JP2002071475A - Pressure-sensitive sensor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive sensor using a rubber-like elastic body having an improved material quality/form for exhibiting an excellent sensor function, and to provided a method for manufacturing the pressure- sensitive sensor for stable and high-sensitivity detection. SOLUTION: In one mode of this invention, the pressure-sensitive sensor has a base body, a first elastic layer provided on the base body, a thin-film silicon substrate provided on the first elastic layer, a semiconductor resistance element provided on the upper surface of the thin-film silicon substrate, a flexible thin-film which is provided on the thin-film silicon substrate and incorporates an electric wiring layer, and a second elastic layer having a thickness distribution provided on the flexible thin-film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor and a method for manufacturing the pressure sensor, and more particularly to a pressure sensor for detecting when an object comes into contact with the object and a method for manufacturing the pressure sensor.

[0002]

2. Description of the Related Art For example, in Japanese Patent Application Laid-Open No. 9-126915, "Semiconductor Load Detecting Device" introduces a sensor using a silicon semiconductor pressure detecting element.

[0003] The sensor of the prior art will be described with reference to FIG.

In this prior example, a silicon semiconductor pressure detecting element 103 is provided on a pedestal 102, and a cover 104 is provided so as to cover the surface of the silicon semiconductor pressure detecting element 103.
The lower end of the transmission rod 105 is in contact with the surface of the cover 104.

[0005] The upper end of the transmission rod 105 is connected to a load table 108.

The load table 108 and the pedestal 10
2, a spring 106 is provided.

A stopper 107 is provided to limit the amount of displacement of the load table 108 in the downward direction.

The semiconductor load detecting device 101 configured as described above is described.

Next, the operation of the semiconductor load detecting device 101 will be described.

When a load is applied to the load table 108, the load is applied to the transmission rod 105 and the spring 106.
And the load shared by the transmission rod 105 is transmitted to the silicon semiconductor pressure detecting element 103 via the cover 104.

Therefore, the silicon semiconductor pressure detecting element 103 outputs a signal corresponding to the load, and detects the load based on the signal.

When an excessive load is applied,
The stopper 107 prevents destruction of the sensor.

As a pressure sensor using a semiconductor thin film according to another conventional example, a pressure sensor using a rubber-like elastic body directly under thinned silicon has been proposed in order to construct a finer sensor than the above-mentioned prior example. is there.

[0014]

However, as described above, in the pressure sensor which is miniaturized, the sensitivity and the sensitivity of the pressure sensor using a semiconductor thin film to the film thickness and elastic modulus of the rubber-like elastic body immediately below the thinned silicon are different. And the stability of the dynamic range and detection are greatly affected.

For this reason, there is a need for a rubber-like elastic material which can form a stable film having a low elastic modulus and a stable shape, and which can be easily processed into a required shape.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and firstly, provides a pressure sensor using a rubber-like elastic body having an improved material shape so as to exhibit an excellent sensor function. A second object of the present invention is to provide a method for manufacturing a pressure sensor capable of performing stable detection with high sensitivity.

[0017]

According to the present invention, in order to solve the above problems, there are provided (1) a base, a first elastic layer provided on the base, and a first elastic layer provided on the first elastic layer. A thinned silicon substrate provided, a semiconductor resistance element provided on the upper surface of the thinned silicon substrate, a flexible thin film provided on the thinned silicon substrate and having an electric wiring layer therein, And a second elastic layer having a thickness distribution provided on the flexible thin film.

(Corresponding Embodiment of the Invention) The embodiment relating to the present invention corresponds to the first embodiment.

In the present embodiment, the first elastic layer of the above-mentioned constituent element corresponds to the first silicon rubber layer 1002, and the second elastic layer of the above-mentioned constituent element corresponds to the second silicon layer. The rubber layer 1004 corresponds.

(Operation) When the pressure sensor contacts something, a contact force is applied to the uppermost member of the pressure sensor, that is, the first elastic layer.

This contact force causes a pressure distribution on the thin film substrate according to the thickness distribution of the first elastic layer.

That is, in the thick portion of the first elastic layer, a stronger compressive force is applied to the thin film substrate, and
In the thin part of the elastic layer, a smaller pressing force is applied.

Since this pressure distribution is also applied to the thinned silicon substrate and the first elastic layer formed integrally with the base, the thinned silicon substrate is bent and deformed.

This bending deformation causes a change in the resistance value of the semiconductor resistance element.

This change in the resistance value is electrically read outside by an electric wiring layer formed inside the flexible thin film.

With the above configuration, it is possible to detect an external contact force.

In such a sensor operation, since the elastic member layer is thin, the amount of deflection of the thinned silicon substrate is easily regulated by the flat surface on the base, and the sensor is prevented from being broken due to the breakage of the thinned silicon substrate. A wide pressure sensor is realized.

According to the present invention, in order to solve the above problems, (2) the pressure sensation according to (1), wherein the first elastic layer and the second elastic layer are made of silicone rubber. A sensor is provided.

(Corresponding Embodiment of the Invention) The embodiment relating to the present invention corresponds to the first embodiment.

In the present embodiment, the first elastic layer of the above-mentioned constituent element corresponds to the first silicon rubber layer 1002, and the second elastic layer of the above-mentioned constituent element corresponds to the second silicon layer. The rubber layer 1004 is formed.

(Operation) By forming the first elastic layer and the second elastic layer from silicon rubber to form an elastic member layer having a low elastic modulus, the pressure sensor has high sensitivity.

According to the present invention, in order to solve the above-mentioned problems, (3) the first elastic layer is made of a negative resist, and the second elastic layer is made of silicon rubber. A pressure sensor according to 1) is provided.

(Function) By forming the elastic member layer of a thick negative resist by photolinography technology, the thickness accuracy of the elastic member layer is improved, and the sensitivity of the pressure sensor is stabilized.

According to the present invention, there is provided (4) the pressure sensor according to (1), wherein the flexible thin film is made of polyimide.

According to the present invention, in order to solve the above problems, (5) a step of forming an impurity diffusion layer on a silicon substrate; and a step of forming a semiconductor resistance element on the impurity diffusion layer of the silicon substrate. Forming a flexible thin film having an electric wiring layer inside on the silicon substrate;
A step of forming a resist thin film on the flexible thin film, a step of forming a resist pattern by exposing and developing the resist thin film, and a step of elastically forming a portion of the flexible thin film where the resist pattern is not formed. A step of pouring a body material to form a first elastic layer, a step of removing the resist pattern, a step of dissolving the silicon substrate other than the periphery of the impurity diffusion layer by etching to make the first elastic layer thin, There is provided a method of manufacturing a pressure sensor including a step of bonding a layer to a sensor substrate and a step of forming a second elastic layer on the flexible thin film.

(Corresponding Embodiment of the Invention) The embodiment relating to the present invention corresponds to the second embodiment.

(Operation) In the steps before the step of forming a thin film substrate by etching the silicon substrate, that is, in the step of forming a resist pattern and the step of forming the first elastic layer using the silicon rubber layer, it is possible to perform the steps depending on the rigidity of the silicon substrate. The surface of the flexible substrate is firmly supported.

Therefore, it is possible to use a photolithography technique or to perform an operation of applying a load on the surface of the flexible substrate.

In this state, a thick resist thin film is formed, and this is exposed and developed to form a resist pattern.

Further, an uncured silicone rubber material is applied on this surface, spread with an edge-shaped member, and cured.

The portion not covered by the resist pattern, that is, the exposed surface of the flexible substrate,
A second elastic layer made of a silicon rubber layer having a thickness substantially equal to that of the resist pattern is formed.

After that, the resist pattern is removed.

In these steps, the formation of a resist thin film can be performed with a precision of several percent in thickness even with a resist having a thickness of several tens of μm by a conventional technique.

The processing accuracy in the plane direction can be assured by a usual exposure / developing apparatus.

By using the resist pattern thus formed with high precision as a mold, the first elastic layer made of a silicon rubber layer can be formed with high precision. By using such a member, the sensor sensitivity can be improved. A high and stable pressure sensor can be manufactured.

According to the present invention, in order to solve the above problems, (6) a step of forming an impurity diffusion layer in a silicon substrate, and a step of forming a semiconductor resistor in the impurity diffusion layer of the silicon substrate; Forming a flexible thin film having an electric wiring layer inside on the silicon substrate;
A step of forming a resist thin film on the flexible thin film, a step of forming a predetermined resist pattern by exposing and developing the resist thin film, and a step of dissolving the silicon substrate by etching other than around the impurity diffusion layer. A method of manufacturing a pressure sensor, comprising: a step of forming a thin film by applying pressure; a step of bonding the first elastic layer to a sensor base; and a step of forming a second elastic layer on the flexible thin film. You.

(Corresponding Embodiment of the Invention) The embodiment relating to the present invention corresponds to the third embodiment.

(Function) In a step prior to the step of forming a thin film substrate by etching a silicon substrate, that is, a step of forming a resist layer having a predetermined shape, the surface of a flexible substrate is strongly supported by the rigidity of the silicon substrate. Have been.

Therefore, the use of the photolithography technique is possible.

In this state, a thick resist thin film is formed, which is exposed and developed to be processed into a predetermined shape.

In this step, a resist thin film can be formed with a precision of several percent in thickness even with a resist having a thickness of several tens of μm by a conventional technique.

The processing accuracy in the plane direction can be assured by a usual exposure / developing apparatus.

By forming the resist with high precision in this manner, a pressure sensor with stable sensor sensitivity can be manufactured.

[0054]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) A first embodiment of the present invention will be described with reference to FIG.

The first embodiment is configured as follows.

The base 1001 is a base made of a highly rigid material such as ceramic for mounting the sensor of the present invention.

The upper surface 1001a of the base 1001 is flat.

A first silicon rubber layer (first elastic layer) 1002 is attached on the upper surface 1001a.

Further, the first silicon rubber layer 100
A thinned silicon substrate 1003 is adhered on the second substrate 2.

Further, the thinned silicon substrate 1003
A second silicon rubber layer (second elastic layer) 10
04 is formed.

As shown in FIG. 2, the second silicon rubber layer 1004 in this embodiment has the thickest shape at the center.

Next, the internal structure of the thinned silicon substrate 1003 will be described in more detail.

The thinned silicon substrate 1003 has a thin film silicon plate 10 having a semiconductor resistance element 1008 therein.
07 and a flexible thin film substrate 1005 having an electric wiring layer 1006 therein.

The semiconductor resistance element 1008 and the electric wiring layer 1006 are electrically connected, and the electric wiring layer 1006 enables the resistance value of the semiconductor resistance element 1008 to be measured from outside.

Then, the one configured as described above is
Hereinafter, it is referred to as a pressure sensor 1010.

Next, the operation of the pressure sensor 1010 will be described with reference to FIG.

FIG. 3 shows a state in which a contact object 1201 is in contact with the pressure sensor 1010 from above, that is, from the back of the paper.

At this time, the second silicon rubber layer 10
04 has the thickest shape at its central portion, and therefore presses the portion immediately below it, that is, the central portion of the thin-film silicon plate 1007 in FIG. 2 most strongly to deform the first silicon rubber layer 1002. At the same time, the thin film silicon plate 1007 is deformed so as to project downward.

The semiconductor resistance element 1008 is
In the present embodiment, since the thin film silicon plate 1007 is located on the upper surface,
The downward convex deformation causes a compressive strain in the thin-film silicon plate 1007, and as a result, causes a change in the resistance value of the thin-film silicon plate 1007.

This change in the resistance value corresponds to the electric wiring layer 1006.
The contact force is measured from outside.

In the sensor operation as described above, the flexibility of the thin-film silicon plate 1007, that is, the sensitivity of the pressure sensor 1010 depends on the first silicon rubber layer 1010.
02, the maximum amount of flexural deformation of the thin-film silicon plate 1007, that is, the fragility of the pressure sensor 1010 is mostly determined by the thickness of the first silicon rubber layer 1002. Is done.

The base 1001 is made of, for example, a high-rigidity material such as a ceramic material. Even if a load is applied, only slight deformation occurs. The amount is regulated to about the thickness of the first silicon rubber layer 1002, and breakage due to excessive deformation of the thin film silicon plate 1007 can be prevented by sufficiently reducing the thickness of the first silicon rubber layer. it can.

If the thickness of the first silicon rubber layer 1002 is the same, the thin film silicon plate 1007 is easily bent, that is, the main pressure sensor 1010
Needless to say, the sensitivity increases as the elastic modulus of the first silicon rubber layer 1002 decreases.

On the other hand, the second silicon rubber layer 1004 is a member having a role of generating a pressure distribution in the thin-film silicon plate 1007 due to its thickness distribution as described above, and improves the sensitivity of the pressure sensor 1010. Therefore, it is desirable that the thickness distribution is large.

Further, by forming such a protruding portion in the second silicon rubber layer 1004, the overall shape of the present pressure sensor 1010 becomes more three-dimensional from a planar one and should be in contact with each other. The shape becomes easier to contact with the object.

As described above, the first silicon rubber layer 1002 used in the present pressure sensor 1010 is preferably formed to be thin and made of a material having a low elastic modulus. The second silicon rubber layer 1004 is desirably formed thick so that at least its maximum thickness portion protrudes.

The pressure sensor 101 thus configured
A value of 0 indicates that the dynamic range is wide and the sensitivity is high, and the sensor sensitivity is stable.

It is needless to say that various changes can be made in the present embodiment.

In the present embodiment, the first silicon rubber layer 1002
However, it is advantageous in terms of stabilizing the sensor sensitivity to use a rubber material that can be precisely processed by patterning by mask exposure, such as a negative resist used in photolithography technology, for example. is there.

In the present embodiment, ceramic is used as the material of the base because of its high rigidity. However, in the present invention, the material of the base is a material that can withstand the force given to the sensor and has an elastic layer. A material other than ceramic can also be used as long as the material has sufficiently high rigidity as compared with.

As a material for such a base, a material having high rigidity other than ceramics, for example, metal, plastic, glass or the like can be used.

In this embodiment, the structure of the thinned silicon substrate 1003 is
Although it is arranged with the surface of 7 facing downward, it goes without saying that the same effect is produced even if it is arranged facing upward.

Further, the semiconductor resistance element 100
8 is formed on the surface of the thin-film silicon plate 1007 that is in contact with the flexible thin-film substrate 1005. Even if this is formed on the other surface of the semiconductor resistance element 1008, the sensor is not operated. There is no problem in the function, only the direction of the change of the resistance value in is reversed.

And, of course, the flexible thin film substrate 1
005 may be on the lower side, and the thinned silicon substrate 1003 may be on the upper side, and the thin silicon substrate 1003 may be attached in the opposite direction, and the position of the semiconductor resistance element 1008 may also be inverted.

Further, in the present embodiment,
Although the second silicon rubber layer 1004 has a convex shape at the center, for example, whether the left end is convex or both ends are convex, the thin film silicon plate 1007 is deformed by contact, and the sensor output is reduced. There is no change to what will be done.

FIG. 4 shows a pressure sensor 1010 using a second silicon rubber layer 1404 having projections 1404a and 1404b at both ends as such a modification.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS.

The second embodiment is configured as follows.

In the present embodiment, "at a predetermined position ...
Is performed, or “performs in a predetermined shape”, etc., the photoresist is formed, exposed, and developed by a normal photolithography technique, and then the operation is performed as described in “…”. , After which the photoresist is removed.

Note that, during the following steps, FIG.
In the steps from to the laser cutting in FIG. 9C, a plurality of thinned silicon substrates 2016 are simultaneously formed on the same wafer surface.

First, as shown in FIG. 5A, an oxide film 2003 having a thickness of several tens nm (corresponding to several hundred angstroms) is formed on the surface of a P-type substrate 2001.

At a predetermined position on the surface, an N-type impurity is implanted by an ion implantation apparatus, and then an N-type diffusion layer 2002 is formed through a heat treatment step.

Next, as shown in FIG.
A P-type impurity is implanted into a predetermined position in the type diffusion layer 2002, and then a P-type semiconductor resistance element 2004 is formed through a heat treatment process.

Next, as shown in FIG. 5C, an insulating film 2005 is formed on the surface of the oxide film 2003.

The insulating film 2005 is a single-layer or multi-layer film whose main element is at least two of Si, O and N.

Next, as shown in FIG. 6A, a predetermined position is subjected to plasma etching, and the insulating film 2005 is formed.
Then, a contact hole 2006 that penetrates through the oxide film 2003 and reaches the P-type semiconductor resistance element 2004 is formed.

At this time, although not shown, a contact hole 2006a for partially exposing the N-type diffusion layer 2002 is also formed.

Next, as shown in FIG. 6B, an aluminum (Al) thin film as an electric wiring layer is formed on the insulating film 2005 by a sputtering technique, and this is etched into a predetermined shape. , The first Al
A layer 2007 is formed.

The first Al layer 2007 is connected to the P-type semiconductor resistance element 200 through the contact hole 2006 and the contact hole 2006a (not shown).
4 and the N-type diffusion layer 2002.

Next, as shown in FIG. 6C, a polyimide undiluted solution is coated, this is etched into a predetermined shape, and then sintered to form a first polyimide coating 20.
08 is formed.

Next, as shown in FIG. 7A, an Al thin film as an electric wiring layer is formed by a sputtering technique, and is etched into a predetermined shape to form a second A thin film.
An l-layer 2009 is formed.

Next, as shown in FIG. 7B, a polyimide undiluted solution is coated, this is etched into a predetermined shape, and then sintered to form a second polyimide film 20.
Form 10.

Although not shown, in this step, the second
An electrode pad for making an electrical connection from the outside is formed on the Al layer 2009.

From the electrode pad, the second Al layer 20 is removed.
09 and the first Al layer 2007 through the N-type diffusion layer 2002 and the P-type semiconductor resistance element 2004
Can be electrically connected to

Next, as shown in FIG. 7C, a thick photoresist is formed, and a resist pattern is formed by exposing and developing to expose only a substantially upper portion of the N-type diffusion layer. 2011 is formed.

Next, as shown in FIG. 8A, an uncured silicone rubber stock 2012 is applied, and the silicone rubber stock solution 2012 is applied from above the resist pattern 2011 to an edge-shaped coating tool 2.
By applying the liquid according to 013, the silicone rubber stock solution 2012 is leveled so as to fill gaps in the resist pattern 2011.

Next, as shown in FIG. 8B, the silicone rubber stock 2012 is cured to form a first silicone rubber layer 2014.

Next, as shown in FIG. 8C, the resist pattern 2011 that has contributed to the formation of the first silicon rubber layer 2014 is removed.

Next, as shown in FIG. 9A, when a positive voltage is applied to the N-type diffusion layer 2002 from the electrode pad (not shown), the P-type substrate 2001 is alkalized from the lower surface side. , For example, with an aqueous potassium hydroxide solution.

At this time, the upper surface of the P-type substrate 2001 is to be protected by a jig made of an alkali-resistant member.

As a result of this etching, the N-type diffusion layer 2
The periphery of 002 remains without being etched, and a thin-film silicon plate 2015 is formed.

Since the etching in the portion where the N-type diffusion layer 2002 is not present is stopped by the oxide film 2003 and the insulating film 2005, the first polyimide film 2008 remains protected.

The one formed by the above steps is hereinafter referred to as a thinned silicon substrate 2016.

In the above steps, in order to explain the details of each part, in particular, a region sandwiched from the first polyimide film 2008 to the second polyimide film 2010, the part has been enlarged and shown. However, FIG. 9B is shown to simplify the following description.

Hereinafter, the relationship between the configuration in FIG. 9B and the configuration in each of the drawings described so far will be described.

The flexible substrate 2017 in FIG.
The first polyimide film 2008 and the second polyimide film 2010 and the first Al layer 2007
And the second Al layer 2009 and the oxide film 20
03 and the insulating film 2005.

However, it is difficult to remove portions of the oxide film 2003 and the insulating film 2005 that are not hidden by the thin-film silicon plate 2015 by, for example, a reactive ion etching method.
It is desirable to make the flexibility of 7 better.

The thin-film silicon plate 2015 and the first silicon rubber layer 2014 are the same members except that the vertical and horizontal enlargement ratios are changed.

Next, as shown in FIG. 9C, the flexible substrate 2017 is cut out by a laser or other means to form a single member.

The two surfaces of the first silicon rubber layer 2014 which are not in contact with the flexible substrate 2017 are bonded to the sensor base 2018.

Next, as shown in FIG. 9D, a silicone rubber before curing is applied on the thin-film silicon plate 2015 using a dispenser or the like, and then this is cured to form a second silicone rubber. By forming the layer 2019, the pressure sensor 2020 is completed.

The production of the pressure sensor 2020 through the above steps has the following advantages.

First, the first silicon rubber layer 201
In the preparation of No. 4, the step of forming the resist pattern 2011 and the step of applying the silicon rubber stock solution 2012 shown in FIG. 8A and the step of removing the resist pattern 2011 in FIG. 8C are used. .

When the silicone rubber stock solution 2012 is applied, the resist pattern 2011 becomes its mold, and the silicone rubber stock solution 2 is kept as it is until curing.
012 shape is maintained.

The first silicon rubber layer 2014 thus formed has a good shape reproducibility and can be positioned with high precision on the flexible substrate 2017.

In this step, all the thinned silicon substrates 201 being formed on the surface of the P-type substrate 2001 are removed.
6 can be performed simultaneously, so that it is suitable for mass production.

Secondly, in order to obtain the first advantage, the surface of the second polyimide film 2010 must have sufficient mechanical strength during the process of forming the first silicon rubber layer 2014. It is necessary to be.

Then, the first silicon rubber layer 201
4 before the step of forming the thin-film silicon plate 2015 shown in FIG.
Before the etching of No. 01, the above process is possible.

Third, the second silicon rubber layer 201
9 before forming, ie, during assembling.
The top surface of the reference numeral 0 is the thin-film silicon plate 2015, which is flat, so that the first silicon rubber layer 2014 can be pressed against the sensor base 2018.

Therefore, the pressure sensor 2020 can be manufactured with good reproducibility of the sensor sensitivity.

By the above steps, the pressure sensor 20
By forming the substrate 20, the sensor performance is guaranteed, and a large amount of the thinned silicon substrate 2016 as a basic constituent member can be obtained.

In addition to these steps, various changes and
Deformation is possible.

In the above process, the P-type semiconductor resistance element 2004, which is a “semiconductor resistance element” as a constituent requirement, is formed inside the N-type diffusion layer 2002.
For example, a pressure sensor having the same function as a single-crystal, polycrystalline, or amorphous semiconductor resistance element can be formed in the insulating layer 2005 as a multilayer film.

In such a configuration, since it is not necessary to be of a different conductivity type from that of the N-type diffusion layer 2002, the "semiconductor resistance element" as a constituent requirement can be formed in an N-type.

Further, in the above step, the N-type diffusion layer 200 is formed for forming the thin film silicon plate 2015.
2 is used, but a relatively low-concentration P or N conductivity type substrate is used as a "thin film silicon substrate" as a constituent requirement, and a high concentration is used as an N or P type "impurity diffusion layer" as a constituent requirement. May be formed.

In the step of FIG. 9A of the present embodiment, a positive voltage is applied to the N-type diffusion layer 2002 which is an N or P-type “impurity diffusion layer” as a constituent element. Although the P-type substrate 2001 is etched in this state, it is not necessary to apply a voltage to the high-concentration P-type diffusion layer which is an N or P-type “impurity diffusion layer” as a constituent element in this modification. There is no.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS.

The third embodiment is configured as follows.

In this embodiment, when there is a description such as “perform in a predetermined position” or “perform in a predetermined shape”, the photoresist film is formed by ordinary photolithography. After exposure and development, "..."
And then removing the photoresist.

In the following steps, a plurality of thin film substrates 3016 are simultaneously formed on the same wafer surface in the steps from (a) of FIG. 10 to cutting out by laser in (b) of FIG. .

First, as shown in FIG. 10A, an oxide film 3003 having a thickness of several tens nm (corresponding to several hundred angstroms) is formed on the surface of a P-type substrate 3001.

Then, an N-type impurity is implanted into a predetermined position on the surface by an ion implantation apparatus, and then, through a heat process, an N-type diffusion layer 3002 is formed.
Is formed.

Next, as shown in FIG. 10B, a P-type impurity is implanted into a predetermined position in the N-type diffusion layer 3002, and then the P-type semiconductor resistance element 3004 is subjected to a heat treatment step. Form.

Next, as shown in FIG. 10C, an insulating film 3005 is formed on the surface of the oxide film 3003.

The insulating film 3005 is a single-layer or multi-layer film whose main element is at least two elements of Si, O and N.

Next, as shown in FIG. 11A, a predetermined position is subjected to plasma etching, and the insulating film 300 is formed.
5 and a contact hole 3006 penetrating through the oxide film 3003 and reaching the P-type semiconductor resistance element 3004.

At this time, although not shown, the N
A contact hole 3006a for partially exposing the mold diffusion layer 3002 is also formed.

Next, as shown in FIG. 11B, an Al film is formed on the insulating film 3005 by a sputtering technique, and is etched into a predetermined shape to form a first Al layer 3007. I do.

The first Al layer 3007 is connected to the P-type semiconductor resistance element 300 through the contact hole 3006 and the contact hole 3006a (not shown).
4 and the N-type diffusion layer 3002.

Next, as shown in FIG. 11C, a polyimide undiluted solution is coated, etched into a predetermined shape, and then sintered to form a first polyimide coating 3.
008 is formed.

Next, as shown in FIG. 12A, an Al thin film is formed by a sputtering technique, and is etched into a predetermined shape to form a second Al layer 3009.

Next, as shown in FIG. 12 (b), a polyimide undiluted solution is coated, this is etched into a predetermined shape, and then sintered to form a second polyimide coating 3.
010 is formed.

Although not shown, in this step, the second
An electrode pad for making electrical connection from the outside is formed on the Al layer 3009.

From this electrode pad, the second Al layer 30 is removed.
09 and the first Al layer 3007 through the N-type diffusion layer 3002 and the P-type semiconductor resistance element 3004
Can be electrically connected to

Next, as shown in FIG. 12C, a thick negative type photoresist is formed, and is exposed and developed so as to cover almost only the upper surface portion of the N-type diffusion layer. A layer 3014 is formed.

Next, as shown in FIG. 13A, when a positive voltage is applied to the N-type diffusion layer 3002 from the electrode pad (not shown), the P-type substrate 3001 is Etching is performed with an etchant, for example, an aqueous solution of potassium hydroxide.

At this time, the upper surface of the P-type substrate 3001 is to be protected by a jig made of an alkali-resistant member.

As a result of this etching, the N-type diffusion layer 3
The periphery of 002 remains without being etched, and a thin film silicon plate 3015 is formed.

In addition, since the etching in the portion where the N-type diffusion layer 3002 is not present is stopped by the oxide film 3003 and the insulating film 3005, the first polyimide film 3008 remains protected.

The substrate formed by the above steps is hereinafter referred to as a thinned silicon substrate 3016.

In the above steps, details of each part, in particular,
In order to explain a region sandwiched from the first polyimide film 3008 to the second polyimide film 3010, this portion has been enlarged and shown. However, in order to simplify the following description, FIG. b) is shown.

The relationship between the configuration in FIG. 13B and the configuration in each of the drawings described so far will be described below.

The flexible substrate 3017 is formed of the first polyimide film 3008 and the second polyimide film 30.
10, the first Al layer 3007, the second Al layer 3009, the oxide film 3003, and the insulating film 3005.

However, it is difficult to remove portions of the oxide film 3003 and the insulating film 3005 that are not hidden by the thin film silicon plate 3015 by, for example, a reactive ion etching method.
It is desirable to make the flexibility of 7 better.

The thin-film silicon plate 3015 and the resist layer 3014 are the same members except that the vertical and horizontal enlargement ratios are changed.

Next, as shown in FIG. 13C, the flexible substrate 3017 is cut out by a laser or other means to form a single member.

The surface of the resist layer 3014 which is not in contact with the flexible substrate 3017 is bonded to the sensor base 3018.

Next, as shown in FIG. 13D, a silicone rubber before curing is applied on the thin-film silicon plate 3015 using a dispenser or the like, and then this is cured to form a silicone rubber layer 3019. By forming, the pressure sensor 3030 is completed.

[0170] Producing the pressure sensor 3030 through the above steps has the following advantages.

First, the formation of the resist layer 3014 is performed by a normal photolithography technique.
Since it can be simultaneously formed on the same wafer, a plurality of the shapes can be formed at the same time.

Second, in order to obtain the first advantage, the surface of the second polyimide film 3010 maintains sufficient mechanical strength during the process of forming the first silicon rubber layer 3014. It is necessary to be.

Then, the first silicon rubber layer 301
During the step of forming the P-type substrate 3 before the step of forming the thin-film silicon plate 3015 shown in FIG.
Before the etching of 001, the above-described steps are possible.

Third, the top surface of the pressure sensor 3030 before the formation of the silicon rubber layer 3019, that is, during assembly, is the thin film silicon plate 3015, and since the flat surface is flat, the first silicon rubber layer 3014 is used as the sensor. It can be crimped to the base 3018.

Therefore, the pressure sensor 3030 can be manufactured with good reproducibility of the sensor sensitivity.

[0176] The pressure sensor 30
By forming the substrate 30, the sensor performance is stabilized, and the thinned silicon substrate 3016, which is a basic constituent member thereof, can be obtained in a large amount.

It should be noted that these steps can of course be modified and modified in various ways. Variations relating to the “semiconductor resistance element” as a component, and N- or P-type “impurity diffusion layer” as a component are highly concentrated. The variation in the case of using the P-type diffusion layer is similar to that of the above-described second embodiment.

[0178]

Therefore, as described above, claim 1 is as follows.
According to the present invention described in any one of (4) to (4), it is possible to provide a pressure sensor using a rubber-like elastic body having an improved material shape so as to exhibit an excellent sensor function.

According to the fifth and sixth aspects of the present invention, it is possible to provide a method of manufacturing a pressure sensor capable of performing stable detection with high sensitivity.

[Brief description of the drawings]

FIG. 1 is a view for explaining a prior example of a sensor using a silicon semiconductor pressure detecting element introduced in “Semiconductor Load Detecting Apparatus” in JP-A-9-126915.

FIG. 2 is a cross-sectional view for explaining a configuration of the pressure sensor according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining an operation of the pressure sensor according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a configuration of a modification of the first embodiment of the present invention.

FIG. 5 is a process chart for describing a method of manufacturing a pressure sensor according to a second embodiment of the present invention.

FIG. 6 is a process diagram for describing a method of manufacturing a pressure sensor according to a second embodiment of the present invention.

FIG. 7 is a process chart for describing a method of manufacturing a pressure sensor according to a second embodiment of the present invention.

FIG. 8 is a process chart for describing a method of manufacturing a pressure sensor according to a second embodiment of the present invention.

FIG. 9 is a process diagram for describing a method of manufacturing the pressure sensor according to the second embodiment of the present invention.

FIG. 10 is a process chart for describing a method of manufacturing a pressure sensor according to a third embodiment of the present invention.

FIG. 11 is a process chart for explaining a method of manufacturing the pressure sensor according to the third embodiment of the present invention.

FIG. 12 is a process chart for describing a method of manufacturing a pressure sensor according to a third embodiment of the present invention.

FIG. 13 is a process chart for describing a method of manufacturing the pressure sensor according to the third embodiment of the present invention.

[Explanation of symbols]

 1001a base, 1001a top surface of base 1001, 1002 first silicon rubber layer (first elastic layer), 1003 thinned silicon substrate, 1004 second silicon rubber layer (second elastic layer), 1005: Flexible thin-film substrate, 1006: Electric wiring layer, 1007: Thin-film silicon plate, 1008: Semiconductor resistance element, 1010: Pressure sensor, 1201: Contact object, 1404a, 1404b: Convex part, 1404: Second silicon Rubber layer, 2016 ... Thinned silicon substrate, 2001: P-type substrate, 2002: N-type diffusion layer, 2003: Oxide film, 2004: P-type semiconductor resistance element, 2005: Insulating film, 2006: Contact hole, 2007: First Aluminum (Al) layer, 2008: first polyimide film, 2009: second Al layer, 2010 Second polyimide film, 2011: resist pattern, 2012: silicon rubber stock solution, 2013: coating tool, 2014: first silicon rubber layer, 2015: thin film silicon plate, 2016: thin film silicon substrate, 2017: flexible substrate 2018 ... sensor base, 2019 ... second silicon rubber layer, 2020 ... pressure sensor, 3001 ... P-type substrate, 3003 ... oxide film, 3002 ... N-type diffusion layer, 3004 ... P-type semiconductor resistance element, 3005 ... insulating film 3006 contact hole, 3007 first Al layer, 3008 first polyimide film, 3009 second Al layer, 3010 second polyimide film, 3014 resist layer, 3015 thin film silicon plate, 3016 ... Thinned silicon substrate, 3017 ... Flexible substrate, 3018 ... Sensor Body. 3019: Silicon rubber layer, 3030: Pressure sensor.

Claims (6)

[Claims] 1. A base, a first elastic layer provided on the base, a thinned silicon substrate provided on the first elastic layer, and provided on an upper surface of the thinned silicon substrate. A semiconductor resistor element, a flexible thin film provided on the thinned silicon substrate and having an electric wiring layer therein, and a second elastic layer having a thickness distribution provided on the flexible thin film. A pressure sensor, comprising: 2. The pressure sensor according to claim 1, wherein the first elastic layer and the second elastic layer are made of silicone rubber. 3. The pressure sensor according to claim 1, wherein the first elastic layer is made of a negative resist, and the second elastic layer is made of silicon rubber. 4. The pressure sensor according to claim 1, wherein the flexible thin film is made of polyimide. 5. A step of forming an impurity diffusion layer on a silicon substrate, a step of forming a semiconductor resistance element on the impurity diffusion layer of the silicon substrate, and a flexible substrate having an electric wiring layer inside on the silicon substrate. Forming a thin film; forming a resist thin film on the flexible thin film; exposing and developing the resist thin film to form a resist pattern; and forming a resist pattern on the flexible thin film. A step of pouring an elastic material into a portion not formed to form a first elastic layer; a step of removing the resist pattern; and a step of melting and thinning the silicon substrate other than the periphery of the impurity diffusion layer by etching. A step of bonding the first elastic layer to the sensor substrate; and a step of forming a second elastic layer on the flexible thin film. Method of manufacturing a sensor. 6. A step of forming an impurity diffusion layer on a silicon substrate, a step of forming a semiconductor resistance element on the impurity diffusion layer of the silicon substrate, and a flexible substrate having an electric wiring layer inside on the silicon substrate. A step of forming a thin film; a step of forming a resist thin film on the flexible thin film; a step of forming a predetermined resist pattern by exposing and developing the resist thin film; and an impurity diffusion layer of the silicon substrate. A pressure sense comprising: a step of dissolving portions other than the periphery by etching to form a thin film; a step of bonding the first elastic layer to the sensor base; and a step of forming a second elastic layer on the flexible thin film. Manufacturing method of sensor.