JP2003035507A - Sensor for sensing surface shape and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor for sensing of surface shape allowing for higher stability, sensitivity and reliability. SOLUTION: In the sensor, a dielectric 107 is formed as to have 0.1 μm thickness, a resist pattern 108 of nearly 1 μm thickness is formed on the upper area of a sensor electrode 104a over this dielectric 107 so as to cover the entire sensor electrode 104a, and then the dielectric 107 is optionally etched by using the resist pattern as a mask to form an electrode dielectric 107a covering the sensor electrode 104a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape recognition sensor used for detecting a surface shape having fine irregularities such as a human fingerprint or an animal nose print, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Interest in security technology is increasing in the development of the information society and the environment of the modern society.
For example, in an information-oriented society, personal authentication technology for system construction such as electronic cashing is an important key. In addition, research and development have also been actively conducted on authentication technology to prevent theft and unauthorized use of credit cards (for example, Yoshimasa Shimizu et al. Academic technique, Technical re
port of IEICE OFS92-32, P25 30 (1992)).

There are various authentication methods such as fingerprints and voice,
Above all, many techniques have been developed so far for the fingerprint authentication technique. As a method for reading a fingerprint, there are an optical reading method provided with an optical system such as a lens and lighting, a pressure type using a pressure sensitive sheet, a semiconductor type in which a sensor is arranged on a semiconductor substrate, and the like. Among these, the semiconductor type is easy to downsize and easy to generalize.

As a semiconductor type, "Marco Tartagni" and others have developed a capacitive fingerprint sensor by using LSI manufacturing technology (Marco Tartagni and Robert Guerrier).
i, A 390 dpi Live Fingerprint Imager Based on Feed
back Capacitive Sensing Scheme, 1997 IEEE Internati
onal Solid-State Circuits Conference, p200 201 (199
7)). This fingerprint sensor uses a small capacitance sensor
This is a method of detecting an uneven pattern of the skin by utilizing a feedback capacitance method by a sensor chip arranged two-dimensionally on I.

This capacitance detection sensor is shown in FIG.
Will be described with reference to the sectional view of This sensor includes a sensor electrode 1203 formed on a semiconductor substrate 1201 via an interlayer insulating film 1202, and a passivation film 1204 covering the sensor electrode 1203. Although not shown in FIG. 12, the semiconductor substrate 12 under the interlayer insulating film 1202 is not shown.
On 01, for example, a detection circuit which is an integrated circuit including a plurality of MOS transistors and a wiring structure is formed.

In this sensor chip, when a finger for fingerprint detection comes into contact with the passivation film 1204, the sensor electrode 1203 and the skin of the finger act as electrodes to form a capacitance. The electrostatic capacitance is detected by the detection circuit via a wire (not shown) connected to the sensor electrode 1203. However, because the skin is an electrode in the electrostatic capacitance type fingerprint sensor, static electricity generated at the fingertip causes
There is a problem that the integrated circuit built in the sensor chip is electrostatically destroyed.

On the other hand, in order to prevent electrostatic breakdown of the above-mentioned electrostatic capacitance type fingerprint sensor, a surface shape recognition sensor provided with an electrostatic capacitance detection sensor having a sectional structure as shown in FIG. 13 has been proposed. There is. The sensor of FIG. 13 will be described. A sensor electrode 1303 formed on a semiconductor substrate 1301 with an interlayer insulating film 1302 interposed therebetween, and a deformable plate-like movable electrode arranged with a predetermined gap from the sensor electrode 1303. An electrode 1304 and a support member 1305 that is disposed around the sensor electrode 1303 and is insulated and separated from the sensor electrode 1303 to support the movable electrode 1304 are provided.

In the sensor thus constructed, when the finger to be fingerprint-detected comes into contact with the movable electrode 1304, the pressure from the finger causes the movable electrode 1304 to bend toward the sensor electrode 1303, so that the distance between the sensor electrode 1303 and the movable electrode 1304 is increased. The capacitance formed on the is changed. This change in capacitance is detected by a detection circuit (not shown) on the semiconductor substrate 1301 via a wire (not shown) connected to the sensor electrode 1303. In this surface shape recognizing sensor, if the movable electrode 1304 is grounded via the conductive support member 1305, the static electricity generated at the fingertip is discharged via the support member 1305 even if discharged to the movable electrode 1304. It flows to the ground. Therefore, the detection circuit incorporated under the sensor electrode 1303 can be protected from electrostatic breakdown.

[0009]

However, in the above-described conventional surface shape recognition sensor, when the pressure from the surface shape recognition target such as a finger is excessive, the movable electrode 1304 is excessively bent and comes into contact with the sensor electrode 1303. There was a problem of short circuit.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a surface shape recognition sensor in consideration of stability, sensitivity and reliability.

[0011]

According to one embodiment of the present invention, there is provided a surface shape recognizing sensor, in which sensor electrodes are respectively insulated and separated and fixedly arranged on the same plane of an interlayer insulating film formed on a semiconductor substrate. A plurality of capacitance detecting elements each composed of an electrode insulating film arranged on the sensor electrode, a deformable plate-like movable electrode made of metal and arranged on the electrode insulating film at a predetermined interval, and a sensor. A sensor electrode is provided around the electrode so as to be insulated from the sensor electrode, and is formed higher than the electrode insulating film to support the movable electrode. According to this surface shape recognition sensor, a space and an electrode insulating film exist between the movable electrode and the sensor electrode.

In the above surface shape recognition sensor, when the movable electrode has a plurality of openings, a protective film may be provided on the movable electrode so as to cover the openings. Further, it may be provided with a projecting structure arranged on the movable electrode. In the above surface shape recognition sensor, when the amount of movement of the central portion of the movable electrode when the movable electrode undergoes maximum deformation within the elastically deformable range is A, the distance between the movable electrode and the electrode insulating film is A or less. can do. Further, in the above surface shape recognition sensor, the electrode insulating film may be formed in substantially the same shape as the sensor electrode and arranged so as to cover the sensor electrode.

A method of manufacturing a surface shape recognition sensor according to one aspect of the present invention includes a step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a sensor electrode on the interlayer insulating film, and a step of forming a sensor electrode around the sensor electrode. A step of forming a support member which is arranged so as to be insulated from the sensor electrode, and a first step of covering the sensor electrode on the sensor electrode in a state lower than the support member.
The step of forming the insulating film, the step of selectively removing the first insulating film to form the electrode insulating film on the sensor electrode, and the step of covering the sensor electrode and the electrode insulating film and exposing the supporting member. A step of forming a sacrificial film on the interlayer insulating film, a step of forming a movable electrode having an opening on the sacrificial film and the supporting member, and a step of forming the movable electrode and then selecting only the sacrificial film through the opening. And the step of removing the sacrificial film,
It comprises a step of forming a protective film on the movable electrode and a step of forming a projecting structure arranged on the protective film in a region above the sensor electrode. According to this manufacturing method, the space and the electrode insulating film exist between the movable electrode and the sensor electrode.

According to another aspect of the present invention, there is provided a method of manufacturing a sensor for surface shape recognition, which comprises a step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a metal film on the interlayer insulating film,
Forming a first mask pattern having an opening in a predetermined region on the metal film, and forming a first metal pattern on the metal film surface exposed at the bottom of the opening of the first mask pattern by a plating method And a step of forming a first insulating film on the first metal pattern so as to cover the first metal pattern, and removing the first mask pattern to insulate electrodes on the first metal pattern. A step of forming a film, a step of forming a second mask pattern having an opening arranged around the first metal pattern after forming the electrode insulating film, on the metal film and the electrode insulating film; A step of forming a second metal pattern on the surface of the metal film exposed at the bottom of the opening of the second mask pattern by a plating method so as to be thicker than the total film thickness of the first metal pattern and the electrode insulating film; Pattern removed The first metal film and the second metal pattern are used as a mask to remove the first metal film by etching, and the sensor electrode including the first metal film and the first metal pattern, the first metal film, and the second metal film are removed. A step of forming a supporting member made of a metal pattern, a step of forming a sacrificial film on the interlayer insulating film so as to cover the sensor electrode and the electrode insulating film and expose the supporting member, and on the sacrificial film and the supporting member, A step of forming a movable electrode having an opening, a step of selectively removing only the sacrificial film through the opening after forming the movable electrode, and a step of removing the sacrificial film on the movable electrode. The method includes a step of forming a protective film and a step of forming a protrusion-shaped structure disposed on the protective film in a region above the sensor electrode. According to this manufacturing method, the space and the electrode insulating film exist between the movable electrode and the sensor electrode.

A method of manufacturing a sensor for recognizing a surface shape according to another aspect of the present invention comprises a step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a metal film on the interlayer insulating film,
Forming a first mask pattern having an opening in a predetermined region on the metal film, and forming a first metal pattern on the metal film surface exposed at the bottom of the opening of the first mask pattern by a plating method And a step of forming a first insulating film on the first metal pattern so as to cover the first metal pattern after removing the first mask pattern, and selectively removing the first insulating film. To form an electrode insulating film on the first metal pattern, and after forming the electrode insulating film, a second mask pattern having openings arranged around the first metal pattern is formed. The step of forming the second metal pattern on the metal film and the electrode insulating film and the second metal pattern on the surface of the metal film exposed at the bottom of the opening of the second mask pattern by the plating method Process of forming thicker than film thickness After removing the second mask pattern, the first metal film is removed by etching using the first metal pattern and the second metal pattern as a mask to form a sensor electrode including the first metal film and the first metal pattern. And a step of forming a supporting member made of the first metal film and the second metal pattern, and a step of forming a sacrificial film on the interlayer insulating film so as to cover the sensor electrode and the electrode insulating film and expose the supporting member. A step of forming a movable electrode having an opening on the sacrificial film and the supporting member; a step of selectively removing only the sacrificial film through the opening after forming the movable electrode; After removing the, the step of forming a protective film on the movable electrode, and the step of forming a projecting structure arranged on the protective film in a region above the sensor electrode are provided. According to this manufacturing method, the space and the electrode insulating film exist between the movable electrode and the sensor electrode.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> First, an example of a method of manufacturing the surface shape recognition sensor according to the first embodiment of the present invention will be described. 1A to 1C are process drawings for explaining the method of manufacturing the surface shape recognition sensor according to the present embodiment. First, Fig. 1
As shown in (a), an interlayer insulating film 101a is formed on a substrate 101 made of a semiconductor material such as silicon. Although not shown, another integrated circuit such as a detection circuit is formed on the substrate 101 below the interlayer insulating film 101a and has a wiring structure including a plurality of wirings. Interlayer insulating film 101
After forming a, the seed layer 102 is formed by a two-layer film including a titanium film having a film thickness of 0.1 μm and a gold film having a film thickness of 0.1 μm by an evaporation method.

Next, as shown in FIG. 1B, a resist pattern 103 having an opening 103a and a film thickness of about 5 μm is formed on the seed layer 102. The resist pattern 103 may be formed by a known photolithography technique, for example. After forming the resist pattern 103, a metal pattern 104 made of a gold-plated film is formed by electrolytic plating to a thickness of about 1 μm on the seed layer 102 exposed in the opening 103a.

Next, as shown in FIG. 1C, the resist pattern 103 is removed. After that, as shown in FIG. 1D, a resist pattern 105 having a film thickness of about 5 μm is newly formed with an opening 105a. At this time, the resist pattern 105 covers the metal pattern 104. After forming the resist pattern 105, a metal pattern 106 made of a gold plating film is formed by electrolytic plating on the seed layer 102 exposed in the opening 105a.
To a film thickness of about 3 μm. After that, as shown in FIG. 1E, the resist pattern 105 is removed.

Then, the seed layer 102 is selectively removed by etching using the metal patterns 104 and 106 as masks. In this etching, first, the gold in the upper layer of the seed layer 102 is selectively removed using an etching solution containing iodine, ammonium iodide, water and ethanol. Then, titanium in the lower layer of the seed layer 102 is selectively removed using an HF-based etching solution. As a result, as shown in FIG. 1F, the sensor electrode 104a whose upper layer is made of gold and the sensor electrode 104a are formed on the substrate 101.
And a support member 106a that is insulated and separated.

The support member 106a supports a movable electrode, which will be described later, and is formed in a lattice shape as shown in FIG. 1 (g), for example. Support member 106a
The sensor electrode 104a is arranged at the center of the area surrounded by. The shape of the support member 106a is not limited to the lattice shape, and a plurality of square poles may be arranged around the sensor electrode 104a.

Next, as shown in FIG. 2A, an insulating film 107 made of a silicon oxide film with a thickness of 0.1 μm is formed.
CR (Electron Cyclotron Resonance) Plasma CVD
(Chemical Vapor Deposition) method.
SiH ₄ and O ₂ gases were used as the source gas, the flow rate of each gas was 10 sccm, 20 sccm, and the microwave power was 2
A silicon oxide film was formed as 00W. The insulating film 107 is not limited to the silicon oxide film and may be another insulating material such as a silicon nitride film.

Next, as shown in FIG. 2B, a resist pattern 108 having a film thickness of about 1 μm is formed in the upper region of the sensor electrode 104a on the insulating film 107 so as to cover the entire sensor electrode 104a. The resist pattern 108 is
It may be formed by a known photolithography technique.
After that, the insulating film 107 is selectively etched using the resist pattern 108 as a mask. This etching is performed by dry etching using CHF ₃ gas and O ₂ gas as etching gas, and each gas flow rate is set to 3
The microwave power was 300 W with 0 sccm and 5 sccm. As a result, as shown in FIG.
An electrode insulating film 107a covering 04a is formed.

Next, as shown in FIG. 2D, the sensor electrode 104a, the electrode insulating film 107a, and the supporting member 106a.
Resin film 1 having photosensitivity on the substrate 101 so as to cover
09 is formed by spin coating. Formed resin film 10
In No. 9, heat treatment at 120 ° C. for about 4 minutes is added. Next, as shown in FIG. 2E, an area above the supporting member 106a is exposed by a known photolithography technique,
Subsequently, the developing process is performed to form the opening 109a in the upper portion of the support member 106a. After that, heat treatment is performed at 310 ° C. for about 1 hour to thermally cure the resin film 109.

Next, the cured resin film 109 is etched back by chemical mechanical polishing to form a sacrificial film 109b whose surface is flattened, as shown in FIG. 2 (f). At this stage, the surface of the supporting member 106a and the surface of the sacrificial film 109b form the same plane, and the surface of the supporting member 106a is exposed. Then, a seed layer 110 composed of a two-layer film of a titanium film having a film thickness of 0.1 μm and a gold film having a film thickness of 0.1 μm is formed on the flattened sacrificial film 109b by a vapor deposition method (FIG. 3A). ).

After the seed layer 110 has been formed, FIG.
As shown in FIG. 3, a seed pattern 110 having a film thickness of about 3.0 μm is formed in an island shape on the seed layer 110, and the seed layer 110 exposed in a region where the resist pattern 111 is not present is exposed.
A metal film 112 made of a gold-plated film is formed thereon to a thickness of 1.0 μm by electrolytic plating.

Next, the resist pattern 111 is removed, and the seed layer 1 is formed by using the formed metal film 112 as a mask.
10 is selectively etched. In this etching,
First, gold in the upper layer of the seed layer 110 is selectively removed using an etching solution containing iodine, ammonium iodide, water, and ethanol. Then, titanium in the lower layer of the seed layer 110 is selectively removed using an HF-based etching solution. As a result, as shown in FIG. 3C, the movable electrode 113 including the plurality of openings 113a and including the metal film 112 and the etched seed layer 110a is formed.

Next, the substrate 101 on which the movable electrode 113 has been formed is exposed to plasma mainly containing oxygen gas, and the etching species generated by the plasma are brought into contact with the sacrificial film 109b through the opening 113a, so that the sacrificial film is formed. 109b is removed. As a result, as shown in FIG. 3D, a space is formed below the movable electrode 113 in a state where the movable electrode 113 is supported by the support member 106a, and the movable electrode 113 and the sensor electrode 104a are separated from each other in the space. Electrode insulating film 107a
A structure is formed that faces each other while sandwiching.

Next, as shown in FIG. 3E, a protective film 114 made of an insulating material is formed in order to seal the opening of the movable electrode 113. The protective film 114 is ST
P (Spin Coating Film Transfer and Hot-pressing)
It was formed using the method. In the STP method, an insulating material is applied and formed on a film in advance, the insulating material on the film is adhered to the surface of the movable electrode 113 by heating and pressing in vacuum, and then the film is peeled off to form a protective film. This is a method of transferring 114 to the surface of the movable electrode 113.

Thereafter, as shown in FIG. 3 (f), a projecting structure 115 was formed on the movable electrode 113 by a known photolithography technique. The formation of the protruding structure 115 will be described. First, a photosensitive resin film is formed on the protective film 114 by coating so as to have a film thickness of about 10 μm. Then, the portion other than the region to be the projecting structure is exposed to be soluble in a developing solution, which is subjected to a development treatment and then heat-treated at 310 ° C. for about 1 hour to be heat-cured to form the projecting structure 115. And

Through the above steps, the surface shape recognition sensor 100 is manufactured as shown in FIG. As a result, as shown in FIG. 3F, according to the surface shape recognition sensor 100 of the present embodiment, since the electrode insulating film 107a is provided on the sensor electrode 104a, the movable electrode 113 is large. Even if the movable electrode 11 bends downward,
The lower part of 3 does not make electrical contact with the sensor electrode 104a.

Further, in the related art, in order to avoid contact between the sensor electrode 104a and the movable electrode 113, the gap between them may be set more than necessary, and the formed capacitance becomes small and the sensitivity is lowered. However, according to the present embodiment, since the distance between the sensor electrode and the movable electrode can be narrowed, the sensitivity is not lowered. Furthermore, when an excessive pressure is applied to the movable electrode 113 in a state where the distance is widened as in the conventional case, the movable electrode 11
There was a case where 3 was plastically deformed and did not return to the original state, but according to the present embodiment, such a problem can be suppressed.

By the way, in the above embodiment, the movable electrode is provided with a plurality of openings, but the invention is not limited to this. For example, if the supporting member is a discontinuous structure as a structure of columns arranged around the sensor electrode, the sacrificial film can be removed from the side even if the movable electrode does not have an opening. Further, if the movable electrode is formed on the support member without using the sacrificial film, there is no object to be removed, so that it is not necessary to provide the movable electrode with an opening.

<Second Embodiment> Next, an example of a manufacturing method according to another embodiment of the present invention will be described. First, similar to the above-described embodiment, as shown in FIG. 4A, a resist pattern 103 having an opening 103a and a film thickness of about 5 μm is formed on the seed layer 102. After forming the resist pattern 103, a metal pattern 104 made of a gold-plated film is formed by electrolytic plating to a thickness of about 1 μm on the seed layer 102 exposed in the opening 103a.

In the present embodiment, thereafter, without removing the resist pattern 103, the insulating film 120 made of a silicon oxide film is formed to a thickness of 0.3 μm by the ECR plasma CVD method.
It is formed to have a film thickness of about 10 μm (FIG. 4B). Again, SiH ₄ and O ₂ gases are used as the source gas, the flow rate of each source gas is 10 sccm and 20 sccm, and the microwave power is 2
A silicon oxide film was formed as 00W.

Next, the resist pattern 103 is removed. At this time, the portion of the insulating film 120 that is in contact with the resist pattern 103 is removed by lift-off. As a result,
Only the insulating film 120a on the metal pattern 104 remains (FIG. 4C). Thereafter, as in the case of FIG. 1D, a resist pattern 105 is formed, and a metal pattern 106 made of a gold plating film is formed by electrolytic plating (FIG. 4).
(D)). After that, the resist pattern 105 is removed (FIG. 4E).

Next, the seed layer 102 is selectively etched by using the formed metal pattern 106 as a mask. In this etching, first, the gold in the upper layer of the seed layer 102 is selectively removed using an etching solution containing iodine, ammonium iodide, water and ethanol. Then, titanium in the lower layer of the seed layer 102 is selectively removed using an HF-based etching solution. At this time, the insulating film 120a is also etched by the HF-based etching solution. However, the film thickness of the insulating film 120a is 0.3 μm,
While the 1 μm titanium film is being etched, the insulating film 12
All of 0a is not removed and remains as an electrode insulating film 120b described below.

As a result, as shown in FIG. 4F, on the substrate 101, the sensor electrode 104a having an upper layer of gold,
The electrode insulating film 120b on this and the sensor electrode 104
Thus, the support member 106a is formed, which is insulated from the electrode a and the electrode insulating film 120b. FIG. 4F corresponds to the state of FIG. 2C, and thereafter, the same steps as those of FIG. 2D and subsequent steps are performed, whereby the surface shape recognition sensor 100 as shown in FIG. Is formed. In the present embodiment,
Although the silicon oxide film is taken as an example of the insulating film 120, other insulating materials such as a silicon nitride film may be used if they are not etched when gold, titanium and the sacrificial film are etched or if a small etching amount is sufficient. You may use the body.

<Third Embodiment> Next, an example of a manufacturing method according to another embodiment of the present invention will be described. First, similar to the above-described embodiment, as shown in FIG. 5A, a resist pattern 103 having an opening 103a and a film thickness of about 5 μm is formed on the seed layer 102. After forming the resist pattern 103, a metal pattern 104 made of a gold-plated film is formed by electrolytic plating to a thickness of about 1 μm on the seed layer 102 exposed in the opening 103a.

Next, in this embodiment, the resist pattern 103 is removed, and thereafter, the insulating film 130 made of a silicon oxide film is formed to a thickness of 0.1 μm on the seed layer 102 so as to cover the metal pattern 104. To do. Insulation film 130
May be formed in the same manner as the insulating film 107 shown in FIG. Next, as shown in FIG. 5C, the insulating film 130
A film thickness of 1.0 in the upper region of the metal pattern 104 and on the metal pattern 104.
A resist pattern 131 of μm is formed by a known photolithography technique.

After forming the resist pattern 131, the insulating film 130 is selectively removed by etching using this as a mask (FIG. 5D). In this dry etching, CHF ₃ and O ₂ were used as etching gases, the flow rates of these gases were 30 sccm and 5 sccm, and the microwave power was 300 W. After that, if the resist pattern 131 is removed, as shown in FIG.
An electrode insulating film 130a made of a silicon oxide film is formed on the electrode 4.

Thereafter, as in FIG. 1D, a metal pattern 106 made of a gold plating film is formed by resist pattern formation and electrolytic plating (FIG. 5F), and the resist pattern is removed (FIG. 5F). FIG. 5 (g)). FIG. 5G corresponds to the state of FIG. 2C, and thereafter, the same steps as those of FIG. 2D and thereafter are performed to form the surface shape recognition sensor 100 shown in FIG. 3F. it can. The insulating film 130
However, another insulator such as a silicon nitride film may be used as long as it is not etched during the etching of gold, titanium and the sacrificial film, or if a small etching amount is sufficient.

Next, the operation of the surface shape recognition sensor whose manufacturing process is shown in the above embodiment will be described.
FIG. 6 shows the operating principle of the surface shape recognition sensor 100. An object such as a finger, which is a surface shape recognition target, is pressed against the sensor chip in which the surface shape recognition sensor 100 is two-dimensionally arranged. At this time, the concave portion of the object having unevenness does not come into contact with the surface shape recognition sensor 100 (FIG. 6).
(A)). On the other hand, the convex portion of the object comes into contact with the upper portion of the surface shape recognition sensor 100 and applies pressure to the protruding structure 115 (FIG. 6B). The movable electrode 113 bends according to the magnitude of the pressure at this time.

When the movable electrode 113 bends, the movable electrode 113
The capacitance formed between the sensor electrode 104a and the sensor electrode 104a increases. This increase in capacitance is detected by an integrated circuit (not shown) on the substrate 101. Further, the magnitude of the change in capacitance is converted into grayscale data to detect the surface shape. In such an operation, when a large pressure is applied from the outside, the movable electrode 113 moves the sensor electrode 104a.
However, according to the present embodiment, the electrode insulating film 1 is bent.
By including 07a, it is possible to avoid contact between the movable electrode 113 and the sensor electrode 104a.

Therefore, it is possible to avoid a short circuit between the movable electrode 113 and the sensor electrode 104a due to the contact, and it is possible to prevent the movable electrode 113 and the metal surface of the sensor electrode 104a from sticking to each other. Furthermore, since the electrode insulating film 107a is a dielectric,
The change in capacitance formed between the movable electrode 113 and the sensor electrode 104a can be increased. In addition, by setting the electrode insulating film 107a to an appropriate thickness and giving an upper limit to the movable depth of the movable electrode 113, the movable electrode 11 accompanying the deformation
It is possible to prevent mechanical fatigue and destruction of No. 3.

A method of designing the electrode insulating film for realizing the above advantages will be described below. For simplicity,
As shown in FIG. 7A, the axis is set with the bending direction of the movable electrode 113 being positive and the center of the movable electrode 113 when no pressure is applied as the origin. In addition, the electrode insulating film 10
The thickness of 7a is t, and the movable electrode 113 and the electrode insulating film 10 are
The distance from 7a is dt. Further, as shown in FIG. 7B, the position when the movable electrode 113 bends due to the pressure from the outside is defined as x.

First, as shown in FIGS. 8 (a), 8 (b) and 8 (c), the movable depth d-t of the movable electrode 113 is kept constant and the film thickness of the electrode insulating film 107a is different. Think In this state, the movable electrode 113 is moved from x = 0 to x = d-
FIG. 8 shows the change in electrostatic capacitance when moved to the position of t.
It shows in (d). As can be seen from this figure, the electrode insulating film 1
The thinner the thickness of 07a, the wider the dynamic range of capacitance.

Next, as shown in FIGS. 9A, 9B and 9C, when the movable depth of the movable electrode 113 is changed with the film thickness of the electrode insulating film 107a being constant (d). _1- t
<Considering the _{d 2 -t <d 3 -t)} . FIG. 9D shows a change in capacitance when the movable electrode 113 is moved from x = 0 to a possible value in this state. By the way, in order to act as a sensor, the movable electrode needs to be deformed by this pressure when pressure is applied, and to return to the original undeformed state when there is no pressure. There is a threshold value in the movable electrode where the amount of deformation equal to or less than a certain value falls within the range of elastic deformation that returns to the original state, but when the amount of deformation exceeds a certain value, the range of plastic deformation does not return to the original state.

In FIG. 9, when the moving amount of the movable electrode, which is the threshold value of the elastic deformation and the plastic deformation, is d2-t, it is 0.
When ≦ x ≦ d ₂ −t, elastic deformation occurs, and when d ₂ −t ≦ x, plastic deformation occurs. Therefore, the movable electrode 11
3 and the electrode insulating film 107a have a large distance d
Even in the case of = d _3, the range in which the sensor is movable is 0 ≦ x ≦ d ₂ −t. For this reason, when the dynamic range of the electrostatic capacitance is viewed in FIG. 9D, it is found that the widest range is when d = d ₂ . That is, the maximum dynamic range is obtained when the movable electrode is capable of maximum deformation within the elastic deformation range.

Next, the case where the film thickness of the electrode insulating film 107a and the movable depth of the movable electrode 113 are made constant and the dielectric constant ε of the electrode insulating film is changed will be described. Figure 10
As shown in (a), (b), and (c), ε ₃ <ε ₂ <ε ₁
When an electrode insulating film having a different dielectric constant is used, the dynamic range of the capacitance corresponding to this is shown in FIG.
As shown in. That is, the larger the dielectric constant of the electrode insulating film, the wider the dynamic range of the capacitance of the sensor.

Next, the shape of the electrode insulating film 107a will be described. Sensor electrode 104a and electrode insulating film 107a
Both are squares, and the axes are set as shown in FIG. FIG. 11B shows a state in which the sensor electrode 104a and the electrode insulating film 107a of FIG. 11A are viewed from above. Sensor electrode 104a
Is a square with one side b, and the electrode insulating film 107a is a square with one side a.

With such a structure, the capacitance formed between the sensor electrode 104a and the movable electrode 113 when a is increased from y = 0 is shown in FIG. 7 (c).
Shown in. The capacitance at a = a ₁ where 0 ≦ a ≦ b is a =
It is smaller than the capacitance at b. The capacitance at a = a ₂ that satisfies a> b is equal to the capacitance at a = b. However, a
In the area of> b, the sensor electrode 104a and the support member 106 are
This is not preferable because the electrostatic capacitance between a and increases.

For the above reasons, the electrode insulating film 107a is
The sensor electrode 104a is formed so as to cover the sensor electrode 104a without excess or deficiency.
In the actual process, it is difficult to form a completely congruent shape, so a margin of about 1 μm is considered. Figure 1
Although the square shape is assumed as the shape of the sensor electrode 104a in the first example, it goes without saying that the above facts can be applied even if the shape is not the square shape.

To summarize the above description, in order to amplify the difference between the external irregularities and detect it with high sensitivity, it is preferable that the dynamic range of the electrostatic capacitance is wide. For this purpose,
If the electrode insulating film 107a is formed as thin as possible, its shape is congruent with the sensor electrode 104a, and the surface of the electrode insulating film 107a is formed at a position where the movable electrode 113 does not exceed the limit of elastic deformation. Good.

[0054]

As described above, according to the present invention,
Since there is a space and an electrode insulating film between the movable electrode and the sensor electrode, even if the movable electrode bends downward, there is no electrical contact with the sensor electrode, so that a short circuit occurs. Therefore, it is possible to provide a surface shape recognition sensor in which stability, sensitivity, and reliability are taken into consideration.

[Brief description of drawings]

FIG. 1 is a process chart showing an example of a method for manufacturing a surface shape recognition sensor according to an embodiment of the present invention.

FIG. 2 is a process diagram showing an example of a method of manufacturing the surface shape recognition sensor, which is subsequent to FIG.

FIG. 3 is a process diagram showing an example of a method of manufacturing the surface shape recognition sensor, which is subsequent to FIG. 2;

FIG. 4 is a process drawing showing an example of a method for manufacturing a surface shape recognition sensor according to another embodiment of the present invention.

FIG. 5 is a process drawing showing an example of a method for manufacturing a surface shape recognition sensor according to another embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view for explaining an operation example of the surface shape recognition sensor according to the embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view for explaining an operation example of the surface shape recognition sensor according to the embodiment of the present invention.

8A to 8C are schematic cross-sectional views (a), (b) and (c) for explaining an operation example of the surface shape recognition sensor according to the embodiment of the present invention, and a characteristic diagram (d).

9A to 9C are schematic cross-sectional views (a), (b), and (c) for explaining an operation example of the surface shape recognition sensor according to the embodiment of the present invention, and a characteristic diagram (d).

FIG. 10 is schematic sectional views (a), (b) and (c) for explaining an operation example of the surface shape recognition sensor according to the embodiment of the present invention, and a characteristic diagram (d).

FIG. 11 is a schematic cross-sectional view (a), a plan view (b), and a characteristic view (c) for explaining an operation example of the surface shape recognition sensor according to the embodiment of the present invention.

FIG. 12 is a schematic cross-sectional view showing the configuration of a conventional surface shape recognition sensor.

FIG. 13 is a schematic cross-sectional view showing the configuration of a conventional surface shape recognition sensor.

[Explanation of symbols]

101 ... Substrate, 101a ... Interlayer insulating film, 102 ... Seed layer, 103, 105 ... Resist pattern, 103a, 1
05a ... Openings, 104, 106 ... Metal patterns, 10
4a ... Sensor electrode, 106a ... Support member, 107 ... Insulating film, 107a ... Electrode insulating film, 108 ... Resist pattern, 109 ... Resin film, 109a ... Opening part, 109b ... Sacrificial film, 110, 110a ... Seed layer, 111 ... Resist pattern, 112 ... Metal film, 113 ... Movable electrode, 113
a ... Opening portion, 114 ... Protective film, 115 ... Projection structure.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroki Morimura             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Katsuyuki Machida             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Tsutomu Kuraki             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 2F063 AA43 BA29 BD20 DA02 DD07                       EB05 EB15 HA04                 4C038 FF01 FG00                 5B047 AA25 BA02 BB04 BC01

Claims (8)

[Claims] 1. A sensor electrode, which is insulated and separated from each other and is fixedly arranged on the same plane of an interlayer insulating film formed on a semiconductor substrate, an electrode insulating film arranged on the sensor electrode, and on the electrode insulating film. A plurality of capacitive sensing elements composed of deformable plate-shaped movable electrodes made of metal, which are arranged at a predetermined interval, and the sensor electrodes are arranged around the sensor electrodes while being insulated and separated from each other. A surface shape recognition sensor, comprising: a support member that is formed higher than an insulating film and supports the movable electrode. 2. The surface shape recognition sensor according to claim 1, wherein a plurality of openings formed in the movable electrode, and a protective film formed on the movable electrode so as to close the opening. A sensor for recognizing a surface shape, comprising: 3. The surface shape recognition sensor according to claim 1, further comprising a protrusion-shaped structure disposed on the movable electrode. 4. The surface shape recognition sensor according to claim 1, wherein the moving amount of the central portion of the movable electrode when the movable electrode is deformed to the maximum in the elastically deformable range is A. In this case, the surface shape recognition sensor is characterized in that the distance between the movable electrode and the electrode insulating film is A or less. 5. The sensor for recognizing surface shape according to claim 1, wherein the electrode insulating film is formed in substantially the same shape as the sensor electrode and covers the sensor electrode. A surface shape recognition sensor characterized by being arranged. 6. A step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a sensor electrode on the interlayer insulating film, and a support disposed around the sensor electrode so as to be insulated from the sensor electrode. A step of forming a member, a step of forming a first insulating film on the sensor electrode so as to cover the sensor electrode in a state lower than the supporting member, and the sensor by selectively removing the first insulating film. Forming an electrode insulating film on the electrode; forming a sacrificial film on the interlayer insulating film so as to cover the sensor electrode and the electrode insulating film and expose the supporting member; A step of forming a movable electrode having an opening on a supporting member; a step of selectively removing only the sacrificial film through the opening after forming the movable electrode; and a step of removing the sacrificial film. later, For surface shape recognition, comprising: a step of forming a protective film on the movable electrode; and a step of forming a projecting structure arranged on the protective film in a region above the sensor electrode. Sensor manufacturing method. 7. A step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a metal film on the interlayer insulating film, and a first mask having an opening in a predetermined region on the metal film. A step of forming a pattern, a step of forming a first metal pattern on the surface of the metal film exposed at the bottom of the opening of the first mask pattern by a plating method, and a step of forming the first metal pattern on the first metal pattern. Forming a first insulating film so as to cover the metal pattern; removing the first mask pattern to form an electrode insulating film on the first metal pattern; forming the electrode insulating film And then forming a second mask pattern having an opening portion arranged around the first metal pattern on the metal film and the electrode insulating film, and an opening portion of the second mask pattern. Exposed on the bottom A step of forming a second metal pattern on the surface of the metal film by a plating method so as to be thicker than the total film thickness of the first metal pattern and the electrode insulating film, and after removing the second mask pattern, The first metal film is removed by etching using the first metal pattern and the second metal pattern as a mask, and the sensor electrode composed of the first metal film and the first metal pattern, the first metal film, and the Forming a supporting member made of a second metal pattern; forming a sacrificial film on the interlayer insulating film so as to cover the sensor electrode and the electrode insulating film and expose the supporting member; Forming a movable electrode having an opening on the sacrificial film and the support member; and after forming the movable electrode, selectively removing only the sacrificial film through the opening. A step of forming a protective film on the movable electrode after removing the sacrificial film, and a step of forming a protrusion-shaped structure disposed on the protective film in a region above the sensor electrode. A method for manufacturing a surface shape recognition sensor, comprising: 8. A step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a metal film on the interlayer insulating film, and a first mask having an opening in a predetermined region on the metal film. A step of forming a pattern, a step of forming a first metal pattern on a surface of the metal film exposed at the bottom of the opening of the first mask pattern by a plating method, and a step of removing the first mask pattern, Forming a first insulating film on the first metal pattern so as to cover the first metal pattern, and selectively removing the first insulating film to form an electrode on the first metal pattern. A step of forming an insulating film; and, after forming the electrode insulating film, a second mask pattern having an opening arranged around the first metal pattern is formed on the metal film and the electrode insulating film. Forming step, and the second Forming a second metal pattern on the surface of the metal film exposed at the bottom of the opening of the mask pattern by a plating method so as to have a thickness larger than the total film thickness of the first metal pattern and the electrode insulating film; After removing the mask pattern, the first metal film is etched and removed using the first metal pattern and the second metal pattern as a mask, and the sensor electrode including the first metal film and the first metal pattern is removed. And a step of forming a support member composed of the first metal film and the second metal pattern, and on the interlayer insulating film so as to cover the sensor electrode and the electrode insulating film and expose the support member. A step of forming a sacrificial film, a step of forming a movable electrode having an opening on the sacrificial film and the support member, and a step of forming the movable electrode after forming the movable electrode. And selectively removing only the sacrificial film, a step of forming a protective film on the movable electrode after removing the sacrificial film, and a region above the sensor electrode on the protective film. And a step of forming an arranged protruding structure.