JPH0918014A - Semiconductor dynamic quantity sensor and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a manufacturing method of a semiconductor dynamic quantity sensor which can improve the step coverage, etc. CONSTITUTION: A recessed part 2 is formed on the surface of a silicon substrate 1, a silicon oxide film 34 is formed on the bottom face of the recessed part 2 as a sacrificial layer, and at the same time, a polysilicon thin film 36, which is a thin film for formation of a movable part, is formed thereon. A microscopic process is conducted using a resist 39 which is arranged on the whole surface of the silicon substrate 1, and the silicon oxide film 34 located under the polysilicon thin film 36 is removed. A movable part is arranged in the recessed part 2 provided on the surface of the silicon substrate 1, a movable part of beam construction is arranged on the upper part of the silicon substrate 1 in the recessed part 2 leaving the prescribed interval, and the movable part is deformed by the action of dynamic quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor dynamic quantity sensor for detecting a mechanical quantity such as acceleration, yaw rate, vibration, and more particularly, to a semiconductor dynamic quantity sensor having a beam-structure movable part on a substrate and the same. The present invention relates to a manufacturing method.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for downsizing and cost reduction of semiconductor acceleration sensors. For this purpose, special table 4-5
JP 04003 discloses a differential capacitance type semiconductor acceleration sensor using polysilicon as electrodes. This type of sensor will be described with reference to FIGS. FIG. 18 shows a plan view of the sensor, and FIG. 19 shows a sectional view taken along line I-I of FIG.

A movable part 116 having a beam structure is arranged above the silicon substrate 115 at a predetermined interval. The movable part 116 made of a polysilicon thin film has the beam parts 121, 12
2, the weight portion 123, and the movable electrode portion 124. The movable part 116 is an anchor part 117, 118, 119, 120.
Is fixed on the upper surface of the silicon substrate 115. That is, the beam portions 121, 122 are extended from the anchor portions 117, 118, 119, 120, and the beam portions 121, 12
The weight portion 123 is supported by the second portion. This weight portion 123
A movable electrode portion 124 is provided so as to project. On the other hand, on the silicon substrate 115, two fixed electrodes 125 are arranged so as to face one movable electrode portion 124. Then, the direction parallel to the surface of the silicon substrate 115 (see FIG.
When the acceleration is applied to the movable electrode section 12
The capacitance between the fixed electrode 125 and the fixed electrode 125 increases on one side and decreases on the other side.

In the manufacture of this sensor, as shown in FIG. 20, a sacrifice layer 126 such as a silicon oxide film is formed on a silicon substrate 115, and an opening 127 is formed in the sacrifice layer 126 at a location to be an anchor portion. . afterwards,
As shown in FIG. 21, the movable portion 116 is formed on the sacrificial layer 126.
Then, a polysilicon thin film 128 is formed to have a desired pattern shape. Subsequently, the sacrificial layer 126 under the polysilicon thin film 128 is removed with an etching solution, and the movable portions 116 are arranged above the silicon substrate 115 with a predetermined space therebetween, as shown in FIG.

[0005]

However, in the semiconductor acceleration sensor having such a configuration, as shown in FIG. 19, in order to maintain the mechanical strength of the beam structure, the movable portion 116 and the silicon substrate 115. In order to maintain a predetermined interval (air gap) La at, the total thickness of the film thickness ta of the movable portion 116 and the interval La reaches 2 μm or more, and in particular, a semiconductor substrate having the same circuit for processing the detected current is the same. When it is formed on the upper side, a large step is generated between the formation region of the movable portion 116 and the peripheral circuit formation region. Then, as shown in FIG. 23, when a resist is arranged on the substrate 115, a step difference is formed in the resist by the total value of the polysilicon thin film 128 (movable part forming thin film) and the sacrifice layer 126, and the step is allowed. Is less than 2 μm,
When there is a step of 2 μm or more like this sensor, a desired fine pattern cannot be formed. That is, a so-called semiconductor fine processing technique for forming a semiconductor integrated circuit is usually used for forming a semiconductor device, and a photolithography technique is used for forming a fine pattern. However, the thickness of the resist used as a mask material for forming this fine pattern is usually 2 μm or less, and if there is a step with a thickness greater than this resist on the semiconductor surface, this resist cannot be applied uniformly on the semiconductor substrate. There is a problem that a desired fine pattern cannot be formed. Note that FIG. 23 shows a case where a wiring is patterned in the MOS transistor in the peripheral circuit.

As a countermeasure for this, there is a method of thickening the resist, but at this time, a fine pattern of the order of μm cannot be formed. Thus, if a step of 2 μm or more occurs in the manufacturing process of the semiconductor acceleration sensor, a desired fine pattern cannot be formed, and a small and inexpensive acceleration sensor cannot be realized.

Therefore, an object of the present invention is to provide a semiconductor dynamic quantity sensor and a method of manufacturing the same, which can improve step coverage in the manufacturing process.

[0008]

According to a first aspect of the present invention, there is provided a beam composed of a semiconductor substrate and a thin film beam which is disposed above the semiconductor substrate with a predetermined distance and which is displaced by the action of a mechanical quantity. A semiconductor dynamic quantity sensor having a movable part having a structure, in which a concave part is provided on a surface of the semiconductor substrate, and the movable part is arranged in the concave part.

The invention according to claim 2 is a semiconductor substrate,
Disposed above the semiconductor substrate at a predetermined interval,
A method for manufacturing a semiconductor mechanical quantity sensor, comprising: a movable part having a beam structure made of a thin film, which is displaced by the action of a mechanical quantity; a first step of forming a concave part on a surface of a semiconductor substrate; and a bottom surface of the concave part. A second step of forming a sacrificial layer on the substrate and forming a thin film for forming a movable portion thereon; and disposing the sacrificial layer and the thin film for forming a movable portion only in the recess, and disposing the sacrificial layer on the entire surface of the semiconductor substrate. The gist is a method for manufacturing a semiconductor dynamical amount sensor, which includes a third step of performing fine processing using a resist and a fourth step of removing a sacrificial layer under the thin film for forming a movable portion.

According to a third aspect of the present invention, in the second aspect of the invention, the depth of the recess is D μm, the thickness of the sacrificial layer is t1 μm, and the thickness of the thin film for forming the movable portion is When t2 μm is set, t1 + t2−C ≦ D ≦ t1 + t2 + C However, the gist is a method of manufacturing a semiconductor mechanical quantity sensor in which C satisfies 2 μm.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the depth of the concave portion is D μm, the thickness of the sacrificial layer is t1 μm, and the thickness of the movable portion forming thin film is The gist is a method of manufacturing a semiconductor dynamical quantity sensor that satisfies (t1 + t2) / 2 ≦ D 2 when t2 μm.

A fifth aspect of the present invention is, in the second aspect, a gist of a method of manufacturing a semiconductor dynamical quantity sensor in which a side wall of the recess is inclined.

[0013]

According to the invention as set forth in claim 1, the movable portion is arranged in the concave portion, and the upper surface of the movable portion is lowered by the depth thereof, so that the height of the movable portion and the height of the substrate surface other than the concave portion are Get closer. That is, the heights are closer to each other and flattening is achieved. As a result, step coverage in the manufacturing process can be improved.

According to the second aspect of the present invention, the concave portion is formed on the surface of the semiconductor substrate by the first step, and the sacrificial layer is formed on the bottom surface of the concave portion by the second step, and the movable portion is formed thereon. A thin film for formation is formed, and in the third step, fine processing is performed using a resist arranged on the entire surface of the semiconductor substrate with the sacrificial layer and the thin film for forming the movable portion left only in the recess. At this time, since the sacrificial layer and the movable portion forming thin film are arranged in the concave portion, the sacrificial layer and the movable portion forming thin film are positioned below by the depth of the concave portion as compared with the case where there is no concave portion, Since the step between the movable portion forming area and the other area is small, the step of the resist can be small. Therefore, it is possible to perform highly accurate wiring and the like in a highly accurate photo process using a thin resist.

In the fourth step, the sacrificial layer under the movable portion forming thin film is removed, and the movable portion having the beam structure is arranged above the semiconductor substrate with a predetermined space. According to the invention described in claim 3, in addition to the effect of the invention described in claim 2, the depth of the concave portion is D μm, the thickness of the sacrificial layer is t 1 μm, and the thickness of the thin film for forming the movable portion is t 2 μm. Then, t1 + t2-C ≦ D ≦ t1 + t2 + C However, if C satisfies 2 μm, the step between the upper surface of the thin film for forming the movable part and the area other than the recess in the recess is within 2 μm, and the step of the resist is Is within 2 μm, and desired fine patterning can be easily performed.

According to the invention described in claim 4, claim 2 is provided.
In addition to the effect of the invention described in (1), the depth of the recess is Dμm,
When the thickness of the sacrificial layer is t1 μm and the thickness of the movable part forming thin film is t2 μm, the sacrificial layer is formed on the surface of the substrate including the recesses by satisfying (t1 + t2) / 2 ≦ D. The step D at that time can be made smaller, and
The step (t1 + t2) due to the disposition of the sacrificial layer and the thin film for forming the movable part in the movable part formation region can be further reduced.

According to the invention of claim 5, claim 2
In addition to the function of the invention described in step 1, when the sacrificial layer is formed on the surface of the substrate and when the thin film for forming the movable portion is formed on the sacrificial layer, the side wall of the concave portion is inclined. The coverage is improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The semiconductor acceleration sensor of this embodiment is
It has an air gap type MIS transistor structure. FIG. 1 shows a plan view of the semiconductor acceleration sensor of this embodiment. Further, FIG. 2 shows a cross section taken along the line AA of FIG. In FIG. 1, a movable portion forming region (sensor element forming region) Z1 and a peripheral circuit forming region Z2 for performing signal processing and the like are provided on a silicon substrate 1. In FIG. 2, a cross section of the movable portion forming region Z1 is shown. And a cross section of the MOS transistor in the peripheral circuit formation region Z2 are also schematically shown.

A recess 2 is formed in the movable portion forming region Z1 on the surface of the P-type silicon substrate 1 as a semiconductor substrate. The recess 2 has a quadrangular shape in plan view as shown in FIG. 1 and has a depth D as shown in FIG. In this embodiment, the depth D of the recess 2 is 1.5 μm. Moreover, the side wall of the recess 2 is inclined. The peripheral region of the recess 2 in the silicon substrate 1 is the peripheral circuit formation region Z2.

A movable part forming region Z on the P-type silicon substrate 1.
Insulating films 3, 4, and 5 are formed on
Is made of SiO ₂ , Si ₃ N ₄ or the like. A movable part 6 made of a polysilicon thin film is provided on the silicon substrate 1 (insulating film 5) on the bottom surface of the recess 2. In this embodiment, the thickness of the movable portion 6 is 2 μm. The movable portion 6 includes beams 7, 8, 9, 10, a weight portion 11, and a movable gate electrode portion 1.
2 and 13 are provided. The movable part 6 includes an anchor part 14,
It is fixed to the substrate 1 at 15, 16 and 17, and is arranged above the substrate 1 with a predetermined gap (air gap). In this embodiment, the interval (air gap) is 0.5.
μm.

The movable part 6 (thin film) is arranged above the silicon substrate 1 by removing the sacrifice layer arranged on the lower side with a gap corresponding to the thickness of the sacrifice layer. More specifically, the polysilicon layer 18 is disposed on the insulating film 4 in the movable portion formation region Z1, and the anchor portions 14, 15, 16, 17 are provided on the polysilicon layer 18. This anchor part 14, 15, 16, 1
Band-shaped beam parts 7, 8, 9, 10 extend from 7, and square-shaped weight parts 11 are supported by the beam parts 7, 8, 9, 10. The weight portion 11 is provided with movable gate electrode portions 12 and 13 in opposite directions. The movable portion 6 (movable gate electrode portions 12 and 13) can be displaced in directions perpendicular to and parallel to the surface of the substrate 1. Then, the directions indicated by X ₊ and X ₋ in FIG. 1 (directions parallel to the substrate surface) and the direction indicated by Z in FIG. 2 (directions perpendicular to the substrate surface) are acceleration detection directions.

Further, the polysilicon layer 18 is drawn out of the movable portion forming region Z1. On the other hand, as shown in FIG. 2, in the silicon substrate 1 below the movable gate electrode portion 13 of the movable portion 6, the first source electrode 19 and the first source electrode 19 made of an N-type impurity diffusion layer are formed on both sides of the movable gate electrode portion 13. One drain electrode 20 is formed. This electrode 19,2
0 has a rectangular shape and extends in the acceleration detection directions X ₊ and X ₋ . Similarly, the movable gate electrode portion 12 is formed on the silicon substrate 1 below the movable gate electrode portion 12 of the movable portion 6.
The second source electrode 2 made of an N-type impurity diffusion layer on both sides of the
1 and a second drain electrode 22 are formed. The electrodes 21 and 22 have a rectangular shape and extend in the acceleration detection directions X ₊ and X ₋ . The electrodes 19 to 22 are formed by implanting arsenic, for example.

In the peripheral circuit formation region Z2, MOSFETs are provided.
A circuit including a plurality of transistors including the above is formed. FIG. 2 shows a MOSFET having a source electrode 23, a drain electrode 24, and a polysilicon gate electrode 26 with a gate oxide film 25 interposed therebetween. In the peripheral circuit formation region Z2, fine aluminum wiring (metal wiring) 4
0 pattern is formed, and the aluminum wiring 40 causes the source electrode 23, the drain electrode 24, and the polysilicon layer 18 to be formed.
Etc. are wired.

As shown in FIG. 1, each of the source / drain electrodes 19 to 22 extends as a diffusion layer to the peripheral circuit forming region Z2 and is connected to a circuit in the peripheral circuit forming region Z2.

Further, as shown in FIG. 2, the surface of the substrate 1 is
It is covered with a surface protection film (passivation film) 27 made of a silicon nitride film. However, the movable part forming area Z
In No. 1, the surface protection film 27 is not provided and the movable portion 6 can be displaced. Further, the upper surface of the movable portion 6 is located below the upper surface of the surface protective film 27. A protective cap 28 is provided on the surface protective film 27 so as to close the opening in the movable portion forming region Z1. The protective cap 28 is made of a glass plate material or the like, and the upper surface of the surface protective film 27 and the lower surface of the protective cap 28 are fixed in close contact with each other. The protective cap 28 protects the movable portion 6 from water flow and water pressure during dicing. Further, the protective cap 28 allows the entire substrate 1 to be resin-molded.

Next, the operation of this acceleration sensor will be described.
The movable gate electrode portions 12 and 13 and the source electrodes 19 and 21 and the drain electrodes 20 and 22 on the silicon substrate 1 constitute a so-called field effect transistor (FET). When a voltage is applied between the source electrode and the drain electrode and between the movable gate electrode portions 12 and 13 and the silicon substrate 1, a channel region is formed on the surface of the silicon substrate 1 between the source electrode and the drain electrode, A current (first drain current) flows between the first source electrode 19 and the first drain electrode 20, and the second source electrode 2
A current (second drain current) flows between 1 and the second drain electrode 22.

When the movable gate electrode portions 12 and 13 (movable portion 6) are displaced in the X ₊ direction (direction parallel to the surface of the substrate 1) of FIG.
The area of the channel region between the source electrode 19 and the first drain electrode 20 (channel width in the transistor) is reduced, and the first drain current flowing between both electrodes is reduced. On the other hand, the area of the channel region between the second source electrode 21 and the second drain electrode 22 (channel width referred to as a transistor) increases, and the second drain current flowing between both electrodes increases. Similarly, when the movable gate electrode portions 12 and 13 (movable portion 6) are displaced in the X ₋ direction (direction parallel to the surface of the substrate 1) of FIG. 1, the first drain current increases and the second drain current increases. The current decreases. As described above, the currents flowing through the source / drain electrodes 19, 20 and the currents flowing through the source / drain electrodes 21, 22 are in opposite phases to each other due to the displacement of the movable gate electrode portions 12, 13 in the acceleration detection directions X ₊ , X ₋ . Will change.

When the movable gate electrode portions 12 and 13 are displaced in the Z direction (direction perpendicular to the surface of the substrate 1) in FIG. Since the carrier concentration in the region increases, the drain currents of both transistors simultaneously increase. As described above, the present sensor can detect the acceleration by increasing / decreasing the amount of current, and the current change is caused by the surrounding peripheral circuit through the diffusion layer forming the source / drain electrodes 19 to 22, as shown in FIG. Transmitted to the formation area Z2,
It is processed.

Next, the manufacturing process of this acceleration sensor will be described with reference to FIGS.
This will be described with reference to FIG. First, as shown in FIG. 3, a silicon substrate 1 in a wafer state is prepared, and the surface of the silicon substrate 1 is about 50 nm.
The silicon oxide film 29 of
A 50 nm silicon nitride film 30 is formed. After that, through a photolithography process, the oxide film 29 and the nitride film 30 in the movable portion formation region Z1 are removed by etching.

Then, as shown in FIG. 4, a silicon oxide film 31 (LOCOS oxide film) of about 2 μm is selectively formed in the movable portion forming region Z1 by a thermal oxidation process. As a result, the silicon surface of the silicon substrate 1 is oxidized to have a dented shape, and the sidewall of the dented shape becomes oblique.

Subsequently, as shown in FIG. 5, the oxide film 2
All 9, 31 and nitride film 30 are removed. As a result, the concave portion 2 is formed in the formation region of the oxide film 31, that is, the movable portion formation region Z1.
Is formed. The depth D of the recess 2 is 1.5 μm and the side wall of the recess 2 is oblique. In addition to the thermal oxidation, the recess 2 may be formed by dry etching using reactive ion etching or wet etching using a mixed solution of hydrofluoric acid / nitric acid or an alkaline solution.

Thereafter, a silicon oxide film 3 having a thickness of about 20 nm and a silicon nitride film 4 having a thickness of about 50 nm are formed on the entire surface of the substrate 1, and a desired region to be a source / drain electrode later is subjected to a photolithography process to form an impurity layer 19, 20, 21, 2
2 is formed by ion implantation of arsenic or the like.

Further, as shown in FIG. 6, after the nitride film 4 in the peripheral circuit forming region Z2 is removed, a thickness of about 350 is formed on the entire surface.
A polysilicon layer 32 having a thickness of nm is formed by a low pressure CVD method or the like. The polysilicon layer 32 is doped with impurities such as phosphorus to reduce its resistance.

Then, as shown in FIG. 7, the polysilicon layer 32 is patterned by dry etching or the like through a photolithography process to form the polysilicon gate electrode 26 and the movable gate electrode 12 of the transistor in the peripheral circuit formation region Z2. An electrode (polysilicon layer 18) for drawing out the wiring is formed outside the movable portion forming region Z1 of 13.

Next, as shown in FIG. 8, source / drain impurity layers 23 and 24 are formed in a desired region of the peripheral circuit formation region Z2 by a photolithography process by ion implantation of boron, arsenic or the like. Then, an interlayer insulating film 33 having a thickness of about 500 nm, such as boron-phosphorus glass (BPSG), is formed on the entire surface by, for example, a plasma CVD method.

Further, as shown in FIG. 9, the interlayer insulating film 33 in the movable portion forming region Z1 is removed. Then, a silicon nitride film 5 having a thickness of about 50 nm is formed on the entire surface, and a silicon oxide film 34 as a sacrifice layer is formed on the silicon nitride film 5.
The thickness t1 of the silicon oxide film 34 is 500 nm (=
0.5 μm).

Next, as shown in FIG. 10, a contact hole 35 to the extraction electrode (polysilicon layer 18) is formed in the silicon oxide film 34 by a dry etching process through a photolithography process. After that, a polysilicon thin film 36 to be the movable portion 6 later is formed on the entire surface by a low pressure CVD method or the like. The thickness t2 of the polysilicon thin film 36 is 2 μm. Incidentally, at least the vicinity of the surface of the polysilicon thin film 36 in contact with the silicon oxide film 34 is doped with impurities such as phosphorus to reduce the resistance.

The silicon oxide film 34 and the polysilicon thin film 3
Since the side wall of the recess 2 is inclined when the film 6 is formed, the step coverage can be improved. Here, the relationship between the depth D of the recess 2, the thickness t1 of the silicon oxide film 34 (sacrificial layer), and the thickness t2 of the polysilicon thin film 36 (movable part forming thin film) will be described. When the depth of the recess 2 is D μm, the thickness of the silicon oxide film 34 is t1 μm, and the thickness of the polysilicon thin film 36 is t2 μm, t1 + t2-C ≦ D ≦ t1 + t2 + C (1) where C is 2 μm is satisfied. That is, in this embodiment, D = 1.5,
t1 = 0.5 and t2 = 2, and 0.5 ≦ 1.5 ≦ 4.5, which satisfies the expression (1). The formula (1) is the recess 2
It defines the conditions for keeping the step between the upper surface of the polysilicon thin film 36 (movable part forming thin film) and the region other than the recess 2 within 2 μm.
Since it is within μm, desired fine patterning can be easily performed.

The depth D of the recess 2 is set to be shallower than the thickness of the photoresist used in the process (usually 2 μm or less), and the thickness t1 of the silicon oxide film 34 and the thickness of the polysilicon thin film 36 are set. For the value (t1 + t2) that is obtained by adding t2,
It is set to 1/2 or less (t1 + t2) / 2 ≦ D).

That is, in this embodiment, D = 1.5 μm,
t1 = 0.5 μm, t2 = 2 μm, and 1.25 ≦
It is 1.5, which satisfies the above formula. This conditional expression is that the silicon oxide film 34 (sacrificial layer) is formed on the surface of the substrate including the recess 2.
The step difference (D1) during the film formation is further reduced and the step difference (t1 + t) due to the arrangement of the silicon oxide film 34 and the polysilicon thin film 36 in the movable portion forming region Z1.
2) is made smaller. As a result, when the film is formed on the recess 2 and when the silicon oxide film 3 is formed in the recess 2.
It is possible to improve the step coverage in the case where 4 and the polysilicon thin film 36 are arranged and the film is formed thereon.

Returning to the description of the manufacturing process, as shown in FIG. 11, the polysilicon thin film 36 and the silicon oxide film 34 in regions other than the movable portion forming region Z1 are removed by etching through a photolithography process. At this time, the 2 μm thick polysilicon thin film 36 is etched, but the side wall of the polysilicon thin film 36 is located above the inclined side wall of the recess 2,
The side wall of the polysilicon thin film 36 is made into an inclined shape by tapering. Thereby, the step formed on the entire surface of the substrate can be made smaller.

Then, as shown in FIG. 12, after the nitride film 5 on the peripheral circuit formation region Z2 is removed, the interlayer insulating film 33 is formed.
Then, a contact hole 37 is formed in a desired region of the above through a photolithography process by dry etching or the like.

Further, as shown in FIG. 13, aluminum 38, which is a metal electrode material, is deposited to a thickness of about 600 nm. Further, as shown in FIG. 14, a photolithography process and an etching process are performed using the resist 39. As a result, FIG.
Aluminum wiring (metal wiring) 4 in the desired area
0 is patterned.

Next, as shown in FIG. 16, a surface protection film (silicon nitride film) 27 is formed on the entire surface by about 1.5 μm, for example, by a plasma CVD method. After that, the surface protection film (silicon nitride film) 27 in the movable portion formation region Z1 is removed by etching through a photolithography process.

Then, as shown in FIG. 17, after the photolithography process, the polysilicon thin film 36 is etched into a desired pattern. That is, the beam portions 7 to 10, the weight portion 11 and the movable gate electrode portions 12 and 13 shown in FIG. 1 are collectively formed.

Then, the silicon oxide film 34, which is a sacrificial layer, is etched with, for example, an aqueous solution of hydrofluoric acid. As a result, as shown in FIG. 2, the movable parts 6 having a beam structure are arranged on the substrate 1 at a predetermined interval. After that, the protective cap 28 is provided to seal the movable portion 6. Furthermore, each chip is diced. At this time, the protective cap 28 protects the movable portion 6 from water flow and water pressure. Further, the production of this sensor is completed by resin molding.

Since the step generated on the substrate 1 in the above series of steps is 2 μm or less and thinner than the resist film thickness used in the photolithography process, a semiconductor device (peripheral circuit) having a desired fine pattern can be formed.

Thus, in this embodiment, the silicon substrate 1
A concave portion 2 is formed on the surface of the concave portion (first step), a silicon oxide film 34 (sacrificial layer) is formed on the bottom surface of the concave portion 2, and a polysilicon thin film 36 (movable portion forming thin film) is formed thereon (first step). (2 step), with the silicon oxide film 34 and the polysilicon thin film 36 left only in the recess 2, fine processing for wiring using a resist 39 arranged on the entire surface of the silicon substrate 1 (third step). , Polysilicon thin film 36
The silicon oxide film 34 underneath is removed (fourth step). As a result, the movable portion 6 is arranged in the concave portion 2 provided on the surface of the silicon substrate 1. In this structure, the upper surface of the movable portion 6 is lowered by the depth of the concave portion 2, and the height of the movable portion 6 and the height of the substrate surface other than the concave portion 2 are close to each other. That is, the heights are closer to each other to achieve flatness and improve step coverage in the manufacturing process. That is, in the above-described third step, since the sacrificial layer and the movable portion forming thin film are arranged in the recess 2, as compared with the case where the recess 2 is not provided,
The sacrifice layer and the movable portion forming thin film are located below by the depth of the recess 2, and the movable portion forming region Z1 and the peripheral circuit forming region Z2 are formed.
The step between the resist and the resist 39 is small, and the step of the resist 39 can be small. Therefore, the thin resist 39 can be used to perform highly accurate wiring in a highly accurate photo process.

Further, since the movable portion 6 is arranged in the concave portion 2, the upper surface of the movable portion 6 is lowered by the depth thereof, and the height of the movable portion 6 and the height of the substrate surface other than the concave portion 2 become closer. The glass plate can be used as a protective cap without using a dome-shaped protective cap (the heights are closer to each other for flattening).

As another aspect of the present invention, the movable portion 6 (movable gate electrode portions 12 and 13) may be an amorphous silicon thin film or a heat resistant metal thin film such as aluminum or tungsten in addition to the polysilicon thin film. .

Further, in addition to acceleration, it can be embodied as a semiconductor dynamic quantity sensor for detecting a mechanical quantity such as yaw rate and vibration.

[0052]

As described above in detail, according to the invention described in claim 1, the excellent effect that the step coverage in the manufacturing process can be improved is exhibited.

According to the second aspect of the present invention, it is possible to perform highly accurate wiring and the like in a highly accurate photo process using a thin resist. According to the invention described in claim 3,
In addition to the effect of the invention described in claim 2, desired fine patterning can be easily performed.

According to the invention of claim 4, claim 2
In addition to the effect of the invention described in (1), the step can be made smaller.
According to the invention described in claim 5, in addition to the effect of the invention described in claim 2, step coverage can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a semiconductor acceleration sensor according to an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 4 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 5 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 6 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 7 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 8 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 9 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 10 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 11 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 12 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 13 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 14 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 15 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 16 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 17 is a cross-sectional view for explaining the manufacturing process of the semiconductor acceleration sensor.

FIG. 18 is a plan view of a semiconductor acceleration sensor for explaining a conventional technique.

19 is a cross-sectional view taken along the line I-I of FIG.

FIG. 20 is a sectional view for explaining a manufacturing process of the conventional semiconductor acceleration sensor.

FIG. 21 is a cross-sectional view for explaining the manufacturing process of the conventional semiconductor acceleration sensor.

FIG. 22 is a sectional view for explaining a manufacturing process of the conventional semiconductor acceleration sensor.

FIG. 23 is a cross-sectional view for explaining the manufacturing process of the conventional semiconductor acceleration sensor.

[Explanation of symbols]

1 ... Silicon substrate as semiconductor substrate, 2 ... Recessed portion, 6 ...
Movable part, 34 ... Silicon oxide film as a sacrificial layer, 36 ...
Polysilicon thin film as movable part forming thin film, 39 ... Resist, 40 ... Aluminum wiring

Claims (5)

[Claims] A semiconductor substrate disposed at a predetermined interval above the semiconductor substrate;
A semiconductor dynamic quantity sensor comprising a movable part having a beam structure made of a thin film, which is displaced by the action of a mechanical quantity, wherein a concave part is provided on the surface of the semiconductor substrate, and the movable part is arranged in the concave part. A semiconductor mechanical quantity sensor characterized by. 2. A semiconductor substrate, disposed at a predetermined interval above the semiconductor substrate,
A method of manufacturing a semiconductor dynamic quantity sensor, comprising: a movable part having a beam structure made of a thin film, which is displaced by the action of a mechanical quantity; a first step of forming a concave part on a surface of a semiconductor substrate; and a bottom surface of the concave part. A second step of forming a sacrificial layer on the substrate and forming a movable part forming thin film thereon; and disposing the sacrificial layer and the movable part forming thin film only in the recesses, and arranging the sacrificial layer on the entire surface of the semiconductor substrate. A method of manufacturing a semiconductor mechanical quantity sensor, comprising: a third step of performing fine processing using a resist; and a fourth step of removing a sacrificial layer under the movable part forming thin film. 3. When the depth of the recess is D μm, the thickness of the sacrificial layer is t1 μm, and the thickness of the movable part forming thin film is t2 μm, t1 + t2-C ≦ D ≦ t1 + t2 + C where C is The method for manufacturing a semiconductor dynamical amount sensor according to claim 2, wherein 2 μm is satisfied. 4. When the depth of the recess is D μm, the thickness of the sacrificial layer is t1 μm, and the thickness of the thin film for forming the movable part is t2 μm, (t1 + t2) / 2 ≦ D is satisfied. The method for manufacturing a semiconductor dynamical amount sensor according to claim 2, wherein 5. The method for manufacturing a semiconductor dynamical amount sensor according to claim 2, wherein the sidewall of the recess is inclined.