JP4783914B2 - Semiconductor dynamic quantity sensor and manufacturing method of semiconductor dynamic quantity sensor - Google Patents

Description

  The present invention relates to a semiconductor dynamic quantity sensor, and more particularly to a semiconductor dynamic quantity sensor suitable for an automobile airbag system, suspension control system, and the like.

  Nikkei Electronics 1991.11.11 (no. 540), P223 to P231 show an acceleration sensor using surface micromachining technology. That is, by laminating a thin polysilicon film on a silicon substrate and etching this polysilicon film, a beam movable in the parallel direction of the surface is formed to form a differential capacitive acceleration sensor. Yes.

  However, when the beam structure having conductivity such as a polysilicon film is laminated on a substrate having the same conductivity as in the above document, it is necessary to electrically insulate the beam structure from the substrate. Yes, it is an issue for the future.

  Accordingly, an object of the present invention is to provide a semiconductor dynamic quantity sensor having a novel structure and electrically insulating a beam structure from a substrate, and a method for manufacturing the semiconductor dynamic quantity sensor.

In order to achieve the above object, a first invention includes a first layer formed of a silicon material, and a second layer formed of a silicon material disposed on the lower surface side of the first layer via an insulating member. The first layer has a movable electrode that is displaced in the horizontal direction in accordance with a mechanical quantity, and is supported by the first layer to form the support beam fixed to the second layer via an insulating member. An insulating groove provided through the insulating groove, a fixed electrode provided on the side of the support beam across the insulating groove and fixed to the second layer via the insulating member, and disposed around the support beam and the fixed electrode And a peripheral portion formed on the insulating member and electrically separated from the supporting beam and the fixed electrode by an insulating groove, and the thickness of the movable electrode in the direction from the upper surface to the lower surface of the first layer is It is characterized by being thinner than the thickness.

  According to the said structure, compared with the case where the thickness of a movable electrode is not thinner than the thickness of a fixed electrode, a 2nd layer and a movable electrode can be electrically insulated more reliably.

A second invention includes a first layer formed of a silicon material, and a second layer formed of a silicon material disposed on the lower surface side of the first layer via an insulating member, , Having a movable electrode that is displaced in the horizontal direction according to the mechanical quantity, and is provided through the first layer to form a support beam fixed to the second layer via an insulating member, and the support beam An insulating groove, a fixed electrode provided on the side of the support beam across the insulating groove, fixed to the second layer via the insulating member, and disposed around the support beam and the fixed electrode, formed on the insulating member And a peripheral portion electrically separated from the support beam and the fixed electrode by an insulating groove, and a recess is provided at a position reaching the insulating groove between the first layer and the insulating member. To do.

  According to the said structure, compared with the case where a recessed part is not provided in the location which reaches an insulation groove | channel, a 2nd layer and a movable electrode can be electrically insulated more reliably.

A third invention comprises a first step of forming a concave portion on the main surface of the first layer formed of a silicon material, and the insulating member side of the second layer formed of a silicon material having an insulating member, said first A second step of joining one side of the side where the concave portion is formed, and a third step of etching the first layer to form a trench reaching the concave portion and defining a support beam. Features.

(First embodiment)
An embodiment embodying the present invention will be described below with reference to the drawings.

1 is a plan view of the acceleration sensor, and FIG. 2 is a cross-sectional view taken along the line AA of FIG. This acceleration sensor is a capacitive acceleration sensor, and as shown in FIG. 2, a single crystal silicon substrate 1 is bonded to a single crystal silicon substrate 8 via a SiO ₂ film 9, and the single crystal silicon substrate 1 is connected to the same substrate. A cantilever beam 13 is formed by a trench 3 penetrating 1. As shown in FIG. 1, the cantilever 13 has a structure in which the tip side is divided into two. The cantilever 13 is movable in a direction parallel to the surface of the single crystal silicon substrate 1 (direction of arrow C in FIG. 1). Further, in the single crystal silicon substrate 1, the signal processing circuit 10 is formed in a state of being electrically insulated from the cantilever 13 by the polysilicon film 6 and the SiO ₂ film 5.

3 to 10 show the manufacturing process. The manufacturing process will be described below. As shown in FIG. 3, an n-type (100) single crystal silicon substrate 1 of 1 to 20 Ω · cm is prepared, an SiO ₂ film 2 of about 1 μm is formed on the main surface by thermal oxidation, and SiO ₂ film is formed by photolithography. _Two films 2 are formed in a predetermined pattern. Subsequently, a trench 3 having a vertical wall with a predetermined depth, for example, about 0.2 to 30 μm is formed on the main surface side of the single crystal silicon substrate 1 by reactive ion etching or the like. In this embodiment, the case of about 3 μm will be described.

Then, after removing the SiO ₂ film 2, as shown in FIG. 4, an n + diffusion layer 4 made of phosphorus, arsenic, or the like is formed on the main surface of the single crystal silicon substrate 1 including the inner wall of the trench 3, and thermal oxidation is performed. The SiO ₂ film 5 having a thickness of 0.1 to 1 μm is formed by, for example. At this time, in order to remove etching damage, so-called sacrificial oxidation in which SiO ₂ is formed and removed by thermal oxidation before the n + diffusion layer 4 is formed may be performed.

  Subsequently, as shown in FIG. 5, a polysilicon film 6 is formed on the main surface of the single crystal silicon substrate 1, and the trench 3 is filled with the polysilicon film 6. In the case where impurities are introduced into the polysilicon film 6 so that the polysilicon film 6 can be used as a conductive path for bias, a thin polysilicon layer is formed before the polysilicon film 6 is formed, and phosphorus or the like is highly concentrated. If it is diffused, impurities can be introduced into the polysilicon film 6.

  Next, as shown in FIG. 6, the surface of the polysilicon film 6 is mirror-polished so that the polysilicon film 6 having a predetermined thickness remains. Subsequently, a p + diffusion layer 7 made of boron is formed in a predetermined region in the polysilicon film 6 by ion implantation or the like.

On the other hand, as shown in FIG. 7, another (100) single crystal silicon substrate 8 is prepared, and a 0.1 to 1.0 μm SiO ₂ film 9 is formed on the main surface by thermal oxidation. Next, the single crystal silicon substrate 1 and the single crystal silicon substrate 8 are placed in, for example, a mixed aqueous solution of hydrogen peroxide and sulfuric acid, and a hydrophilic treatment is performed. Then, after drying, as shown in FIG. 8, the main surface of the single crystal silicon substrate 1 and the main surface of the single crystal silicon substrate 8 are superposed at room temperature and placed in a furnace at 400 to 1100 ° C. for 0.5 to Perform strong bonding for 2 hours.

Next, as shown in FIG. 9, the back side of the single crystal silicon substrate 1 is selectively polished using an alkaline aqueous solution such as a KOH solution until the SiO ₂ film 2 appears. As a result, the thickness of the single crystal silicon substrate 1 becomes about 3 μm, for example, and is thinned.

  Then, as shown in FIG. 10, a signal processing circuit (IC circuit portion) 10 is formed in a predetermined region of the single crystal silicon substrate 1 using a normal CMOS process, a bipolar process, or the like. 1 and 10, only a MOS transistor is shown as a part of the signal processing circuit 10. Furthermore, a plasma SiN film (P-SiN) is formed as a passivation film 11 on the upper surface of the signal processing circuit 10 by, for example, a plasma CVD method. Subsequently, a window 12 is opened in a predetermined region of the passivation film 11.

Then, as shown in FIG. 2, the passivation film 11 is formed from the back side (upper side in FIG. 2) of the single crystal silicon substrate 1 using an approximately 20% solution of TMAH (tetramethylammonium hydroxide) (CH 3) 4 NOH. The polysilicon film 6 is removed by etching through the window 12. At this time, the passivation film 11 (P-SiN), the SiO ₂ film 5, the aluminum wiring layer, and the p + diffusion layer (p + polysilicon film) 7 are hardly etched by selective etching.

  When the polysilicon film 6 is removed by etching, an etching hole 48 is provided in the wide portion of the cantilever 13 in FIG. 1, and the polysilicon film 6 is more reliably removed by etching through the etching hole 48. Like to do.

  As a result, a cantilever 13 is formed. At this time, as shown in FIG. 2, the cantilever 13 has a smaller thickness L2 in the direction parallel to the surface of the single crystal silicon substrate 1 than the thickness L1 in the depth direction of the single crystal silicon substrate 1. It has become.

  In the capacitive acceleration sensor, the tip portion of the cantilever 13 (part divided into two) serves as a movable electrode and, as shown in FIG. 1, single crystal silicon facing the tip portion of the cantilever 13 The substrate 1 becomes the fixed electrodes 14, 15, 16, and 17. Further, as shown in FIG. 1, the fixed electrode 14 and the fixed electrode 16 are taken out by the aluminum wiring layer 18a, the fixed electrode 15 and the fixed electrode 17 are taken out by the aluminum wiring layer 18b, and the cantilever The (movable electrode) 13 is taken out by the aluminum wiring layer 18c. The aluminum wiring layers 18a, 18b, and 18c are connected to the signal processing circuit 10, and the signal processing circuit 10 performs signal processing accompanying the displacement of the cantilever (movable electrode) 13 due to acceleration. The potential is kept constant by the n + diffusion layer 4 (see FIG. 2) disposed on the cantilever 13 (movable electrode) and the fixed electrodes 14, 15, 16, and 17.

  In this embodiment, the capacitive acceleration sensor is used. However, if a piezoresistive layer is formed on the surface of the base portion of the cantilever 13, a piezoresistive acceleration sensor can be obtained. Of course, if both types of sensors are formed on the same substrate, the accuracy and reliability can be further improved.

In the acceleration sensor manufactured as described above, the single crystal silicon substrate 1 is bonded to the single crystal silicon substrate 8 via the SiO ₂ film to form an SOI structure. Further, in the cantilever 13, the thickness L 2 in the direction parallel to the surface of the single crystal silicon substrate 1 is smaller than the thickness L 1 in the depth direction of the single crystal silicon substrate 1. Therefore, the cantilever 13 can move in the direction parallel to the surface of the single crystal silicon substrate 1, and acceleration in the direction parallel to the substrate surface is detected.

As described above, in this embodiment, the trench (groove) 3 having a predetermined depth for forming the cantilever 13 is formed on the main surface of the single crystal silicon substrate 1 (first step), and the single crystal silicon substrate 1 is formed. A polysilicon film 6 was formed on the main surface of the silicon film 6 and the trench 3 was filled with the polysilicon film 6, and the surface of the polysilicon film 6 was smoothed (second step). Then, the main surface of the single crystal silicon substrate 1 and the single crystal silicon substrate 8 on which the SiO ₂ film (insulating film) 9 is formed are joined via the SiO ₂ film 9 (third step), and the single crystal silicon substrate A single crystal silicon substrate 1 was thinned by polishing a predetermined amount on the back side of 1 (fourth step). Further, after forming the signal processing circuit 10 on the surface of the single crystal silicon substrate 1, the polysilicon film 6 was etched away from the back side of the single crystal silicon substrate 1 to form the cantilever 13 (fifth step).

  Therefore, in the formation process of the signal processing circuit 10 in the middle of the wafer process, the trench 3 is buried in the surface portion of the single crystal silicon substrate 1 by the polysilicon film 6, and contamination of the IC element, contamination of the manufacturing apparatus, Accordingly, it is possible to prevent electrical characteristics from being deteriorated or deteriorated. In other words, in the wafer process, by preventing surface structures such as recesses and through-holes from appearing on the wafer surface during heat treatment, photolithography processing, etc. during the process, contamination is prevented and the wafer process is stabilized. A highly accurate acceleration sensor can be stably supplied.

The acceleration sensor manufactured as described above is bonded to the single crystal silicon substrate 8 via the SiO ₂ film (insulating film) 9 and formed into a thin single crystal silicon substrate 1 and the single crystal silicon substrate 1. And a signal processing circuit 10 which is formed on the single crystal silicon substrate 1 and performs signal processing accompanying the operation of the cantilever 13 by acceleration. When acceleration acts in a direction parallel to the surface of the single crystal silicon substrate 1, the cantilever 13 formed on the single crystal silicon substrate 1 operates. Signal processing is performed by the signal processing circuit 10 formed on the single crystal silicon substrate 1 in accordance with the operation of the cantilever 13. In this way, an acceleration sensor is formed by surface micromachining technology using single crystal silicon, and high accuracy and high reliability can be achieved with a novel structure.

In addition, since the surface of the cantilever 13 and the single crystal silicon substrate 1 facing the cantilever 13 are covered with the SiO ₂ film (insulator) 5, an electrode short circuit in the capacitive acceleration sensor can be prevented. can do. Note that at least one of the surface of the cantilever 13 and the single crystal silicon substrate 1 facing the cantilever 13 may be covered with the SiO ₂ film (insulator) 5.

  In this embodiment, as shown in FIGS. 11 and 12, the cantilever 13 may be separated from the signal processing circuit (IC circuit unit) 10 to reduce the parasitic capacitance, and may be an air bridge wiring. Also, the fixed electrodes 14, 15, 16, and 17 may have the same structure. Further, although the aluminum wiring layer is used in the above embodiment, the wiring portion may be formed of a polysilicon layer. Furthermore, in the above embodiment, the two movable electrodes are formed at the tip of the beam and the four fixed electrodes 14, 15, 16, and 17 are formed. In order to further improve the sensitivity, the movable electrode portion and the fixed electrode portion are formed. And may be comb-like.

(Second embodiment)
Next, the second embodiment will be described focusing on the differences from the first embodiment.

  In the first embodiment, in order to form the cantilever 13, the p + diffusion layer (p + polysilicon film) 7 is formed for the purpose of separating this portion from the single crystal silicon substrate by a certain distance, but in this embodiment, In order to leave this constant distance, a recess is formed before the trench is formed.

13 to 21 show the manufacturing process. As shown in FIG. 13, an n-type (100) single crystal silicon substrate 20 is prepared, and a recess 21 is formed on the main surface of the single crystal silicon substrate 20 by a dry etching or a wet etching to a predetermined depth, for example, 0.1 to 5 μm. Form with a depth of. Then, as shown in FIG. 14, a SiO ₂ film 22 is formed on the main surface of the single crystal silicon substrate 20, and a pattern is formed by a photolithography technique. Subsequently, a trench 23 of about 0.1 to 30 μm is formed on the main surface of the single crystal silicon substrate 20 including the bottom of the recess 21 by dry etching or the like.

Then, as shown in FIG. 15, an n + diffusion layer 24 is formed on the main surface of the single crystal silicon substrate 20 including the inner wall of the trench 23, and an SiO ₂ film 25 is formed by thermal oxidation. Thereafter, as shown in FIG. 16, a polysilicon film 26 is buried in the trench 23 by LPCVD.

Subsequently, as shown in FIG. 17, the surface of the polysilicon film 26 is polished using the SiO ₂ film 25 as a stopper to smooth the surface. At this time, it is desirable that the surfaces of the polysilicon film 26 and the SiO ₂ film 25 be smooth. However, even if the polysilicon film 26 is dented, the surface of the SiO ₂ film 25 is smooth. Subsequent wafer bonding may be performed.

On the other hand, as shown in FIG. 18, another (100) single crystal silicon substrate 27 is prepared, and a 0.1 to 1.0 μm SiO ₂ film 28 is formed on the main surface by thermal oxidation. Next, the single crystal silicon substrates 20 and 27 are placed in, for example, a mixed aqueous solution of hydrogen peroxide and sulfuric acid, and a hydrophilic treatment is performed. After drying, the main surfaces of the single crystal silicon substrates 20 and 27 are superposed at room temperature and placed in a furnace at 400 to 1100 ° C. for 0.5 to 2 hours to perform strong bonding.

Next, as shown in FIG. 19, the back surface side of the single crystal silicon substrate 20 is selectively polished using an alkaline aqueous solution such as a KOH solution until the SiO ₂ film 25 appears. As a result, the thickness of the single crystal silicon substrate 20 becomes about 3 μm, for example, and is thinned.

  Then, as shown in FIG. 20, a signal processing circuit (IC circuit portion) 10 is formed through a normal CMOS process or a bipolar process. Further, a plasma SiN film (P-SiN film) is formed as a passivation film 11 on the upper surface of the signal processing circuit 10 by, for example, a plasma CVD method. Subsequently, a window 12 is opened in a predetermined region of the passivation film 11.

Then, as shown in FIG. 21, a polysilicon film is formed from the back surface side of the single crystal silicon substrate 20 through the window 12 of the passivation film 11 using an approximately 20% solution of TMAH (tetramethylammonium hydroxide) (CH 3) 4 NOH. 26 is etched away. At this time, the passivation film 11 (P-SiN), the SiO ₂ film 25, and the aluminum wiring layer are hardly etched by selective etching.

  As a result, a cantilever 13 is formed.

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

  In the first and second embodiments, polysilicon is buried in the trench before wafer bonding, but in this embodiment, polysilicon is buried in the trench after wafer bonding, and the buried polysilicon is removed in the final step. The acceleration sensor is manufactured.

22 to 28 show the manufacturing process. As shown in FIG. 22, an n-type (100) single crystal silicon substrate 30 is prepared, and a recess 31 having a depth of 0.1 to 5 μm is formed on the main surface. On the other hand, as shown in FIG. 23, a single crystal silicon substrate 32 is prepared, and a SiO ₂ film 33 is formed on the main surface by thermal oxidation. Then, the main surface of single crystal silicon substrate 30 and the main surface of single crystal silicon substrate 32 are joined.

Further, as shown in FIG. 24, the back surface side of the single crystal silicon substrate 30 is mirror-polished until a predetermined thickness (0.1 to 30 μm) is reached. Then, as shown in FIG. 25, a SiO ₂ film 34 is formed in a thickness of 0.1 to 2 μm, and then a trench 35 is formed by etching. At this time, the cantilever 13 is formed.

Next, N-type impurities such as arsenic and phosphorus are introduced at a high concentration by a thermal diffusion method or the like, and an n + high concentration layer 36 is formed in a region not covered with the SiO ₂ films 33 and 34. Subsequently, as shown in FIG. 26, a polysilicon film 37 is formed on the surface of the single crystal silicon substrate 30, and the trench 35 is filled with the polysilicon film 37. Thereafter, as shown in FIG. 27, the surface of the polysilicon film 37 is selectively polished and flattened until the SiO ₂ film 34 appears. Further, as shown in FIG. 28, after the signal processing circuit 10 is formed, finally, the polysilicon film 37 is etched away from the back surface (upper surface) of the single crystal silicon substrate 30 to form the cantilever 13.

As described above, in this embodiment, the main surface of the single crystal silicon substrate 30 and the single crystal silicon substrate 32 on which the SiO ₂ film (insulating film) 33 is formed are bonded via the SiO ₂ film 33 (first step). ) A predetermined amount of the back side of the single crystal silicon substrate 30 is polished to reduce the thickness of the single crystal silicon substrate 30 (second step). Then, a trench (groove) 35 having a predetermined depth for forming the cantilever 13 is formed on the back surface of the single crystal silicon substrate 30 (third step), and the polysilicon film 37 is formed on the back surface of the single crystal silicon substrate 30. The trench 35 is filled with the polysilicon film 37, and the surface of the polysilicon film 37 is smoothed (fourth step). Further, after forming a signal processing circuit on the single crystal silicon substrate 30, the polysilicon film 37 was etched away from the back side of the single crystal silicon substrate 30 to form the cantilever 13 (fifth step).

  Therefore, in the formation process of the signal processing circuit 10 in the middle of the wafer process, the trench 35 is buried in the upper surface portion of the single crystal silicon substrate 30 by the polysilicon film 37, contamination of the IC element, contamination of the manufacturing apparatus, Accordingly, it is possible to prevent electrical characteristics from being deteriorated or deteriorated. In other words, in the wafer process, by preventing surface structures such as recesses and through-holes from appearing on the wafer surface during heat treatment, photolithography processing, etc. during the process, contamination is prevented and the wafer process is stabilized. A highly accurate acceleration sensor can be stably supplied.

(Fourth embodiment)
Next, the fourth embodiment will be described focusing on the differences from the third embodiment.

  This embodiment is for manufacturing a sensor at a lower cost than the third embodiment. 29 to 31 show the manufacturing process.

As shown in FIG. 29, a 0.1 to ₂ μm SiO ₂ film 41 is formed on the main surface of the single crystal silicon substrate 40, and the single crystal silicon substrate 42 is bonded with the SiO ₂ film 41 interposed therebetween. Then, as shown in FIG. 30, the upper surface of the single crystal silicon substrate 42 is polished so that the single crystal silicon substrate 42 has a predetermined thickness. That is, the thickness of the single crystal silicon substrate 42 is reduced to about 3 μm, for example. Thereafter, a high concentration n + diffusion layer 43 is formed on the upper surface of the single crystal silicon substrate 42, and an SiO ₂ film 44 is further formed thereon.

Subsequently, as shown in FIG. 31, a trench 45 is formed in the single crystal silicon substrate 42, and the SiO ₂ film 41 below the trench 45 is partially removed by etching with a hydrofluoric acid solution. At this time, the SiO ₂ film 41 below the portion that becomes the cantilever 13 is completely removed.

Subsequent processing is the same as that shown in FIGS. Next, an application example of the fourth embodiment will be described with reference to FIGS. As shown in FIG. 32, a 0.1 to ₂ μm SiO ₂ film 41 is formed on the main surface of the single crystal silicon substrate 40, and a depth of 0.1 to 0.1 in a predetermined region on the main surface of the single crystal silicon substrate 42. A concave portion 47 of 3 μm is formed. Then, the main surface of the single crystal silicon substrate 42 is bonded with the SiO ₂ film 41 interposed therebetween. Further, as shown in FIG. 33, the upper surface of the single crystal silicon substrate 42 is polished so that the single crystal silicon substrate 42 has a predetermined thickness. That is, the thickness of the single crystal silicon substrate 42 is reduced to about 3 μm, for example. Thereafter, a high concentration n + diffusion layer 43 is formed on the upper surface of the single crystal silicon substrate 42, and an SiO ₂ film 44 is further formed thereon.

  Subsequently, as shown in FIG. 34, a trench 45 reaching the recess 47 is formed in the single crystal silicon substrate 42, and the cantilever 13 is formed. Subsequent processing is the same as that shown in FIGS.

By doing so, the electrical insulation can be more reliably obtained as compared with the case where the SiO ₂ film 41 is partially etched away as shown in FIG.

  The present invention is not limited to the above embodiments, and can be applied to, for example, a cantilever beam structure or a multi-beam structure other than a cantilever beam structure. As shown in FIG. 35, two acceleration sensors 13a and 13b are formed on the single crystal silicon substrate 50, and the X direction is detected by the acceleration sensor 13a and the acceleration in the Y direction is detected by the acceleration sensor 13b. Good. Further, an acceleration sensor that can detect acceleration in the surface vertical direction may be formed on the same substrate with respect to the X and Y direction acceleration sensors 13a and 13b to detect acceleration in a three-dimensional direction. Furthermore, when this acceleration sensor is used as a capacitive type, the characteristics can be further stabilized by using a so-called servo type (closed loop circuit configuration).

  In each of the above embodiments, the trenches (grooves) 3, 23, and 35 are filled with the polysilicon films 6, 26, and 37. However, a polycrystalline silicon film, a non-condensed silicon film, or a mixed silicon film may be used. In other words, polysilicon, amorphous silicon, or a silicon film in which polysilicon and amorphous silicon are mixed may be used.

  As described above in detail, according to the present invention, an excellent effect of achieving high accuracy and high reliability with a novel structure is exhibited.

It is a top view of an acceleration sensor. It is a figure which shows the AA cross section of FIG. It is a figure which shows the manufacturing process of 1st Example. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a top view which shows the application example of 1st Example. It is a figure which shows the BB cross section of FIG. It is a figure which shows the manufacturing process of 2nd Example. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows the manufacturing process of 3rd Example. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows the manufacturing process of 4th Example. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a figure which shows the manufacturing process of the application example of 4th Example. It is a figure which shows a manufacturing process. It is a figure which shows a manufacturing process. It is a top view of the acceleration sensor of another example.

Explanation of symbols

1 Single crystal silicon substrate 2 SiO ₂ film (insulating film)
3 Trench
6 Polysilicon film 8 Single crystal silicon substrate 9 SiO ₂ film (insulating film)
10 Signal processing circuit 13 Cantilever beam

Claims (8)

A first layer formed of a silicon material, and a second layer formed of a silicon material disposed on the lower surface side of the first layer via an insulating member,
The first layer is
A support beam having a movable electrode that is displaced in a horizontal direction according to a mechanical quantity, and fixed to the second layer via the insulating member;
An insulating groove provided through the first layer to form the support beam;
A fixed electrode provided on a side of the support beam across the insulating groove and fixed to the second layer via the insulating member ;
A peripheral portion disposed around the support beam and the fixed electrode, and formed on the insulating member and electrically separated from the support beam and the fixed electrode by an insulating groove ;
The thickness of the movable electrode in the direction from the upper surface to the lower surface of the first layer is smaller than the thickness of the fixed electrode. A first layer (42) formed from a silicon material, and a second layer (40) formed from a silicon material disposed via an insulating member (41) on the lower surface side of the first layer,
The first layer is
A support beam (13) having a movable electrode that is displaced in a horizontal direction according to a mechanical quantity, and fixed to the second layer via the insulating member;
Insulating grooves (35, 45) provided through the first layer to form the support beam;
A fixed electrode (14, 15, 16, 17) provided on the side of the support beam across the insulating groove and fixed to the second layer via the insulating member;
A peripheral portion disposed around the support beam and the fixed electrode, and formed on the insulating member and electrically separated from the support beam and the fixed electrode by an insulating groove ;
A semiconductor dynamic quantity sensor characterized in that a recess (31, 47) is provided between the first layer and the insulating member at a location reaching the insulating groove. The first layer and the second layer are electrically insulated from each other by the insulating member,
The said 1st layer has the peripheral part (10) fixed to the said 2nd layer through the said insulating member around the said fixed electrode and the said support beam, The Claim 1 or 2 characterized by the above-mentioned. Semiconductor dynamic quantity sensor.   The semiconductor dynamic quantity sensor according to claim 1, wherein the insulating member is disposed below the movable electrode. The semiconductor mechanical quantity sensor according to claim 1, wherein the insulating member is SiO ₂ .   6. The semiconductor dynamic quantity sensor according to claim 1, wherein the insulating groove is provided on the entire circumference of the support beam. A first step of forming a recess (47) in the main surface of the first layer formed of a silicon material ;
A second step of joining the insulating member side of the second layer formed of a silicon material having an insulating member and the side of the first layer on which the concave portion is formed;
A method of manufacturing a semiconductor dynamic quantity sensor, comprising: a third step of etching the first layer to form a trench reaching the recess (47) and defining a support beam. After the third step, a fourth step of further filling the trench with a filling and smoothing the filling;
A fifth step of forming a circuit in the first layer;
The method according to claim 7, further comprising a sixth step of removing the filler.

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