JP4175309B2 - 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, if a beam structure is formed using polysilicon and a signal processing circuit is formed around the beam structure, sensor characteristics become unstable. That is, since it is a polycrystal or an amorphous body, the dispersion | variation for every manufacturing lot will become large. As a result, it is desirable to form a semiconductor dynamic quantity sensor by surface micromachining technology using single crystal silicon.

  In addition, it is necessary to devise when routing the wiring on the sensor surface.

  Accordingly, an object of the present invention is to provide a semiconductor dynamic quantity sensor having a novel wiring structure and capable of achieving high accuracy and high reliability.

A first invention includes a silicon layer formed on the insulator, a weight portion, a beam portion, and a movable electrode formed on the silicon layer, and in a direction parallel to the silicon substrate according to a mechanical quantity. A movable portion that is displaced to the movable portion; a support portion that supports the movable portion; an insulating groove provided through the silicon layer around the movable portion; and the silicon layer sandwiched between the insulating grooves. A fixed electrode portion facing the movable electrode and having a lower portion fixed on the insulator, and disposed around the movable portion and the fixed electrode portion, and formed on the insulator and the movable portion And a peripheral part electrically separated from the fixed electrode part by an insulating groove, and a semiconductor dynamic quantity sensor for detecting a capacitance according to the dynamic quantity between the movable electrode and the fixed electrode part, A movable portion, the fixed electrode portion, and the The recon substrate is electrically insulated and separated by the insulator, and is further disposed along the surface of the silicon layer between at least one of the movable part and the fixed electrode part and the peripheral part. The gist of the present invention is a semiconductor dynamic quantity sensor characterized in that an air bridge wiring is formed. According to the above configuration, the parasitic capacitance of the wiring can be reduced by the air bridge structure.

According to a second aspect of the present invention, there is provided a support substrate, a beam structure made of a semiconductor material supported on the support substrate in a state of being electrically insulated from the support substrate, and displaced according to the action of a mechanical quantity, and the beam a movable electrode provided on the structure integral with said supporting the supporting substrate on a substrate and electrically said supported in insulated state semiconductor material made of the fixed electrode, and the supporting substrate to the support substrate comprising electrically said supported in insulated state semiconductor material made of the peripheral portion, and an insulating groove provided through the semiconductor material, and a wiring portion provided on the peripheral portion, the beam structure A semiconductor mechanical quantity sensor configured to detect a mechanical quantity acting on the beam structure based on a change in capacitance between the movable electrode and the fixed electrode accompanying a displacement of a body, the sensor being provided on the insulating groove The wiring portion, the movable electrode, and the fixed electrode. The semiconductor physical quantity sensor, characterized in that the formation of the wiring of the air-bridge structure between at least one of the electrodes and the gist thereof. According to the above configuration, the parasitic capacitance of the wiring can be reduced by the air bridge structure.

A third invention is a substrate having an insulator on the surface, while being formed separated from each other by etching a silicon layer provided on the substrate, the lower is fixed on said insulator fixing And a movable part, and a peripheral part disposed around the fixed part and the movable part , wherein the fixed part is integrally formed with the fixed part, and the movable part has a small gap between the fixed electrode and the movable part. A movable electrode that is opposed to each other through a mass part, a mass part that moves the movable electrode closer to and away from the fixed electrode by an external mechanical quantity, and is connected to the mass part via a beam. in air-bridge wiring between at least one said peripheral portion of the front Symbol movable electrode and the fixed electrode and a supporting portion for displaceably supporting the electrode on the substrate Te semiconductor dynamic quantity sensor odor comprising integrally formed Result As its gist the semiconductor dynamic quantity sensor, characterized in that it. According to the above configuration, the parasitic capacitance of the wiring can be reduced by the air bridge structure.

(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. 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 has 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. _{2 The} film 2 is 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, 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 as shown in FIG. A 0.1 to 1 μm SiO ₂ film 5 is formed by oxidation or the like. 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 may be 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 SiO ₂ film 9 of 0.1 to 1.0 μm 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 surface 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, a passivation film 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 ) 4NOH. The polysilicon film 6 is removed by etching through the 11 windows 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 such an acceleration sensor that is manufactured, a single crystal silicon substrate 8 monocrystalline silicon substrate 1 through the SiO ₂ film on becomes an SOI structure are joined. 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 in this way 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. Has formed a recess before forming the trench in order to keep this constant distance.

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, but even if the portion of 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. Then, 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, the 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 a single crystal silicon substrate 40, and a 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 SiO ₂ film 41 having a thickness of 0.1 to ₂ μm 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 of 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 (20)

A silicon substrate having an insulator on the surface;
A silicon layer formed on the insulator;
A movable part formed in the silicon layer, having a weight part, a beam part and a movable electrode, and being displaced in a direction parallel to the silicon substrate according to a mechanical quantity;
A support part for supporting the movable part;
An insulating groove provided through the silicon layer around the movable part;
A fixed electrode part formed in the silicon layer across the insulating groove and facing the movable electrode, and a lower part fixed on the insulator; and
A peripheral portion disposed around the movable portion and the fixed electrode portion, formed on the insulator and electrically separated from the movable portion and the fixed electrode portion by an insulating groove, and the movable electrode and the A semiconductor dynamic quantity sensor for detecting a capacitance according to the dynamic quantity between fixed electrode parts,
The movable part, the fixed electrode part, and the silicon substrate are each electrically insulated and separated by the insulator, and further, at least between any one of the movable part and the fixed electrode part and the peripheral part. A semiconductor dynamic quantity sensor characterized in that an air bridge wiring disposed along the surface of a silicon layer is formed.   2. The semiconductor dynamic quantity sensor according to claim 1, wherein a signal processing circuit for processing a signal accompanying the operation of the movable part is integrally provided in the silicon layer.   The semiconductor dynamic quantity sensor according to claim 2, wherein the signal processing circuit is a closed loop circuit.   The movable portion has a thickness of the beam portion in the thickness direction of the silicon layer larger than a width of the beam portion in a plane direction of the silicon layer, and the movable direction of the movable portion is parallel to the surface of the silicon layer. 4. The semiconductor dynamic quantity sensor according to claim 1, wherein the sensor is in a direction substantially perpendicular to the longitudinal direction of the beam portion.   5. The semiconductor dynamic quantity sensor according to claim 1, wherein at least either the surface of the movable electrode or the surface of the fixed electrode portion facing the movable electrode is covered with an insulator.   6. The semiconductor dynamic quantity sensor according to claim 1, wherein high concentration n + electrodes are set on the movable part and the fixed electrode part.   7. The semiconductor dynamic quantity sensor according to claim 1, wherein a specific resistance of the silicon layer is 1 to 20 [Omega] .cm.   A second movable portion different from the movable portion is formed in the silicon layer in a state where it is electrically insulated from the movable portion by an insulator and movable in a direction orthogonal to the movable direction of the movable portion. The semiconductor dynamic quantity sensor according to claim 1, wherein the sensor is a semiconductor dynamic quantity sensor.   A third movable part different from the movable part and the second movable part is electrically insulated by the movable part, the second movable part and the insulator, and the movable direction of the movable part and the movable of the second movable part. 9. The semiconductor dynamic quantity sensor according to claim 8, wherein the semiconductor dynamic quantity sensor is formed in the silicon layer so as to be movable in directions orthogonal to each other.   The semiconductor dynamic quantity sensor according to claim 1, wherein the silicon layer is a single crystal silicon layer.   The semiconductor dynamic quantity sensor according to claim 1, wherein the silicon substrate is a single crystal silicon substrate.   12. The semiconductor mechanical quantity sensor according to claim 1, wherein the movable part is displaced in a uniaxial direction parallel to the surface of the silicon layer in accordance with the mechanical quantity. A support substrate;
A beam structure made of a semiconductor material that is supported on the support substrate in a state of being electrically insulated from the support substrate and is displaced according to the action of the mechanical quantity;
A movable electrode provided integrally with the beam structure;
A fixed electrode made of the semiconductor material supported on the support substrate in a state of being electrically insulated from the support substrate;
A peripheral portion made of the semiconductor material supported on the support substrate in a state of being electrically insulated from the support substrate;
An insulating groove provided through the semiconductor material;
A wiring portion provided in the peripheral portion,
A semiconductor mechanical quantity sensor configured to detect a mechanical quantity acting on the beam structure based on a change in capacitance between the movable electrode and the fixed electrode accompanying the displacement of the beam structure,
An air bridge structure wiring is formed on the insulating groove between the wiring portion and at least one of the movable electrode and the fixed electrode.   14. The semiconductor dynamic quantity sensor according to claim 13, wherein the wiring of the air bridge structure is an aluminum wiring.   14. The semiconductor dynamic quantity sensor according to claim 13, wherein the air bridge structure wiring is a polysilicon wiring layer.   The semiconductor dynamic quantity sensor according to claim 13, wherein the wiring of the air bridge structure is covered with an insulator. A substrate having an insulator on the surface, and a fixed part and a movable part formed separately from each other by etching a silicon layer provided on the substrate; and a lower part fixed on the insulator; And a peripheral portion disposed around the fixed portion and the movable portion, the fixed portion is integrally formed with the fixed portion, and the movable portion is opposed to the fixed electrode through a minute gap. An electrode, a mass part for moving the movable electrode toward and away from the fixed electrode by a mechanical quantity from the outside, and a mass part connected to the mass part via a beam, and the mass part and the movable electrode on the substrate In a semiconductor dynamic quantity sensor formed integrally with a support portion that is displaceably supported,
A semiconductor dynamic quantity sensor characterized in that at least one of the movable electrode and the fixed electrode and the peripheral portion are connected by an air bridge wiring.   The movable electrode of the movable part is formed by a plurality of electrode plates protruding in a comb shape from the mass part, and the fixed electrode of the fixed part is a comb-like shape facing each electrode plate of the movable electrode with a minute gap. The semiconductor dynamic quantity sensor according to claim 17, which is formed by a plurality of electrode plates.   19. The semiconductor dynamic quantity sensor according to claim 17, wherein a silicon oxide film is formed on the surface of the single crystal silicon substrate.   The semiconductor dynamic quantity sensor according to claim 17, wherein the air bridge wiring is disposed along a surface of the silicon layer.

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