JP3455459B2 - Surface shape recognition sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape recognizing sensor, and more particularly to a surface shape recognizing sensor for detecting fine irregularities such as a human fingerprint or an animal nose print.

[0002]

2. Description of the Related Art The interest in security technology is increasing in the information society and the environment of modern society. For example, in an information-oriented society, personal authentication technology for system construction such as electronic cashing becomes an important key. Also,
The fact is that research and development are also actively underway for authentication technology for protection against theft and unauthorized use of cards (for example, Yoshimasa Shimizu et al. Technical report of IEICE,
OFS92-32, p25-30 (1992)). There are various authentication methods for preventing illegal use, such as those using fingerprints and voiceprints. Among them, many fingerprint authentication technologies have been developed so far. The fingerprint authentication method is roughly classified into an optical reading method and a method of detecting unevenness of a fingerprint by replacing the unevenness of the fingerprint with an electric signal by utilizing electric characteristics of human.

The optical reading method is a method which mainly uses light reflection and a CCD image sensor and takes in a fingerprint as optical image data to perform collation (Japanese Patent Laid-Open No. 61-22).
1883). As another method, a method using a piezoelectric thin film for reading the pressure difference between fingerprints of a finger has been developed (Japanese Patent Laid-Open No. 5-61965). Similarly, as a method for detecting the shape of a fingerprint by replacing the change in electrical characteristics caused by contact with the skin with the distribution of electrical signals, an authentication method based on the amount of resistance change or the amount of capacitance change using a pressure sensitive sheet is available. Proposed (Japanese Patent Laid-Open No. 7-1689)
30 publication). However, in the above technique, the method using light is difficult to miniaturize, it is difficult to use for general purpose, and there is a problem that the application is limited. Next, it is considered that the method of detecting the unevenness of the finger using a pressure-sensitive sheet or the like is difficult to put into practical use and poor in reliability because the material is special and the workability is difficult.

On the other hand, a capacitive fingerprint sensor manufactured by using the LSI manufacturing technology has been developed (Marco Tartag
ni and Roberto Guerrieri, A 390dpi Live Fingerprint
Imager Based on Feedback Capacitive Sensing Schem
e, 1997 IEEE International Solid-State Circuits Conf
erence, p200-201 (1997).). This is a method of detecting a concavo-convex pattern on the skin by using a feedback capacitance method with a small sensor arranged two-dimensionally on an LSI chip. In this capacitive sensor, two plates are formed on the uppermost layer of the LSI wiring, and a passivation film is formed thereon. When a fingertip touches this sensor, the surface of the skin functions as a third plate and is isolated by an insulating layer composed of air, and the fingerprint is detected by sensing the difference in the distance. This structure is characterized by the fact that it does not require a special interface and can be downsized as compared with the conventional optical type.

Here, in principle, the fingerprint sensor is
This is a method in which a sensor electrode is formed on a semiconductor substrate and a passivation film is formed on the sensor electrode, and the capacitance between the skin and the sensor is detected through the passivation film to detect irregularities of a fine structure. Here, a conventional capacitive fingerprint sensor will be briefly described with reference to the drawings. This capacitive sensor is configured as shown in the sectional view of FIG. That is, first, a semiconductor substrate 1901 on which an LSI or the like is formed
A wiring 1903 is formed over the lower insulating film 1902, and an interlayer insulating film 1904 is formed thereover.

A sensor electrode 1906 having a rectangular planar shape, for example, is formed on the interlayer insulating film 1904. The sensor electrode 1906 is an interlayer insulating film 1904.
Is connected to the wiring 1903 through the plug 1905 in the through hole formed in the. And the interlayer insulating film 1
A passivation film 1907 is formed on 904 so as to cover the sensor electrode 1906 to form a sensor element. Then, as shown in the plan view of FIG. 20, those sensor elements have the sensor electrodes 190 of the adjacent sensor elements.
Two or more are arranged two-dimensionally so that 6 does not contact.

The operation of this capacitive sensor will be described. When detecting a fingerprint, first, the finger for fingerprint detection contacts the passivation film 1907. In this way, when the finger touches, the skin touching the passivation film 1907 functions as an electrode on the sensor electrode 1906, and a capacitance is formed between the sensor electrode 1906 and the sensor electrode 1906. This capacity is
It is detected via the wiring 1903. Here, since the fingerprint of the fingertip is formed by the unevenness of the skin, when the finger is brought into contact with the passivation film 1907, the distance between the skin as the electrode and the sensor electrode 1906 is the protrusion forming the fingerprint. The part and the recess are different. Then, this difference in distance is detected as a difference in capacity.
Therefore, if the distribution of these different capacities is detected, it becomes the shape of the protrusion of the fingerprint. That is, the capacitive sensor can detect the fine unevenness of the skin.

Further, such a capacitance type fingerprint sensor does not require a special interface as compared with the conventional optical sensor and can be miniaturized. This capacitive sensor is, for example, an integrated circuit (LSI) as shown below.
It can be mounted on the chip at the same time. That is, the above-mentioned integrated circuit chip in which a storage unit storing fingerprint data for collation, a fingerprint processing unit prepared in the storage unit, and a recognition processing unit for comparing and collating the read fingerprint are integrated, Capacitive sensors can be installed at the same time. As described above, by configuring on one integrated circuit chip, it becomes difficult to falsify information in the data transfer between the units, and the confidentiality keeping performance can be improved.

[0009]

However, in the above-mentioned sensor, since the skin is used as the electrode, the LS which is simultaneously mounted by the static electricity generated at the time of contact is used.
There is a problem that I is easily damaged by static electricity. Therefore, conventionally, a sensor that senses minute unevenness such as a human fingerprint or an animal nose print, which is considered to be stable, sensitive, and reliable, and is also considered to be compact and versatile, and manufacturing thereof. Development of a method was desired.

The present invention has been made in order to solve the above-mentioned problems, and is not electrostatically destroyed by static electricity generated during sensing.
The object is to enable stable and highly sensitive surface shape detection in a highly reliable state.

[0011]

Means for Solving the Problems] surface shape recognition sensor of the present invention, respectively in the same plane of the interlayer insulating film formed on a semi-conductor substrate is insulated and separated, and has a sensor electrode fixed arranged A plurality of capacitance detection elements, capacitance detection means for detecting the capacitance of each of the capacitance detection elements, a ground electrode disposed on the interlayer insulating film so as to be insulated from the sensor electrode, and the interlayer insulation film covering the sensor electrode. Yo
And a passivation formed from an insulating member
And a grounding electrode, and the ground electrode is a passivation film surface.
Target to recognize the surface shape that becomes the counter electrode that is partly in contact with the surface
Part of it is passivated so that it contacts the surface of the object
It is exposed on the film surface and is formed on the interlayer insulating film.
The steps are the ground electrode and the surface of the recognition target and the sensor electrode.
The capacity between and is detected . With this configuration, when the recognition target touches, the capacitance detected by the capacitance detection element changes according to the unevenness of the surface , and
When the object touches, this becomes one counter electrode,
While it is in contact with the ground electrode, the surface to be recognized and the
A capacitance is formed between the sensor electrode and the sensor electrode
Detected by.

[0012] In thus constructed this, the sensor electrode and the ground electrode may be constructed of copper. Further, the sensor electrode and the ground electrode may be made of gold. Further, the passivation film may be made of polyimide, and the polyimide may be polybenzoxazole. Also, to cover the side surface and the upper surface of the sensor electrode and the side surface and the upper surface of the ground electrode,
A conductive protective film may be provided. The protective film may be made of gold or ruthenium, for example. Also,
First and second wirings connected to the sensor electrode and the ground electrode are provided under the interlayer insulating film on the semiconductor substrate, and the sensor electrode and the ground electrode are connected through the first and second wirings. It may be connected to the capacitance detecting means. Further, the capacitance detecting means may be simultaneously mounted on the semiconductor substrate.

Further, in these configurations, the ground electrode is such that the exposed portion is formed in a grid pattern at least on the surface of the passivation film, and the sensor electrode is arranged at the central portion of the mass formed by the ground electrode. did. Therefore, the distances between the sensor electrode and the ground electrode are all uniform. Among them, the ground electrode is formed in the shape of a square lattice, and the capacitance detection element is constituted by one mass thereof, and the passivation film has a film thickness of 0.
If the thickness is set to 3 μm or more and 20 μm or less, the capacitance between the sensor electrode and the surface shape recognition target in contact with the passivation film on the sensor electrode can be detected. Among them, when trying to detect the state of a human fingerprint, A
Lattice spacing of over scan electrode was formed to have formed on the 100μm or less. Further, by adopting these configurations, for example, the passivation film may have a relative permittivity in the range of more than 2 and less than 7. For example, when a material having a relative dielectric constant of 4 is used for the passivation film and the film thickness on the sensor electrode is set to 2 μm, the sensor electrode may be formed in a square with one side of 20 μm or more. The distance to the ground electrode arranged at 2 is preferably 2 μm.

Further, in the surface shape recognition sensor of the present invention, the passivation film surface and the exposed surface of the ground electrode are formed to be substantially flat. In addition, the semiconductor device includes first and second wirings arranged under the interlayer insulating film on the semiconductor substrate and connected to the sensor electrode and the ground electrode,
The sensor electrode and the ground electrode are configured to be connected to the capacitance detecting means via the first and second wirings. Here, the capacitance detecting means may be simultaneously mounted on the semiconductor substrate.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First Embodiment First, a surface shape recognition sensor according to a first embodiment of the present invention will be described with reference to FIG. Although FIG. 1 shows two sensor elements constituting the surface shape recognition sensor, first, for example, on the interlayer insulating film 104 formed on the lower insulating film 102 on the semiconductor substrate 101, for example, sensor electrode 105 of the 80μm square, and were to include the ground electrodes 1 06. Thus, here, a case where one sensor element is provided with one sensor electrode 105 will be described. Further, on the lower insulating film 102, the wiring 103 connected to the sensor electrode 105 through the through hole 104a is formed.

Although not shown in FIG. 1, a wiring connected to the ground electrode 106 is also formed on the lower insulating film 102. Although not shown, they are connected to each other through through holes formed in the interlayer insulating film 104. Further, the passivation film 107 was formed so as to cover the sensor electrode 105, and the upper portion of the ground electrode 106 was exposed on the surface of the passivation film 107. Here, a plurality of sensor electrodes 105, that is, one sensor element are arranged at intervals of 100 μm. Also,
The passivation film 107 is made of, for example, an insulator such as silicon oxide having a relative dielectric constant of about 4.0, and the film thickness on the sensor electrode 105 is set to about 5 μm.

A sense unit 108 is formed on the semiconductor substrate 101 below the sensor element corresponding to each sensor element. The sense unit 108 is connected to each of the ground electrode 106 and the sensor electrode 105 via the wiring 103 described above. The sense unit 108 detects the capacitance formed between the ground electrode 106 and each sensor electrode 105. In addition, the output of each sense unit 108 is processed by a processing unit (not shown), and this processing unit generates image data in which the capacitance formed in each sensor electrode 105 is converted into light and shade.

The sense unit 108 does not have to be provided under one sensor element, but a plurality of sensor elements may be provided with one sense unit. Further, the sensor unit may be formed in another region on the semiconductor substrate 101 together with the above-mentioned processing means. Further, the processing means may be arranged below the sensor element together with the sensor unit. The sense unit 108 and the processing means do not necessarily need to be monolithically integrated on the semiconductor substrate 101.
However, the sensor electrode 105, the sense unit 108, and the processing means should be arranged as close as possible.

In the surface shape recognition sensor configured as described above, when the tip of the finger comes into contact with the passivation film 107, first, the protrusion of the fingerprint comes into contact with the upper portion of the ground electrode 106. Since a human fingerprint has a width of about 200 to 300 μm, it always contacts the earth electrodes 106 arranged at 100 μm intervals. As a result, the tip of the finger placed on the passivation film 107 and in contact with the protrusion of the fingerprint has the same potential as the ground electrode 106. A capacitance is formed between each part of the finger tip and the sensor electrode 105, and the capacitance is detected by the sense unit 108.

Here, on the passivation film 107 on which the tip of the finger is placed, the fingerprint protrusion is the passivation film 10.
7 and the fingerprint recess is separated from the passivation film 107. Therefore, the distance d1 between the surface of the fingerprint protrusion and the sensor electrode 105 below it is different from the distance d2 between the surface of the fingerprint recess and the sensor electrode 105 below it.
d1 <d2. The capacitance C1 between the surface of the fingerprint protrusion and the sensor electrode 105 below it is different from the capacitance C2 between the surface of the fingerprint recess and the sensor electrode 105 below it.
Therefore, the capacitance between the sensor electrode 105 and the ground electrode 106 below the fingerprint protrusion and the sensor electrode 10 below the fingerprint recess.
5 and the capacitance between the ground electrode 106 will be detected differently.

For example, in the above configuration, C1 is 45f
It will be about F. On the other hand, since the fingerprint depth is about 100 μm, C2 is about 2.3 fF. If a plurality of sensor electrodes 105 are arranged in a matrix,
The capacitance due to the unevenness of the fingerprint can be detected corresponding to the arrangement state. As a result, the shape of the fingerprint can be reproduced by adding grayscale data by the processing means corresponding to the respective capacitances detected at the respective sensor electrodes 105. For example, the sensor electrodes are arranged in a matrix at intervals of 100 μm.
When 00 × 300 (pieces) are arranged, a fingerprint image of 300 × 300 dots can be obtained with a resolution of about 250 dots / inch.

On the other hand, although not shown in FIG. 1, in the other area on the semiconductor substrate 101, a storage section in which fingerprint data for collation is stored, or fingerprint data prepared in the storage section and read-in are read. It has an integrated circuit in which a recognition processing unit for comparing and collating the obtained fingerprint image is integrated. Note that all of them may be arranged on the semiconductor substrate 101 below the sensor electrode 105. With this configuration, in a more compact state, it is possible to compare the detected fingerprint shape and the fingerprint data stored in the storage unit with the recognition processing unit configured in the integrated circuit to collate the fingerprint. Becomes

In the surface shape recognition sensor according to the first embodiment, for example, when recognizing the shape of a fingerprint, part of the finger touches the ground electrode. Therefore, when the finger comes into contact, static electricity is generated on the surface of the surface shape recognition sensor. However, since the static electricity flows to the ground electrode, it is possible to prevent other integrated circuit portions formed below from being destroyed by the static electricity.

Next, a part of the method of manufacturing the surface shape recognition sensor according to the first embodiment described above will be briefly described. First, another integrated circuit such as the above-described sense unit is formed on the semiconductor substrate 101, and then, as shown in FIG.
As shown in (a), a lower insulating film 102 is formed on the semiconductor substrate 101 so as to cover the integrated circuits, and a wiring 103 is formed thereon. Although not shown, the wiring to be connected to the ground electrode 106 described later is also formed at this time.

Next, as shown in FIG. 2B, the wiring 10
3 on the lower insulating film 102 so as to cover the interlayer insulating film 10.
4 is formed. Next, as shown in FIG. 2C, the through hole 1 is formed at a predetermined position on the wiring 103 of the interlayer insulating film 104.
04a is formed. Although not shown, through holes are also formed at the wiring points connected to the ground electrode 106 described later at the same time. Next, as shown in FIG. 3D, the sensor electrode 105 connected to the wiring 103 via the through hole 104a is formed on the interlayer insulating film 104.

Next, as shown in FIG. 3E, a ground electrode 106 thicker than the sensor electrode 105 is formed on the interlayer insulating film 104 so as to be separated from the sensor electrode 105. In addition,
Although not shown, the ground electrode 106 is connected to a corresponding wiring formed on the lower insulating film 102 through a through hole (not shown) formed in the interlayer insulating film 104. Connected. And FIG.
As shown in (f), a passivation film 107 is formed so as to fill the recess formed by the ground electrode 106 and cover the sensor electrode 105. At this time, the upper portion of the ground electrode 106 is exposed on the surface of the passivation film 107. By the above, the electrode portion of the surface shape recognition sensor of the first embodiment shown in FIG. 1 can be formed.

Second Embodiment Next, a surface shape recognition sensor according to a second embodiment of the present invention will be described. 4 (a), (b), (c)
FIG. 4 is a configuration diagram showing a configuration of a surface shape recognition sensor according to the second embodiment. Here, FIGS. 4A and 4B
Shows a cross section, and FIG. 4 (c) is a plan view. And, the AA ′ cross section of FIG. 4C is FIG. 4A, and FIG.
The BB ′ cross section of FIG. In the second embodiment, first, an insulating film 401 on a semiconductor substrate (not shown)
80 μm, for example, on the interlayer insulating film 403 formed above
A corner sensor electrode 405 and a ground electrode 406 are provided. Thus, here, the case where one sensor element is provided with one sensor electrode 405 will be described. That is, FIG. 4A shows one sensor element which constitutes the surface shape recognition sensor of the second embodiment.

[0028] The sensor electrode 405, the wiring 402 a made of aluminum formed on the insulating film 401, are connected via a barrier film 404 made of titanium nitride. As shown in FIG. 4B, a wiring 402a made of aluminum is also formed on the insulating film 401, and is connected to the ground electrode 406 via the barrier film 404. Here, the ground electrode 406 is composed of a lower electrode 406a made of copper and an electrode column 406b also formed of copper on the lower electrode 406a. Then, a protective film 406c made of gold was formed on the surface of the ground electrode 406. Also,
A protective film 405 made of gold is also formed on the surface of the sensor electrode 405.
a was formed. Also, to cover the sensor electrode 405,
For example, a passivation film 407 made of silicon oxide was formed, and the surface of the passivation film 407 exposed the upper portion of the ground electrode 406, that is, the surface of the protective film 406c.

Here, as shown in FIG. 4C, the ground electrodes 406 were formed in a grid pattern with 100 μm intervals. In addition, a sensor electrode 405 is formed in the center between the lattices.
A plurality of them were arranged in a matrix at intervals of 0 μm. Therefore, in the second embodiment, each of the squares of the lattice constitutes one sensor element.
In (c), nine sensor elements are arranged in a matrix. In addition, the passivation film 4
07 is made of an insulating material having a relative dielectric constant of about 4.0, is filled in between the lattices of the ground electrode 406, and is formed so that the film thickness on the sensor electrode 405 is, for example, about 5 μm.

Although not shown, a sense unit is formed on the semiconductor substrate below the sensor element.
This sense unit is connected to each of the ground electrode 406 and the sensor electrode 405 via the wiring 402 described above. Then, this sense unit detects the capacitance formed between the ground electrode 406 and each sensor electrode 405 and outputs a signal corresponding to them. Further, the output of each sense unit is processed by a processing unit (not shown), and this processing unit generates image data in which the capacitance formed in each sensor electrode 405 is converted into light and shade. The sense unit and the processing unit are not limited to those arranged on the semiconductor substrate (not shown) below the sensor electrode 405, but may be arranged on other regions of the semiconductor substrate.

The surface shape recognition sensor configured as described above is the same as that in the first embodiment described above. When the tip of the finger comes into contact with the passivation film 407, the fingerprint is first printed on the ground electrode 406. The protrusion contacts. Since the width of a human fingerprint is about 200 to 300 μm, 10
Earth electrodes 406 formed in a grid pattern at intervals of 0 μm
The protrusion of the fingerprint will always come into contact with. As a result, the tip of the finger placed on the passivation film 407 and in contact with the fingerprint protrusion has the same potential as the ground electrode 406. Then, each part of the finger tip and the sensor electrode 4
Capacitors are formed between the respective capacitors 05 and 05, and the capacitors are detected by the sense unit.

Here, on the passivation film 407 on which the tip portion of the finger is placed, the fingerprint protrusion is the passivation film 40.
7, and the fingerprint recess is separated from the passivation film 407. Therefore, the distance d1 between the surface of the fingerprint protrusion and the sensor electrode 405 below it is different from the distance d2 between the surface of the fingerprint recess and the sensor electrode 405 below it.
d1 <d2. The capacitance C1 between the surface of the fingerprint protrusion and the sensor electrode 405 below it is different from the capacitance C2 between the surface of the fingerprint recess and the sensor electrode 405 below it.
Therefore, the capacitance between the sensor electrode 405 and the ground electrode 406 below the fingerprint protrusion and the sensor electrode 40 below the fingerprint recess.
5 and the capacitance between the ground electrode 406 will be detected differently.

For example, in the above configuration, C1 is 45f
It will be about F. On the other hand, since the fingerprint depth is about 100 μm, C2 is about 2.3 fF. A plurality of sensor electrodes 405 are arranged in a matrix, and the capacitance due to the unevenness of the fingerprint is detected according to the arrangement state.
As a result, the shape of the fingerprint can be reproduced by corresponding to each capacitance detected at the location of each sensor electrode 405 and adding the grayscale data by the processing means. For example,
When the sensor electrodes are arranged at 100 μm intervals of 300 × 300 (pieces), the resolution of about 250 dots / inch is 30.
A fingerprint image of 0 × 300 dots can be obtained.

On the other hand, although not shown in FIG. 4, in other areas on the semiconductor substrate, a storage unit storing fingerprint data for collation or fingerprint data prepared in the storage unit is read. It has an integrated circuit in which a recognition processing unit for comparing and collating the fingerprint image is integrated. Note that all of these may be arranged on the semiconductor substrate below the sensor electrode 405. With this configuration, in a more compact state, it is possible to compare the detected fingerprint shape and the fingerprint data stored in the storage unit with the recognition processing unit configured in the integrated circuit to collate the fingerprint. Becomes

Also in the surface shape recognition sensor of the second embodiment, for example, when recognizing the shape of a fingerprint, a part of the finger touches the ground electrode. Therefore, when the finger comes into contact, static electricity is generated on the surface of the surface shape recognition sensor. However, since the static electricity flows to the ground electrode, it is possible to prevent other integrated circuit portions formed below from being destroyed by the static electricity. Further, according to the second embodiment, since the exposed surface of the ground electrode is covered with gold, formation of an oxide film on the contact surface of the ground electrode can be suppressed. Further, according to the second embodiment, since the ground electrode is formed in a grid shape and the sensor electrode is arranged at the center of the mass, the distance between the ground electrode and each sensor electrode becomes equal.

Next, a part of the method of manufacturing the surface shape recognition sensor of the second embodiment described above will be described. First, other integrated circuits such as the above-described sense unit are formed on a semiconductor substrate, and thereafter, as shown in FIG. 5A, on the semiconductor substrate so as to cover the integrated circuits,
An insulating film 401 made of silicon oxide is formed, and a wiring 402 made of aluminum is formed thereon. The wiring 402 may be formed by forming an aluminum film and then patterning it by a known photolithography technique. Next, the insulating film 4 is formed so as to cover the wiring 402.
An interlayer insulating film 403 is formed on 01. Next, the through hole 40 is formed at a predetermined position on the wiring 402 of the interlayer insulating film 403.
3a is formed.

At least the through hole 403a
A barrier film 404 made of titanium nitride is formed so as to cover the surface of the wiring 402 exposed at the bottom. This barrier film 4
Formation of 04 may be performed as follows. First, a titanium nitride film is formed by sputtering or the like on the interlayer insulating film 403 having the through holes 403a formed therein. Then, a resist pattern is formed by a photolithography technique so as to hide the through hole forming portion. Then, using this resist pattern as a mask, the titanium nitride film is selectively removed by dry etching such as RIE, and the resist pattern is removed, whereby the barrier film 404 is formed. The barrier film 404 is not limited to one made of titanium nitride. The barrier film 404 may be made of another conductive material capable of suppressing mutual diffusion.

Next, as shown in FIG. 5B, a metal thin film 501 made of copper is formed to a thickness of about 0.1 μm on the interlayer insulating film 403 including the barrier film 404. This may be performed, for example, by a sputtering method. Then, FIG. 5 (c)
As shown in FIG. 5, a resist pattern 502 having an opening 502a in a predetermined region corresponding to the upper portion of the through hole 403a is formed on the metal thin film 501. Then, by an electroplating method using the metal thin film 501 as a cathode, on the surface of the metal thin film 501 exposed at the bottom of the opening 502a,
A protective film 405a is formed by forming a copper film with a film thickness of 0.3 μm and a gold film with a film thickness of 0.2 μm. The formation of the protective film 405a is not limited to the electrolytic plating method.

Next, after removing the resist pattern 502, this time, as shown in FIG. 5D, a protective film 405a is formed.
Forming a resist pattern 503 having a groove 503a surrounding the. Note that the groove 503a is also opened above the barrier film 404 portion connected to the wiring 402a shown in FIG. 4B. Next, as shown in FIG. 6E, the groove 5 is formed by electrolytic plating using the metal thin film 501 as a cathode.
Copper is grown to a film thickness of about 5 μm on the surface of the metal thin film 501 exposed at the bottom of 03a to form the electrode pillar 406b. Continuing on, as shown in FIG.
Similarly, a gold film with a thickness of 0.1μ is electrolytically plated on the upper surface of b.
A film having a thickness of about m is formed to form a protective film 406c. Note that, for example, the formation of the electrode pillar 406b is not limited to the electrolytic plating method, and an electroless plating method may be used.

Next, after removing the resist pattern 503, as shown in FIG. 6G, the metal thin film 501 is selectively removed by etching using the protective films 405a and 406c as masks. This etching is performed with phosphoric acid, nitric acid,
Alternatively, a wet process using an aqueous solution of a mixed acid of acetic acid as an etching solution may be performed. As a result, the ground electrodes 406 are formed in a grid pattern on the interlayer insulating film 403,
At the center of the square of the ground electrode 406, the sensor electrode 4
05 will be formed. Next, as shown in FIG. 6H, a passivation film 407 is formed so as to fill the mass of the ground electrode 406. The passivation film 407 may be formed as follows.
First, on the interlayer insulating film 403 on which the sensor electrode 405 and the ground electrode 406 are formed, SO is applied by spin coating or the like.
A G material is applied to form an SOG film.

Here, in order to form the SOG film thick, S
The OG material is applied three times. By this coating, the surface of the SOG film is made flat by absorbing the irregularities on the interlayer insulating film 403 due to the ground electrode 406 and the sensor electrode 405. After forming the SOG film by coating these, 300 ℃
The coating film is transformed into a film made of silicon oxide by heating to a certain degree. Then, by etching back the SOG film until the surface of the ground electrode 406 is exposed, the ground electrode 406 is formed.
A passivation film 407 having a flat surface can be formed so as to fill the inside of the cell. By the above, the electrode portion of the surface shape recognition sensor of the second embodiment shown in FIG. 4 can be formed.

The passivation film 407 does not need to be formed as described above, and is made of an insulating material.
As shown in (h), it suffices if the surface can be formed flat. Therefore, for example, a silicon oxide film is deposited and formed so as to cover the ground electrode 406 by the CVD method or the like, and the ground electrode 406 is formed by the chemical mechanical polishing method.
The passivation film 407 whose surface is flattened may be formed by cutting and polishing until the upper surface is exposed. In addition, it is not always necessary to provide a pair of ground electrodes whose surfaces are exposed beside each sensor electrode, and a plurality of sensor electrodes may be provided with one ground electrode. However, as in the second embodiment, by forming the ground electrodes in a grid pattern and providing the sensor electrodes in the center of the mass, the sensor electrodes and the ground electrodes arranged in a matrix are formed. The intervals can be equal.

Third Embodiment Next, a surface shape recognition sensor according to a third embodiment of the present invention will be described. In this Embodiment 3, FIG.
As shown in, first, on the interlayer insulating film 703 formed on the insulating film 701, for example, a sensor electrode 705 made of copper 80μm square, and were to include the ground electrodes 7 06. Although not shown, the insulating film 701 is formed on a semiconductor substrate on which integrated circuits such as a sense unit and a processing unit described later are formed. Earth electrode 7
06, for example, has a size of 100 μm in the mass.
It is formed in a grid shape with square corners. Also,
A sensor electrode 705 is arranged at the center of the mass. The number of masses is about 300 × 300, so that the sensor electrodes 705 are arranged in a matrix of 300 × 300.
300 pieces are arranged.

On the insulating film 701, a wiring 702a made of aluminum is provided which is connected to the sensor electrode 705 via a barrier film 704 made of titanium nitride. The sensor electrode 705 includes a lower electrode 705a having a two-layer structure made of chromium and copper and having a film thickness of about 0.1 μm, and an upper electrode 705b having a film thickness of about 0.3 μm formed thereon. Configured. The upper electrode 705b was made of copper.

Similarly, the insulating film 701 is provided with a wiring 702b made of aluminum, which is connected to the ground electrode 706 through the barrier film 704 made of titanium nitride. The ground electrode 706 is also composed of a lower electrode 706a having a two-layer structure made of chromium and copper, and an electrode pillar 706b made of copper and having a thickness of about 5 μm formed thereon. In addition, as in the second embodiment described above, the lower electrode 7
The metal of the lower layer constituting 05a and 706a is not limited to chromium, and for example, another metal such as titanium or nickel that suppresses diffusion of copper and improves adhesion to an insulating material may be used. In the third embodiment, the protective film 705 made of ruthenium covers the upper surface and the side surface of the sensor electrode 705 and the ground electrode 706.
c and the protective film 706c.

Further, a passivation film 707 made of polyimide is provided so as to cover the sensor electrode 705, and the upper part of the ground electrode 706 is exposed on the surface of the passivation film 707. The passivation film 707 is formed so as to fill the space between the lattices of the ground electrode 706 and have a film thickness on the sensor electrode 705 of, for example, about 5 μm. Further, the above-mentioned sense unit is the same as the above-mentioned wiring 702a,
They are connected to the respective sensor electrodes 705 and ground electrodes 706 via 702b and the like. The sense unit includes a ground electrode 706 and each sensor electrode 705.
It detects the capacitance formed between and and outputs a signal corresponding to them.

The output of each sense unit is processed by a processing means (not shown), and this processing means generates image data in which the capacitance formed in each sensor electrode 705 is converted into light and shade. These are the same as in the first and second embodiments described above. That is, the third embodiment
Even in the surface shape recognizing sensor, the shape of the fingerprint can be reproduced by adding the grayscale data by the processing means corresponding to the respective capacities detected at the respective sensor electrodes 705 forming one sensor element. become.

Incidentally, although not shown in FIG. 7, in other areas on the semiconductor substrate, a storage unit in which fingerprint data for collation is stored, and fingerprint data prepared in the storage unit are read. It has an integrated circuit in which a recognition processing unit for comparing and collating the fingerprint image is integrated. Note that all of these may be arranged on the semiconductor substrate below the sensor electrode 705. With this configuration, in a more compact state, it is possible to compare the detected fingerprint shape and the fingerprint data stored in the storage unit with the recognition processing unit configured in the integrated circuit to collate the fingerprint. Becomes

Also in the surface shape recognition sensor of the third embodiment, for example, when recognizing the shape of a fingerprint, a part of the finger touches the ground electrode. Therefore, when the finger comes into contact, static electricity is generated on the surface of the surface shape recognition sensor. However, since the static electricity flows to the ground electrode, in the surface shape recognition sensor of the third embodiment, it is possible to prevent other integrated circuit portions formed below from being destroyed by the static electricity. Further, according to the third embodiment, since the exposed surface of the ground electrode is covered with ruthenium, formation of an oxide film on the contact surface of the ground electrode can be suppressed.
Further, according to the third embodiment, since the ground electrode is formed in a grid shape and the sensor electrode is arranged in the central portion of the mass, the distance between the ground electrode and each sensor electrode becomes equal.

Next, a part of the method of manufacturing the surface shape recognition sensor of the third embodiment described above will be described. First, other integrated circuits such as the above-described sense unit are formed on a semiconductor substrate, and thereafter, as shown in FIG. 8A, on the semiconductor substrate so as to cover the integrated circuits,
An insulating film 701 made of silicon oxide is formed, and wirings 702a, 702b made of aluminum are formed thereon. The wirings 702a and 702b may be formed by forming an aluminum film and then patterning it by a known photolithography technique. Next, the wiring 70
An interlayer insulating film 703 is formed on the insulating film 701 so as to cover 2a and 702b. Next, through holes 703 are formed at predetermined locations on the wirings 702a and 702b of the interlayer insulating film 703.
a, 703b is formed.

At least the through hole 703
A barrier film 704 made of titanium nitride is formed so as to cover the surfaces of the wirings 702a and 702b exposed at the bottoms of the a and 703b. The barrier film 704 may be formed as follows. First, a titanium nitride film is formed by a sputtering method or the like on the interlayer insulating film 703 in which the through holes 703a and 703b are formed. Next, a resist pattern is formed by a photolithography technique so as to hide the through hole forming portion. Then, using this resist pattern as a mask, the titanium nitride film is selectively removed by dry etching such as RIE, and the resist pattern is removed, whereby the barrier film 704 is formed. Note that the barrier film 704 is not limited to one made of titanium nitride. Barrier film 704
Alternatively, another conductive material that can suppress mutual diffusion may be used.

Next, as shown in FIG. 8B, 0.1 μm is formed on each of the interlayer insulating films 703 including the barrier film 704.
A metal thin film 8 having a two-layer structure consisting of a chromium film and a copper film of about m
01 is formed. For example, this chromium film may be formed by a vapor deposition method and the copper film may be formed by a sputtering method. in this way,
By providing the chrome film below, the diffusion of copper can be suppressed and the adhesion of copper can be improved. Note that, again, instead of this chromium, for example, a metal capable of suppressing the diffusion of copper and improving the adhesiveness, such as titanium or nickel, may be used.

Next, as shown in FIG. 8C, a resist pattern 8 having an opening 802a on a predetermined area corresponding to the upper portion of the through hole 703a on the metal thin film 801.
02 is formed to a film thickness of about 5 μm. Then, the opening 8 is formed by an electrolytic plating method using the metal thin film 801 as a cathode.
02a By forming a copper film with a thickness of 0.3 μm on the surface of the metal thin film 801 exposed at the bottom, the upper electrode 705b
To form. The formation of the upper electrode 705b is not limited to the electrolytic plating method.

Next, after removing the resist pattern 802, this time, as shown in FIG. 9D, the upper electrode 705 is formed.
a resist pattern 903 having a groove 903a surrounding b.
The film thickness is formed to about 5 μm. The groove 903a is a region where the ground electrode 706 shown in FIG. 7 is arranged. Then, by an electrolytic plating method using the metal thin film 801 as a cathode,
Copper is grown to a film thickness of about 5 μm on the surface of the metal thin film 801 exposed at the bottom of the groove 903a to form an electrode pillar 706b.

Next, after removing the resist pattern 903, as shown in FIG. 9E, the metal thin film 801 on the exposed surface is removed by etching. In this etching, first, the upper copper film is removed by a wet process using an aqueous solution of a mixed acid of phosphoric acid, nitric acid, and acetic acid as an etching solution. Next, the lower layer of chromium may be removed by a wet process using an aqueous solution of potassium ferricyanide and sodium hydroxide as an etching solution. As a result, a height of 5 μm is formed on the interlayer insulating film 703.
The ground electrode 706 is formed in a grid pattern. Then, in the center of the grid of the grid-shaped ground electrode 706,
The sensor electrode 705 will be formed. Next, FIG.
As shown in (f), a protective film 705c and a protective film 706c made of ruthenium are formed on the exposed surfaces of the sensor electrode 705 and the ground electrode 706. This formation can be performed by growing ruthenium by about 0.1 μm only on the surface of each electrode made of copper by the electroless plating method.

Then, as shown in FIG. 7, a passivation film 707 is formed so as to fill the grid of the grid-shaped ground electrode 706. This passivation film 70
Formation of 7 may be performed as follows. First, a polyimide material is applied by spin coating or the like on the interlayer insulating film 703 on which the sensor electrode 705 and the ground electrode 706 are formed to form a polyimide film. As the polyimide material, for example, a polyimide resin based on a polybenzoxazole precursor was used. By this application,
The surface of the polyimide film is formed flat by absorbing irregularities on the interlayer insulating film 703 due to the ground electrode 706 and the sensor electrode 705. After forming the polyimide film by applying these, the polyimide film applied is heated to about 310 ° C. to be thermoset.

Then, the cured polyimide film is etched back until the surface of the ground electrode 706 is exposed, so that the passivation film 7 made of polyimide has a flat surface so as to fill the mass of the ground electrode 706.
07 can be formed. This etch back may be performed by dry etching using plasma of oxygen gas, for example. Since polyimide is an organic material, it can be etched by using plasma of oxygen gas.
The etch back may be performed by, for example, a chemical mechanical polishing method. By the above, the electrode portion of the surface shape recognition sensor of the third embodiment shown in FIG. 7 can be formed.

By the way, although the ground electrode 706 is formed in a lattice shape in the above description, the present invention is not limited to this. In this state, a plurality of ground electrodes 703 may be formed. However, it is assumed that the ground electrodes 703 are connected to each other in the lower wiring layer and have the same potential. In addition, it is not always necessary to provide a pair of ground electrodes whose surfaces are exposed beside each sensor electrode, and a plurality of sensor electrodes may be provided with one ground electrode. However, as in the third embodiment, by forming the ground electrodes in a grid pattern and providing the sensor electrodes at the center of the mass, the sensor electrodes and the ground electrodes arranged in a matrix are formed. The intervals can be equal.

Fourth Embodiment Next, a surface shape recognition sensor according to a fourth embodiment of the present invention will be described. In this Embodiment 4, FIG.
As shown in FIG. 0, first, the inter-layer insulating film 1003 formed on the insulating film 1001 was provided with the sensor electrode 1005 made of, for example, 80 μm square gold and the ground electrode 1006. Although not shown, the insulating film 1001 is formed on a semiconductor substrate on which integrated circuits such as a sense unit and a processing unit described later are formed.

The ground electrode 1006 is similar to that of the third embodiment, and the size of the inside of the mass is 100 and 100.
It is formed in a lattice shape in the form of a square of μm square. Further, a sensor electrode 1005 is arranged at the center of the mass. The number of masses is about 300 × 300, so that the sensor electrodes 1005 are arranged in a matrix of 300 × 300. The insulating film 100
A wiring 1002a made of aluminum, which is connected to the sensor electrode 1005 via a barrier film 1004 made of titanium nitride, is provided on the first layer. The sensor electrode 1005 includes a lower electrode 1005a having a two-layer structure of chromium and gold each having a film thickness of about 0.1 μm, and an upper electrode 1005 made of gold and having a film thickness of about 0.3 μm formed thereon.
and b.

Similarly, the ground electrode 100 is formed on the insulating film 1001 via the barrier film 1004 made of titanium nitride.
The wiring 1002b made of aluminum and connected to No. 6 is provided. The ground electrode 1006 is also composed of a lower electrode 1006a having a two-layer structure made of chromium and gold, and an electrode pillar 10 made of gold and formed on the lower electrode 1006a having a thickness of about 5 μm.
And 06b. By thus disposing the chromium film as the lower layer, the adhesion between the gold film and the underlying interlayer insulating film 1003 can be improved. As described above, instead of chromium, for example, titanium or nickel,
A metal capable of suppressing the diffusion of gold and improving the adhesion with the insulating material may be used.

Further, so as to cover the sensor electrode 1005,
A passivation film 1007 made of polyimide,
On the surface of the passivation film 1007, the earth electrode 100
The top of 6 was exposed. In addition, the passivation film 100
7 was formed so that the grid of the ground electrode 1006 was filled, and the film thickness on the sensor electrode 1005 was, for example, about 5 μm. As described above, in the fourth embodiment, the sensor electrode 1005 and the ground electrode 1006 are made of gold, so that they do not corrode and need not have a protective film or the like. Further, since polyimide made of polybenzoxazol is used for the passivation film 1007, it has good adhesion to gold. It can be suppressed almost.

The above-mentioned sense unit is connected to the respective sensor electrode 1005 and ground electrode 1006 via the above-mentioned wirings 1002a and 1002b. Then, this sense unit has the ground electrode 10
The capacitance formed between 06 and each sensor electrode 1005 is detected, and the signal corresponding to them is output. Further, the output of each sense unit is processed by a processing unit (not shown), and this processing unit processes each sensor electrode 1005.
Image data is generated by converting the formed capacitance into a shade.

In the surface shape recognition sensor constructed as described above, when the tip of the finger comes into contact with the passivation film 1007, the protrusion of the fingerprint comes into contact with the upper part of the ground electrode 1006. Human fingerprint width is about 200-300μ
Since it is about m, the protrusions of the fingerprint will surely come into contact with the ground electrodes 1006 formed in a grid pattern at intervals of 100 μm. As a result, the finger tip portion, which is placed on the passivation film 1007 and is in contact with the protrusion of the fingerprint, has the same potential as the ground electrode 1006. A capacitance is formed between each part of the finger tip and the sensor electrode 1005, and the capacitance is detected by the sense unit.

Then, as described in the first embodiment, the capacitance between the sensor electrode 1005 below the fingerprint protrusion and the ground electrode 1006 and the sensor electrode 10 below the fingerprint recess.
The capacitance between 05 and the ground electrode 1006 will be detected differently. As a result, each sensor electrode 1005
If the grayscale data is added by the processing means corresponding to the respective capacities detected at the points, the shape of the fingerprint can be reproduced. On the other hand, although not shown in FIG. 10, it is similar to the third embodiment described above, and in other areas on the semiconductor substrate, a storage unit storing fingerprint data for collation or prepared in the storage unit. It is provided with an integrated circuit in which a recognition processing unit for comparing and collating the fingerprint data being read and the read fingerprint image is integrated. All of these may be arranged on the semiconductor substrate below the sensor electrode 1005. With this configuration, in a more compact state,
It becomes possible to collate the fingerprints by comparing the detected fingerprint shape and the fingerprint data stored in the storage unit by the recognition processing unit configured in the integrated circuit.

Even in the surface shape recognition sensor of the fourth embodiment, for example, when recognizing the shape of a fingerprint, part of the finger touches the ground electrode. Therefore, when the finger comes into contact, static electricity is generated on the surface of the surface shape recognition sensor. However, since the static electricity flows to the ground electrode, in the surface shape recognition sensor according to the fourth embodiment, it is possible to prevent other integrated circuit portions formed below from being destroyed by the static electricity.

Further, according to the fourth embodiment, since the ground electrode is made of gold, no oxide film is formed on the contact surface of the ground electrode. Further, according to the fourth embodiment, since the ground electrode is formed in a grid shape and the sensor electrode is arranged in the central portion of the mass, the distance between the ground electrode and each sensor electrode becomes equal. Also in the fourth embodiment, the side surface and the upper surface of the sensor electrode and the side surface and the upper surface of the ground electrode may be covered with a protective film made of, for example, ruthenium. By covering with the protective film as described above, the adhesion with the passivation film may be improved in some cases.

Next, a part of the method of manufacturing the surface shape recognition sensor of the fourth embodiment described above will be described. First, other integrated circuits such as the above-described sense unit are formed on a semiconductor substrate, and thereafter, as shown in FIG. 11A, silicon oxide is formed on the semiconductor substrate so as to cover the integrated circuits. Forming an insulating film 1001
Wirings 1002a, 100 made of aluminum
2b is formed. The wirings 1002a and 1002b are
It may be formed by forming an aluminum film and then patterning it by a known photolithography technique.
Next, an interlayer insulating film 1003 is formed over the insulating film 1001 so as to cover the wirings 1002a and 1002b. next,
Through holes 1003a and 1003b are formed at predetermined locations on the wirings 1002a and 1002b of the interlayer insulating film 1003.

Then, similarly to the first to third embodiments described above, the barrier film 1004 made of titanium nitride is formed so as to cover at least the surfaces of the wirings 1002a and 1002b exposed at the bottoms of the through holes 1003a and 1003b. Next, as shown in FIG. 11B, the barrier film 100
A metal thin film 1101 made of chromium and gold is formed to a thickness of about 0.2 μm on the inter-layer insulating film 1003 containing 4 and 4. This may be performed, for example, by a vapor deposition method. In this way, by providing the chrome film below, it is possible to suppress the diffusion of gold,
Further, the adhesion of gold to the interlayer insulating film 1003 can be improved. As described above, instead of this chromium, for example, a metal that can suppress the diffusion of gold and improve the adhesion such as titanium or nickel may be used.

Next, as shown in FIG. 11C, a resist pattern 1102 having an opening 1102a in a predetermined region above the through hole 1003a is formed on the metal thin film 1101 to a film thickness of about 5 μm. Then, an upper electrode 1005b is formed by forming a gold film with a thickness of 0.3 μm on the surface of the metal thin film 1101 exposed at the bottom of the opening 1102a by electrolytic plating using the metal thin film 1101 as a cathode. . Next, after removing the resist pattern 1102, as shown in FIG. 12D, a resist pattern 1203 having a groove 1203a surrounding the upper electrode 1005b is formed to a film thickness of about 5 μm. The groove 1203a is a region where the ground electrode 1006 shown in FIG. 10 is arranged. And the metal thin film 1
The groove 120 is formed by an electrolytic plating method using 101 as a cathode.
Gold is grown to a film thickness of about 5 μm on the surface of the metal thin film 1101 exposed at the bottom of 3a to form the electrode pillar 1006b.

Next, after removing the resist pattern 1203, the metal thin film 1101 in the portion where the surface is exposed is removed by etching. In this etching, first, the upper gold film is removed by a wet process using an aqueous solution of a mixed solution of iodine, ammonium iodide, and ethanol as an etching solution. In this case, the etching rate is 0.
It was about 05 μm. Next, the lower layer of chromium may be removed by a wet process using an aqueous solution of potassium ferricyanide and sodium hydroxide as an etching solution.

As a result of the above, as shown in FIG. 10, the ground electrode 1006 is formed on the inter-layer insulating film 1003 in a grid pattern with a height of about 5 μm. Then, the sensor electrode 1005 is formed at the center of the grid of the grid-shaped ground electrode 1006.
Will be formed. Then, similarly to the third embodiment described above, if the passivation film 1007 is formed so as to be embedded in the grid of the grid-shaped ground electrode 1006, the surface shape recognition for the fourth embodiment shown in FIG. A sensor is formed. Also in the fourth embodiment, it is not necessary to form the ground electrode 1006 in a grid shape, and for example, one side around the sensor electrode 1005 embedded in the passivation film 1007 is separated on the surface of the passivation film 1007. Alternatively, a plurality of ground electrodes 1003 may be formed.

By the way, as described above, when the ground electrode is formed in a grid pattern and the sensor electrode is arranged at the center of the grid mass, the ground electrode and the sensor electrode are arranged close to each other. Therefore, a parasitic capacitance is generated between them. If this parasitic capacitance is too large, it becomes difficult to detect the capacitance between the sensor electrode and the surface of the finger touching the passivation film. Here, in the case of detecting the fingerprint of a human finger, the surface shape recognition sensor uses 250 to 5
A resolution of 00 dpi will be required. In order to satisfy this requirement, the size of one sensor element arranged in a matrix, that is, the pitch of the sensor elements needs to be 100 μm square or less.

Here, when the cross section of the sensor element is schematically considered as shown in FIG. 13, a square sensor electrode 1302 and a grid-shaped ground electrode 1 are formed on the interlayer insulating layer 1301.
The passivation film 1304 having a relative permittivity of 4 is formed so that 303 is disposed and the space between the ground electrodes 1303 is filled. Then, when the fingerprint is detected, the finger 1305 comes into contact with the passivation film 1304. The finger 1305 is in contact with the ground electrode 1303 in a region not shown. At this time, the finger 1305, the ground electrode 1303, and the sensor electrode 130
A capacitance is formed between the two. However, there is a parasitic capacitance Cp between the sensor electrode 1302 and the ground electrode 1303.
Since There has been formed, from above volume generated by the finger 130 5 are in contact, is minus the parasitic capacitance Cp,
The capacitance Cf is related to surface shape detection.

The relationship between the capacitance Cf and the distance L between the sensor electrode 1302 and the ground electrode 1303 is, for example, 1
When the size of one sensor element is 80 μm square and the ground electrode 1303 has almost no width, that is, when W ₀ = 80 μm, a simulation can be performed as shown in FIG. Note that here, the passivation film 1304
This is the case when the film thickness on the sensor electrode 1302 is 2 μm and the relative dielectric constant is 2. 14, first, the parasitic capacitance Cp represents the case where shall be generated only between the sensor electrode 1302 side and the ground electrode 1303 by dashed lines.

However, in reality, the parasitic capacitance C is present between the side surface and the upper surface of the sensor electrode 1302 and the ground electrode 1303.
Since p is formed, the results in consideration of that are shown by the dotted line and the solid line. Among them, the solid line shows the effect of the upper surface more largely. In addition, in FIG.
The maximum area where the sensor electrode 1302 can be formed is 80 μm
Since the area is smaller than the corner, the area of the sensor electrode 1302 becomes smaller and the capacitance Cf becomes smaller as L becomes larger. On the contrary, if the sensor electrode 1302 is made larger, in other words, if L is made smaller, the detectable capacitance Cf becomes larger.

[0077] Therefore, when assumed that the parasitic capacitance Cp only in side is formed, as shown by dashed lines, capacitance Cf can detect the smaller as much as possible L increases. However, in reality, since a parasitic capacitance is formed between the upper surface of the sensor electrode 1302 and the ground electrode 1303, the parasitic capacitance Cp also increases as the area of the sensor electrode 1302 increases, and as a result, the dotted line and the solid line As shown, the detectable capacitance Cf also becomes small. As is apparent from FIG. 14, the detectable capacitance Cf has a maximum value when the distance L between the sensor electrode 1302 and the ground electrode 1303 is 2 μm. Therefore, from the above, when the ground electrode is formed in a grid shape and the sensor electrode is arranged in the mass as in the third embodiment, the sensor electrode and the ground electrode are 2 μm apart.
It is considered to be the best if the intervals are set approximately.

On the other hand, as described above, when L is increased, the area of the sensor electrode 1302 is decreased, which reduces the detectable capacitance Cf. If L is made too large, the capacitance Cf becomes so small that it cannot be exposed by the sense unit. Therefore, the size of L is defined by the sensitivity limit of the sense unit. In consideration of fingerprint detection, as described above, the upper limit of the size of one sensor element, that is, the value of W ₀ shown in FIG. 13 is about 100 μm.

Considering those matters, the relationship between L and W ₀ is as shown in FIG. In FIG. 15, the film thickness d of the passivation film 1304 on the sensor electrode 1302.
Shows a case of 2 μm and a case of 4 μm. Figure 15
As shown in FIG. 14, when W _{0 is set} to 100 μm or less due to the limitation of resolution, first, the effect of the parasitic capacitance Cp is smallest when L is around 2 μm, as shown in FIG.
This is almost constant even if the value of W ₀ changes, and is almost uniquely determined corresponding to d. Further, if L is made too small, as shown in FIG.
Since f is reduced, it is better not to make L smaller than 2 μm.

On the other hand, when L is made larger than 2 μm,
Since the area of the sensor electrode 1302 is reduced, the detectable capacitance Cf is also reduced in this case. That is, if L is set too large, the sense unit cannot detect the capacitance Cf as described above. Generally, the capacitance that can be detected is about several fF. That is, when the relative dielectric constant of the passivation film 1304 is about 2 and the film thickness is about 2 μm, the capacitance Cf cannot be detected unless the area of the sensor electrode 1302 is 400 μm ² or more. Therefore, in general, a square sensor electrode 1
In 302, one side W needs to be 20 μm or more. And here, W ₀ = W + 2L and L = (W ₀ −
Since W) / 2, as shown in FIG. 15, L ≦ (W ₀
/ 2) -10. Incidentally, moderation and whose thickness relative dielectric constant larger passivation film 1304 shown in FIG. 13 is small, the area of the triangle shown in FIG. 15 it is possible to widen upwardly, as shown in FIG. 16, 17 and 18 Changes to.

[0081]

As described above, according to the present invention, the surface shape recognizing sensor has the sensor electrodes which are insulated and separated from each other on the same plane of the interlayer insulating film formed on the semiconductor substrate. A plurality of capacitance detecting elements, a capacitance detecting means for detecting the capacitance of each of the capacitance detecting elements, a ground electrode disposed on the interlayer insulating film so as to be insulated from the sensor electrode, and a sensor electrode on the interlayer insulating film.
Made of insulating material formed over the poles
Equipped with a passivation film, and the ground electrode is a passivation film.
Surface shape that becomes the counter electrode that is partially in contact with the surface of the membrane
Part of the object to be touched so that
Exposed on the surface of the basation film and formed on the interlayer insulating film,
The capacitance detecting means is connected to the ground electrode and the surface of the recognition object.
The capacitance between the sensor electrode and the sensor electrode is detected. With this configuration, when the recognition target touches, the capacitance detected by the capacitance detection element changes corresponding to the unevenness of the surface. Further, since the ground electrode is newly provided, static electricity generated at the time of sensing is prevented from electrostatically destroying the elements mounted at the same time. The highly sensitive surface shape detection enables the surface shape to be recognized in a highly reliable state.

[0082] Further, when the recognition target touches this becomes one of the counter electrode, also, it is in contact with the ground electrode, capacitance is formed between the surface and the sensor electrode to be recognized, which is detected by the capacitance detecting means To be done. Therefore, even if static electricity is generated by the recognition target touch, this is ah
Since it flows to the electrodes, it is possible to suppress electrostatic discharge damage to the elements mounted at the same time. As a result, according to the present invention, stable and highly sensitive surface shape detection can recognize the surface shape in a highly reliable state.

Further, in the surface recognition sensor of the present invention,
In these configurations, the ground electrode has an exposed portion formed in a grid pattern at least on the surface of the passivation film,
The sensor electrode was arranged at the center of the mass formed by the ground electrode. Therefore, the distances between the sensor electrode and the ground electrode are all uniform.
Among them, the ground electrode is formed in the shape of a square lattice, the capacitance detection element is constituted by one mass, and the passivation film is formed so that the film thickness on the sensor electrode is 0.3 μm or more and 20 μm or less. Then, the capacitance between the sensor electrode and the surface shape recognition target in contact with the passivation film on the sensor electrode can be detected. Among them, when detecting the state of a human fingerprint, the grid spacing of the ground electrodes is set to 100 μm or less. Further, by adopting these configurations, for example, the passivation film may have a relative permittivity in the range of more than 2 and less than 7. For example, when a material having a relative dielectric constant of 4 is used for the passivation film and the film thickness on the sensor electrode is set to 2 μm, the sensor electrode may be formed in a square with one side of 20 μm or more. Ar located in
The distance from the electrode is preferably 2 μm.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of, in particular, one capacitance detection element of a surface shape recognition sensor according to a first embodiment of the present invention.

FIG. 2 is a process diagram showing a manufacturing process of the surface shape recognition sensor according to the first embodiment.

FIG. 3 is a process diagram showing the manufacturing process of the surface shape recognition sensor according to the first embodiment, which is subsequent to FIG. 2;

FIG. 4 is a cross-sectional view and a plan view showing a configuration of a surface shape recognition sensor according to a second embodiment of the present invention.

FIG. 5 is a process diagram showing a manufacturing process of the surface shape recognition sensor according to the second embodiment.

FIG. 6 is a process diagram showing the manufacturing process of the surface shape recognition sensor according to the second embodiment, which is subsequent to FIG. 5;

FIG. 7 is a cross-sectional view showing the configuration of, in particular, one capacitance detection element of the surface shape recognition sensor according to the third embodiment of the present invention.

FIG. 8 is a process diagram showing a manufacturing process of the surface shape recognition sensor according to the third embodiment.

FIG. 9 is a process diagram showing the manufacturing process of the surface shape recognition sensor according to the third embodiment, which is subsequent to FIG. 8;

FIG. 10 is a cross-sectional view showing the configuration of, in particular, one capacitance detection element of the surface shape recognition sensor according to the fourth embodiment of the present invention.

FIG. 11 is a process drawing showing the manufacturing process of the surface shape recognition sensor according to the fourth embodiment.

FIG. 12 is a process diagram showing the manufacturing process of the surface shape recognition sensor according to the fourth embodiment, which is subsequent to FIG. 11;

FIG. 13 is a cross-sectional view showing another form of the surface shape recognition sensor according to the fourth embodiment, and particularly showing schematically the configuration of one capacitance detection element.

14 is a correlation diagram showing a result of simulating the relationship between the capacitance Cf and the distance L between the sensor electrode and the ground electrode in the surface shape recognition sensor shown in FIG.

15 is a correlation diagram showing the relationship between L and W0 in the surface shape recognition sensor shown in FIG.

16 is a graph showing L in the surface shape recognition sensor shown in FIG. 13 when the relative permittivity of the passivation film is 2. FIG.
It is a correlation diagram showing the relationship between W0 and d.

FIG. 17 shows L in the surface shape recognition sensor shown in FIG. 13 when the relative permittivity of the passivation film is 4.
It is a correlation diagram showing the relationship between W0 and d.

18 is a graph showing L in the surface shape recognition sensor shown in FIG. 13 when the relative permittivity of the passivation film is 7. FIG.
It is a correlation diagram showing the relationship between W0 and d.

FIG. 19 is a cross-sectional view schematically showing the configuration of one capacitance detection element of a conventional surface shape recognition sensor.

FIG. 20 is a plan view schematically showing a configuration of a conventional surface shape recognition sensor.

[Description of Reference Signs] 101 ... Semiconductor substrate, 102 ... Lower insulating film, 103 ... Wiring, 104 ... Interlayer insulating film, 105 ... Sensor electrode, 106
... grounding electrodes, 107 ... passivation film, 108 ... sense unit.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-231803 (JP, A) Patent 3400347 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 7/28 A61B 5/117 G06T 7/00

Claims (13)

(57) [Claims] 1. A plurality of capacitance detecting elements each having a sensor electrode which is insulated and separated from each other on the same plane of an interlayer insulating film formed on a semiconductor substrate, and a capacitance of each of the capacitance detecting elements. A capacitance detecting unit for detecting, a ground electrode disposed on the interlayer insulating film so as to be insulated from the sensor electrode, and an insulating member formed on the interlayer insulating film to cover the sensor electrode. A part of the ground electrode is exposed at the surface of the passivation film so that the ground electrode comes into contact with the surface of the recognition object having a surface shape which is a counter electrode partly in contact with the surface of the passivation film. Is formed on the interlayer insulating film, and the ground electrode is formed in a square lattice shape.
The capacitance detection element is composed of a box, and the sensor electrode is in a box formed by the ground electrode.
And the passivation film has a thickness of 0.
A surface shape recognition sensor , which is formed to have a thickness of 3 μm or more and 20 μm or less, and wherein the capacitance detection unit detects a capacitance between the surface of the ground electrode and the recognition target and the sensor electrode. 2. The surface shape recognition sensor according to claim 1, wherein the grid of the ground electrode is formed with a spacing of 100 μm or less.
A sensor for surface shape recognition, which is characterized in that 3. The surface shape recognition sensor according to claim 1 , wherein the passivation film has a relative permittivity of more than 2 and 7 or more.
A sensor for surface shape recognition, which is characterized by its small size . 4. The surface shape recognition sensor according to claim 1, wherein the passivation film has a relative dielectric constant of 4.
The thickness of the passivation film on the electrode is 2 μm.
The sensor electrode is shaped like a square with a side of 20 μm or more.
A sensor for surface shape recognition, which is characterized by being made . 5. The surface shape recognition sensor according to claim 4 , wherein the sensor electrode and the earth arranged around the sensor electrode.
A surface shape recognition sensor characterized in that the distance from the electrode is 2 μm . 6. A surface shape recognition sensor of claims 1 to 5 any one of claims, to cover the upper surface of the ground electrode and the upper surface of the sensor electrode
A surface shape recognition sensor comprising a conductive protective film formed as described above . 7. The surface shape recognition sensor according to claim 6 , wherein the protective film is made of gold . 8. An interlayer insulating film formed on a semiconductor substrate
Each is isolated and fixed on the same plane
A plurality of capacitance detecting elements having arranged sensor electrodes, and a capacitance detecting means for detecting the capacitance of each of the capacitance detecting elements.
And the sensor electrode on the interlayer insulating film, which is isolated from the sensor electrode.
The ground electrode, the upper surface of the sensor electrode and the upper surface of the ground electrode.
Is the protective film made of gold formed as described above and formed on the interlayer insulating film so as to cover the sensor electrode?
One Bei and configured passivation film of an insulating member
A part of the earth electrode is formed on the surface of the passivation film.
The surface of the recognition object whose surface shape is the contacting counter electrode
Part of the surface of the passivation film is in contact with
And is formed on the interlayer insulating film, and the capacitance detecting means includes the ground electrode and the recognition pair.
A surface shape recognition sensor, which detects a capacitance between the surface of an elephant and the sensor electrode . 9. A surface shape recognition sensor of claim 1 to 5 any one of claims protection with side and top surfaces and the earth formed conductive so as to cover the side and top surfaces of the electrodes of the sensor electrode A surface shape recognition sensor characterized by comprising a film. 10. An interlayer insulating film formed on a semiconductor substrate
Are isolated and separated on the same plane of
Multiple capacitive sensing elements having fixedly arranged sensor electrodes
And a capacitance detecting device for detecting the capacitance of each of the capacitance detecting elements.
And the sensor electrode on the interlayer insulating film, which is isolated from the sensor electrode.
The ground electrode, the side and top surfaces of the sensor electrode and the side of the ground electrode.
Conductive layer formed to cover the surface and the top surface.
Is it formed on the protective film and the interlayer insulating film so as to cover the sensor electrode?
One Bei and configured passivation film of an insulating member
A part of the earth electrode is formed on the surface of the passivation film.
The surface of the recognition object whose surface shape is the contacting counter electrode
Part of the surface of the passivation film is in contact with
And is formed on the interlayer insulating film, and the capacitance detecting means includes the ground electrode and the recognition pair.
A surface shape recognition sensor, which detects a capacitance between the surface of an elephant and the sensor electrode . 11. The surface shape recognition sensor according to claim 9 , wherein the protective film is made of ruthenium . 12. The surface shape recognition sensor according to claim 1, wherein the surface shape recognition sensor is arranged below the interlayer insulating film on the semiconductor substrate.
A first and a first electrode connected to the sensor electrode and the ground electrode
A second wiring is provided, and the sensor electrode and the ground electrode are connected to the first and second electrodes.
And a sensor for recognizing a surface shape, which is connected to the capacitance detecting means via a second wiring . 13. The method according to any one of claims 1 to 12.
In the surface shape recognition sensor, the capacitance detection means is simultaneously mounted on the semiconductor substrate.
A sensor for recognizing surface shape, which is characterized by