity sensor (hereinafter simply referred to as a physical quantity sensor) according to an embodiment for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings. The configuration of the following embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

<Outline of physical quantity sensor>
FIG. 1A illustrates a perspective view of the physical quantity sensor, and FIG. 1B illustrates a cross-sectional view of the physical quantity sensor when the physical quantity sensor is cut by moving the line L1 in the direction of the arrow A1 in FIG. 1A. This physical quantity sensor is provided with a silicon substrate (hereinafter referred to as a diaphragm substrate 6, which corresponds to the “center substrate” of the present invention) and the diaphragm substrate 6 sandwiched from both sides, and a glass substrate 7 </ b> A bonded to the diaphragm substrate 6. , 7B (corresponding to “a pair of insulating substrates” of the present invention) and glass substrates 7A, 7B are sandwiched from both outer surfaces, and silicon outer substrates 8A, 8B (joined to glass substrates 7A, 7B, respectively) Corresponding to the “outer substrate” of the present invention.

  The diaphragm substrate 6 includes a beam portion 4 (also referred to as a cantilever) formed by wet etching using a tetramethylammonium hydroxide aqueous solution (hereinafter referred to as TMAH), and the movable electrode 1. The movable electrode 1 is supported in a cantilevered state on the base portion 16 of the diaphragm substrate 6 by the beam portion 4, and can be swung by the elasticity of the beam portion 4. As shown in FIG. 1B, the upper and lower surfaces of the movable electrode 1 are provided with an insulating protrusion 3 for maintaining a gap between the inner surfaces of the glass substrates 7A and 7B. However, in the state where the external force such as acceleration is not applied to the physical quantity sensor and the beam portion 4 is not bent, that is, in the normal state where the movable electrode 1 is maintained parallel to the glass substrates 7A and 7B, the protrusion 3 is The glass substrates 7A and 7B or the fixed electrodes 2A and 2B formed on the glass substrates 7A and 7B are separated from each other. A metal movable electrode pad 10 for connecting a lead wire to an external circuit is formed on the base portion 16 of the diaphragm substrate 6 from which the beam portion 4 protrudes.

  The glass substrates 7A and 7B are bonded to the diaphragm substrate 6 at the bonding surfaces 20A to 20D. Further, gaps 11A and 11B exist between the upper and lower surfaces of the movable electrode 1 of the glass substrates 7A and 7B. Fixed electrodes 2A and 2B (corresponding to the “metal film” of the present invention) are formed on the inner surfaces of the glass substrates 7A and 7B facing the upper and lower surfaces of the movable electrode 1 with the gaps 11A and 11B interposed therebetween. The fixed electrodes 2A and 2B are usually formed by forming a metal film on the surfaces of the glass substrates 7A and 7B by sputtering or the like. Since the fixed electrodes 2A and 2B form a gap between the upper and lower surfaces of the movable electrode 1, the movable electrode 1 is displaced in the inner space sandwiched between the fixed electrodes 2A and 2B. Due to the displacement, the capacitance formed by the fixed electrodes 2A and 2B and the movable electrode 1 changes, and a physical quantity is detected. The protrusion 3 formed on the surface of the movable electrode 1 prevents direct contact with the fixed electrode even when the movable electrode 1 is extremely displaced.

In addition, a feedthrough structure 5 is formed in a portion of the glass substrates 7A and 7B facing the beam portion 4. The feedthrough structure 5 is formed by making a through hole in the glass substrates 7A and 7B. Through the feedthrough structure 5, the metal thin film which is a part of the fixed electrodes 2A and 2B is drawn from the glass substrates 7A and 7B to the outside direction, that is, toward the outer substrate outer substrates 8A and 8B. The metal drawn in the direction of the outer substrates 8A and 8B is referred to as a fixed electrode lead metal (corresponding to the “conductive path” of the present invention). The outer substrates 8A and 8B are provided with fixed electrode pads 9A and 9B, and the fixed electrode pads 9A and 9B are connected to a fixed electrode lead metal drawn out by the feedthrough structure 5.

The outer substrates 8A and 8B are bonded to the glass substrates 7A and 7B, respectively. Hereinafter, the joined outer substrate 8A (8B) and the glass substrate 7A (7B) are referred to as a cap layer 17A (17B). Insulating grooves 12A, 12B, 13A, and 13B (corresponding to the “groove-like gap” of the present invention) are formed at positions sandwiching the fixed electrode pads 9A and 9B of the outer substrates 8A and 8B. For example, the insulating grooves 12A and 12B are formed such that the fixed electrode pad 9A and the mountain-shaped portion 14A of the outer substrate 8A on which the fixed electrode pad 9A is formed (corresponding to the “first belt-like portion” of the present invention). It is electrically separated from the other portion 15A (hereinafter also referred to as a belt-like portion 15A, which corresponds to the “second belt-like portion” of the present invention). That is, the insulating grooves 12A and 12B are formed in the depth direction until reaching the glass substrates 7A and 7B. Accordingly, the mountain-shaped portions 14A and 14B and the band-shaped portions 15A and 15B are in contact with each other through the surfaces of the glass substrates 7A and 7B, but are electrically insulated. In addition, since the through holes of the feed-through structure 5 are formed in the glass substrates 7A and 7B that contact the mountain-shaped portions 14A and 14B of the outer substrate 8A, the insulating grooves 12A and 12B are formed.
Are formed at an interval wider than the diameter of the through hole of the feedthrough structure 5. The same applies to the insulating grooves 13A and 13B.

  Therefore, the fixed electrode 2A, the fixed electrode 2A lead metal, and the fixed electrode pad 9A are insulated from the band-shaped portion 15A of the outer substrate 8A. Similarly, the insulating grooves 13A and 13B are formed so that the fixed electrode pad 9B and the mountain-shaped portion 14B of the outer substrate 8B where the fixed electrode pad 9B is formed are connected to the other portion 15B of the outer substrate 8B (hereinafter also referred to as the band-shaped portion 15B). Is electrically separated from the

  As described above, the physical quantity sensor according to this embodiment is characterized in that the insulating electrodes 12A, 12B, 13A, and 13B cause the fixed electrodes 2A and 2B lead metal and the fixed electrode pads 9A and 9B to be formed on the outer substrates 8A and 8B. Is separated from the belt-like portions 15A and 15B. Therefore, when the diaphragm substrate 6 and the cap layers 17A and 17B on both sides are anodic bonded, the fixed electrodes 2A and 2B, the lead metal, and the fixed electrode pad are separated from the strip portions 15A and 15B of the outer substrates 8A and 8B. 9A and 9B can be grounded.

  That is, in the anodic bonding of the diaphragm substrate 6 and the cap layers 17A and 17B on both sides, the diaphragm substrate 6 is grounded, while the cap layers 17A and 17B on both sides apply a voltage up to about minus several hundred volts. At this time, if the fixed electrodes 2A and 2B, the lead metal, and the fixed electrode pads 9A and 9B are grounded, the fixed electrodes 2A and 2B and the movable electrode 1 of the diaphragm substrate 6 have the same potential. Therefore, the phenomenon that the movable electrode 1 is attracted to the fixed electrode 2A or 2B by electrostatic attraction can be suppressed. Note that this process can be realized by grounding the fixed electrode pads 9A and 9B at the time of anodic bonding, so that a physical quantity sensor can be manufactured extremely simply and stably.

  FIG. 2 schematically illustrates a plan view of the diaphragm substrate 6 having a plurality of movable electrodes. 1A and 1B are configuration diagrams of an element portion 21 that finally becomes an element of one physical quantity sensor. On the other hand, the diaphragm substrate 6 of FIG. 2 includes a plurality of such portions of the movable electrode 1 of the element 21. In the example of FIG. 2, a pair of the beam portions 4 are formed and hold a rectangular movable electrode from the side. However, the beam portion 4 is not limited to such a structure. For example, the beam portion 4 may be formed of one columnar member, or may be formed of three or more columnar members. In FIG. 2, the element portions 21 are schematically shown in a 3 × 4 arrangement, but the actual diaphragm substrate 6 includes a larger number of element portions 21.

FIG. 3 is a plan view of the substrate of the cap layer 17A that is anodically bonded to the diaphragm substrate of FIG. 2 as viewed from the outside (the outer substrate 8A on the side opposite to the bonding surface with the diaphragm substrate). As shown in FIG. 3, a narrow band-shaped mountain-shaped portion 14A is formed on the outer substrate 8A by the insulating grooves 12A and 12B. Further, the band-shaped portion 15A wider than the mountain-shaped portion 14A is electrically separated from the mountain-shaped portion 14A by the insulating groove 12A. In FIG. 3, three sets of a wide band-shaped portion 15A and a narrow band-shaped mountain-shaped portion 14A are schematically illustrated. However, in an actual outer substrate, more band-shaped portions 15A and mountain-shaped portions 14A are further illustrated. Are formed. Further, in the configuration of the present embodiment, the band-shaped portion 15A is configured rather than the mountain-shaped portion 14A. However, depending on the dimensions of the movable electrode 1 and the feedthrough structure 5, the band-shaped portion 15A is narrower than the mountain-shaped portion 14A. It can happen. In that sense, the mountain-shaped portion 14A is referred to as a first belt-shaped portion, and the belt-shaped portion 15A is referred to as a second belt-shaped portion.

<Example of physical quantity sensor manufacturing process>
4 and 5 illustrate the physical quantity sensor manufacturing process. The numbers (1) to (10) below correspond to (1) to (10) in FIGS. 4 and 5. (0) indicates the silicon substrate before processing.

(0) Necessary Material As the diaphragm substrate 6, for example, a silicon wafer having a low resistance, a thickness of 300 μm, and both surfaces polished is used. As the glass substrates 7A and 7B, for example, glass having a thickness of 300 μm and polished on both sides is used. The glass used as the glass substrates 7A and 7B is preferably a glass containing alkali ions such as sodium ions. For example, Pyrex glass or Tempax glass. As the outer substrates 8A and 8B, for example, a silicon wafer having a low resistance and a thickness of about 500 μm and polished on one side is used. As a material for forming the fixed electrodes 2A and 2B, for example, gold (element symbol Au), platinum (element symbol Pt), and titanium (element symbol Ti) are used.

(1) Formation of a gap (also referred to as a gap) A silicon wafer as the diaphragm substrate 6 is thermally oxidized to form an oxide film. After transferring the pattern to the photoresist by photolithography, the oxide film is patterned using the photoresist as a mask. At this time, patterning is performed while masking a portion corresponding to a portion (peripheral portion 6A in FIG. 2) surrounding a portion corresponding to the movable electrode 1 and the beam portion 4 of the silicon wafer as the diaphragm substrate 6. This process is performed on both surfaces of the movable electrode forming silicon wafer as the diaphragm substrate 6. Thereafter, the silicon not masked by the photoresist is etched by TMAH (Tetra Methyl Ammonium Hydroxide). At this time, the etching amount of silicon in a portion not masked by the photoresist becomes a gap between the movable electrode 1 and the fixed electrodes 2A and 2B. By this step, the silicon wafer other than the peripheral edge portion 6A of the diaphragm substrate 6 is etched.

(2) Formation of the protrusion 3 (stopper) The silicon wafer as the diaphragm substrate 6 is further thermally oxidized to form an oxide film 100 (for example, a thickness of 1.5 μm). After the photoresist pattern is transferred by photolithography, the oxide film 100 is patterned using the photoresist as a mask. At this time, the portion corresponding to the projection 3 of the silicon wafer as the diaphragm substrate 6 is masked and patterned. Through this step, the protrusion 3 is formed as a stopper when the movable electrode 1 (diaphragm) is formed.

(3) Pattern Formation of Movable Electrode 1 A silicon wafer as the diaphragm substrate 6 is transferred to a photoresist pattern by photolithography, and then the oxide film 100 is patterned using the photoresist as a mask. At this time, patterning is performed while masking portions corresponding to the peripheral portion 6A of the silicon wafer as the diaphragm substrate 6 and the movable electrode 1. By this step, the pattern of the movable electrode 1 is formed.

(4) Pattern formation of the beam part 4 Furthermore, after transferring the pattern of the photoresist to the silicon wafer as the diaphragm substrate 6 by photolithography, the oxide film 100 is patterned. At this time, patterning is performed by masking portions corresponding to the peripheral portion 6A, the movable electrode 1 and the beam portion 4 of the silicon wafer as the diaphragm substrate 6. Steps (2) to (4) are performed on both surfaces of the diaphragm substrate 6. Thereafter, the portion of silicon not covered (masked) with the photoresist is etched by TMAH to form a beam portion 4 (also referred to as a beam). By this step, silicon other than the portions corresponding to the peripheral portion 6A, the movable electrode 1 and the beam portion 4 starts to be etched, and the pattern of the beam portion 4 is formed.

(5) Formation of Movable Electrode 1 and Beam 4 Further, a silicon wafer as the diaphragm substrate 6 is subjected to pattern transfer of a photoresist by photolithography, and then the oxide film 100 is patterned. At this time, patterning is performed while masking portions corresponding to the peripheral portion 6A as the diaphragm substrate 6 and the movable electrode 1. This process is performed on both sides of the silicon wafer as the diaphragm substrate 6. Thereafter, the silicon not covered (masked) with the photoresist is etched by TMAH. By this wet etching of TMAH, silicon other than the portions corresponding to the peripheral portion 6A, the movable electrode 1 and the beam portion 4 penetrates. In the portion corresponding to the beam portion 4, silicon is etched to form the beam portion 4. By the steps (1) to (5), the movable electrode 1, the insulating protrusion 3, and the beam portion 4 of the diaphragm substrate 6 are formed.

(6) Manufacture and anodic bonding of cap layers on both sides A chip identification marking is made on an unpolished surface of a silicon wafer as the outer substrate 8A (8B) (not shown here). The mark is formed by, for example, DRIE (Deep Reactive Ion Etching). Next, the polished surface of the silicon wafer as the outer substrate 8A (8B) and the polished surface of the glass as the glass substrate 7A (7B) are aligned and anodically bonded. At this time, for example, anodic bonding is performed by applying a negative voltage of several hundred volts to 1 kilovolt as a bonding voltage to the glass substrate 7A (7B) while being heated to about 350 degrees. FIG. 5 illustrates the outer substrate 8B and the glass substrate 7B in FIGS. 1A and 1B. Hereinafter, FIG. 5 illustrates portions of the silicon substrate 8B and the glass substrate 7B.

(7) Formation of electrode take-out hole (feedthrough structure 5) Dry film for sandblasting on the polished surface of glass as glass substrate 7A (7B) (the surface not anodically bonded to the silicon wafer in step (6)) A resist is attached and a resist pattern is formed by photolithography. According to the resist pattern, the glass as the glass substrate 7A (7B) is penetrated by sandblasting and stopped when reaching the silicon wafer as the outer substrate 8A (8B), and the glass substrate 7A (7B) has a hole (feedthrough) Structure 5) is formed. The feedthrough structure 5 may be formed at any position on the glass substrates 7A and 7B as long as the fixed electrodes 2A and 2B can be retracted. 1A and 1B, a feedthrough structure 5 is formed in the vicinity of the center of the pair of beam portions 4 of the diaphragm substrate 6.

(8) Formation of fixed electrode (2A, 2B) The material of fixed electrode 2A (2B), for example, gold, platinum, titanium is sputtered on the polished surface of glass as glass substrate 7A (7B), and fixed electrode is formed by lift-off. 2A (2B) is patterned. For example, on the glass as the glass substrate 7A (7B), a portion where a metal film is unnecessary is protected with a resist, and a metal is formed thereon. When the resist is removed, a pattern remains in a necessary portion, and the fixed electrode 2A (2B) is formed. A metal film forming the fixed electrode 2A (2B) is drawn into the feedthrough structure 5 and connected to the outer substrate 8A (8B).

(9) Separation of electrodes Insulating grooves (12A, 12B, 13A, 13B) are formed by dicing on an unpolished surface (surface that is not anodically bonded to glass) of the silicon wafer as the outer substrate 8A (8B). To do. The insulating grooves 12A (12B, 13A, 13B) are formed by cutting at least the thickness of the silicon wafer from the surface of the silicon wafer as the outer substrate 8A (8B). For example, if the thickness of the silicon wafer as the outer substrate 8A (8B) is 50 μm, the insulating grooves 12A (12B, 13A, 13B) are formed by cutting 50 μm to several 50 μm. Further, at least two insulating grooves 12A (12B, 13A, 13B) are formed so as to sandwich the through holes of the feedthrough structure 5 of the glass substrates 17A and 17B. The insulating groove 12A (12B, 13A, 13B) may be formed in either the vertical direction or the horizontal direction with respect to the beam portion 4 (in FIGS. 1A, 1B, and 3, in the direction perpendicular to the beam portion 4). An insulating groove 12 is formed). By forming the insulating grooves 12A (12B, 13A, 13B) in this way, the metal portion drawn into the feedthrough structure 5 from the fixed electrode 2A (2B) is electrically connected from the surrounding outer substrate 8A (8B). Can be separated. The cap layers 17A and 17B on both sides of the element are formed by the steps (6) to (9).

(10) Anodic bonding, dicing, chipping diaphragm substrate 6 and glass substrates 7A and 7B side of cap layers 17A and 17B are overlapped. At this time, alignment is performed so that the fixed electrodes 2A and 2B are positioned on the opposite side of the movable electrode 1. The feedthrough structure 5 is preferably positioned in the vicinity of the beam portion 4. For alignment, an alignment mark may be attached to the silicon wafer in the processing step, or an orientation flat of the silicon wafer may be used. An alignment window is formed in the silicon layer as the outer substrate 8A of the upper cap layer 17A so that the movable electrode 1 of the diaphragm substrate 6 can be seen during alignment by sandblasting or the like, so that misalignment or the like can be confirmed during alignment. It may be.

  Next, the diaphragm substrate 6 and the crest portions 14A and 14B of the outer substrates 8A and 8B are grounded, and a negative voltage of several hundred volts to 1 kilovolt is applied as a junction voltage to the strip portions 15A and 15B of the outer substrates 8A and 8B. Then, the bonding surfaces 20A to 20D are anodically bonded. Since the fixed electrodes 2A and 2B and the movable electrode 1 have the same potential by grounding the mountain-shaped portions 14A and 14B of the outer substrates 8A and 8B, the movable electrode 1 is attracted to the fixed electrodes 2A and 2B by electrostatic attraction. It is possible to prevent the phenomenon of being generated.

  The element of the physical quantity sensor is formed into a chip by dicing. Further, the electrode pads (movable electrode pad 10, fixed electrode pad 9 and the like) shown in FIG. 1 are formed on the side surface of the element.

<Processing equipment used for anodic bonding of diagram substrate and cap layer>
When performing anodic bonding between the diaphragm substrate 6 and the cap layers 17A and 17B on both sides, for example, the following processing apparatus is used.

FIG. 6 is a diagram illustrating the concept of the anodic bonding process. As shown in FIG. 6, the substrate in which the diaphragm substrate 6 and the cap layers 17 </ b> A and 17 </ b> B on both sides thereof are overlapped is mounted on the bonding base 30 before anodic bonding. The position of the beam portion 4 of the diaphragm substrate 6 and the feedthrough structure 5 of the cap layers 17A and 17B are aligned so that they are overlapped with each other and mounted on the joining base 30. . Hereinafter, the substrate W that is a processing target of the present processing apparatus and the diaphragm layers 6 and the cap layers 17A and 17B are overlapped is referred to as a substrate W.

  The bonding base 30 includes a glass substrate 32 that secures insulation from the base portion 50 and a silicon substrate 31 bonded (for example, anodic bonded) to the glass substrate 32. In the silicon substrate 31, insulating grooves 43A and 43B similar to the insulating grooves 13A and 13B formed in the outer substrate 8B included in the cap layer 17B have substantially the same gap width and substantially the same interval (pitch). Is formed. The insulating grooves 43A and 43B form a mountain-shaped portion 54, and the mountain-shaped portion 54 is electrically separated from the other portion of the silicon substrate 31 (hereinafter referred to as a band-shaped portion 55) by the insulating groove 43A. .

  Therefore, by mounting the cap layer 17B on the bonding base 30 so that the insulating grooves 13A and 13B formed in the outer substrate 8B overlap with the insulating grooves 43A and 43B of the silicon substrate 31, the outer substrate 8B The insulation between the mountain-shaped portion 14B and the belt-shaped portion 15B can be maintained, and the mountain-shaped portion 14B and the belt-shaped portion 15B can be brought into contact with the mountain-shaped portion 54 and the belt-shaped portion 55 of the silicon substrate 31, respectively. That is, the mountain-shaped portion 14B is brought into contact with the mountain-shaped portion 54 while being insulated from the band-shaped portion 55 of the silicon substrate 31, and the band-shaped portion 15B is brought into contact with the band-shaped portion 55 while being insulated from the mountain-shaped portion 54 of the silicon substrate 31. The cap layer 17B including the outer substrate 8B can be mounted on the bonding base 30.

  In this state, the metal portion including the fixed electrode 2A can be grounded by grounding the mountain-shaped portion 14A of the outer substrate 8A with the terminal 144. Similarly, by grounding the mountain-shaped portion 54 of the silicon substrate 31 with the terminal 141, the metal portion including the fixed electrode 2B can be grounded through the mountain-shaped portion 14B of the outer substrate 8B.

  Then, the diaphragm substrate 6 is grounded through the terminal 47, and a voltage of about minus several hundred volts to minus 1000 volts (for example, minus 500 volts) is applied to the strip portion 15A of the outer substrate 8A through the terminal 143. Since a plurality of terminals 143 are arranged corresponding to the plurality of strip-like portions 15A, when distinguishing the plurality of terminals 143, they will be referred to as 143-1 and 143-2. The same applies to the terminal 144.

  Similarly, a voltage of minus several hundred volts to minus 1000 volts is applied to the band-like portion 55 of the silicon substrate 31 by the terminal 142. Since a plurality of terminals 142 are arranged corresponding to the plurality of belt-like portions 55, when distinguishing the plurality of terminals 142, they will be referred to as 142-1 and 142-2. The same applies to the terminal 141.

  As described above, by applying a voltage of minus several hundred volts to minus 1000 volts to the strip portions 15A and 15B of the outer substrates 8A and 8B, and grounding the diaphragm substrate 6, the glass adjacent to the outer substrates 8A and 8B. As a result, the same voltage is applied between the substrates 7A and 7B and the diaphragm substrate 6, and the outer substrates 8A and 8B are anodically bonded to the diaphragm substrate 6. In this process, the fixed electrodes 2A and 2B are grounded.

  Although omitted in FIG. 6, in the process of anodic bonding, the anodic bonding portion between the diaphragm substrate 6 to be processed and the glass substrates 7A and 7B included in the cap layers 17A and 17B is heated by a heating means. Is done. The heating means is, for example, a heater that is grounded below the bonding base 30 and heats the anodic bonding portion through the bonding base 30. The heating means may be a heating lamp that emits radiant heat to the diaphragm substrate 6 to be processed and the cap layers 17A and 17B.

FIG. 7 is an example of a perspective view of the processing apparatus. The present processing apparatus is constructed on the base unit 50. On the base part 50, the joining base 30 is mounted. The bonding base 30 is insulated from the base by the glass substrate 32 as shown in FIG. Further, the substrate W (including the diaphragm substrate 6 and the cap layers 17A and 17B on both sides thereof) is mounted on the bonding base 30.

  In addition, bridge-shaped bridging members 71 and 72 are arranged on the upper side of the joining base 30. The bridging members 71 and 72 are made of stainless steel, for example, and have a shape of a square member obtained by cutting a plate material having a predetermined thickness. Both ends of the bridging member 71 are fixed to the base portion 50 by the fixture 161. The fixture 161 includes a pressing structure 161A on the disk, a washer 161B on the pressing structure 161A, and a screw portion 161C on the washer. The support 161D (see FIGS. 15A and 15B) that supports the fixture 161 and the bridging member 71 from below is made of, for example, stainless steel. Further, at least the surfaces of the fixture 161 and the support portion 161D may be covered with a material having higher conductivity than stainless steel. The washer 161B is not essential and may be omitted.

  That is, the screw part 161C presses the pressing structure 161A via the washer 161B, and the pressing structure 161A presses the bridging member 71 to the joining base 30 via the support part 161D. In the example of FIG. 7, the screw portion 161 </ b> C is a male screw, and is screwed into a screw hole provided in the base portion 50. However, the screw portion 161C may be a female screw. In that case, a male screw may be raised upward from the base portion 50. In this way, the bridging member 71 is in contact with the fixture 161 and is grounded through the base portion 50.

  On the other hand, the bridging member 72 is mounted on the base portion 50 via an insulating support portion 162 </ b> D (see FIG. 15B), and is fixed to the base portion 50 by the fixture 162. Similarly to the fixture 161, the fixture 162 also includes a holding structure 162A on the disk, a washer 162B on the holding structure 162A, and a screw portion 162C on the washer. The structure of the screw part 162C is the same as that of the screw part 161C. However, the holding structure 162A is an insulator, and the bridging member 72 is insulated from the screw portion 161C, the washer 161B, and the base portion 50 (see FIG. 15B). Further, the fixture 162 presses the high-voltage conductive plate 65 against the bridging member 72. The high voltage conductive plate 65 can be supplied with a voltage of minus several hundred volts to minus 1000 volts from a high voltage power source (not shown).

  The bridging member 71 is provided with a projecting terminal 141 so that the mountain-shaped portion 54 of the silicon substrate 31 can be grounded. Further, a terminal 142 is disposed on the bridging member 72 so that a voltage of minus several hundred volts to minus 1000 volts can be transmitted to the band-like portion 55 of the silicon substrate 31.

  Similarly, bridge-shaped bridging members 73 and 74 are disposed on the upper side of the substrate W. The structure and action of the bridging member 73 are the same as those of the bridging member 72. That is, the bridging member 73 is mounted on the base portion 50 via an insulator, and is fixed to the base portion 50 together with the high-voltage conductive plate 65 by the fixture 163. Since the structure of the fixture 163 is the same as that of the fixture 162, the description thereof is omitted.

  The bridging member 74 is mounted on the base unit 50 and is fixed to the base unit 50 by a fixture 164. Since the structure of the fixture 164 is the same as that of the fixture 161, the description thereof is omitted.

  Further, the base portion 50 is provided with a metal support portion 85 that supports the ground electrode 86. The support portion 85 has an L-shaped angle shape, bridges the upper side of the joining base 30, and guides the ground electrode 86 to the terminal position of the diaphragm substrate 6 in the substrate W. The ground electrode 86 grounds the diaphragm substrate 6 through the support portion 85 and the base portion 50.

  The orientation flat detectors 81 and 82 detect the orientation flat of the substrate W. When aligning the substrate W and the bonding base, the orientation flat of the substrate W is aligned with the orientation flat detectors 81 and 82.

  FIG. 8 is an enlarged view illustrating the contact state of the bonding base 30, the terminal 141, and the terminal 142. FIG. 8 is an enlarged view of the processing apparatus as seen from the direction of the arrow A2 in FIG. In FIG. 8, a terminal 142 connected to a high voltage (minus several hundred volts to minus 1000 volts) is in contact with the band-like portion 55 of the silicon substrate 31 on the bonding base 30. Further, the terminal 141 connected to the ground potential is in contact with the mountain-shaped portion 54 (a strip-shaped portion narrower than the strip-shaped portion 55).

  9 to 14 illustrate details of the structure of the terminals 141, 142, 143, and 144. FIG. 9 is a perspective view showing a state in which the terminal 142 attached to the bridging member 72 is in contact with the band-like portion 55 of the silicon substrate 31. Here, the detailed structure will be described using the terminal 142 as an example, but the structure of the terminals 141, 143, and 144 is the same.

  FIG. 10 is an external view of the spring built-in protruding screw 100 constituting the terminals 141, 142, 143, and 144. FIG. 11 is a front view of the spring built-in protruding screw 100. FIG. 12 is a cross-sectional view of the cross section of the spring built-in protruding screw 100 taken along the plane P1 shown in the front view, as viewed in the direction of the arrow A3. As shown in FIG. 12, the spring built-in protrusion screw 100 includes a cylindrical outer shell portion 101 having a thread (male screw) formed on the outer surface, and a cylindrical length direction of the outer shell portion 101 within the outer shell portion 101. A spring 102 that can be expanded and contracted, and a protrusion 104 whose end surface is elastically pressed by the spring 102 in the cylindrical length direction of the outer shell 101. A disc-shaped collar 103 is formed on the end surface of the protrusion 104 that contacts the spring 102, and receives the pressing force of the spring 102. The protruding portion 104 extends from the collar portion 103 and includes a shaft portion having a smaller radius than the collar portion 103. In FIG. 12, the spring 102 is a helical spring, but the implementation of the present invention is not limited to such a spring shape. For example, the spring 102 may be a leaf spring.

  The outer shell portion 101 has a cylindrical shape and has a cylindrical inner space. One end of the cylinder in the longitudinal direction is closed, and the other end is provided with a hole 106 smaller than the inner surface radius of the cylindrical internal space. The shaft portion of the protruding portion 104 protrudes through the hole portion 106. And the spring part 102 urges | biases the collar part 103 in the direction where the axial part of the projection part 104 is extended, and is pressing it against the side wall of inner wall space.

  When the protrusion 104 is urged from the outside in a direction against the elastic force of the spring 102, the protrusion 104 can be elastically pushed into the outer shell 101. When the biasing in the direction against the elastic force of the spring 102 is stopped, the protruding portion 104 protrudes from the outer shell portion 101 in the cylindrical length direction again. At this time, the elastic force that the protrusion 104 protrudes outward from the outer shell 101 increases in proportion to the contracted length of the spring 102. FIG. 13 shows a state in which the protruding portion 104 extends the longest from the outer shell portion 101 (a state in which the elastic force is minimum), and FIG. 14 shows a state in which the protruding portion 104 is pushed into the outer shell portion 101 (elasticity). Force is in the maximum state).

  The spring built-in protruding screw 100 constituting the terminal 142 is screwed into a screw hole (female screw) formed in the bridging member 71 as shown in FIG. Although not clearly shown in the figure, an adhesive for preventing loosening may be applied to the external thread of the built-in protruding screw 100. When the bridging member 72 is pressed against the silicon substrate 31 and fixed with the fixture 162, the protrusion 104 elastically presses the silicon substrate 31 due to the elastic force of the spring 102. This structure is the same for the terminal 141 and the bridging member 71, the terminal 143 and the bridging member 73, and the terminal 144 and the bridging member 74.

  15A is a side view as seen from the direction of the arrow A2 in FIG. 7 (however, the central right side of the bridging members 71 and 72 is omitted). FIG. 15B is a side view seen from the direction of the arrow A2 in FIG. 7 with the bridging member 71 removed (however, the central right side of the bridging member 72 is omitted).

  As illustrated in FIG. 15A, the bridging member 71 (74) is grounded through the fixture 161 (164) and the base unit 50. On the other hand, as shown in FIG. 15B, the bridging member 72 is electrically fixed by the insulating holding structure 162A and the support portion 162D while being insulated from the base portion 50. This structure is the same for the bridging member 72. In this way, the bridging member 71 (74) is grounded by the base portion 50. The bridging member 72 (73) can be supplied with a high voltage from the high-voltage conductive plate 65.

  Further, the base portion 50 is provided with a metal support portion 85 that supports the ground electrode 86. Further, orientation flat detectors 81 and 82 for detecting the orientation flat of the substrate W are provided on the side of the base unit 50.

  Further, a heating unit 90 is provided below the base unit 50. The heating means 90 is, for example, a heater that includes a heating wire inside.

  With this configuration, the present processing apparatus mounts the bonding base 30 on the base portion 50 and further mounts the substrate W thereon. In the present processing apparatus, the substrate W is heated to a predetermined temperature by the heating means 90. The following steps are performed in this heated state.

  The insulating grooves 13A and 13B of the outer substrate 8B of the substrate W and the insulating grooves 43A and 43B of the silicon substrate 31 of the bonding base 30 are aligned, and the substrate W is mounted on the bonding base 30. At this time, by aligning the orientation flat of the substrate W with the orientation flat detectors 81 and 82, alignment is easy and reliable.

  Then, the bridging member 71 is placed so that the terminal 141 is in contact with the mountain-shaped portion 54 of the silicon substrate 31 of the bonding base 30, and is screwed with the fixture 161. Thereby, the terminal 141 is stably pressed against the mountain-shaped portion 54 by the elastic force of the spring 102. As a result, the fixed electrode 2B is reliably grounded.

  Further, the bridging member 72 is placed so that the terminal 142 is in contact with the band-like portion 55 of the silicon substrate 31 of the bonding base 30, and is screwed with the fixture 162. As a result, the terminal 142 is stably pressed against the belt-like portion 55 by the elastic force of the spring 102.

  Further, the bridging member 74 is placed so that the terminal 144 is in contact with the mountain-shaped portion 14 </ b> A of the outer substrate 8 </ b> A of the substrate W, and is screwed with the fixture 164. Thus, the terminal 144 is stably pressed against the mountain-shaped portion 14A by the elastic force of the spring 102. As a result, the fixed electrode 2A is reliably grounded.

  Further, the bridging member 73 is placed so that the terminal 143 comes into contact with the belt-like portion 15 </ b> A of the outer substrate 8 </ b> A of the substrate W, and is screwed with the fixture 163. As a result, the terminal 143 is stably pressed against the belt-like portion 15A by the elastic force of the spring 102.

  Further, the ground electrode 86 is pressed against the pad 10 of the diaphragm substrate 6 through the support portion 85. As a result, the diaphragm substrate 6 is grounded through the ground electrode 86.

Then, the high-voltage conductive plate 65, the bridging members 72 and 73, and the band-shaped portion 5 of the silicon substrate 31.
5 is applied to the strips 15A and 15B of the cap layers 17A and 17B through 5 by applying a voltage of, for example, minus several hundred volts to minus 1000 volts from a high-voltage power source. At this time, since the diaphragm substrate 6 and the fixed electrodes 2A and 2B facing the movable electrode 1 of the diaphragm substrate 6 are both grounded, the electrostatic attractive force acting on the diaphragm substrate 6 hardly exists or is at a very weak level. Can be suppressed. Therefore, anodic bonding can be performed in a state where the fixing of the movable electrode 1 to the fixed electrodes 2A and 2B is suppressed. Further, after the anodic bonding is performed, the high voltage from the power source to the high-voltage conductive plate 65 is cut off, the substrate W is removed from the processing apparatus, the substrate W is cut in a dicing process, and the individual elements 21 (FIGS. 1 and 2). Reference) may be formed. Therefore, anodic bonding can be performed stably without adding a special process after anodic bonding.

<Effects of physical quantity sensor and physical quantity sensor manufacturing method>
In the physical quantity sensor of this embodiment, the outer substrate 8A (8B) is provided with insulating grooves 12A and 12B (13A and 13B), and the mountain-shaped portion 14A (14B) sandwiched between the insulating grooves 12A and 12B (13A and 13B). And the diaphragm substrate 6 are grounded, the fixed electrode 2A (2B) and the diaphragm substrate 6 (movable electrode 1) can be set to the same potential. When the fixed electrodes 2A and 2B and the diaphragm substrate 6 (movable electrode 1) are set to the same potential, the movable electrode 1 is attracted to the fixed electrodes 2A and 2B by electrostatic attraction when performing anodic bonding. Occurrence can be prevented.

  In the physical quantity sensor manufacturing method of the present embodiment, before the anodic bonding of the diaphragm substrate 6 and the cap layers 17A and 17B, the insulating substrates 12A, 12B, 13A and 13B are formed in the outer substrates 8A and 8B of the cap layers 17A and 17B. Form. This can prevent a phenomenon in which the movable electrode 1 is attracted and stuck to the fixed electrodes 2A and 2B by electrostatic attraction during anodic bonding. Furthermore, after the anodic bonding, a special process such as cutting and removing the short-circuit line as in the conventional case is not required. Therefore, according to the physical quantity sensor manufacturing method of the present embodiment, the physical quantity sensor can be manufactured by a simple procedure without the movable electrode sticking to the fixed electrode.

DESCRIPTION OF SYMBOLS 1 Movable electrode 2 Fixed electrode 4 Beam part 6 Diaphragm board | substrate 7A, 7B Glass board | substrate 8A, 8B Outer board | substrate 17A, 17B Cap layer 21 Element 30 Joining base 50 Base 65 High voltage conductive plate 71,72,73,74 Bridging part 141,142 , 143, 144 Terminal 161, 162, 163, 164 Fixing part 161C (conductive) holding structure 161D (conductive) support part 162C (insulating) holding structure 162D (insulating) support part

Claims (2)

A pair of insulating substrates each having a through hole;
A movable electrode that is cantilevered and supported by a beam portion in an inner space sandwiched between the pair of insulating substrates and has a gap between the pair of insulating substrates and is swingable by elasticity of the beam portions; A central substrate bonded to the inner surfaces of the pair of insulating substrates and having higher conductivity than the insulating substrates;
An outer substrate bonded to the outer surface of the pair of insulating substrates and having higher conductivity than the insulating substrate;
An electrode film formed on the inner surface of each of the pair of insulating substrates facing the movable electrode, and a conductive path extending from the electrode film to the outer substrate on the outer surface of the pair of insulating substrates through the through hole. And a metal layer including
Each of the outer substrates has a plurality of groove-like gaps formed at a depth reaching at least the insulating substrate at positions sandwiching the through holes at intervals wider than the width of the through holes,
A first band-shaped portion that is sandwiched between the gaps and is in contact with the conductive path;
A physical quantity sensor having a second belt portion insulated from the first belt portion by the gap. A pair of insulating substrates;
A central substrate sandwiched between the pair of insulating substrates and having higher conductivity than the insulating substrate;
A method of manufacturing a physical quantity sensor comprising an outer substrate having higher conductivity than the insulating substrate on the outer surface of the pair of insulating substrates,
Forming a beam portion in a hole-like space penetrating the central substrate, and a movable electrode that is cantilevered by the beam portion and can be swung by the elasticity of the beam portion, and is thinner than the thickness of the central substrate;
Forming a through hole in each of the pair of insulating substrates;
Forming an electrode film on each inner surface of the pair of insulating substrates and a conductive path extending from the electrode film to the outer surface of the insulating substrate through the through hole;
Bonding the outer substrate to each outer surface of the pair of insulating substrates to form a pair of bonded substrates;
Each of the outer substrates of the pair of bonded substrates has a plurality of groove-shaped gaps at least deep enough to reach the insulating substrate at positions where the through holes are sandwiched at intervals wider than the width of the through holes of the insulating substrate. Forming and forming a first strip portion sandwiched between the gaps and contacting the conductive path and a second strip portion insulated from the first strip portion by the gaps;
The central substrate and the insulating substrate side of the pair of bonded substrates are overlapped so that the movable electrode and the electrode film face each other and the through hole is positioned in the vicinity of the beam portion of the central substrate, Contacting the insulating substrate on the back side of the two band-shaped portions with a portion around the movable electrode of the central substrate;
The first strip and the central substrate are grounded, a junction voltage is applied to the second strip that is insulated from the first strip by the gap, and the insulation on the back side of the second strip A physical quantity sensor manufacturing method comprising: bonding a substrate and a portion of the central substrate around the movable electrode.

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