JP2008175825A - Semiconductor dynamic quantity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor dynamic quantity sensor of high reliability capable of restraining a leakage current. <P>SOLUTION: A beam structure is arranged in a position separated by a prescribed space on an upper face of a substrate 1, and has a movable electrode. Fixed electrodes 9a-9d, 11a-11d are arranged opposed to a side face of the movable electrode. A laminate comprising a lower layer side insulator thin film, a conductive thin film and an upper layer side insulator thin film is arranged on an upper face part of the substrate 1, and a wiring pattern 22 of the fixed electrodes is formed of the conductive thin film. The wiring pattern 22 is connected electrically to the fixed electrodes 9a, 9b, 11c, 11d through an opening part 30 and an anchor part 28a for the fixed electrodes, and a lower electrode is connected electrically to the beam structured through the opening part in the upper layer side insulator thin film and the anchor part of the beam structure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor dynamic quantity sensor having a beam-structured movable part, for example, a semiconductor dynamic quantity sensor for detecting mechanical quantities such as acceleration, yaw rate, and vibration.

  In general, the basic principle of a mechanical quantity sensor such as an acceleration sensor is to measure a displacement or a force when a mechanical quantity acts on a mass part (mass part) connected to the beam using a beam called a flexible beam.

  In recent years, there is an increasing demand for downsizing and cost reduction of mechanical quantity sensors such as acceleration sensors used for suspension control of automobiles and airbags. Therefore, Japanese Patent Publication No. 6-44008 discloses a differential capacitance type semiconductor acceleration sensor using polysilicon as a beam structure having electrodes. This type of sensor will be described with reference to FIGS. FIG. 34 shows a plan view of the sensor, FIG. 35 shows a XXXV-XXXV sectional view in FIG. 34, and FIG. 36 shows a XXXVI-XXXVI sectional view in FIG.

  On the silicon substrate 130, a beam 132 extends from the anchor portion 131, a mass 133 is supported on the beam 132, and a movable electrode 134 projects from the mass 133. On the other hand, two fixed electrodes 135 a and 135 b are arranged on the silicon substrate 130 so as to face one movable electrode 134. The movable electrode 134 and the fixed electrodes 135a and 135b form an electrostatic capacity to perform a servo operation. The anchor part 131, the beam 132, the mass 133, and the movable electrode 134 are formed of polysilicon, and the mass 133 and the movable electrode 134 are arranged at a predetermined interval from the silicon substrate 130. Further, the fixed electrodes 135a and 135b are fixed to the substrate 130 at the anchor portions 136 at the ends. These are formed on the silicon substrate 130 using surface micromachining technology.

  The detection principle will be described with reference to FIG. The movable electrode 134 is at the center of the fixed electrodes 135a and 135b on both sides, and the capacitances C1 and C2 between the movable electrode 134 and the fixed electrodes 135a and 135b are equal. In addition, voltages V1 and V2 are applied between the movable electrode 134 and the fixed electrodes 135a and 135b. When acceleration is not generated, V1 = V2, and the movable electrode 134 has the same electrostatic force from the fixed electrodes 135a and 135b. It is drawn. Here, when the acceleration acts in a direction parallel to the substrate surface and the movable electrode 134 is displaced, the distance between the movable electrode 134 and the fixed electrodes 135a and 135b changes, and the capacitances C1 and C2 are not equal. For example, if the movable electrode 134 is displaced toward the fixed electrode 135a so that the capacitances are equal, the voltage V1 decreases and the voltage V2 increases. Thereby, the movable electrode 134 is pulled to the fixed electrode 135b side by electrostatic force. If the movable electrode 134 is at the center position and the capacitances C1 and C2 are equal, the acceleration and the electrostatic force are equally balanced, and the magnitude of the acceleration can be obtained from the voltages V1 and V2 at this time.

  Manufacture is performed in the steps shown in FIGS. As shown in FIG. 37, a sacrificial layer (silicon oxide film) 138 is deposited on a silicon substrate 137 and an opening 139 is provided in a predetermined region. A polysilicon thin film 140 is deposited on the sacrificial layer 138 including the opening 139, and the polysilicon thin film 140 is patterned into a predetermined shape. Further, as shown in FIG. 38, the sacrificial layer 138 is removed by etching to form an air gap 141 to form a beam structure made of the polysilicon thin film 140.

  On the other hand, it is also known to form an acceleration sensor (semiconductor dynamic quantity sensor) using single crystal silicon as a beam structure using an SOI (Silicon on Insulator) substrate. This type of sensor will be described with reference to FIGS. 39 is a plan view of the sensor, FIG. 40 is a sectional view of XXX-XXXX in FIG. 39, and FIG. 41 is a sectional view of XXXXI-XXXXI in FIG.

  In this acceleration sensor, the vibrating mass 147 is joined to the fixed support 146 by the flexible beam 145, and the vibrating mass 147 can move. The vibration mass body 147 is made of single crystal silicon doped with phosphorus. The fixed support 146 is fixed on the substrate 148 in an electrically insulated state. The vibration mass body 147 includes movable electrodes 149 extending in directions parallel to each other. These members 145, 146, 147, and 149 constitute a beam structure 150. In addition, fixed electrodes 151 and 152 are arranged to face the movable electrode 149, and a capacitance is formed between the movable electrode 149 and the fixed electrodes 151 and 152. When the beam 145 is displaced in a direction parallel to the surface of the substrate 148 (Y-axis direction in FIG. 39), the movable electrode 149 is displaced, thereby changing the capacitance.

Next, a method for manufacturing the acceleration sensor will be described with reference to FIGS. First, as shown in FIG. 42, in order to form a SIMOX layer on the substrate 148, oxygen ions (O ⁺ or O ₂ ⁺ ) are applied to the single crystal silicon substrate 148 at 100 keV to 1000 keV and 10 ¹⁶ to 10 ¹⁸ dose / cm ^{2 is} injected and heat treatment is performed at 1150 ° C. to 1400 ° C. As a result, an SOI substrate in which the silicon oxide film layer 153 has a thickness of about 400 nm and the surface silicon layer 154 has a thickness of about 150 nm is formed. Thereafter, as shown in FIG. 43, the silicon layer 154 and part of the silicon oxide film layer 153 are etched through photolithography. Further, as shown in FIG. 44, a single crystal silicon layer 155 is formed to a thickness of 1 μm to 100 μm (usually 10 to 20 μm) by epitaxial growth. Next, as shown in FIG. 45, after forming an electrode 156 made of a metal for connection to the measurement circuit, it is formed into a predetermined electrode shape through photolithography. Further, as shown in FIG. 46, reactive gas phase dry etching or the like is performed on the silicon layer 155 to form fixed electrodes 151 and 152, a movable electrode 149, and the like. Finally, the oxide film layer 153 is etched away by liquid phase etching with HF or the like to make the beam structure movable.
Japanese Patent Publication No. 6-44008

  However, in the acceleration sensor (semiconductor dynamic quantity sensor) shown in FIGS. 39 to 46, if servo control is performed like the sensor shown in Japanese Patent Publication No. 6-44008, the first fixed electrode In order to cross the energization line and the second fixed electrode energization line, wiring using an impurity diffusion layer is performed on the silicon substrate. That is, a comb-like movable portion 157 having rod-like electrode portions 157 a extending in parallel above the silicon substrate 160 is disposed, and the first fixed electrode 158 and the second fixed electrode 159 are disposed on the silicon substrate 160. Then, the first fixed electrode 158 is opposed to one side surface of each rod-shaped electrode portion 157a of the movable portion 157, and the second fixed electrode 159 is opposed to the other side surface of each rod-shaped electrode portion 157a. Furthermore, each fixed electrode 159 is connected to the upper surface of the substrate 160 (and is made into a comb-shaped electrode), and each fixed electrode 158 is electrically connected to the impurity diffusion layer 161 formed on the surface layer portion of the silicon substrate 160. Will be connected. However, in this case, a leak current is generated in the portion where the impurity diffusion layer 161 is formed, making it difficult to accurately detect acceleration. In particular, it is easily affected by leakage current and the like in a high temperature atmosphere.

  In addition, a silicon oxide film is usually used for the insulator, but it is difficult to control the lateral etching amount when removing the silicon oxide film in the sacrificial layer etching process for making the beam structure movable. Therefore, since the beam length of the beam structure varies depending on the sacrifice layer etching time, the spring constant of the beam structure varies. In other words, in the case where a partial region of the silicon oxide film that becomes the sacrificial layer is left as an anchor portion, it is difficult to keep the concentration and temperature of the etchant accurately constant, and it is also possible to accurately manage the time of completion of etching. It was difficult to process the beam into a desired shape.

  Accordingly, an object of the present invention is to provide a semiconductor dynamic quantity sensor in which a beam structure is formed on a substrate and wirings or electrodes are arranged on the substrate side, and leakage current is suppressed and reliability is high. In particular, in a semiconductor dynamic quantity sensor having a plurality of paired first and second fixed electrodes and having a beam structure formed on a semiconductor substrate, leakage current is suppressed and the reliability is improved.

  According to the first aspect of the present invention, a substrate in which a lower-layer insulator thin film and a conductive thin film are laminated in this order on a semiconductor substrate, and a position spaced apart from the upper surface of the substrate by a predetermined distance, are parallel to each other. A beam structure having a plurality of movable electrodes extending to the substrate, fixed to the upper surface of the substrate, and arranged to face one side surface of each movable electrode, and the first capacitor together with the movable electrodes of the beam structure A plurality of first fixed electrodes to be configured, and a plurality of second fixed electrodes that are arranged opposite to the other side surface of each of the movable electrodes and constitute a second capacitor together with the movable electrodes of the beam structure; A first electrode extraction portion fixed to the upper surface of the substrate and electrically connected to the first fixed electrode; a second electrode extraction portion electrically connected to the second fixed electrode; and the conductive property Composed of thin film A first wiring pattern for electrically connecting the plurality of first fixed electrodes and the first electrode extraction portion to each other, and a plurality of the second fixed electrodes and the second electrode extraction portion for each other And a second wiring pattern to be electrically connected.

  As described above, the laminated body of the lower-layer-side insulator thin film and the conductive thin film is disposed on the upper surface portion of the substrate, and the conductive thin film is patterned, whereby the plurality of first fixed electrodes and the first electrodes are arranged. A first wiring pattern that electrically connects the extraction portions to each other, and a second wiring pattern that electrically connects the plurality of second fixed electrodes and the second electrode extraction portion to each other are configured. By using this structure, a wiring pattern by insulator isolation can be formed, and junction leakage can be reduced as compared with the case where the impurity diffusion layer 161 is used (in the case of pn junction isolation). In particular, it is possible to reduce junction leakage in a high temperature range. In this way, leakage current is suppressed and reliability is improved.

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a semiconductor acceleration sensor. More specifically, the present invention is applied to a servo-controlled differential capacitance type semiconductor dynamic quantity sensor.

  1 is a plan view of a semiconductor acceleration sensor according to the present embodiment, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. IV sectional view, FIG. 5 is a VV sectional view in FIG.

  1 and 2, a beam structure 2 made of single crystal silicon (single crystal semiconductor material) is disposed on the upper surface of a substrate 1. The beam structure 2 is constructed by four anchor portions 3 a, 3 b, 3 c, 3 d protruding from the substrate 1 side, and is arranged at a position spaced apart from the upper surface of the substrate 1. Anchor portions 3a, 3b, 3c and 3d are made of a polysilicon thin film. The beam portion 4 is constructed between the anchor portion 3a and the anchor portion 3b, and the beam portion 5 is constructed between the anchor portion 3c and the anchor portion 3d. A mass portion (mass portion) 6 having a rectangular shape is installed between the beam portion 4 and the beam portion 5. The mass portion 6 is provided with a through-hole 6a penetrating vertically, and this through-hole 6a facilitates entry of an etching solution during the sacrifice layer etching. Furthermore, four movable electrodes 7a, 7b, 7c, and 7d protrude from one side surface (the left side surface in FIG. 1) of the mass portion 6. The movable electrodes 7a, 7b, 7c, and 7d are rod-shaped and extend in parallel at equal intervals. Further, four movable electrodes 8a, 8b, 8c, and 8d protrude from the other side surface (the right side surface in FIG. 1) of the mass portion 6. The movable electrodes 8a, 8b, 8c and 8d are rod-shaped and extend in parallel at equal intervals. Here, the beam portions 4 and 5, the mass portion 6, and the movable electrodes 7 a to 7 d and 8 a to 8 d are movable by removing a part of the sacrificial layer oxide film 37 by etching. This etching region is indicated by Z1 in FIG.

  Thus, the beam structure 2 has two comb-shaped movable electrodes. Four first fixed electrodes 9a, 9b, 9c, 9d are fixed on the upper surface of the substrate 1, and the fixed electrodes 9a-9d are made of single crystal silicon. The first fixed electrodes 9a to 9d are supported by anchor portions 10a, 10b, 10c, and 10d that protrude from the substrate 1 side, and are formed on one side surface of each movable electrode (bar-shaped portion) 7a to 7d of the beam structure 2. Opposed to each other. Further, four second fixed electrodes 11a, 11b, 11c, and 11d are fixed on the upper surface of the substrate 1, and the fixed electrodes 11a to 11d are made of single crystal silicon. The second fixed electrodes 11a to 11d are supported by anchor portions 12a, 12b, 12c, and 12d protruding from the substrate 1 side, and are arranged on the other side surfaces of the movable electrodes (bar-shaped portions) 7a to 7d of the beam structure 2. Opposed to each other.

  Similarly, the first fixed electrodes 13a, 13b, 13c, 13d and the second fixed electrodes 15a, 15b, 15c, 15d are fixed on the upper surface of the substrate 1, and the fixed electrodes 13a-13d and 15a-15d are single. Made of crystalline silicon. The first fixed electrodes 13a to 13d are supported by the anchor portions 14a, 14b, 14c, and 14d, and are disposed to face one side surface of each movable electrode (bar-shaped portion) 8a to 8d of the beam structure 2. Yes. The second fixed electrodes 15a to 15d are supported by the anchor portions 16a, 16b, 16c, and 16d, and are arranged to face the other side surfaces of the movable electrodes (rod-like portions) 8a to 8d of the beam structure 2. Has been.

  As shown in FIG. 2, the substrate 1 has a structure in which a lower-layer insulator thin film 18, a conductive thin film 19, and an upper-layer insulator thin film 20 are stacked on a silicon substrate (semiconductor substrate) 17. . That is, it has a structure in which a laminated body 21 of a lower-layer-side insulator thin film 18, a conductive thin film 19, and an upper-layer insulator thin film 20 is disposed on the upper surface portion of the silicon substrate 17, and the conductive thin film 19 is an insulator thin film. 18 and 20 are embedded. The lower-layer-side insulator thin film 18 is made of a silicon oxide film, and the upper-layer-side insulator thin film 20 is made of a silicon nitride film, which is formed by a CVD method or the like. The conductive thin film 19 is made of a polysilicon thin film doped with impurities such as phosphorus.

  The conductive thin film 19 forms the four wiring patterns 22, 23, 24, and 25 shown in FIG. 1 and the lower electrode (static force canceling fixed electrode) 26. The wiring pattern 22 is a wiring of the first fixed electrodes 9a, 9b, 9c, and 9d, has a strip shape as shown in FIG. 1, and extends in an L shape. The wiring pattern 23 is a wiring pattern of the second fixed electrodes 11a, 11b, 11c, and 11d, has a strip shape as shown in FIG. 1, and extends in an L shape. Similarly, the wiring pattern 24 is a wiring of the first fixed electrodes 13a, 13b, 13c, and 13d, and the wiring pattern 25 is a wiring of the second fixed electrodes 15a, 15b, 15c, and 15d, as shown in FIG. It has a strip shape and extends in an L shape. The lower electrode 26 is formed in a region facing the beam structure 2 on the upper surface portion of the substrate 1.

  A first capacitor is provided between the movable electrodes (rod-like portions) 7a to 7d of the beam structure 2 and the first fixed electrodes 9a to 9d, and the movable electrodes (rod-like portions) 7a to 7a of the beam structure 2 are also provided. A second capacitor is formed between 7d and the second fixed electrodes 11a to 11d. Similarly, a first capacitor is provided between the movable electrodes (bar-shaped portions) 8a to 8d of the beam structure 2 and the first fixed electrodes 13a to 13d, and the movable electrode (bar-shaped portion) 8a of the beam structure 2 is also provided. A second capacitor is formed between ˜8d and the second fixed electrodes 15a-15d.

  Further, electrode extraction portions 27a, 27b, 27c, 27d made of single crystal silicon are formed on the upper surface of the substrate 1, and the electrode extraction portions 27a, 27b, 27c, 27d are anchor portions 28a, 28b, It is supported by 28c and 28d.

  As shown in FIG. 3, openings 29a, 29b, 29c, 29d, and 30 are formed in the upper insulating thin film 20, and the above-described anchor portions (impurity doped polycrystals) are formed in the openings 29a, 29b, 29c, 29d. Silicon) 10a to 10d are arranged. An anchor portion (impurity doped polysilicon) 28 a is disposed in the opening 30. Therefore, the wiring pattern 22 and the first fixed electrodes 9a to 9d are electrically connected through the openings 29a to 29d and the anchor portions (impurity doped polysilicon) 10a to 10d, and the openings 30 and the anchor portions (impurities). The wiring pattern 22 and the electrode extraction part 27a are electrically connected through a doped polysilicon) 28a.

  As shown in FIG. 4, openings 31 a, 31 b, 31 c, 31 d, and 32 are formed in the upper insulating thin film 20. The aforementioned anchor portions (impurity doped polysilicon) 12a to 12d are disposed in the openings 31a to 31d, and the aforementioned anchor portion 28c is disposed in the opening 32. Therefore, the wiring pattern 23 and the second fixed electrodes 11a to 11d are electrically connected through the openings 31a to 31d and the anchor portions (impurity doped polysilicon) 12a to 12d, and the openings 32 and the anchor portions (impurities). The wiring pattern 23 and the electrode extraction portion 27c are electrically connected through the doped polysilicon) 28c.

  Similarly, the wiring pattern 24 of the first fixed electrode and the first fixed electrodes 13a to 13d are electrically connected through an opening (not shown) in the upper insulating thin film 20 and the anchor portions 14a to 14d of the first fixed electrode. The wiring pattern 24 and the electrode extraction part 27b are electrically connected through the anchor part 28b. In addition, the wiring pattern 25 of the second fixed electrode and the second fixed electrodes 15a to 15d are electrically connected through the opening (not shown) in the upper insulating thin film 20 and the anchor portions 16a to 16d of the second fixed electrode. The wiring pattern 25 and the electrode extraction part 27d are electrically connected through the anchor part 28d.

  As shown in FIG. 2, an opening 33 is formed in the upper insulating thin film 20, and the above-described anchor portions (impurity doped polysilicon) 3 a to 3 d are arranged in the opening 33. Therefore, the lower electrode 26 and the beam structure 2 are electrically connected through the anchor portions 3a to 3d of the beam structure.

  As described above, the substrate 1 has a configuration in which the wiring patterns 22 to 25 and the lower electrode 26 made of polysilicon are embedded under the SOI layer, and this structure is formed by using surface micromachining technology. is there.

  On the other hand, as shown in FIGS. 1 and 2, an electrode (bonding pad) 34 made of an aluminum thin film is provided above the anchor portion 3 a of the silicon substrate (semiconductor substrate) 17. As shown in FIGS. 1, 3, and 4, electrodes (bonding pads) 35a, 35b, 35c, and 35d made of an aluminum thin film are provided on the upper surfaces of the electrode extraction portions 27a, 27b, 27c, and 27d, respectively. An interlayer insulating film 38 and a silicon nitride film 36 are formed on the upper surfaces of the electrode extraction portions 27a to 27d. The films 38 and 36 are formed in a region other than Z1 in FIG.

  The capacitance of the first capacitor formed between the movable electrodes 7a to 7d and the first fixed electrodes 9a to 9d of the beam structure 2 (and the movable electrodes 8a to 8d and the first fixed electrodes 13a to 13d). And the capacitance of the second capacitor formed between the movable electrodes 7a to 7d and the second fixed electrodes 11a to 11d of the beam structure 2 (the capacitance of the first capacitor formed between the second fixed electrodes 11a to 11d). And the acceleration acting on the beam structure 2 can be detected based on the capacitance of the second capacitor formed between the movable electrodes 8a to 8d and the second fixed electrodes 15a to 15d. Yes. More specifically, two differential capacitances are formed by the movable electrode and the fixed electrode, and a servo operation is performed so that the two capacitances are equal.

  Further, the electrostatic force generated between the beam structure 2 and the substrate 1 is canceled by setting the beam structure 2 and the lower electrode 26 to the same potential. That is, the lower electrode 26 is electrically equipotential because it is coupled to the beam portions 4, 5 and the mass portion 6 through the anchor portions 3 a to 3 d, and the beam portions 4, 5 and the mass portion 6 are made of the substrate 1 by electrostatic force. Can be prevented from adhering to. That is, since the beam structure 2 is insulated from the silicon substrate 17, the beam structure 2 tries to adhere to the substrate 17 side even by a slight potential difference between the beam structure 2 and the silicon substrate 17. Can be prevented.

  By using the wiring patterns 22 to 25 and the lower electrode 26 separated from each other as described above, the aluminum electrodes (bonding pads) 34 and 35a to 35d can be taken out from the substrate surface, and the acceleration sensor manufacturing process is facilitated. It becomes possible to.

  Next, the detection principle of the acceleration sensor will be described with reference to FIG. The movable electrodes 7a to 7d (8a to 8d) are positioned at the centers of the fixed electrodes 9a to 9d (13a to 13d) and 11a to 11d (15a to 15d) on both sides, and the capacitance C1, between the movable electrode and the fixed electrode. C2 is equal. The voltage V1 is between the movable electrodes 7a to 7d (8a to 8d) and the fixed electrodes 9a to 9d (13a to 13d), and the movable electrodes 7a to 7d (8a to 8d) and the fixed electrodes 11a to 11d (15a to 15d). ) Is applied with the voltage V2. When acceleration is not generated, V1 = V2, and the movable electrodes 7a to 7d (8a to 8d) are attracted by the same electrostatic force from the fixed electrodes 9a to 9d (13a to 13d) and 11a to 11d (15a to 15d). It is. Here, when the acceleration acts in a direction parallel to the substrate surface and the movable electrodes 7a to 7d (8a to 8d) are displaced, the distance between the movable electrode and the fixed electrode is changed, and the capacitances C1 and C2 are not equal. If the movable electrodes 7a to 7d (8a to 8d) are displaced toward the fixed electrodes 9a to 9d (13a to 13d) so that the electrostatic forces are equal at this time, the voltage V1 decreases and the voltage V2 increases. Thereby, the movable electrodes 7a to 7d (8a to 8d) are pulled toward the fixed electrodes 11a to 11d (15a to 15d) by electrostatic force. If the movable electrodes 7a to 7d (8a to 8d) return to the center position and the capacitances C1 and C2 are equal, the acceleration and the electrostatic force are equally balanced, and the magnitude of the acceleration is obtained from the voltages V1 and V2 at this time. be able to.

  In this way, in the first capacitor and the second capacitor, the voltage of the fixed electrode forming the first and second capacitors is controlled so that the movable electrode does not displace with respect to the displacement due to the action of the mechanical quantity. The acceleration is detected by the change in voltage.

  Next, the manufacturing process of this acceleration sensor is demonstrated using FIGS. 6 to 16 are schematic cross-sectional views showing a manufacturing process in the AA cross section in FIG. First, as shown in FIG. 6, a single crystal silicon substrate 40 as a first semiconductor substrate is prepared, and a silicon oxide film 41 as a sacrificial layer thin film is formed on the silicon substrate 40 by thermal oxidation, CVD, or the like. . Then, as shown in FIG. 7, the silicon oxide film 41 is partially etched through photolithography to form a recess 42. Further, a silicon nitride film (first insulator thin film) 43 is formed to increase the surface unevenness and serve as an etching stopper during the sacrifice layer etching. Thereafter, openings 44a, 44b, and 44c are formed in the anchor portion formation region by dry etching or the like through photolithography on the stacked body of the silicon oxide film 41 and the silicon nitride film 43. The openings 44a to 44c are for connecting the beam structure and the substrate (lower electrode), and for connecting the fixed electrode (and electrode extraction portion) and the wiring pattern.

  Subsequently, as shown in FIG. 8, a polysilicon thin film 45 to be a conductive thin film is formed on the silicon nitride film 43 including the openings 44a to 44c, and then impurities are introduced by phosphorus diffusion or the like, and photolithography is performed. Then, a wiring pattern 45a, a lower electrode 45b, and an anchor portion 45c are formed in a predetermined region on the silicon nitride film 43. Further, as shown in FIG. 9, a silicon oxide film 46 as a second insulator thin film is formed on the silicon nitride film 43 including the polysilicon thin film (45) by the CVD method or the like.

  Further, as shown in FIG. 10, a polysilicon thin film 47 as a thin film for bonding is formed on the silicon oxide film 46, and the surface is flattened by mechanical polishing or the like for bonding to the polysilicon thin film 47. Turn into.

  Then, as shown in FIG. 11, a single crystal silicon substrate (supporting substrate) 48 different from the silicon substrate 40 is prepared, and the surface of the polysilicon thin film 47 and the silicon substrate 48 as the second semiconductor substrate are bonded together. .

  Further, as shown in FIG. 12, the silicon substrates 40 and 48 are turned upside down, and the silicon substrate 40 side is mechanically polished to reduce the thickness to a desired thickness (for example, 1 to 2 μm). After that, a trench is etched with a certain width by trench etching using a photolithographic technique on the silicon substrate 40, and thereafter a trench pattern 49 for forming a beam structure is formed. Thus, the unnecessary region (49) in the silicon substrate 40 is removed to obtain a desired shape. Further, here, impurities are introduced into the silicon substrate 40 by phosphorus diffusion or the like in order to form an electrode for detecting the capacitance later.

  In this step (step of removing unnecessary regions in the silicon substrate 40 to obtain a desired shape), the silicon substrate 40 is thin (for example, 1 to 2 μm) to the extent that the lower pattern resolution of the stepper is satisfied. The shape of the openings (44a to 44c in FIG. 7) of the silicon oxide film 41 can be seen through, and photomask alignment can be performed accurately.

  Thereafter, as shown in FIG. 13, a silicon oxide film 50 is formed by a CVD method or the like, and etched back by dry etching or the like to flatten the substrate surface. Further, as shown in FIG. 14, an interlayer insulating film 51 is formed, and a contact hole 52 is formed by dry etching or the like through photolithography. Then, a silicon nitride film 76 is formed in a predetermined region on the interlayer insulating film 51.

  Further, as shown in FIG. 15, an aluminum electrode 53 is formed through film formation / photolithography, and then a passivation film 54 is formed through film formation / photolithography.

  Finally, as shown in FIG. 16, the silicon oxide films 41 and 50 are removed by etching with an HF-based etchant, and the beam structure 56 having the movable electrode portion 55 and the like is made movable. That is, the silicon oxide film 41 in a predetermined region is removed by sacrificial layer etching using an etching solution, so that the silicon substrate 40 is made movable. At this time, in order to prevent the movable part from adhering to the substrate in the course of drying after etching, a sublimation agent such as rose dichlorobenzene is used.

  In this step (step of removing the silicon oxide film 41 in a predetermined region by sacrificial layer etching using an etchant to make the silicon substrate 40 a movable structure), the anchor portion 45c in the movable portion is made of a conductive thin film (polysilicon). Thus, the etching stops at the anchor portion 45c, and the variation is eliminated. That is, in this example using a silicon oxide film as a sacrificial layer thin film, a polysilicon thin film as a conductive thin film, and using an HF-based etching solution, the silicon oxide film is melted by HF but the polysilicon thin film is not melted. Therefore, it is not necessary to accurately manage the concentration and temperature of the HF-based etching solution or to perform the etching end by accurate time management, and the manufacturing becomes easy.

  That is, when the sacrificial layer is etched, the length of the beam changes depending on the etching time when the SOI substrate shown in FIG. 42 is used. In this embodiment, the anchor portion is etched regardless of the etching time. Since the etching is selectively terminated, the length of the beam is always constant.

  Since the anchor portion can be formed in this way, it is not necessary to perform end point control by time control in the sacrificial layer etching process when releasing the beam structure, and control of the spring constant and the like can be facilitated.

  Further, in this sacrificial layer etching process, since the protrusions 57 shown in FIG. 16 are formed by the recesses 42 in FIG. 7, the liquid movable part and the substrate are not replaced in the etching liquid replacement process after the beam structure is released. A droplet of a rinse liquid (substitution liquid) such as pure water remains in between, but the surface area due to the droplet is reduced by reducing the adhesion area of the droplet, and the movable part is fixed to the substrate when the rinse liquid evaporates. Is prevented.

  In this manner, a servo-controlled acceleration sensor can be formed by using the buried SOI substrate and forming the wiring pattern 45a and the lower electrode 45b by insulating separation.

  As described above, the present embodiment has the following features (b) to (f).

  (A) The beam structure 2 is arranged at a position spaced apart from the upper surface of the substrate 1 and receives an acting force that is displaced by acceleration (mechanical quantity). The fixed electrodes 9 a to 9 d, 11 a to 11 d, 13 a to 13 d, and 15 a to 15 d are fixed to the upper surface of the substrate 1, and are connected to the movable electrodes 7 a to 7 d and 8 a to 8 d that are part of the beam structure 2. Opposed to each other. In this type of sensor, a laminated body 21 of a lower-layer insulator thin film 18, a conductive thin film 19, and an upper-layer insulator thin film 20 shown in FIG. 22 to 25 and the electrode 26 are formed, and the wirings 22 to 25 and the electrode 26 are formed on the substrate 1 through the openings 29a to 29d, 31a to 31d, 30, 32, and 33 formed in the upper insulating thin film 20. The fixed electrodes 9a to 9d, 11a to 11d, 13a to 13d, 15a to 15d, the beam structure 2 and the electrode extraction portions 27a to 27d (electric connection members) were electrically connected. In this manner, an insulating film is arranged on the upper surface portion of the substrate 1, a thin film wiring or electrode is embedded therein, and an SOI substrate using a buried thin film (polysilicon layer) as the wiring or electrode on the substrate side ( Embedded SOI substrate). By using this structure, a wiring or an electrode can be formed by insulator isolation, and junction leakage can be reduced as compared with the case where an impurity diffusion layer (not shown) is used (in the case of pn junction isolation). In particular, it is possible to reduce junction leakage in a high temperature range.

  (B) In particular, a laminated body 21 of a lower-layer-side insulator thin film 18, a conductive thin-film 19, and an upper-layer-side insulator thin film 20 is disposed on the upper surface portion of the substrate 1, and the first fixed electrode is formed by the conductive thin film 19. The wiring patterns 22 and 24 and the second fixed electrode wiring patterns 23 and 25 are formed, and the first and second through the openings 29a to 29d and 31a to 31d in the upper insulating thin film 20 and the anchor portion of the fixed electrode. The fixed electrode wiring patterns 22 to 25 were electrically connected to the first and second fixed electrodes 9a to 9d, 11a to 11d, 13a to 13d, and 15a to 15d. As described above, the insulating film is arranged on the upper surface portion of the substrate 1, and the thin wiring patterns 22 to 25 are embedded therein, and the first fixed electrode energization line and the second wiring pattern 22 to 25 are used. The fixed electrode energization lines can be crossed.

  Thus, by using an SOI substrate (embedded SOI substrate) using a buried thin film (polysilicon layer) as the wiring on the substrate side, a wiring by insulator separation can be formed. Therefore, a conductive thin film separated by an insulator thin film can be formed, and junction leakage can be reduced as compared with the case where an impurity diffusion layer (not shown) is used (by pn junction isolation). In particular, it is possible to reduce junction leakage in a high temperature range.

  (C) Furthermore, a laminated body 21 of the lower-layer-side insulator thin film 18, the conductive thin-film 19, and the upper-layer-side insulator thin film 20 is disposed on the upper surface portion of the substrate 1. The wiring patterns 22, 24 and the second fixed electrode wiring patterns 23, 25 are formed, and the lower electrode (static force canceling fixed electrode) 26 is formed by the conductive thin film 19, and the opening in the upper insulating thin film 20 is formed. 29a-29d, 31a-31d, and first and second fixed electrode anchor portions 10a-10d, 12a-12d, and first and second fixed electrode wiring patterns 22-25 and first and second fixed electrodes. 9a to 9d, 11a to 11d, 13a to 13d, and 15a to 15d are electrically connected, and further, the opening 33 in the upper insulating film 20 and the anchor portions 3a to 3d of the beam structure are passed through. And electrically connecting the lower electrode 26 and the beam structure 2 Te. As described above, the insulating film is disposed on the upper surface portion of the substrate 1, and the thin-film wiring patterns 22 to 25 and the lower electrode 26 are embedded therein, and the first fixed electrode energization line and the first wiring are formed using the wiring pattern. The two fixed electrode energization lines can be crossed, and the electrostatic force generated between the beam structure (movable part) and the substrate is offset by making the beam structure (movable part) and the lower electrode equipotential. It is possible to prevent the beam structure (movable part) from adhering to the substrate due to a slight potential difference between the beam structure (movable part) and the substrate.

  (D) Since the single crystal silicon which is a brittle material with known physical properties such as Young's modulus is used as the material of the beam structure 2, the reliability of the beam structure can be increased.

  (E) By using a polysilicon thin film as the conductive thin film 19 and separating the periphery with an insulator thin film, the influence of a leakage current or the like in a high temperature region as in the case of pn junction isolation can be further reduced.

  (F) Since the servo mechanism (servo control) is employed, the displacement of the beam structure due to the action of acceleration can be minimized, and therefore the reliability of the sensor can be enhanced.

  As an application example of the present embodiment, the first fixed electrode wiring patterns 22 and 24 and the second fixed electrode wiring patterns 23 and 25 are formed by the conductive thin film 19 in the above-described example. Only one of them may be formed by the conductive thin film 19, and the other may be electrically connected by aluminum wiring or electrically connected as a comb-like electrode. In the example described above, the wiring pattern of the fixed electrode and the lower electrode are formed of the buried conductive thin film, but may be embodied in a sensor that does not use the lower electrode.

(Second Embodiment)
Next, a second embodiment will be described based on the drawings with a focus on differences from the first embodiment.

  17 to 27 are sectional views showing a process flow in manufacturing the semiconductor acceleration sensor according to the present embodiment. First, as shown in FIG. 17, a single crystal silicon substrate 60 as a first semiconductor substrate is prepared. Then, grooves are formed in the silicon substrate 60 with a certain width by trench etching, and then a groove pattern 61 for forming a beam structure is formed. That is, a groove (61) is formed in a predetermined region of the silicon substrate 60. Here, impurities are introduced by phosphorus diffusion or the like in order to form an electrode for detecting the capacitance later. Thereafter, as shown in FIG. 18, a silicon oxide film 62 as a sacrificial layer thin film is formed on the silicon substrate 60 including the groove (61) by the CVD method or the like, and the surface of the silicon oxide film 62 is further flattened. Turn into.

  Further, as shown in FIG. 19, the silicon oxide film 62 is partially etched through photolithography to form a recess 63. This is to reduce the adhesion area in order to prevent adhesion to the substrate due to surface tension or the like after the beam structure is released in the sacrificial layer etching process. Further, a silicon nitride film (first insulator thin film) 64 is formed to increase unevenness on the surface and serve as an etching stopper during the sacrifice layer etching. Then, openings 65a, 65b, and 65c are formed in the anchor portion formation region by dry etching or the like through photolithography on the stacked body of the silicon nitride film 64 and the silicon oxide film 62. The openings 65a to 65c are for connecting the beam structure and the substrate (lower electrode), and for connecting the fixed electrode (and electrode extraction portion) and the wiring pattern.

  Subsequently, as shown in FIG. 20, a polysilicon thin film 66 is formed on the silicon nitride film 64 including the openings 65a to 65c, and then impurities are introduced by phosphorus diffusion or the like, and further, wiring is performed through photolithography. A pattern 66a, a lower electrode 66b, and an anchor portion 66c are formed. In this way, an impurity-doped polysilicon thin film (66) as a conductive thin film is formed in a predetermined region on the silicon nitride film 64 including the openings 65a to 65c. The thickness of the polysilicon thin film is about 1-2 μm.

  In this step (the step of forming the impurity-doped polysilicon thin film 66 in a predetermined region on the silicon nitride film 64 including the opening), the polysilicon thin film 66 is thin enough to satisfy the lower pattern resolution of the stepper (1-2 μm). Therefore, the shapes of the openings 65a to 65d of the silicon nitride film 64 under the polysilicon thin film 66 can be seen through, and photomask alignment can be performed accurately.

  Then, as shown in FIG. 21, a silicon oxide film 67 as a second insulator thin film is formed on the silicon nitride film 64 including the polysilicon thin film (66). Furthermore, as shown in FIG. 22, a polysilicon thin film 68 as a thin film for bonding is formed on the silicon oxide film 67, and the surface of the polysilicon thin film 68 is flattened by mechanical polishing or the like for bonding. To do.

  Next, as shown in FIG. 23, a single crystal silicon substrate (support substrate) 69 different from the silicon substrate 60 is prepared, and the surface of the polysilicon thin film 68 and the silicon substrate 69 as the second semiconductor substrate are attached. Match.

  Further, as shown in FIG. 24, the silicon substrates 60 and 69 are turned upside down, and the silicon substrate 60 side is thinned by mechanical polishing or the like. That is, the silicon substrate 60 is polished to a desired thickness. At this time, as shown in FIG. 17, when polishing is performed to the depth of the trench formed by trench etching, the layer of the silicon oxide film 62 appears and the hardness in polishing changes, so that the polishing end point can be easily detected. Can do.

  Thereafter, as shown in FIG. 25, an interlayer insulating film 70 is formed, and contact holes 71 are formed by photolithography through dry etching or the like. Then, a silicon nitride film 77 is formed in a predetermined region on the interlayer insulating film 70.

  Further, as shown in FIG. 26, an aluminum electrode 72 is formed through film formation / photolithography, and then a passivation film 73 is formed through film formation / photolithography.

  Finally, as shown in FIG. 27, the silicon oxide film 62 is removed by etching with an HF-based etchant, and the beam structure 75 having the movable electrode 74 is made movable. That is, the silicon oxide film 62 in a predetermined region is removed by sacrificial layer etching using an etching solution, so that the silicon substrate 60 is made a movable structure. At this time, in order to prevent the movable part from adhering to the substrate in the course of drying after etching, a sublimation agent such as rose dichlorobenzene is used.

In this step (step of removing the silicon oxide film 62 in a predetermined region by sacrificial layer etching using an etching solution to make the silicon substrate 60 a movable structure), the anchor portion 66c in the movable portion is made of a conductive thin film, and the anchor portion At 66c, the etching stops and there is no variation. That is, in this example in which a silicon oxide film is used as the sacrificial layer thin film and a polysilicon thin film is used as the conductive thin film, when an HF-based etchant is used, the silicon oxide film is dissolved in HF, but the polysilicon thin film is used. Therefore, it is not necessary to accurately control the concentration and temperature of the HF-based etching solution or to perform the etching end with accurate time management, which facilitates manufacture.
Since the anchor can be formed in this way, it is not necessary to perform end point control by time control in the sacrificial layer etching step when releasing the beam structure, and control of the spring constant and the like can be facilitated.

  In this way, a servo-controlled acceleration sensor can be formed by using the buried SOI substrate and forming the wiring pattern and the lower electrode by insulator separation.

(Third embodiment)
Next, the third embodiment will be described with a focus on differences from the first embodiment.

  FIG. 28 shows a plan view of semiconductor acceleration in the present embodiment. In the first embodiment shown in FIG. 1, the mass portion 6 is structured to be supported by beams 4 and 5 extending linearly with respect to the anchor portions 3a to 3d. In this embodiment, the beam structure is bent as shown in FIG.

  By doing so, it is possible to avoid the beam from buckling due to the influence of the residual stress of the film used for the beam structure 2 when compressive stress remains in the film. In addition, when tensile stress remains in the film, it is possible to avoid the spring constant of the beam from deviating from the design value. As a result, a sensor as designed can be formed.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to the drawings.

  In this embodiment, the present invention is applied to an excitation type yaw rate sensor. More specifically, two beam structures (movable structures) are provided, and both beam structures (movable structures) are excited in opposite phases. The differential detection is performed.

  29 is a plan view of the yaw rate sensor according to the present embodiment, FIG. 30 is a sectional view taken along XXX-XXX in FIG. 29, FIG. 31 is a sectional view taken along XXX-XXXI in FIG. 29, and FIG. It is XXXII-XXXII sectional drawing in.

  In FIG. 30, a beam structure 81 and a beam structure 82 (see FIG. 29) made of single crystal silicon (single crystal semiconductor material) are disposed adjacent to each other on the upper surface of a substrate 80. The beam structure 81 is constructed by four anchor portions 83 a, 83 b, 83 c, 83 d protruding from the substrate 80 side, and is disposed at a position spaced apart from the substrate 80 by a predetermined interval. Anchor portions 83a to 83d are made of a polysilicon thin film. A beam portion 84 is installed between the anchor portion 83a and the anchor portion 83c, and a beam portion 85 is installed between the anchor portion 83b and the anchor portion 83d. A mass portion (mass portion) 86 having a rectangular shape is installed between the beam portion 84 and the beam portion 85. The mass portion 86 is provided with a through-hole 86a penetrating vertically. Further, a large number of exciting movable electrodes 87 protrude from one side surface (the left side surface in FIG. 29) of the mass portion 86. Each movable electrode 87 has a rod shape and extends in parallel at equal intervals. Further, a large number of excitation movable electrodes 88 protrude from the other side surface (the right side surface in FIG. 29) of the mass portion 86. Each movable electrode 88 has a rod shape and extends in parallel at equal intervals. Here, the beam portions 84 and 85, the mass portion 86, and the movable electrodes 87 and 88 are movable by removing a part of the sacrificial layer oxide film 89 by etching. This etching region is indicated by Z2 in FIG.

  Thus, the beam structure 81 has two comb-like movable electrodes, that is, the movable electrode 87 as the first movable electrode and the movable electrode 88 as the second movable electrode.

  A configuration similar to that of the beam structure 81 is also adopted in the beam structure 82, and the description thereof is omitted by giving the same reference numerals. On the upper surface of the substrate 80, comb electrodes 90, 91, and 92 are arranged as excitation fixed electrodes. The comb-tooth electrode 90 has a rod-shaped electrode portion 90a on one side, the comb-tooth electrode 91 has rod-shaped electrode portions 91a and 91b on both sides, and the comb-tooth electrode 92 has a rod-shaped electrode portion 92a on one side. Each of the comb electrodes 90, 91, 92 is made of single crystal silicon. The comb electrodes 90, 91, 92 are supported and fixed by anchor portions 93, 94, 95 protruding from the substrate 80 side. The bar-shaped electrode portion 90 a of the comb-teeth electrode 90 is opposed and disposed between the movable electrodes (bar-shaped portions) 87 of the beam structure 81. The bar-shaped electrode portion 91 a of the comb-tooth electrode 91 is opposed and arranged between the movable electrodes (bar-shaped portions) 88 of the beam structure 81. The rod-shaped electrode portion 91 b of the comb-tooth electrode 91 is opposed and disposed between the movable electrodes (bar-shaped portions) 87 of the beam structure 82. The bar-shaped electrode portion 92 a of the comb-teeth electrode 92 is opposed to and disposed between the movable electrodes (bar-shaped portions) 88 of the beam structure 82.

  In the present embodiment, the comb electrode 90 constitutes a first excitation fixed electrode, and the comb electrode 91 constitutes a second excitation fixed electrode. In addition, as shown in FIG. 29, a lower electrode (for yaw rate detection) serving as a mechanical quantity detection fixed electrode is provided in a region facing a part of the beam structure 81 (mainly the mass portion 86) on the upper surface portion of the substrate 80. Fixed electrode) 101 is arranged. Similarly, a lower electrode (fixed electrode for yaw rate detection) 102 as a mechanical quantity detection fixed electrode is disposed in a region of the upper surface portion of the substrate 80 facing a part of the beam structure 82 (mainly the mass portion 86). Has been. A first capacitor is formed between the beam structure 81 and the lower electrode 101, and a second capacitor is formed between the beam structure 82 and the lower electrode 102.

  Then, by applying an anti-static electrostatic force between the movable electrode 87 and the comb electrode 90 of the beam structure 81 and between the movable electrode 88 and the comb electrode 91 of the beam structure 81, the beam structure 81 can be forcedly vibrated (excited). Further, by applying a reverse phase electrostatic force between the movable electrode 87 and the comb electrode 91 of the beam structure 82 and between the movable electrode 88 and the comb electrode 92 of the beam structure 82, the beam structure is provided. 82 can be forcedly vibrated (excited). Further, during this excitation, the yaw rate acting on the beam structures 81 and 82 is detected based on the capacitance (capacitance Co) of the capacitor formed between the beam structures 81 and 82 and the lower electrodes 101 and 102. Can be done.

As shown in FIG. 31, the substrate 80 has a structure in which a lower insulating film 97, a conductive thin film 98, and an upper insulating thin film 99 are stacked on a silicon substrate (semiconductor substrate) 96. . That is, the laminated body 100 of the lower-layer-side insulator thin film 97, the conductive thin film 98, and the upper-layer-side insulator thin film 99 is disposed on the upper surface portion of the silicon substrate 96, and the conductive thin film 98 is the insulator thin film. 97 and 99 are embedded. The lower insulator thin film 97 is made of a silicon oxide film, and the upper insulator thin film 99 is made of a silicon nitride film, which is formed by a CVD method or the like. The conductive thin film 98 is made of an impurity-doped polysilicon thin film.
Lower electrodes (fixed electrodes for yaw rate detection) 101 and 102 and wiring patterns 103 and 104 shown in FIG. 29 are formed by the conductive thin film 98. 29 and 31, electrode extraction portions 105 and 106 made of single crystal silicon are formed on the upper surface of the substrate 80, and the electrode extraction portions 105 and 106 are anchor portions 107 and 108 protruding from the substrate 80. Is supported by In the present embodiment, the electrode connecting portions 105 and 106 constitute an electrical connection member.

  As shown in FIG. 31, an opening 109 is formed in the upper insulating thin film 99, and the aforementioned anchor (impurity doped polysilicon) 107 is disposed in the opening 109. Therefore, the lower electrode 101 is electrically connected to the electrode extraction portion 105 through the wiring pattern 103 through the opening 109 and the anchor portion (impurity doped polysilicon) 107. A similar configuration is also adopted in the electrode extraction portion 106, and the lower electrode 102 is electrically connected to the electrode extraction portion 106 via the wiring pattern 104 through the anchor portion (impurity doped polysilicon) 108.

  As shown in FIG. 29, the anchor portions 93, 94, 95 of the comb electrodes 90, 91, 92 and the anchor portions 83a, 83b, 83c, 83d of the beam structures 81, 82 are also from the conductive thin film 98. An embedded portion 110 is formed.

  Thus, the substrate 80 has a structure in which the lower electrodes 101 and 102 made of polysilicon and the wiring patterns 103 and 104 are buried under the SOI layer, and this structure is formed by using the surface micromachining technique. It is a thing.

  On the other hand, as shown in FIG. 32, electrodes (bonding pads) 111, 112, 113 made of an aluminum thin film are provided on the upper surfaces of the comb electrodes 90, 91, 92. Further, electrodes (bonding pads) 114 and 115 made of an aluminum thin film are provided on the upper surfaces of the anchor portions 83a of the beam structures 81 and 82, respectively. Further, as shown in FIG. 31, electrodes (bonding pads) 116 made of an aluminum thin film are provided on the upper surfaces of the electrode extraction portions 105 and 106, respectively. An interlayer insulating film 118 and a silicon nitride film 117 are formed on the electrode extraction portions 105 and 106.

  By using the lower electrodes 101 and 102 and the wiring patterns 103 and 104 separated as described above, the aluminum electrode (bonding pad) 116 can be taken out from the substrate surface.

  Next, the detection principle of this yaw rate sensor will be described with reference to FIG. A voltage is applied between the comb-tooth electrodes (excitation fixed electrodes) 90, 91, 92 and the excitation movable electrodes 87, 88. Thereby, the mass part 86 of the beam structures 81 and 82 is vibrated in a direction parallel to the surface of the substrate (Y direction in FIG. 29). At this time, if yaw Ω is generated in a direction parallel to the surface of the substrate and perpendicular to the vibration direction (Y direction), the direction perpendicular to the surface of the substrate with respect to the mass portion 86 of the beam structures 81 and 82 Coriolis force is generated (see FIG. 29). The displacement of the mass portion 86 of the beam structures 81 and 82 due to the Coriolis force is detected as a change in the capacitance Co.

  Here, the Coriolis force fc depends on the mass m of the mass portion 86 of the beam structures 81 and 82, the vibration speed V, and the yaw Ω, and is expressed by the following equation.

fc = 2mVΩ (1)
In the vibration in the direction parallel to the substrate surface, the speed of the mass portion 86 of the beam structures 81 and 82 is “0” on the fixed end side and the maximum at the center, so the Coriolis force is the same as shown in FIG. The displacement in the direction perpendicular to the surface of the beam structure is also “0” on the fixed end side, the maximum at the center, and the mass portion 86 of the beam structures 81 and 82 draws an ellipse. Here, the mass portions 86 (that is, the two mass portions 86) of the beam structures 81 and 82 are displaced in phase by 180 degrees, so that the displacement direction is reversed and differential detection is possible. If the mass part 86 of the beam structures 81 and 82 is single (without differential excitation), Coriolis force and acceleration due to vibration or the like cannot be separated, but noise components due to acceleration can be canceled by performing differential detection. . In general, since the Coriolis force is very small, the resonance effect is used. Specifically, in order to increase the velocity V shown in the equation (1), the excitation (the direction parallel to the surface of the substrate) of the mass portion 86 of the beam structures 81 and 82 is set as the resonance frequency to increase the amplitude. Here, since the Coriolis force is generated at the same period as the vibration, if the detection (perpendicular to the surface of the substrate) direction has a resonance frequency equal to the excitation, the displacement due to the Coriolis force can be increased.

  Here, assuming that one of the capacitances is “Co + ΔC” and the other is “Co−ΔC” due to the gap change due to the Coriolis force, the gap change due to the Coriolis force is sufficiently larger than the initial value. If it is smaller, Coriolis force fc is fc∝2ΔC by differential detection, and yaw Ω is Ω∝2ΔC, and yaw can be detected from two capacitance changes.

  The manufacturing method of this yaw rate sensor can be created by the same method as in the first and second embodiments. Thus, the present embodiment has the following features.

  On the upper surface portion of the substrate 80, a laminated body 100 of a lower-layer-side insulator thin film 97, a conductive thin film 98, and an upper-layer-side insulator thin film 99 is disposed. (102) and the wiring pattern 103 (104) of the lower electrode are formed, and the lower electrode 101 (102) is passed through the wiring pattern 103 (104) from the opening 109 in the upper insulating thin film 99 and the electrode extraction portion on the substrate 80. (Electrical connection member) It electrically connected to 105 (106). In this way, by disposing an insulating film on the upper surface of the substrate 80 and embedding the thin film lower electrode (mechanical quantity detection fixed electrode) and wiring pattern therein, wiring or electrodes can be formed by insulator separation. As compared with a case where an impurity diffusion layer (not shown) is used (by pn junction isolation), junction leakage can be reduced. In particular, it is possible to reduce junction leakage in a high temperature range.

  In this way, by using an SOI substrate (embedded SOI substrate) using a buried thin film (polysilicon layer) as the lower electrodes 101 and 102 on the substrate side and wiring therefor, it is possible to form electrodes and wirings by insulator isolation. .

  The present invention is not limited to the above-described embodiments. For example, in the above-described embodiment, acceleration is detected using an electrostatic servo system (a voltage is applied to displacement due to acceleration so as not to be displaced. However, the present invention may be embodied in a sensor that directly detects displacement as a change in capacitance.

  In addition to acceleration and yaw rate, the present invention can be embodied in a semiconductor dynamic quantity sensor that detects a dynamic quantity such as vibration.

The top view which shows the acceleration sensor of 1st Embodiment. II-II sectional drawing of FIG. III-III sectional drawing of FIG. IV-IV sectional drawing of FIG. VV sectional drawing of FIG. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 1st Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. Sectional drawing which shows the manufacturing method of the acceleration sensor of 2nd Embodiment. The top view of the acceleration sensor of 3rd Embodiment. The top view of the yaw rate sensor of 4th Embodiment. XXX-XXX sectional drawing of FIG. XXXI-XXXI sectional drawing of FIG. XXXII-XXXII sectional view of FIG. 29 (when Ω = 0). Sectional drawing for demonstrating the effect | action of the yaw rate sensor of 4th Embodiment (when (omega | ohm) ≠ 0). The top view which shows the conventional acceleration sensor. XXXV-XXXV sectional drawing of FIG. XXXVI-XXXVI sectional drawing of FIG. Sectional drawing which shows the manufacturing method of the conventional acceleration sensor. Sectional drawing which shows the manufacturing method of the conventional acceleration sensor. The top view which shows the conventional acceleration sensor. FIG. 40 is a sectional view of XXXX-XXXX in FIG. 39. XXXXI-XXXXI sectional drawing of FIG. Sectional drawing which shows the manufacturing method of the conventional acceleration sensor. Sectional drawing which shows the manufacturing method of the conventional acceleration sensor. Sectional drawing which shows the manufacturing method of the conventional acceleration sensor. Sectional drawing which shows the manufacturing method of the conventional acceleration sensor. Sectional drawing which shows the manufacturing method of the conventional acceleration sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Beam structure as electrical connection member, 7a, 7b, 7c, 7d ... Movable electrode, 8a, 8b, 8c, 8d ... Movable electrode, 9a, 9b, 9c, 9d ... 1st fixed electrode 10a, 10b, 10c, 10d ... anchor portion, 11a, 11b, 11c, 11d ... second fixed electrode, 12a, 12b, 12c, 12d ... anchor portion, 13a, 13b, 13c, 13d ... first fixed electrode , 14a, 14b, 14c, 14d ... anchor portion, 15a, 15b, 15c, 15d ... second fixed electrode, 16a, 16b, 16c, 16d ... anchor portion, 17 ... silicon substrate as semiconductor substrate, 18 ... lower layer side Insulator thin film, 19 ... conductive thin film, 20 ... upper insulator thin film, 21 ... laminated body, 22, 23, 24,25 ... wiring pattern, 26 ... below as electrostatic force canceling fixed electrode Electrode, 27a, 27b, 27c, 27d ... Electrode extraction part as electrical connecting member, 29a, 29b, 29c, 29d ... Opening, 31a, 31b, 31c, 31d ... Opening, 32 ... Opening, 33 ... Opening , 40... Single crystal silicon substrate as first semiconductor substrate, 41... Silicon oxide film as sacrificial layer thin film, 43. Silicon nitride film as first insulator thin film, 44 a, 44 b, 44 c, 44 d. 45, polysilicon thin film as a conductive thin film, 46 ... silicon oxide film as a second insulator thin film, 46 ... polysilicon thin film as a bonding thin film, 48 ... single crystal as a second semiconductor substrate Silicon substrate, 49... Groove pattern (groove), 60... Silicon substrate as first semiconductor substrate, 61... Groove pattern (groove), 62. A film, 64 ... a silicon nitride film as a first insulator thin film, 65a, 65b, 65c ... an opening, 66 ... a polysilicon thin film as a conductive thin film, 67 ... a silicon oxide film as a second insulator thin film, 68: polysilicon thin film as a bonding thin film, 69: single crystal silicon substrate as second semiconductor substrate, 80 ... substrate, 81 ... beam structure, 82 ... beam structure, 87 ... as first movable electrode , Excitation movable electrode as a second movable electrode, 90. Comb electrode as a first excitation fixed electrode, 91 ... comb electrode as a second excitation fixed electrode, 97: Lower insulating thin film, 98: Conductive thin film, 99: Upper insulating thin film, 100: Laminate, 101: Lower electrode, 102: Lower electrode, 103: Wiring pattern, 104: Wiring pattern, 105: Electricity With connecting members Electrode extraction part 106... Electrode extraction part as an electrical connection member 109 109 opening.

Claims (3)

A substrate in which a lower-layer insulator thin film and a conductive thin film are laminated in this order on a semiconductor substrate;
A beam structure having a plurality of movable electrodes arranged parallel to each other at a position spaced from the upper surface of the substrate;
A plurality of first fixed electrodes fixed to the upper surface of the substrate and arranged to face one side surface of each of the movable electrodes, constituting a first capacitor together with the movable electrodes of the beam structure; A plurality of second fixed electrodes that are respectively disposed opposite to the other side surfaces of the movable electrode and constitute a second capacitor together with the movable electrode of the beam structure;
A first electrode extraction portion fixed to the upper surface of the substrate and electrically connected to the first fixed electrode; and a second electrode extraction portion electrically connected to the second fixed electrode;
A first wiring pattern configured by the conductive thin film and electrically connecting the plurality of first fixed electrodes and the first electrode lead-out portion to each other, and between the plurality of second fixed electrodes and the above A semiconductor dynamic quantity sensor, comprising: a second wiring pattern that electrically connects the second electrode extraction portions to each other. An upper insulating thin film having an opening in a predetermined region is disposed on the conductive thin film,
The first wiring pattern is connected to the first electrode extraction portion via a first anchor portion arranged in the opening,
2. The semiconductor dynamic quantity according to claim 1, wherein the second wiring pattern is connected to the second electrode extraction portion via a second anchor portion disposed in the opening. Sensor.   The first fixed electrode and the first wiring pattern constitute a first fixed electrode energization line, and the second fixed electrode and the second wiring pattern constitute a second fixed electrode energization line. The semiconductor dynamic quantity sensor according to claim 1, wherein the first fixed electrode energization line and the second fixed electrode energization line intersect each other.

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