JP6922528B2 - Manufacturing method of dynamic quantity sensor - Google Patents

Description

The present disclosure relates to a dynamic quantity sensor and a method for manufacturing the same.

Anode bonding is known as a method for bonding glass to a metal or a semiconductor material. In the anode bonding, a glass containing an alkali metal oxide as a subcomponent is brought into contact with a metal or a semiconductor material to be heated, and a voltage is applied with the glass side as a cathode and the metal or semiconductor material side as an anode to obtain a voltage. This is a method in which an electrostatic attraction acts between a metal or a semiconductor material to strongly adhere the two, and a covalent bond occurs at the interface between the glass and the metal or the semiconductor material to bond the glass to the metal or the semiconductor material. It is used in the manufacture of MEMS (Micro Electrical Semiconductor Systems) devices including transducers such as pressure sensors and acceleration sensors made of materials.

When manufacturing a MEMS device having a movable part, one side of the glass substrate facing the movable part is charged negatively by applying a voltage at the time of anodizing the metal or semiconductor provided with the movable part and the glass substrate. There is a problem that the movable part is attracted to the electrode provided on one surface of the glass substrate facing the movable part or the glass substrate facing the movable part due to the electrostatic attraction, and comes into contact with the electrode, and adheres to the glass substrate.

In Reference 1, when the semiconductor substrate provided with the movable portion and the glass substrate are anodically bonded, the electrode provided on one surface of the glass substrate facing the movable portion is grounded to have the same potential as the semiconductor substrate. By making the electrode function as a shield layer of the electric field, the generation of electrostatic attraction is prevented, and by preventing the movable part from being attracted to the glass substrate by the electrostatic attraction and coming into contact with the glass substrate, the movable part and the glass substrate are attached to each other. A method for manufacturing a dynamic quantity sensor that prevents sticking is disclosed. Further, in Cited Document 2, by using a specific material for the electrode provided on the lower surface of the movable portion and one surface of the glass substrate facing the movable portion, the movable portion and the glass substrate are stuck to each other even if they come into contact with each other. Disclosed is a method for manufacturing a dynamics sensor that prevents the occurrence of the above-mentioned problems and prevents the moving parts from sticking to the glass substrate.

Japanese Unexamined Patent Publication No. 2009-008437 JP-A-2009-168800

However, even when the dynamics sensor is manufactured by using the methods described in Cited Document 1 and Cited Document 2, the prevention of sticking between the movable portion provided on the semiconductor substrate and the glass substrate facing the semiconductor substrate is not sufficient. There is a problem that it becomes difficult to stably manufacture the dynamic quantity sensor, and the yield of the dynamic quantity sensor in the manufacturing process decreases.

Further, when the semiconductor substrate and the glass substrate are joined to the anode, cations such as sodium ions contained in the glass substrate move to the feeding electrode side, so that the surface of the glass substrate is opposite to the surface on which the feeding electrode is provided. When surface roughness occurs or an electrode is provided on the glass substrate, the electrode ^{deteriorates due to excess oxygen ions (O 2-} ) remaining due to the movement of cations to the feeding electrode side, resulting in a dynamics sensor. There is a problem that the reliability of the is lowered.

In view of such a problem, an object of the embodiment of the present disclosure is to prevent the movable portion provided on the semiconductor substrate from sticking to the glass substrate in the manufacture of the dynamic quantity sensor including the movable portion, and to prevent the electrode from deteriorating. By preventing this, it is necessary to stably manufacture a highly reliable mechanical quantity sensor.

The mechanical quantity sensor according to the embodiment of the present disclosure connects a frame portion having an opening, a displacement portion provided in the opening and displaced with respect to the frame portion, and the frame portion and the displacement portion. A second structure having a first structure having a flexible portion, a fixing portion joined to the frame portion, and a weight portion provided separately from the fixing portion and joined to the displacement portion. It is composed of a body and silicate glass containing an alkali metal, has a first surface facing the second structure and a second surface located on the side opposite to the first surface, and the first surface is fixed. A support substrate to be joined to the portion is provided, and the concentration of alkali metal in the portion of the support substrate facing the weight portion on the first surface and the alkali metal in the portion of the first surface facing the fixed portion. Is different from the concentration of.

The first structure may be made of a first semiconductor material, and the second structure may be made of a second semiconductor material.

The mechanical quantity sensor may further include a piezoresistive effect provided on the flexible portion. Alternatively, the mechanical quantity sensor may further include a conductive layer provided on the first surface of the support substrate.

In the method for manufacturing a dynamics sensor according to an embodiment of the present disclosure, the first semiconductor layer in the semiconductor substrate having the first semiconductor layer and the second semiconductor layer is etched to form a frame portion, a displacement portion, and the frame portion. A flexible portion connecting the displaced portion is formed to form a first structure, and a fixed portion joined to the frame portion by etching the second semiconductor layer is provided separately from the fixed portion. A first conductive layer and a second conductive layer are formed on one surface of a support substrate made of siliceous glass containing an alkali metal to form a second structure by forming a weight portion joined to the displaced portion. The anodic bonding includes forming a layer and anodic bonding the other surface of the support substrate opposite to one surface and the fixing portion of the second structure, and the anodic bonding includes the second conductivity. The first conductive layer is at least partially superimposed on the fixed portion, including grounding the layer and the semiconductor substrate and applying a voltage between the other surface of the support substrate and the fixed portion. The second conductive layer is formed so that at least a part thereof overlaps the weight portion.

The method for manufacturing a dynamic quantity sensor may further include diffusing impurities into the flexible portion of the first semiconductor layer to form a plurality of piezoresistive effects. Alternatively, the method of manufacturing a dynamic quantity sensor may further include forming a third conductive layer on the other surface of the support substrate.

The mechanical quantity sensor according to the embodiment of the present disclosure is connected to a first structure having a frame portion having an opening, a fixed portion joined to the frame portion, and the fixed portion, and is displaced with respect to the fixed portion. It is composed of a second structure having a displacement portion and a silicate glass containing an alkali metal, and has a first surface facing the second structure and a second surface located on the opposite side of the first surface. A support substrate whose first surface is joined to the fixing portion, and a concentration of alkali metal in a portion of the support substrate facing the displacement portion of the first surface and the fixing of the first surface. The concentration of the alkali metal in the portion facing the portion is different.

A first electrode may be provided on the displacement portion, or a second electrode may be provided on the first surface of the support substrate facing the displacement portion.

According to one embodiment of the present disclosure, in the manufacture of a dynamic quantity sensor including a movable part, reliability is obtained by preventing the movable part provided on the semiconductor substrate from sticking to the glass substrate and preventing the deterioration of the electrode. It is possible to stably manufacture a high dynamic quantity sensor.

It is a perspective view of the dynamic quantity sensor which concerns on one Embodiment of this disclosure. It is an exploded perspective view of the dynamic quantity sensor shown in FIG. It is a partially enlarged view of the dynamic quantity sensor shown in FIG. It is a circuit diagram which shows an example of the detection circuit for detecting the acceleration in the X-axis direction from a piezoresistive effect. It is a circuit diagram which shows an example of the detection circuit for detecting the acceleration in the Y-axis direction from a piezoresistive effect. It is a circuit diagram which shows an example of the detection circuit for detecting the acceleration in the Z-axis direction from a piezoresistive effect. It is a top view of the support substrate of the dynamic quantity sensor shown in FIG. It is sectional drawing of the dynamic quantity sensor along AA shown in FIG. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is sectional drawing which shows an example of the dynamic quantity sensor which concerns on one Embodiment of this disclosure. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is sectional drawing which shows an example of the dynamic quantity sensor which concerns on one Embodiment of this disclosure. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor. It is a figure for demonstrating the manufacturing process of a dynamic quantity sensor.

Hereinafter, the mechanical quantity sensor and the manufacturing method thereof according to the embodiment of the present disclosure will be described with reference to the drawings. However, each of the embodiments shown below is an example of the embodiments of the present disclosure, and the present disclosure is not construed as being limited to these embodiments, and can be implemented in many different embodiments. .. In each of the present embodiments and the drawings referred to in the embodiments shown below, the same parts or parts having the same functions are designated by the same reference numerals, and the repeated description thereof will be omitted. In addition, the dimensional ratio of the drawing may differ from the actual ratio for convenience of explanation, or a part of the configuration may be omitted from the drawing.

[First Embodiment]
(Mechanical quantity sensor)
As the mechanical quantity sensor according to the embodiment of the present disclosure, a piezoresistive 3-axis acceleration sensor will be described below as an example. However, the dynamic quantity sensor according to the embodiment of the present disclosure is not limited to the piezoresistive acceleration sensor, and may be a capacitance type acceleration sensor, a pressure sensor, an angular velocity sensor, or the like. FIG. 1 is a perspective view of the mechanical quantity sensor 100 according to the embodiment of the present disclosure, and FIG. 2 is an exploded perspective view of the dynamic quantity sensor 100 shown in FIG.

Referring to FIGS. 1 and 2, the mechanical quantity sensor 100 is an accelerometer main body composed of a silicon oxide film 101b formed on a silicon substrate 101a and an SOI substrate 101 on which a silicon film 101c is laminated. 103 and a support substrate 105 are included.

The acceleration sensor main body 103 has a first frame portion 109, a displacement portion 111 that is displaced with respect to the frame portion 109, and a flexible portion 113 (113a, 113b) that connects the frame portion 109 and the displacement portion 111. The second structure 203 includes a fixed portion 117 joined to the structure 201 and the frame portion 109, and a weight portion 119 provided separately from the fixed portion 117 and joined to the displacement portion 111. In the mechanical quantity sensor 100 shown in FIGS. 1 and 2, a part of the configuration including the wiring layer provided on the first structure 201 of the acceleration sensor main body 103 is omitted.

The first structure 201 is composed of a silicon oxide film 101b and a silicon film 101c. A plurality of piezoresistors Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 are provided on the flexible portions 113 (113a, 113b) of the first structure 201. The piezoresistives Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 are composed of a semiconductor material containing impurities such as boron (B). The piezoresistives Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 detect the deflection of the flexible portion 113 (113a, 113b), in other words, the displacement of the displacement portion 111 with respect to the frame portion 109. Further, the first structure 201 is provided with a plurality of openings 115 surrounded by a frame portion 109, a displacement portion 111, and a flexible portion 113.

FIG. 3 is an enlarged view of the flexible portion 113a in the X-axis direction of the first structure 201. As shown in FIG. 3, the flexible portion 113a in the X-axis direction is provided with piezoresistors Rx1 to Rx4 in order to detect the acceleration in the X-axis direction. Further, the flexible portion 113a in the X-axis direction is provided with piezoresistors Rz1 to Rz4 in order to detect acceleration in the Z-axis direction. Similarly, the flexible portion 113b in the Y-axis direction is provided with piezoresistive Ry1 to Ry4 in order to detect the acceleration in the Y-axis direction. The piezoresistives Rz1 to Rz4 may be provided on the flexible portion 113b in the Y-axis direction. The piezoresistives Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 are electrically connected to the wiring layer 301 provided on the first structure 201. The wiring layer 301 may be connected to the electrode 303 and electrically connected to an external device via the contact hole 305.

The direction and magnitude of acceleration are determined by the pattern of the sign of the change in resistance value due to expansion and contraction of the piezo resistors Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 provided in the flexible portions 113 (113a, 113b) and the absolute value of the change. Can be detected. 4A to 4C are circuit diagrams showing an example of a detection circuit for detecting acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction from the piezoresistives Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4. As shown in FIGS. 4A to 4C, the piezoresists Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 are connected so as to form a bridge circuit, respectively.

The relationship between the input voltage (Vx_in, Vy_in, Vz_in) and the output voltage (Vx_out, Vy_out, Vz_out) shown in FIGS. 4A to 4C is as follows.

The magnitude of acceleration is proportional to the magnitude of expansion and contraction of each piezoresistive Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4, and the magnitude of expansion and contraction of piezoresistives Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4 and each piezoresistive resistance. It is proportional to the magnitude of the resistance value of Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4. Therefore, the magnitude of the output voltage (Vx_out, Vy_out, Vz_out) with respect to the input voltage (Vx_in, Vy_in, Vz_in) is proportional to the magnitude of the acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction.

The second structure 203 is composed of a silicon substrate 101a. The fixing portion 117 of the second structure 203 is joined to the frame portion 109 of the first structure 201. Further, the weight portion 119 of the second structure 203 is joined to the displacement portion 111 of the first structure 201.

The acceleration sensor main body 103 is joined to the support substrate 105. The support substrate 105 is made of silicate glass containing silicic acid as a main component, and contains auxiliary components such as an alkali metal oxide. Examples of the subcomponent contained in the silicate glass include alkali metal oxides such as sodium oxide. Further, as a sub-component, alumina, lead oxide, magnesium oxide and the like may be contained in addition to the alkali metal oxide. The support substrate 105 has a first surface 107a facing the second structure 203 and a second surface 107b located on the opposite side of the first surface 107a. The support substrate 105 and the acceleration sensor main body 103 are joined to each other by anode joining. Specifically, the first surface 107a of the support substrate 105 and the fixing portion 117 of the second structure 203 are joined by anode joining.

The concentration of the alkali metal differs between a part of the first surface 107a of the support substrate 105 joined to the acceleration sensor main body 103 and the other part excluding the part. Specifically, the concentration of the alkali metal in the portion of the first surface 107a facing the fixed portion 117 of the second structure 203 and the weight portion 119 of the second structure 203 on the first surface 107a of the support substrate 105. It is different from the concentration of the alkali metal in the portion facing the above.

FIG. 5 is a top view of the first surface 107a of the support substrate 105 facing the acceleration sensor main body 103. In FIG. 5, the acceleration sensor main body 103 of the dynamic quantity sensor 100 is omitted. In FIG. 5, the portion 501 of the first surface 107a facing the fixed portion 117 of the second structure 203 is a region shown by an oblique line. Further, in FIG. 5, the portion 503 of the first surface 107a facing the weight portion 119 of the second structure 203 is a region indicated by a horizontal line. As described above, in the mechanical quantity sensor 100 according to the embodiment of the present disclosure, the portion 501 of the first surface 107a of the support substrate 105 facing the fixed portion 117 of the second structure 203 and the second structure 203. The concentration of the alkali metal contained in the support substrate 105 is different between the weight portion 119 and the portion 503 facing the weight portion 119.

For example, when sodium oxide (Na ₂ O) is contained as an alkali metal oxide as a sub-component, sodium (Na) in the portion 501 of the first surface 107a of the support substrate 105 facing the fixed portion 117 of the second structure 203. ) Concentration and the sodium (Na) concentration of the portion 503 facing the weight portion 119 of the second structure 203 are different. Specifically, the sodium (Na) concentration of the portion 503 of the first surface 107a of the support substrate 105 facing the weight portion 119 of the second structure 203 is substantially the same as the sodium (Na) concentration before the anode bonding. On the other hand, the sodium (Na) concentration of the portion 501 of the second structure 203 facing the fixed portion 117 is lower than the sodium (Na) concentration before the anode bonding.

FIG. 6 is a cross-sectional view taken along the line AA shown in FIG. As shown in FIG. 6, sodium in the portion 501 of the first surface 107a of the support substrate 105 facing the fixed portion 117 of the second structure 203 and the portion 503 facing the weight portion 119 of the second structure 203. Ions (Na ⁺ ) differ not only from the surface of the first surface 107a but also in the thickness direction of the support substrate 105, that is, in the region from the surface of the first surface 107a to the depth d from the surface of the first surface 107b toward the second surface 107b. .. Here, d is 0.5 μm to 1.6 μm.

Therefore, the charge amount of the portion 403 facing the weight portion 119 of the second structure 203 on the first surface 107a of the support substrate 105 is compared with the charge amount of the portion 401 facing the fixed portion 117 of the second structure 203. Very small. As a result, it is possible to prevent the weight portion 119 from sticking to the support substrate 105 due to the Coulomb force (electrostatic attraction) between the portion 403 facing the weight portion 119 and the weight portion 119 of the second structure 203. It is possible to improve the reliability of the dynamic quantity sensor 100.

(Manufacturing method of dynamic quantity sensor)
A method of manufacturing a dynamic quantity sensor according to an embodiment of the present disclosure will be described. Hereinafter, a method for manufacturing the mechanical quantity sensor 100 shown in FIG. 1 will be described with reference to FIGS. 7A to 7I and FIG. 7A-7I and 8 are cross-sectional views taken along the cross section of AA shown in FIG. 1 for explaining the manufacturing process of the dynamic quantity sensor 100. The manufacturing method of the dynamic quantity sensor 100 described with reference to FIGS. 7A to 7I and FIG. 8 is an example, and the manufacturing method of the dynamic quantity sensor 100 is not limited to the manufacturing method described below. ..

As shown in FIG. 7A, an SOI substrate (semiconductor substrate) in which a silicon oxide film 101b formed on a silicon substrate 101a (first semiconductor layer) and a silicon film (second semiconductor layer) 101c are laminated on the silicon oxide film 101b is prepared. .. The SOI substrate is manufactured by a SIMOX method, a bonding method, or the like. The silicon oxide film 101b also functions as an etching stopper layer in the process described later.

Next, the piezoresistives Rx1 to Rx4, the piezoresistives Ry1 to Ry4, and the piezoresistives Rz1 to Rz4 are formed, respectively. As shown in FIG. 7B, first, a mask 701 for diffusion of impurities is formed on the silicon film 101c of the SOI substrate. The material of the mask 701, can be used, for example a silicon nitride film (SiN _X) or a silicon oxide film (SiO _X). After forming a silicon oxide film on the entire surface of the silicon film 101c by thermal oxidation or plasma CVD method, a silicon nitride film is formed, a resist pattern (not shown) is formed on the silicon nitride film, and the silicon nitride film and silicon are formed. An opening 702 corresponding to piezo resistance is formed in the oxide film by wet etching using RIE (Reactive Ion Etching) or hydrofluoric acid. The mask 701 may have a one-layer structure, or may have a two-layer structure of a silicon oxide film and a silicon nitride film from the silicon film 101c side. When the mask 701 has a two-layer structure, the silicon nitride film can be used to prevent the diffusion of impurities described later.

As shown in FIG. 7C, the piezoresistive effect is formed by a thermal diffusion method or an ion implantation method. For example, when boron is diffused in the silicon film 101c by the thermal diffusion method, BBr ₃ or the like is exposed to at least the surface on which the mask 701 is formed, and impurities are deposited and thermally diffused to form an impurity diffusion layer. The piezoresistive effect can adjust the impurity concentration on the surface of the diffusion region by appropriately adjusting the formation conditions. Further, the resistance value of the piezoresistive effect can be adjusted according to the width, length and cross-sectional area formed. The design of the resistance value can be easily changed by adjusting the length. In FIG. 7C, only the piezoresistive Rz1 to Rz4 are shown.

Next, as shown in FIG. 7D, the insulating layer 703 is formed on the silicon film 101c. For example, the insulating layer 703 of _{the silicon oxide film (SiO X} ) is formed on the surface of the silicon film 101c by thermal oxidation or plasma CVD method. The SiO _X film can be formed by using a gas such as TEOS (Si (OC ₂ H ₅ ) ₄ ) / O ₂ or SiH ₄ / N _{2 O.} The insulating layer 703 is preferably formed with a thin film having a small internal stress so as not to affect the mechanical characteristics of the flexible portion 113 of the acceleration sensor main body 103.

Next, as shown in FIG. 7E, the wiring 301 connected to the piezoresistive through the contact hole 705 is formed. The wiring 301 is formed by forming a metal material such as Al, Al—Si, and Al—Nd into a film by a sputtering method or the like and patterning the film. It is preferable to perform heat treatment (380 ° C. to 420 ° C.) in order to reduce the ohmic contact resistance between the wiring 301 and the piezoresistive effect. Further, the electrode 303 (see FIG. 3) can be formed in the same process by using the same material as the wiring layer 301. Although not shown, a protective film may be formed consisting of a silicon nitride film (SiN _X) on the wiring 301. In this case, an opening is provided in the protective film to form a contact hole 305 (see FIG. 3) that exposes the electrodes.

Next, as shown in FIG. 7F, the acceleration sensor main body 103 is formed. The silicon film 101c is etched by RIE or the like until the upper surface of the silicon oxide film 101b is exposed, an opening 115 (see FIG. 2) is provided, and the frame portion 109 (see FIGS. 1 and 2) can be displaced in the X-axis direction. The flexible portion 113a, the flexible portion 113a in the Y-axis direction, and the displacement portion 111 (see FIGS. 1 and 2) are formed to form the first structure 201 (see FIG. 2).

Further, a mask is formed on the lower surface of the silicon substrate 101a. Using this mask, the silicon substrate 101a is etched until the lower surface of the silicon oxide film 103b is exposed to form the fixing portion 117 and the weight portion 119 as shown in FIG. 7F to form the second structure 203. For etching, for example, DRIE (Deep Reactive Ion Etching) is used. In DRIE, the etching step of digging while eroding the material layer in the thickness direction and the deposition step of forming a polymer wall on the side wall formed by the progress of erosion by etching are alternately repeated. Since the side wall of the dug hole is protected by sequentially forming a polymer wall, the etching does not spread in the lateral direction, and erosion can proceed only in the substantially thickness direction. _{SF 6} or the like can be used as the etching gas, and _{C 4} F ₈ or the like can be used as the deposition gas. Then, the unnecessary silicon oxide film 103b of the portion used as the etching stopper is removed by RIE or wet etching. As a result, the silicon oxide film 103b is present only between the frame portion 109 and the fixing portion 117, and between the displacement portion 111 and the weight portion 119. The acceleration sensor main body 103 is formed by the above steps.

Next, the accelerometer body 103 and the support substrate 105 made of silicate glass containing an alkali metal that can be a movable ion such as sodium (Na) are anode-bonded. First, as shown in FIG. 7G, the first conductive layer 707 and the second conductive layer 709 are formed on the second surface 107b on the side opposite to the first surface 107a of the support substrate 105 facing the acceleration sensor main body 103. .. The first conductive layer 707 and the second conductive layer 703 are formed in the same step by forming a metal material such as Al, Al—Si, Al—Nd, and Al—Cu by a sputtering method or the like and patterning the metal materials. Is formed by. The first conductive layer 707 is formed so that at least a part thereof overlaps with the fixed portion 117 of the acceleration sensor main body 103, and the second conductive layer 709 is formed so that at least a part thereof overlaps with the weight portion 119 of the acceleration sensor main body 103. NS.

Next, as shown in FIG. 7H, the acceleration sensor main body 103 and the support substrate 105 are adhered and anodized. The support substrate 105 is adhered to the second structure 203 of the acceleration sensor main body 103 so that the first surface 107a faces the acceleration sensor main body 103. When the acceleration sensor main body 103 and the support substrate 105 are joined to the anode, the first conductive layer 707 formed on the second surface 107b of the support substrate is used as a feeding electrode, and the second conductive layer 709 is connected to a ground electrode connected to GND. do. Further, at the time of anode bonding, the acceleration sensor main body 103 is connected to the GND.

As shown in FIG. 8, a negative voltage (about -1 kV) is applied using the first conductive layer 707 of the support substrate 105 as a cathode while heating to 300 ° C. to 400 ° C. ^{Then, alkali metal ions such as sodium ions (Na +} ) in the portion of the support substrate 105 superposed on the first conductive layer 707 move to the first conductive layer 707 side. Therefore, the alkali metal ion is deficient in the portion of the support substrate 105 that is superimposed on the first conductive layer 707 on the first surface 107a side opposite to the second surface 107b on which the first conductive layer 707 is formed. A space charge layer 801 in which oxygen ions (O ^{2-) remain is formed.} As a result, a Coulomb force (electrostatic attraction) acts between the support substrate 105 and the fixed portion 117 of the acceleration sensor main body 103, and they come into strong contact with each other and are covalently bonded at the interface between the support substrate 105 and the fixed portion 117 of the acceleration sensor main body 103. , And the support substrate 105 and the fixing portion 117 of the acceleration sensor main body 103 are joined.

As described above, in the method for manufacturing a dynamic quantity sensor of the present disclosure, the second conductive layer 709 having at least a part superimposed on the weight portion 119 of the acceleration sensor main body 103 is connected to GND as a ground electrode. Therefore, in the portion of the support substrate 105 that overlaps with the second conductive layer 709, the movement of movable ions in the support substrate 105 is suppressed, and the charge neutralized state is maintained. That is, at the time of the anode bonding between the acceleration sensor main body 103 and the support substrate 105, the space charge layer is not formed at the portion overlapping the second conductive layer 709 on the first surface 107a side of the support substrate 105. As a result, no Coulomb force (electrostatic attraction) is generated between the support substrate 105 and the acceleration sensor main body 103 at the portion overlapping the second conductive layer 709 on the first surface 107a side of the support substrate 105, and the acceleration sensor main body 103 It is possible to prevent the weight portion 119 from sticking to the facing support substrate 105. Further, since the movement of movable ions is suppressed in the portion of the support substrate 105 that overlaps with the second conductive layer 709, surface roughness occurs in the portion of the support substrate 105 that overlaps with the second conductive layer 709 of the first surface 107a. It can be prevented, and it is possible to prevent electrostatic attraction that affects the performance during use of the product.

After the anodic bonding of the acceleration sensor main body 103 and the support substrate 105, as shown in FIG. 7I, the first conductive layer 707 and the second conductive layer 709 are removed from the second surface 107b of the support substrate 105, and the dynamic quantity sensor 100 is used. Manufactured.

As described above, in the anode bonding step, the dynamic quantity sensor 100 has sodium (a portion overlapping the first conductive layer 707 on the first surface 107a side of the support substrate 105 and a portion overlapping the second conductive layer 709). The concentrations of alkali metals such as Na) are different. Since the space charge layer is not formed at the portion overlapping the second conductive layer 709 on the first surface 107a side of the support substrate 105 where the movement of alkali metals such as sodium (Na) is suppressed, the charge neutralized state is maintained. Will be done. Therefore, it is possible to prevent the weight portion 119 from sticking to the support substrate 105 at the time of anode bonding and when the dynamic quantity sensor 100 is used, and the reliability of the dynamic quantity sensor 100 is improved.

[Second Embodiment]
In one embodiment of the present disclosure described above, a piezoresistive acceleration sensor is mentioned as an example of the dynamic quantity sensor. However, the dynamic quantity sensor of the present disclosure is not limited to the piezoresistive acceleration sensor. For example, the dynamic quantity sensor may be a capacitance type acceleration sensor, a pressure sensor, an angular velocity sensor, or the like. Hereinafter, a capacitance type acceleration sensor will be described as an example of the dynamic quantity sensor according to the embodiment of the present disclosure.

(Mechanical quantity sensor)
FIG. 9 is a cross-sectional view showing an example of the dynamic quantity sensor 900 according to the embodiment of the present disclosure. The dynamic quantity sensor 900 is a capacitance type acceleration sensor. In a capacitance type acceleration sensor, a weight portion that can be displaced with a predetermined degree of freedom is generally provided in a semiconductor substrate that is sandwiched and joined between a pair of glass substrates, and the weight portion is displaced due to acceleration. It is used as a moving part to detect. Displacement detection is performed based on the value of the capacitance of the capacitive element.

As shown in FIG. 9, the dynamic quantity sensor 900 has a silicon oxide film 901b formed on a silicon substrate 901a and an SOI substrate 901 on which a silicon film 901c is laminated, and a displacement portion is provided on the SOI substrate 901. Includes a first structure 902 having a 911, a flexible portion 913 and a frame portion 915, and a second structure 904 having a fixing portion 917 and a weight portion 919. Since the first structure 902 and the second structure 904 are substantially the same as the first structure 201 and the second structure 203 of the dynamic quantity sensor 100 described above, detailed description thereof will be omitted.

The dynamic quantity sensor 900 has a support substrate 903 and a counter substrate 908 bonded to the SOI substrate 901. The support substrate 903 and the counter substrate 908 are made of silicate glass and contain auxiliary components such as alkali metal oxides. Examples of the subcomponent contained in the silicate glass include alkali metal oxides such as sodium oxide. Further, as a sub-component, alumina, lead oxide, magnesium oxide and the like may be contained in addition to the alkali metal oxide.

The support substrate 903 has a first surface 906a facing the second structure 904 and a second surface 906b located on the opposite side of the first surface 906a. The support substrate 903 and the fixing portion 917 of the second structure 904 are joined to each other by anode bonding. On the first surface 906a of the support substrate 903, a driving electrode 905 and a detecting electrode 907 are provided as internal electrodes in a portion corresponding to the weight portion 919. Although not shown, a wiring layer electrically connected to the internal electrodes is provided on the first surface 906a of the support substrate 903.

The facing substrate 908 has a first surface 912a facing the first structure 902 and a second surface 912b located on the opposite side of the first surface 912a. The first surface 912a facing the first structure 902 is provided with recesses corresponding to the displacement portion 911 and the flexible portion 913. The facing substrate 908 and the frame portion 915 of the first structure 902 are joined to each other by anode bonding. On the first surface 912a of the opposed substrate 908, a driving electrode 909 and a detecting electrode 910 are provided as internal electrodes in a portion corresponding to the weight portion 919. Although not shown, a wiring layer electrically connected to the internal electrodes is formed on the first surface 912a of the facing substrate 908.

In the mechanical quantity sensor 900, similarly to the mechanical quantity sensor 100 described above, a part of the first surface 906a of the support substrate 903 bonded to the SOI substrate 901 and the other part excluding the part are made of an alkali metal. Concentration is different. Specifically, the concentration of the alkali metal in the portion of the first surface 906a of the support substrate 903 facing the fixed portion 917 of the second structure 904 and the second structure 904 on the first surface 906a of the support substrate 903. It is different from the concentration of the alkali metal in the portion facing the weight portion 919 of the above.

Similarly, in the dynamic quantity sensor 900, the concentration of the alkali metal is different between a part of the first surface 912a of the facing substrate 908 joined to the SOI substrate 901 and the other part excluding the part. Specifically, the concentration of the alkali metal in the portion of the first surface 912a of the opposing substrate 908 facing the frame portion 915 of the first structure 902 and the concentration of the alkali metal on the first surface 912a of the opposing substrate 908 and the first structure 902 on the first surface 912a of the opposing substrate 908. It is different from the concentration of the alkali metal in the portion facing the displacement portion 911 of.

For example, when the support substrate 903 and the counter substrate 908 contain sodium oxide (Na ₂ O) as an alkali metal oxide as a sub-component, the fixing portion 917 of the second structure 904 on the first surface 906a of the support substrate 903 The sodium (Na) concentration of the opposite portion and the sodium (Na) concentration of the portion facing the weight portion 919 of the second structure 904 are different.

Specifically, the sodium (Na) concentration of the portion of the first surface 906a of the support substrate 903 facing the weight portion 919 of the second structure 904 is substantially the same as the sodium (Na) concentration before the anode bonding. On the other hand, the sodium (Na) concentration of the portion of the second structure 904 facing the fixed portion 917 is lower than the sodium (Na) concentration before the anode bonding. Therefore, the charge amount of the portion of the first surface 906a of the support substrate 903 facing the weight portion 919 of the second structure 904 is extremely larger than the charge amount of the portion of the second structure 904 facing the fixed portion 917. small. As a result, the Coulomb force (electrostatic attraction) between the portion of the second structure 904 of the support substrate 903 facing the weight portion 919 and the weight portion 919 prevents the weight portion 919 from sticking to the support substrate 903. The reliability of the dynamic quantity sensor 900 can be improved. Further, since the neutralized state of the electric charge of the portion of the first surface 906a of the support substrate 903 facing the weight portion 919 of the second structure 904 is maintained at the time of the anode bonding, it is provided on the first surface 906a of the support substrate 903. Oxidation of the driven electrode 905 and the detection electrode 907 can be prevented.

Similarly, the sodium (Na) concentration of the portion of the first surface 912a of the facing substrate 908 facing the displacement portion 911 of the first structure 902 is substantially the same as the sodium (Na) concentration before the anode bonding. , The sodium (Na) concentration of the portion of the first structure 902 facing the frame portion 915 is lower than the sodium (Na) concentration before the anode bonding. Therefore, the charge amount of the portion of the first surface 912a of the facing substrate 908 facing the displacement portion 911 of the first structure 902 is extremely larger than the charge amount of the portion of the first structure 902 facing the frame portion 915. small. As a result, it is possible to prevent the weight portion 919 from sticking to the opposing substrate 908 due to the Coulomb force (electrostatic attraction) between the portion of the first structure 902 facing the displacement portion 911 and the displacement portion 911. , The reliability of the dynamic quantity sensor 900 can be improved. Further, since the neutralized state of the electric charge of the portion of the first surface 912a of the facing substrate 908 facing the displacement portion 911 of the first structure 902 is maintained at the time of the anode bonding, it is provided on the first surface 912a of the facing substrate 908. Oxidation of the driven electrode 909 and the detection electrode 910 can be prevented.

(Manufacturing method of dynamic quantity sensor)
Hereinafter, a method of manufacturing the dynamic quantity sensor 900 will be described with reference to FIGS. 10A to 10C. In the method for manufacturing the dynamic quantity sensor 900, detailed description of the same steps as the manufacturing method for the dynamic quantity sensor 100 described with reference to FIGS. 7A to 7I and 8 will be omitted. The manufacturing method of the dynamic quantity sensor 900 described with reference to FIGS. 10A to 10C is an example, and the manufacturing method of the dynamic quantity sensor 900 is not limited to the manufacturing method described below.

Similar to the formation of the first structure 201 and the second structure 203 of the dynamic quantity sensor 100, the first structure 902 and the second structure 904 are formed on the SOI substrate 901, except that the step of forming the piezoresistive effect is omitted. To form. Further, a conductive layer is formed on the support substrate 903 and the opposing substrate 908 by a sputtering method or the like, respectively. As the material of the conductive layer, a metal material such as Al, Au, Pt can be used. The formed conductive layer is patterned to form a drive electrode 905 and a detection electrode 907, and a drive electrode 909 and a detection electrode 910 as internal electrodes on the support substrate 903 and the counter substrate 908, respectively. Further, a wiring that is electrically connected to the internal electrode may be formed. The wiring is formed by forming a metal material such as Al, Al—Si, Al—Nd, and Al—Cu into a film by a sputtering method or the like and patterning the metal material.

Next, the SOI substrate 901 on which the first structure 902 and the second structure 904 are formed, and the support substrate 903 composed of silicate glass containing an alkali metal that can be a movable ion such as sodium (Na) are used as anodes. Join. First, the first conductive layer 1001 and the second conductive layer 1003 are formed on the second surface 906b on the side opposite to the first surface 906a of the support substrate 903 facing the SOI substrate 901. The first conductive layer 1001 and the second conductive layer 1003 are formed in the same step by forming a metal material such as Al, Al—Si, Al—Nd, Al—Cu by a sputtering method or the like and patterning the metal materials. Is formed by. At least a part of the first conductive layer 1001 is overlapped with the fixed portion 917 of the second structure 904, and at least a part of the second conductive layer 1003 is overlapped with the weight portion 919 of the second structure 904. It is formed.

Next, as shown in FIG. 10A, the SOI substrate 901 and the support substrate 903 are adhered to each other to perform anodic bonding. The support substrate 903 is adhered to the SOI substrate 901 so that the first surface 906a faces the second structure 904. When the SOI substrate 901 and the support substrate 903 are joined to the anode, the first conductive layer 1001 formed on the second surface 906b of the support substrate 903 is used as a feeding electrode, and the second conductive layer 1003 is used as a ground electrode connected to GND. do. Further, at the time of anode bonding, the SOI substrate 901 is connected to the GND.

A negative voltage (about -1 kV) is applied using the first conductive layer 1001 of the support substrate 903 as a cathode while heating to 300 ° C. to 400 ° C. ^{Then, alkali metal ions such as sodium ions (Na +} ) in the portion of the support substrate 903 superposed on the first conductive layer 1001 move to the first conductive layer 1001 side. Therefore, alkali metal ions are deficient in the portion of the support substrate 903 that is superimposed on the first conductive layer 1001 on the first surface 906a side opposite to the second surface 906b on which the first conductive layer 1001 is formed. A space charge layer in which oxygen ions (O ^{2-) remain is formed.} As a result, a Coulomb force (electrostatic attraction) acts between the support substrate 903 and the fixed portion 917 of the second structure 904, and a covalent bond is generated at the interface between the support substrate 903 and the fixed portion 917 of the second structure 904. The support substrate 903 and the SOI substrate 901 are joined.

Similar to the method for manufacturing the dynamic quantity sensor 100, the second conductive layer 1003 having at least a part superimposed on the weight portion 919 of the second structure 904 is connected to GND as a ground electrode. Therefore, in the portion of the support substrate 903 that overlaps with the second conductive layer 1003, the movement of movable ions in the support substrate 903 is suppressed, and the charge neutralized state is maintained. That is, at the time of the anode bonding between the SOI substrate 901 and the support substrate 903, the space charge layer is not formed at the portion overlapping the second conductive layer 1003 on the first surface 906a side of the support substrate 903. As a result, no Coulomb force (electrostatic attraction) is generated between the support substrate 903 and the SOI substrate 901 at the portion overlapping the second conductive layer 1003 on the first surface 906a side of the support substrate 903, and the second structure 904 It is possible to prevent the weight portion 919 from sticking to the facing support substrate 903. Further, since the movement of movable ions is suppressed in the portion of the support substrate 903 that overlaps with the second conductive layer 1003, surface roughness occurs in the portion of the first surface 906a of the support substrate 903 that overlaps with the second conductive layer 1003. It can be prevented and electrostatic attraction that affects the performance can be prevented during use of the product.

Next, the SOI substrate 901 and the opposing substrate 908 made of silicate glass containing an alkali metal that can be a movable ion such as sodium (Na) are anodized. First, the first conductive layer 1005 and the second conductive layer 1007 are formed on the second surface 912b on the side opposite to the first surface 912a of the facing substrate 908 facing the SOI substrate 901. The first conductive layer 1005 and the second conductive layer 1007 can be formed in the same manner as the first conductive layer 1001 and the second conductive layer 1003 formed on the support substrate 903 described above. At least a part of the first conductive layer 1005 is superimposed on the frame portion 915 of the first structure 902, and at least a part of the second conductive layer 1007 is superimposed on the displacement portion 911 of the first structure 902. It is formed.

Next, as shown in FIG. 10B, the SOI substrate 901 and the facing substrate 908 are adhered and anodized. The facing substrate 908 is adhered to the SOI substrate 901 so that the first surface 912a faces the first structure 902. When the SOI substrate 901 and the opposing substrate 908 are joined to the anode, the first conductive layer 1007 formed on the second surface 912b of the opposing substrate 908 is used as a feeding electrode, and the second conductive layer 1005 is used as a ground electrode connected to GND. do. Further, at the time of anode bonding, the SOI substrate 901 is connected to the GND.

A negative voltage (about -1 kV) is applied using the first conductive layer 1005 of the opposing substrate 908 as a cathode while heating to 300 ° C. to 400 ° C. ^{Then, alkali metal ions such as sodium ions (Na +} ) in the portion superimposed on the first conductive layer 1005 on the opposed substrate 908 move to the first conductive layer 1005 side. Therefore, the alkali metal ion is deficient in the portion superposed on the first conductive layer 1005 on the first surface 912a side opposite to the second surface 912b on which the first conductive layer 1005 is formed, and oxygen ions (O ^2). A space charge layer with ( ^{-) remaining is formed.} As a result, a Coulomb force (electrostatic attraction) acts between the facing substrate 908 and the frame portion 915 of the first structure 902, and a covalent bond occurs at the interface between the facing substrate 908 and the frame portion 915 of the first structure 902. The facing substrate 908 and the SOI substrate 901 are joined.

The second conductive layer 1007, which is at least partially superimposed on the displacement portion 911 of the first structure 902, is connected to GND as a ground electrode. Therefore, in the portion of the facing substrate 908 that overlaps with the second conductive layer 1007, the movement of movable ions in the facing substrate 908 is suppressed, and the charge neutralized state is maintained. That is, at the time of the anode bonding between the SOI substrate 901 and the opposing substrate 908, the space charge layer is not formed at the portion overlapping the second conductive layer 1007 on the first surface 912a side of the opposing substrate 908. As a result, no Coulomb force (electrostatic attraction) is generated between the corresponding substrate 908 and the SOI substrate 901 at the portion overlapping the second conductive layer 1007 on the first surface 912a side of the opposed substrate 908, and the first structure 902 It is possible to prevent the displacement portion 911 from sticking to the opposing substrate 908. Further, since the movement of movable ions is suppressed in the portion of the facing substrate 908 that overlaps with the second conductive layer 1007, surface roughness occurs in the portion of the first surface 912a of the opposing substrate 908 that overlaps with the second conductive layer 1007. Can be prevented.

After the anode bonding between the SOI substrate 901 and the opposing substrate 908, as shown in FIG. 10C, the first conductive layer 1001 and the second conductive layer 1003 formed on the second surface 906b of the support substrate 903, and the facing substrate 908 are the first. The first conductive layer 1005 and the second conductive layer 1007 formed on the two surfaces 912b are removed, and the dynamic quantity sensor 900 is manufactured.

As described above, in the anode bonding step, the dynamic quantity sensor 900 has sodium (a portion overlapping the first conductive layer 1001 on the first surface 906a side of the support substrate 903 and a portion overlapping the second conductive layer 1003). The concentrations of alkali metals such as Na) are different. Since the space charge layer is not formed at the portion overlapping the second conductive layer 1003 on the first surface 906a side of the support substrate 903 where the movement of the alkali metal such as sodium (Na) is suppressed, the charge neutralized state is maintained. Will be done. Therefore, it is possible to prevent the weight portion 919 from sticking to the support substrate 903 at the time of anode bonding and when the dynamic quantity sensor 900 is used, and the reliability of the dynamic quantity sensor 900 is improved. Further, since the charge neutralized state is maintained at the portion overlapping the second conductive layer 1003 on the first surface 906a side of the support substrate 903 where the movement of the alkali metal such as sodium (Na) is suppressed, the support substrate is maintained. It is possible to prevent the driving electrode 905 and the detection electrode 907 from being oxidized by ^{the oxygen ions (O 2-} ) in the 903 and increasing the resistance.

Similarly, in the anode bonding step, the dynamic quantity sensor 900 has sodium (Na) in the portion overlapping the first conductive layer 1005 on the first surface 912a side of the facing substrate 908 and the portion overlapping the second conductive layer 1007. The concentration of alkali metals such as is different. Since the space charge layer is not formed at the portion overlapping the second conductive layer 1007 on the first surface 912a side of the facing substrate 908 where the movement of the alkali metal such as sodium (Na) is suppressed, the charge neutralized state is maintained. Will be done. Therefore, it is possible to prevent the displacement portion 911 from sticking to the facing substrate 908 at the time of anode bonding and when the dynamic quantity sensor 900 is used, and the reliability of the dynamic quantity sensor 900 is improved. Further, the charge neutralized state is maintained at the portion overlapping the second conductive layer 1007 on the first surface 912a side of the facing substrate 908 where the movement of the alkali metal such as sodium (Na) is suppressed. Therefore, it is possible to prevent the drive electrode 909 and the detection electrode 910 from being oxidized by ^{oxygen ions (O 2-} ) in the counter substrate 908 to increase the resistance.

[Third Embodiment]
Hereinafter, the pressure sensor will be described as an example of the dynamic quantity sensor according to the embodiment of the present disclosure.

(Mechanical quantity sensor)
FIG. 11 is a cross-sectional view showing an example of the dynamic quantity sensor 1100 according to the embodiment of the present disclosure. The dynamic quantity sensor 1100 is a pressure sensor, and here, as an example, a capacitance type pressure sensor will be described. The capacitance type pressure sensor is provided with a displacement portion (diaphragm) that can be displaced with a predetermined degree of freedom in a semiconductor substrate bonded to a glass substrate, and the displacement portion is used as a movable portion that detects displacement due to pressure. do. Displacement detection is performed based on the value of the capacitance of the capacitive element.

As shown in FIG. 11, the dynamics sensor 1100 has a silicon oxide film 1101b formed on the silicon substrate 1101c, and an SOI substrate 1101 on which the silicon film 1101a is laminated, and the SOI substrate 901 has a frame portion. It includes a pressure sensor body 1112 including a first structure 1103 having 1107, a second structure 1105 having a displacement portion 1109 and a fixing portion 1111, and a support substrate 1113.

The first structure 1103 is composed of a silicon film 1101c and a silicon oxide film 1101b. The first structure 1103 has a frame portion 1107. The frame portion 1107 has an opening 1108. The second structure 1105 is composed of a silicon substrate 1101a. The second structure 1105 has a fixed portion 1111 joined to the frame portion 1107 of the first structure 1103 and a displacement portion 1109 connected to the fixed portion 1111. The displacement portion 1109 is displaced with respect to the fixed portion 1111.

The pressure sensor body 1112 is joined to the support substrate 1113. The support substrate 1113 is made of silicate glass containing silicic acid as a main component, and contains auxiliary components such as an alkali metal oxide. Examples of the sub-component include alkali metal oxides such as sodium oxide. Further, in addition to the alkali metal oxide, alumina, lead oxide, magnesium oxide and the like may be contained in the silicate glass as subcomponents.

The support substrate 1113 has a first surface 1115a facing the second structure 1103 and a second surface 1115b located on the opposite side of the first surface 1115a. The support substrate 1113 and the pressure sensor main body 1112 are joined by anode joining. Specifically, the first surface 1115a of the support substrate 1113 and the fixing portion 1111 of the second structure 1105 are joined by anode joining.

Although not shown, a movable electrode (first electrode) is provided on the displacement portion 1109 of the second structure 1105 of the pressure sensor main body 1112. Although not shown, a fixed electrode (second electrode) is provided on the first surface 1115a of the support substrate 1113 facing the displacement portion 1109. The magnitude of the capacitance between the movable electrode (first electrode) and the fixed electrode (second electrode) depends on the pressure applied to the dynamic quantity sensor 1100. When the mechanical quantity sensor 1100 is pressurized, the displacement portion 1109 of the pressure sensor main body 1112 is displaced, and the distance between the movable electrode (first electrode) and the fixed electrode (second electrode) fluctuates, so that the capacitance is increased. The size of is also fluctuating. Displacement is detected based on the value of capacitance, and the pressure applied to the dynamic quantity sensor 1100 is calculated. A wiring layer electrically connected to a fixed electrode may be provided on the first surface 1115a of the support substrate 1113.

In the mechanics sensor 1100, similarly to the above-mentioned mechanics sensors 100 and 900, a part of the first surface 1115a of the support substrate 1113 joined to the SOI substrate 1101 and another part excluding the part are different. The concentration of alkali metal is different. Specifically, the concentration of alkali metal in the portion of the first surface 1115a of the support substrate 1113 facing the fixed portion 1111 of the second structure 1105, and the concentration of the alkali metal in the first surface 1115a of the support substrate 1113, the second structure 1105. It is different from the concentration of the alkali metal in the portion facing the displacement portion 1109 of.

For example, when the support substrate 1113 contains sodium oxide (Na ₂ O) as an alkali metal oxide as a sub-component, the portion of the first surface 1115a of the support substrate 1113 that faces the fixed portion 1111 of the second structure 1105. The sodium (Na) concentration and the sodium (Na) concentration of the portion of the second structure 1105 facing the displacement portion 1109 are different.

Specifically, the sodium (Na) concentration of the portion of the first surface 1115a of the support substrate 1113 facing the displacement portion 1119 of the second structure 1105 is substantially the same as the sodium (Na) concentration before the anode bonding. On the other hand, the sodium (Na) concentration of the portion of the second structure 1105 facing the fixed portion 1111 is lower than the sodium (Na) concentration before the anode bonding. Therefore, the charge amount of the portion of the first surface 1115a of the support substrate 1113 facing the displacement portion 1109 of the second structure 1105 is extremely larger than the charge amount of the portion of the second structure 1105 facing the fixed portion 1111. small. As a result, the displacement portion 1109 is prevented from sticking to the support substrate 1113 due to the Coulomb force (electrostatic attraction) between the portion of the second structure 1105 of the support substrate 1113 facing the displacement portion 1109 and the displacement portion 1109. And the reliability of the dynamics sensor 1100 can be improved. Further, since the charge neutralized state of the portion of the first surface 1115a of the support substrate 1103 facing the displacement portion 1109 of the second structure 1105 is maintained at the time of anode bonding, it is provided on the first surface 1115a of the support substrate 1113. Oxidation of the fixed electrode can be prevented.

(Manufacturing method of dynamic quantity sensor)
The features of the manufacturing method of the mechanical quantity sensor 1100 according to the present embodiment are the same as those of the mechanical quantity sensor 100 according to the first embodiment and the dynamic quantity sensor 900 according to the second embodiment described above. In the manufacturing method of the mechanical quantity sensor 1100 described below, the manufacturing method of the mechanical quantity sensor 100 described with reference to FIGS. 7A to 7I and FIG. 8 and the mechanical quantity sensor 900 described with reference to FIGS. 10A to 10C. A detailed description of the same process as the manufacturing method of the above will be omitted. The manufacturing method of the mechanical quantity sensor 1100 described with reference to FIGS. 12A to 12C is an example, and the manufacturing method of the dynamic quantity sensor 1100 is not limited to the manufacturing method described below.

As shown in FIG. 12A, the first structure 1103 and the second structure 1105 are formed on the SOI substrate 1101. A movable electrode (first electrode) 1201 facing the support substrate 1113 of the displacement portion 1109 of the second structure 1105 is formed. A fixed electrode (second electrode) 1203 is formed on the first surface 1115a of the support substrate 1113 facing the displacement portion 1109. First, a conductive layer is formed on the displacement portion 1109 of the second structure 1105. The conductive layer can be formed by sputtering or the like. As the material of the conductive layer, a metal material such as Al, Au, or Pt can be used. The formed conductive layer is patterned to form a movable electrode (first electrode) 1201. Similarly, a fixed electrode (second electrode) 1203 is formed on the first surface 1115a of the support substrate 1113.

Next, the SOI substrate 1101 and the support substrate 1113 are anodically bonded. First, as shown in FIG. 12B, the first conductive layer 1205 and the second conductive layer 1207 are formed on the second surface 1115b on the side opposite to the first surface 1115a of the support substrate 1103 facing the SOI substrate 1101. The first conductive layer 1205 and the second conductive layer 1207 are formed in the same step by forming a metal material such as Al, Al—Si, Al—Nd, Al—Cu by a sputtering method or the like and patterning the metal materials. Is formed by. At least a part of the first conductive layer 1205 is superimposed on the fixed portion 1111 of the second structure 1105, and at least a part of the second conductive layer 1207 is superimposed on the displacement portion 1109 of the second structure 1105. It is formed.

As shown in FIG. 12C, the SOI substrate 1101 and the support substrate 1113 are bonded to each other to perform anodic bonding. The support substrate 1113 is adhered to the SOI substrate 1101 so that the first surface 1115a faces the second structure 1105. When the SOI substrate 1101 and the support substrate 1113 are joined to the anode, the first conductive layer 1205 formed on the second surface 1115b of the support substrate 1113 is used as a feeding electrode, and the second conductive layer 1207 is used as a ground electrode connected to GND. do. Further, at the time of anode bonding, the SOI substrate 1101 is connected to the GND.

A negative voltage (about -1 kV) is applied using the first conductive layer 1205 of the support substrate 1113 as a cathode while heating to 300 ° C. to 400 ° C. ^{Then, alkali metal ions such as sodium ions (Na +} ) in the portion of the support substrate 1113 superimposed on the first conductive layer 1205 move to the first conductive layer 1205 side. Therefore, alkali metal ions are deficient in the portion of the support substrate 1113 that is superimposed on the first conductive layer 1205 on the first surface 1115a side opposite to the second surface 1115b on which the first conductive layer 1205 is formed. A space charge layer in which oxygen ions (O ^{2-) remain is formed.} As a result, a Coulomb force (electrostatic attraction) acts between the support substrate 1113 and the fixed portion 1111 of the second structure 1105, and a covalent bond is generated at the interface between the support substrate 1113 and the fixed portion 1111 of the second structure 1105. The support substrate 1113 and the SOI substrate 1101 are joined.

Similar to the manufacturing method of the dynamic quantity sensors 100 and 900, the second conductive layer 1207 whose at least a part overlaps with the displacement portion 1109 of the second structure 1105 is connected to GND as a ground electrode. Therefore, in the portion of the support substrate 1113 that overlaps with the second conductive layer 1207, the movement of movable ions in the support substrate 1113 is suppressed, and the charge neutralized state is maintained. That is, at the time of the anode bonding between the SOI substrate 1101 and the support substrate 1113, the space charge layer is not formed at the portion overlapping the second conductive layer 1207 on the first surface 1115a side of the support substrate 1113. As a result, no Coulomb force (electrostatic attraction) is generated between the support substrate 1113 and the SOI substrate 1101 at the portion overlapping the second conductive layer 1207 on the first surface 1115a side of the support substrate 1113, and the second structure 1105 It is possible to prevent the displacement portion 1109 from sticking to the facing support substrate 1113. Further, since the movement of movable ions is suppressed in the portion of the support substrate 1113 that overlaps with the second conductive layer 1207, surface roughness occurs in the portion of the support substrate 1113 that overlaps with the second conductive layer 1157. It can be prevented and electrostatic attraction that affects the performance can be prevented during use of the product.

After the anode bonding between the SOI substrate 1101 and the support substrate 1113, the first conductive layer 1205 and the second conductive layer 1207 formed on the second surface 1115b of the support substrate 1103 are removed, and the dynamic quantity sensor 1100 is manufactured.

As described above, in the anode bonding step, the dynamic quantity sensor 1100 has sodium (a portion overlapping the first conductive layer 1205 on the first surface 1115a side of the support substrate 1113 and a portion overlapping the second conductive layer 1207). The concentrations of alkali metals such as Na) are different. Since the space charge layer is not formed at the portion overlapping the second conductive layer 1207 on the first surface 1115a side of the support substrate 1113 where the movement of alkali metals such as sodium (Na) is suppressed, the charge neutralization state is maintained. Will be done. Therefore, it is possible to prevent the displacement portion 1109 from sticking to the support substrate 1113 at the time of anode bonding and when the dynamic quantity sensor 1100 is used, and the reliability of the dynamic quantity sensor 1100 is improved. Further, since the charge neutralized state is maintained at the portion overlapping the second conductive layer 1207 on the first surface 1115a side of the support substrate 1113 where the movement of alkali metals such as sodium (Na) is suppressed, the support substrate is supported. It is possible to prevent the fixed electrode 1203 from being oxidized by oxygen ions (O ^{2-) in 1113 to increase the resistance.}

As described above, in the mechanical quantity sensor according to the embodiment of the present disclosure, a Coulomb force (electrostatic force) is not generated between the movable portion including the weight portion and / or the displacement portion of the sensor and the substrate facing the substrate. Therefore, it is possible to prevent the movable portion from sticking to the facing substrate and improve the reliability of the dynamic quantity sensor. In the above, as the dynamic quantity sensor according to the embodiment of the present disclosure, a piezo resistance type acceleration sensor, a capacitance type acceleration sensor and a capacitance type pressure sensor have been described as examples, but sensors other than these sensors have been described. However, it is clear that the same effect is achieved.

100, 900, 1100: Mechanical quantity sensor 101, 901: SOI substrate 103: Acceleration sensor main body 1112: Pressure sensor main body 105, 903, 1113: Support substrate 109, 915, 1107: Frame portion 111, 911, 1109: Displacement portion 113 , 913: Flexible part 115, 1108: Opening 117, 917, 1111: Fixed part 119, 919: Weight part Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4: Piezo resistance 201, 902, 1103: First structure 203,904,1105: Second structure 301: Wiring layer 707: First conductive layer 709: Second conductive layer 908: Opposing substrate 905,909: Drive electrode 907,910: Detection electrode 1001,1005: First Conductive layer 1003, 1007: Second conductive layer

Claims (3)

The first semiconductor layer in the semiconductor substrate having the first semiconductor layer and the second semiconductor layer is etched to form a frame portion, a displacement portion, and a flexible portion connecting the frame portion and the displacement portion. Form a structure,
A second structure is formed by forming a fixing portion that is bonded to the frame portion by etching the second semiconductor layer and a weight portion that is provided at a distance from the fixing portion and is bonded to the displacement portion. death,
A first conductive layer and a second conductive layer are formed on one surface of a support substrate made of silicate glass containing an alkali metal.
Anode bonding of the other surface on the side opposite to one surface of the support substrate and the fixing portion of the second structure.
Including
The anode bonding means that the second conductive layer and the semiconductor substrate are grounded and a voltage is applied between the other surface of the support substrate and the fixed portion.
Including
A method for manufacturing a dynamic quantity sensor, wherein the first conductive layer is formed so that at least a part thereof overlaps the fixed portion, and the second conductive layer is formed so that at least a part thereof overlaps the weight portion. .. First forming a plurality of piezo resistance by diffusing impurities into the flexible portion of the semiconductor layer further includes a method of manufacturing a mechanical quantity sensor according to claim 1. Wherein the other surface of the supporting substrate to form a third conductive layer further comprises a method of manufacturing a mechanical quantity sensor according to claim 1.

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