JP4025261B2 - Surface shape recognition sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a surface shape recognition sensor used for sensing a surface shape having fine irregularities such as human fingerprints and animal noseprints, and a manufacturing method thereof.

  Interest in security technology is increasing in the recent progress of the information society and changes in the environment of modern society. For example, personal authentication technology for constructing a system such as electronic money has attracted a great deal of attention. Research and development has also been actively conducted on authentication techniques for preventing unauthorized use of credit cards, and many techniques have been proposed (see, for example, Non-Patent Document 1).

  For such authentication, there are various methods using fingerprints and voices. Among them, many techniques have been developed for authentication using fingerprints. For fingerprint authentication, it is necessary to read a fingerprint. As a method for reading a fingerprint, there are an optical method including an optical system such as a lens and illumination, and a pressure method using a pressure sensitive sheet. Further, there is a semiconductor type in which a sensor is arranged on a semiconductor substrate. Among these systems, the semiconductor type is easy to downsize and has versatility.

  As a semiconductor sensor, there is a capacitance type fingerprint sensor using LSI manufacturing technology (see Non-Patent Document 2 and Patent Document 1). This type of fingerprint sensor detects a concave / convex pattern on the skin using a feedback electrostatic capacitance method with a sensor chip in which small electrostatic capacitance detection sensors are two-dimensionally arranged on an LSI.

  Here, a capacitive fingerprint sensor will be briefly described. As shown in FIG. 10, this fingerprint sensor includes a plurality of sensor electrodes 1003 formed on a semiconductor substrate 1001 through an interlayer insulating layer 1002, a passivation film 1004 covering the sensor electrodes 1003, and an interlayer insulating layer 1002. And an earth electrode 1005 formed on the surface of the passivation film 1004 and exposed on the surface.

  Although not shown in FIG. 10, an integrated circuit including, for example, a plurality of MOS transistors and wirings connecting them is formed on the semiconductor substrate 1001 below the interlayer insulating layer 1002, and a part of the integrated circuit A detection circuit is formed. The sensor electrode 1003 is connected to a detection circuit, and the earth electrode 1005 is set to the ground potential.

  In the fingerprint sensor chip configured as described above, when the finger to be detected comes into contact with the passivation film 1004, the skin on the surface of the contacted finger acts as an electrode facing the sensor electrode 1003, and the capacitance between them is increased. Form. This capacitance is detected by the detection circuit, and fingerprint image data is obtained from a plurality of capacitance values detected by the sensor electrodes. In the fingerprint sensor shown in FIG. 10, since static electricity generated on the surface of the passivation film 1004 flows to the ground electrode 1005, the integrated circuit formed over the semiconductor substrate 1001 is protected from electrostatic breakdown. It has a structure.

  As a semiconductor sensor, a fingerprint sensor using MEMS (Micro Electro Mechanical Systems) has also been proposed (see Patent Document 2). This fingerprint sensor will be briefly described. As shown in FIG. 11, the fingerprint sensor is disposed so as to face a plurality of lower electrodes 1103 formed on a semiconductor substrate 1101 with an interlayer insulating layer 1102 interposed between the lower electrodes 1103 at a predetermined interval. The upper electrode 1104 is provided. Although not shown, the upper electrode 1104 is provided with a through hole.

  The upper electrode 1104 is provided in common to the plurality of lower electrodes 1103 and is supported by a support electrode 1105 provided so as to partition the plurality of lower electrodes 1103. It can be deformed downward. In addition, a sealing film 1106 is provided on the upper electrode 1104 so as to cover the entire area of the upper electrode 1104, and the sealing film 1106 is provided on the sealing film 1106 so as to correspond to the plurality of lower electrodes 1103. A plurality of protrusions 1107 are provided.

  Although not shown in FIG. 11, an integrated circuit including, for example, a plurality of MOS transistors and wirings for connecting them is formed on the semiconductor substrate 1101 below the interlayer insulating layer 1102. A detection circuit is formed in part. Each lower electrode 1103 is connected to the detection circuit via a wiring.

  In the fingerprint sensor shown in FIG. 11, when a finger to be detected comes into contact with the sealing film 1106, first, the protrusion 1107 comes into contact with the surface of the finger, and the protrusion 1107 is pushed downward by pressure from the finger. As a result, the upper electrode 1104 is also pushed down and bent together with the sealing film 1106, and the distance between the upper electrode 1104 and the lower electrode 1103 changes in this portion. As a result, the capacitance formed between the upper electrode 1104 and the lower electrode 1103 changes. This change in capacitance is detected by the detection circuit, and fingerprint image data is obtained from a plurality of capacitance values detected by the sensor electrodes.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
JP 2000-230801 A JP 2002-328003 A Ryoma Shimizu et al., A study on IC card with personal authentication function, Science technique, Technical report of IEICE OFS92-32, p.25-30 (1992) Marco Tartagni and Robert Guerrieri, A 390 dpi Live Fingerprint Imager Based on Feedback Capacitive Sensing Scheme, 1997 IEEE International Solid-state Circuits Conference, pp.200-201 (1997)

However, in the fingerprint sensor shown in FIG. 10, when a finger in a so-called dry skin is targeted, the capacitance formed between the sensor electrode 1003 and the finger surface is small and clear. There is a problem that it is difficult to obtain a simple fingerprint image.
On the other hand, in the fingerprint sensor shown in FIG. 11, since the surface shape is detected by a mechanical operation, a clear fingerprint image can be obtained in the case of the above-mentioned finger with dry skin. However, in the fingerprint sensor shown in FIG. 11, when the skin of the finger to be detected is extremely soft because of moisture such as sweat, the surface of the finger that is in contact is deformed and the protrusion 1107 In some cases, the step is absorbed, and the force received from the surface of the touched finger is dispersed, so that the upper electrode 1104 cannot be sufficiently bent.

  Accordingly, the present invention has been made to solve the above-described problems. For example, the surface of the detection target such as a dry finger, a wet finger, a hard fingertip, or a soft fingertip is in various states. Another object of the present invention is to make it possible to detect the surface shape of an object more clearly.

A surface shape recognition sensor according to the present invention includes a plurality of first detection elements arranged on the same plane of an interlayer insulating layer formed on a semiconductor substrate, and a plurality of sensors arranged on the same plane of an interlayer insulating layer. The second detection element and an integrated circuit provided below the interlayer insulating layer , the integrated circuit including a first detection circuit connected to the first detection element and a second detection circuit connected to the second detection element. And a control circuit that controls the first detection circuit and the second detection circuit, and the first detection element and the second detection element have different detection mechanisms.

In the surface shape recognition sensor, the control circuit includes a first control circuit that controls the plurality of first detection circuits, a second control circuit that controls the plurality of second detection circuits, a first control circuit, and a second control circuit. And a general control circuit for synthesizing the output of the circuit .

The surface shape recognition sensor according to the present invention is arranged on the same plane of the plurality of first detection elements arranged on the same plane of the interlayer insulating layer formed on the semiconductor substrate and the interlayer insulating layer. A plurality of second detection elements and an integrated circuit provided below the interlayer insulating layer, the integrated circuit including a first detection element and a detection circuit connected to the second detection element, and a control for controlling the detection circuit The first detection element and the second detection element have different detection mechanisms .

The detection circuit may include a changeover switch that switches connection between the first detection element and the second detection element .

The method for manufacturing a surface shape recognition sensor according to the present invention includes a step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a first metal film on the interlayer insulating film, and a step of forming on the first metal film. Forming a first mask pattern having a plurality of openings, forming a first metal pattern by plating on the surface of the first metal film exposed at the bottom of the opening of the first mask pattern, Forming a second mask pattern having an opening disposed around the first metal pattern on the first metal film and the first metal pattern after removing the first mask pattern; Forming a second metal pattern thicker than the first metal pattern by plating on the surface of the first metal film exposed at the bottom of the opening, removing the second mask pattern, and then forming the first metal pattern and the second metal pattern Metal pattern Etching away the first metal film as a mask to form a plurality of lower electrodes made of the first metal film and the first metal pattern, a plurality of sensor electrodes, and a support member made of the first metal film and the second metal pattern A step of forming an insulating film on the interlayer insulating film so as to cover the sensor electrode and the lower electrode and exposing the upper surface of the supporting member; and an adhesion layer made of a conductive material on the insulating film. A step of forming, a step of forming a seed layer made of a conductive material on the adhesion layer, and a third mask pattern having an opening in an upper region of the lower electrode on the seed layer. Forming a third metal pattern having an opening on the surface of the seed layer exposed at the bottom of the opening of the third mask pattern by plating, and removing the third mask pattern, Etching the seed layer using the turn as a mask, forming a fourth mask pattern covering the adhesion layer in the upper region of the sensor electrode where the third metal pattern is not formed, the fourth mask pattern and the third metal Using the pattern as a mask, the step of etching away the adhesion layer exposed at the bottom of the opening of the third metal pattern, the step of removing the fourth mask pattern, and the upper portion of the lower electrode through the opening of the third metal pattern Etching the insulating film, forming a space in the region sandwiched between the lower electrode and the third metal pattern, removing the adhesion layer covering the surface of the insulating film in the upper region of the sensor electrode, and removing the third metal And a step of forming an upper electrode comprising a pattern and a seed layer and an adhesion layer below the pattern, and a plurality of sensor electrodes and an insulating film covering the sensor electrode on the semiconductor substrate. A plurality of capacitance type capacitance detection elements, and a plurality of MEMS type capacitance detection elements each including a lower electrode and an upper electrode opposed to the lower electrode are formed.
The method for manufacturing the surface shape recognition sensor may include a step of forming a planarizing insulating film on the insulating film and the upper electrode for planarizing a step difference between the insulating film and the upper electrode.

  Further, another method for manufacturing a surface shape recognition sensor according to the present invention includes a step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a first metal film on the interlayer insulating film, Forming a first mask pattern having openings in a plurality of first regions on the metal film, and plating the surface of the first metal film exposed at the bottom of the opening of the first mask pattern by a plating method; A step of forming one metal pattern, and after removing the first mask pattern, an opening disposed at the center of each of the plurality of second regions other than the first region and the periphery of the first region and the second region Forming a second mask pattern having an opening disposed on the first metal film and the first metal pattern; and exposing the surface of the first metal film exposed at the bottom of the opening of the second mask pattern. A second metal pattern thicker than the first metal pattern by plating. Forming a pattern, and removing the second mask pattern, and then etching and removing the first metal film using the first metal pattern and the second metal pattern as a mask to form the first metal film and the first metal in the first region. A plurality of lower electrodes made of a pattern, a plurality of sensor electrodes made of a first metal film and a second metal pattern disposed in the center of the second region, and a first region disposed around the first region and the second region. A step of forming a supporting member comprising one metal film and a second metal pattern, a step of forming an insulating film on the interlayer insulating film so as to cover the lower electrode and expose the upper surface of the supporting member, Forming an adhesion layer made of a conductive material on the adhesion layer; forming a seed layer made of a conductive material on the adhesion layer; and an upper portion of a lower electrode on the seed layer With an opening in the area Forming a third mask pattern, forming a third metal pattern having an opening on the surface of the seed layer exposed at the bottom of the opening of the third mask pattern by plating, and removing the third mask pattern Then, the step of etching away the seed layer using the third metal pattern as a mask, the step of forming the fourth mask pattern covering the adhesion layer in the upper region of the sensor electrode where the third metal pattern is not formed, and the fourth Using the mask pattern and the third metal pattern as a mask, the step of etching and removing the adhesion layer exposed at the bottom of the opening of the third metal pattern, the step of removing the fourth mask pattern, and the opening of the third metal pattern A step of etching away the insulating film above the lower electrode to form a space in a region sandwiched between the lower electrode and the third metal pattern, and a third metal The step of removing the adhesion layer in the region other than the pattern to form the third metal pattern and the lower seed layer, the upper electrode composed of the adhesion layer, and flattening the step due to the insulating film, the sensor electrode, and the upper electrode Forming an insulating insulating film on the insulating film, the sensor electrode, and the upper electrode. The semiconductor device includes a lower electrode disposed on the semiconductor substrate in the first region and an upper electrode disposed opposite thereto. And a plurality of capacitance type capacitance detection elements including a sensor electrode and an insulating film covering the sensor electrode in the second region.

  In the method for manufacturing the surface shape recognition sensor described above, a step of forming a protrusion on the upper electrode may be provided.

  As described above, in the present invention, since a plurality of first detection elements and second detection elements having different detection mechanisms are arranged on a semiconductor substrate, even if the surface of the detection target is in various states, An excellent effect that the surface shape of the object can be detected more clearly is obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view (a) and sectional views (b) and (c) schematically showing a configuration example of a surface shape recognition sensor in the present embodiment. The surface shape recognition sensor shown in FIG. 1 is configured by alternately arranging a capacitance type capacitance detection element 110 and a MEMS (Micro Electro Mechanical Systems) type capacitance detection element 120. In the example shown in FIG. 1A, MEMS capacitance detection elements 120 are arranged on the upper, lower, left and right sides of the capacitance type capacitance detection element 110, and capacitance type capacitance detection is provided on the upper, lower, left and right sides of the MEMS type capacitance detection element 120. Element 110 is arranged. Each element is formed in a square shape of 50 μm square in plan view, and is therefore arranged at intervals of 50 μm.

  The surface shape recognition sensor shown in FIG. 1 includes an interlayer insulating layer 102 on a substrate 101 made of, for example, silicon, and a capacitance type capacitance detection element 110 and a MEMS type capacitance detection element 120 are formed thereon. It is arranged. On the substrate 101 below the interlayer insulating layer 102, for example, an integrated circuit including a plurality of MOS transistors and wirings for connecting them is formed, and a detection circuit is formed as a part of the integrated circuit.

On the interlayer insulating layer 102, first, sensor electrodes 113 constituting the capacitance-type capacitance detection element 110 are arranged in a matrix at intervals of 100 μm and connected to a part of the detection circuit. The sensor electrode 113 is disposed in the center of the area of the capacitive detection element 110 in plan view.
On the interlayer insulating layer 102, lower electrodes 123 constituting the MEMS capacitive detection element 120 are arranged in a matrix at intervals of 100 μm and connected to a part of the detection circuit. The lower electrode 123 is disposed in the center of the area of the MEMS capacitive detection element 120 in plan view.

  On the interlayer insulating layer 102, each detection element is partitioned by a support member 105 formed in a lattice shape. The support member 105 is made of a conductive material such as gold. In each mass of the support member 105, the capacitance type capacitance detecting element 110 is filled with the capacitive insulating film 104 and the sensor electrode 113 is buried below the capacitive insulating film 104.

  In each mass of the support member 105, the area of the MEMS capacitive detection element 120 is covered with the upper electrode 106 formed on the support member 105. In the area of each MEMS capacitive detection element 120, a space is formed above the lower electrode 123, and the upper electrode 106 is disposed above the lower electrode 123 at a predetermined distance. . The upper electrode 106 is provided in common to each MEMS capacitance detection element 120 and is supported on the support member 105. Further, the upper part of the capacitance type capacitance detecting element 110 of the upper electrode 106 is open. Note that an upper electrode may be individually provided for each MEMS capacitance detection element 120.

  Note that the MEMS capacitance detecting element 120 may be configured as shown in FIG. In the example shown in FIG. 1C, a sealing film 107 is provided on the upper electrode 106, and a plurality of protrusions 108 are provided on the sealing film 107 corresponding to the plurality of lower electrodes 123. . By providing the protrusion 108, the amount of deflection of the upper electrode 106 can be increased, and the sensitivity can be improved.

  According to the surface shape recognition sensor shown in FIG. 1, the detection surface is configured by alternately arranging a plurality of capacitance type capacitance detection elements 110 and a plurality of MEMS type capacitance detection elements 120. Regardless of the state of the finger surface, the shape of the fingerprint can be detected clearly. For example, even when the surface (skin) of the finger to be detected is in a dry skin state, the MEMS capacitive detection element 120 can accurately detect the unevenness of the fingerprint. Further, for example, even when the surface of the finger to be detected is in a soft state due to wetness or the like, the capacitance-type capacitive detection element 110 can accurately detect the unevenness of the fingerprint.

  Next, a detection circuit constituted by a part of an integrated circuit provided under the interlayer insulating layer 102 will be described. As shown in FIG. 2, the surface shape recognition sensor shown in FIG. 1 includes a capacitance type capacitance detection circuit 210 connected to each capacitance type capacitance detection device 110 and each MEMS type capacitance detection device 120. The MEMS type capacitance detection circuit 220 connected to each of these is provided. The capacitance type capacitance detection circuit 210 and the MEMS type capacitance detection circuit 220 may have the same circuit configuration, or may have different configurations suitable for each element.

  The capacitance type capacitance detection circuit 210 measures the capacitance detected by the capacitance type capacitance detection element 110 and passes the result (signal) to the control circuit 300. Similarly, the MEMS capacitance detection circuit 220 measures the capacitance detected by the MEMS capacitance detection element 120 and passes the result (signal) to the control circuit 300. The control circuit 300 receives a signal from each detection circuit, corresponds to the position of each detection element, for example, converts the detected capacitance to gray scale, and forms a fingerprint image.

  Further, the detection circuit may be configured as shown in FIG. In the example shown in FIG. 3, a capacitance type control circuit 310 and a MEMS type control circuit 320 are newly provided, and these outputs are synthesized by the total control circuit 301. The capacitance type control circuit 310 receives signals from each capacitance type capacitance detection circuit 210, adds position information of the capacitance type capacitance detection element 110, and corresponds to these positions to be detected. The size of the capacity is converted into a gray scale to form one fingerprint image (image data).

Similarly, the MEMS control circuit 320 receives a signal from each MEMS capacitance detection circuit 220, adds the position information of the MEMS capacitance detection element 120 to correspond to these positions, and detects the detected capacitance. A fingerprint image (image data) is converted into a gray scale.
The overall control circuit 301 evaluates each image data obtained from each detection circuit as described above based on a predetermined index, and then synthesizes each result of the evaluation with weighting.

  Hereinafter, an operation example of the above-described evaluation in the integrated control circuit 301 will be described. For example, consider a case where a finger with dry skin is a target for fingerprint detection. In this case, since the capacitance formed by the dry finger is small in the capacitance type capacitance detection element 110, the output from the capacitance type control circuit 310 is weak, and the value in the dry finger column of FIG. As shown on the left, clear image data cannot be obtained.

  On the other hand, in the MEMS capacitance detection element 120, the upper electrode 106 bends corresponding to the unevenness of the fingerprint due to the dry and hard finger skin, and a large capacitance change is obtained. As a result, a large output is obtained from the MEMS control circuit 320, and clear image data is obtained as shown in the center of the dry finger column in FIG.

  The comprehensive control circuit 301 evaluates the sharpness of both of these image data, generates an evaluation value, compares them, and detects that the finger is in a dry state based on the comparison result. The overall control circuit 301 generates and outputs a clear fingerprint image by combining each image data with a predetermined weight.

  When a finger in a normal state is a target for fingerprint detection, both the capacitance type capacitance detection element 110 and the MEMS type capacitance detection element 120 detect the unevenness of the fingerprint according to the initial performance, and A clear fingerprint image is obtained from both the capacitive control circuit 310 and the MEMS control circuit 320. Accordingly, when the overall control circuit 301 evaluates the sharpness of both of these image data, generates an evaluation value, and compares them, there is no significant difference between them, so that the finger to be detected is determined to be in a normal state. . As a result of this determination, the total control circuit 301 adds the obtained two image data and outputs it as a fingerprint image.

  Further, when a finger wet with sweat or the like is a target for fingerprint detection, the capacitance type capacitance detection element 110 can obtain a sufficient capacitance change corresponding to the unevenness of the fingerprint, and the capacitance type control circuit 310. A large output is obtained, and clear image data is obtained as shown on the left of the wet finger column in FIG.

  On the other hand, in the MEMS capacitive detection element 120, since the skin of the finger is wet and soft, the upper electrode 106 does not bend so much and a large capacitance change cannot be obtained. Therefore, the output from the MEMS control circuit 320 is weak, and clear image data cannot be obtained as shown in the center of the wet finger column in FIG.

  The comprehensive control circuit 301 evaluates the sharpness of both of these image data, generates an evaluation value, compares them, and detects that the finger is in a damp state based on the comparison result. The overall control circuit 301 generates and outputs a clear fingerprint image by combining each image data with a predetermined weight.

  Further, the detection circuit may be configured as shown in FIG. In the example shown in FIG. 4, a changeover switch 330 that switches the outputs of the adjacent capacitance type capacitance detection element 110 and the MEMS type capacitance detection element 120 is provided. By switching the output of the capacitance type capacitance detection element 110 and the MEMS type capacitance detection element 120 using the changeover switch 330, the capacitance detection circuit 230 can be shared. The changeover operation of the changeover switch 330 is controlled by the control signal generation circuit 340.

  For example, by setting both of the two contacts of the changeover switch 330 to be connected, outputs of both the capacitance type capacitance detection element 110 and the MEMS type capacitance detection element 120 are input to the capacitance detection circuit 230. As a result, a clear fingerprint image can be obtained from the control circuit 300 regardless of the state of the detection target finger.

  Further, by switching between the connection of the contact 330b and the connection of the contact 330a at the two contacts of the changeover switch 330, the control circuit 300 allows the fingerprint image by the capacitance type capacitance detection element 110 and the MEMS type capacitance detection element 120 to be switched. It is possible to acquire two pieces of image data with the fingerprint image by the switching timing of the changeover switch 330, and the same effect as the circuit shown in FIG. 3 can be obtained. Further, when the state of the finger to be detected is known in advance, the detection can be performed at a higher speed by switching the connection state of the changeover switch 330 according to the known state.

Next, a method for manufacturing the surface shape recognition sensor will be described.
First, as shown in FIG. 5A, an element such as a MOS transistor (not shown) is formed on a substrate 101 made of a semiconductor material such as silicon, and a wiring for connecting them is formed. An integrated circuit including the above is formed. Next, an insulating film is formed so as to cover the unillustrated integrated circuit, and an interlayer insulating layer 102 is formed over the substrate 101.
Next, as shown in FIG. 5B, on the surface of the interlayer insulating layer 102, a seed layer (for example, a two-layered film of a 0.1 μm-thick titanium film and a 0.1 μm-thick gold film is formed by vapor deposition). First metal film) 501 is formed.

  Next, on the seed layer 501, a mask pattern in which regions serving as the sensor electrode and the lower electrode are opened is formed by a known photolithography technique, and an electrolytic plating method is performed on the seed layer 501 using this mask pattern as a mask. Thus, a gold plating film is selectively formed to a thickness of about 1 μm. After removing the mask pattern, a gold plating film is selectively formed to a thickness of about 2 μm in the region where the support member is disposed by the same process.

  As a result, as shown in FIG. 5C, the electrode pattern 502 and the support pattern 503 are formed on the seed layer 501. As shown in the plan view of FIG. 5C ′, the electrode patterns 502 are arranged in a matrix at predetermined intervals, and the column patterns 503 are formed in a lattice.

  Next, the seed layer 501 is selectively etched using the electrode pattern 502 and the support pattern 503 as a mask. In this etching, first, the gold film on the upper layer of the seed layer 501 is selectively removed using an etching solution made of iodine, ammonium iodide, water, and ethanol. Next, the titanium film under the seed layer 501 is selectively removed using an HF-based etchant. In the gold wet etching, the etching rate is 0.05 μm per minute.

  As a result, as shown in FIG. 6D, the sensor electrode 113, the lower electrode 123, and the support member 105 are formed on the interlayer insulating layer 102 by being insulated and separated. Each electrode is connected to a predetermined circuit of an integrated circuit formed under the interlayer insulating layer 102, and the support member 105 is connected to a ground potential. In the figure, the wiring connecting them is omitted.

  Next, as illustrated in FIG. 6E, the capacitor insulating film 104 is formed so as to fill the region surrounded by the support member 105. Due to the capacitive insulating film 104, the sensor electrode 113 and the lower electrode 123 are buried. The capacitor insulating film 104 can be formed from, for example, a photosensitive resin film. For example, a photosensitive resin obtained by adding a positive photosensitive agent to a base resin (polyimide) such as polyamide, polyamic acid, or polybenzoxazole (or a precursor thereof) is applied onto the substrate 101 by spin coating or the like. A conductive resin film is formed. It is also possible to use a negative photosensitive resin mainly composed of the base resin.

  Next, after pre-baking the applied photosensitive resin film, the upper region of the support member 105 is exposed and developed to remove the photosensitive resin film on the support member 105. State. After these exposure and development processes, the photosensitive resin film remaining between the support members 105 is thermally cured, and then etched back by, for example, a chemical mechanical polishing method as shown in FIG. Thus, a state is obtained in which the capacitor insulating film 104 having a flat surface on which the same plane as the upper surface of the support member 105 is formed is formed.

Next, a 0.1 μm-thick titanium film (adhesion layer) and a 0.1 μm-thick gold film (seed layer) are formed on the surfaces of the support member 105 and the capacitor insulating film 104 formed flat as described above by, for example, vapor deposition. A metal layer 504 formed of a two-layer film is formed.
Next, a resist pattern is formed on the metal layer 504. The resist pattern includes a pattern that covers a region surrounded by the support member 105 on which the sensor electrode 113 is disposed. In addition, the resist pattern includes a columnar pattern in an upper region outside the lower electrode 123 in an upper region surrounded by the support member 105 where the lower electrode 123 is disposed.

  Next, a gold plating film is selectively formed to a thickness of about 1.0 μm on the exposed region of the metal layer 504 by electrolytic plating using the resist pattern as a mask. Thereafter, by removing the resist pattern, as shown in FIG. 6G, an opening was partially provided in the upper part of the region surrounded by the support member 105 where the lower electrode 123 is disposed. It is assumed that the electrode pattern 505 is formed. The electrode pattern 505 is a part of the upper electrode 106. Here, in FIG. 6G and subsequent figures, the electrode pattern 505 and the upper electrode 106 are in a state where openings (through holes) are shown for convenience. The opening is a square having a side of 4 μm in plan view. Further, four openings are arranged outside the four corners of the lower electrode 123.

After the electrode pattern 505 is formed as described above, first, the gold film (seed layer) that is the upper layer of the metal layer 504 is removed by etching using the electrode pattern 505 as a mask. For this etching, an etching solution composed of iodine, ammonium iodide, water, and ethanol may be used.
Next, as shown in FIG. 6H, a resist pattern 506 is formed to cover the region where the sensor electrode 113 is disposed. Thereafter, using the resist pattern 506 and the electrode pattern 505 as a mask, the titanium film (adhesion layer) that is the lower layer of the metal layer 504 exposed in the opening of the electrode pattern 505 is selectively removed. As a result, as shown in FIG. 7 (i), a state in which the upper electrode 106 is formed above the lower electrode 123 is obtained. In the opening of the upper electrode 106, the surface of the lower capacitive insulating film 104 is It will be exposed.

  Next, after removing the resist pattern 506, the capacitive insulating film 104 in the upper region of the lower electrode 123 is removed by applying, for example, oxygen plasma through the opening of the upper electrode 106 formed as described above. These can be realized, for example, by exposing the substrate 101 to oxygen plasma. As a result, a space is formed in the upper region of the lower electrode 123 as shown in FIG.

Next, as illustrated in FIG. 7K, a sealing film 107 is formed on the upper electrode 106 so that the opening of the upper electrode 106 is closed.
Here, an example of forming the sealing film 107 will be described. The sealing film 107 is formed, for example, by forming a photosensitive resin film by a known STP (Spin-coating film Transfer and hot-Pressing technique) method. First, a sheet film on which the resin film is applied and formed is prepared, and the resin film forming surface of the sheet film is attached onto the substrate 101 in an atmosphere evacuated to a predetermined pressure, and these are thermocompression bonded. Thereafter, the sheet film may be peeled off from the resin film.

  As shown in FIG. 7 (k), the resin film adhered by these is exposed and developed by a known lithography technique, and the formed pattern is thermally cured, for example, by heat treatment at 300 ° C. for 1 hour. The sealing film 107 can be formed. The resin film described above may be a photosensitive resin obtained by adding a positive photosensitive agent to a base resin (polyimide) such as polyamide, polyamic acid, or polybenzoxazole (or a precursor thereof). Further, it may be a negative photosensitive resin mainly composed of the base resin.

  After forming the sealing film 107 as described above, the metal layer 504 in the upper region of the sensor electrode 113 where the sealing film 107 and the upper electrode 106 are not formed is removed with an HF-based etching solution, and FIG. As shown in (k), the surface of the capacitive insulating film 104 in the upper region of the sensor electrode 113 is exposed.

Thereafter, a photosensitive resin film having a film thickness of about 5 μm is formed by the STP method or the known spin coating method described above, and this is exposed and developed into a predetermined pattern, and is heated and thermally cured, whereby FIG. As shown in FIG. 1L, the protrusion 108 is formed on the sealing film 107 so as to correspond to the lower electrode 123.
As described above, a surface shape recognition sensor in which the capacitance type capacitance detection element 110 and the MEMS type capacitance detection element 120 are alternately arranged is completed.

The protrusion 108 is not always necessary. For example, when the unevenness of the surface shape of the detection target is smaller than the dimensions of each element, the upper electrode 106 can be bent corresponding to the unevenness state without the protrusion 108.
Further, the sealing film 107 does not need to be formed so as to cover the entire area of the upper electrode 106. As shown in FIG. 7M, the sealing film 707 may be formed so as to close the opening of the upper electrode 106, and the surface of the upper electrode 106 may be exposed. Since the upper surface of the upper electrode 106 is exposed, static electricity generated on the surface of the sensor can be passed to the ground via the support member 105, and resistance to static electricity can be improved.

Further, as illustrated in FIG. 8A, a planarization insulating layer 801 that fills a step between the upper electrode 106 and the sealing film 107 and the surface of the capacitor insulating film 104 may be formed.
When the planarization insulating layer 801 is formed, as shown in FIG. 8B, the thick sensor electrode 813 is formed, the thickness of the insulating layer above the sensor electrode 813 is reduced, and the capacitance formed is reduced. It may be made larger. The sensor electrode 813 can be formed in the same manner as the process from the support pattern 503 to the formation of the support member 105.

Incidentally, in the above-described embodiment, as shown in FIG. 9A, the capacitance type capacitance detection element 110 and the MEMS type capacitance detection element 120 are substantially perpendicular to the direction indicated by the finger to be detected. It was arranged in various directions.
However, the present invention is not limited to this, and as shown in FIG. 9B, each element may be arranged in a direction rotated by 45 ° with respect to the direction indicated by the finger to be detected.
Further, as shown in FIG. 9C, the MEMS capacitance detection elements 920 having a circular shape in plan view may be arranged in a matrix, and the capacitance type capacitance detection elements 910 may be arranged in these gaps. .

  In the above description, a capacitive detection element that uses the surface of the finger as one electrode and does not have a movable part is used as the first detection element, and is fixed to the movable upper electrode as the second detection element. However, the present invention is not limited to this. For example, the first detection element may be a detection element that detects an electrical variable in a sensor electrode covered with an insulating film.

  As another example of the first detection element, an electric field detection element in which a high frequency signal is applied to a detection target such as a finger to generate an electric field from the detection target and the sensor electrode detects the electric field can be used. For example, a pressure-sensitive detection element including a piezoelectric element may be used as the second detection element. The present invention is characterized in that a detection surface for recognizing (detecting) a surface shape such as a fingerprint is provided with a first detection element and a second detection element having different detection mechanisms.

  In the above description, the first detection elements and the second detection elements are alternately arranged. However, the present invention is not limited to this. For example, four first detection elements and four second detection elements may each be a unit, and these one units may be alternately arranged. Further, the first detection elements and the second detection elements may be arranged side by side for each column or for each row.

  By arranging a plurality of first detection elements and second detection elements having different detection mechanisms on a semiconductor substrate, for example, a surface of a detection target such as a dry finger, a wet finger, a hard fingertip, or a soft fingertip Can be applied to fingerprint authentication for various states.

It is the top view (a), sectional drawing (b), (c) which shows the structural example of the sensor for surface shape recognition in embodiment of this invention. It is a block diagram which shows the example of a partial structure of the sensor for surface shape recognition in embodiment of this invention. It is the block diagram (a) which shows the partial structural example of the sensor for surface shape recognition in embodiment of this invention, and explanatory drawing (b) for demonstrating a detection state. It is a block diagram which shows the example of a partial structure of the sensor for surface shape recognition in embodiment of this invention. It is process drawing which shows the manufacturing process of the sensor for surface shape recognition in embodiment of this invention with a typical cross section. FIG. 6 is a process diagram illustrating the manufacturing process of the surface shape recognition sensor according to the embodiment of the present invention with a schematic cross section following FIG. 5; FIG. 7 is a process diagram illustrating the manufacturing process of the surface shape recognition sensor according to the embodiment of the present invention with a schematic cross section following FIG. 6; It is typical sectional drawing which shows the other structural example of the sensor for surface shape recognition in embodiment of this invention. It is a typical top view which shows the other structural example of the surface shape recognition sensor in embodiment of this invention. It is sectional drawing which shows the structural example of the conventional sensor for surface shape recognition. It is sectional drawing which shows the structural example of the conventional sensor for surface shape recognition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Substrate 102 Interlayer insulation layer 104 Capacitance insulation film 105 Support member 106 Upper electrode 107 Sealing film 108 Protrusion 110 Capacitance type capacitance detection element 113 Sensor electrode 120 MEMS type capacitance detection element 123 Lower electrode 210 Capacitance type capacitance detection circuit 220 MEMS type capacitance detection circuit 300 Control circuit

Claims (8)

A plurality of first detection elements arranged on the same plane of an interlayer insulating layer formed on a semiconductor substrate;
A plurality of second detection elements arranged on the same plane of the interlayer insulating layer ;
An integrated circuit provided below the interlayer insulating layer ,
The integrated circuit comprises:
A first detection circuit connected to the first detection element;
A second detection circuit connected to the second detection element;
A control circuit for controlling the first detection circuit and the second detection circuit;
Including
A sensor for recognizing a surface shape, wherein the first detection element and the second detection element have different detection mechanisms. The surface shape recognition sensor according to claim 1,
The control circuit includes:
A first control circuit for controlling a plurality of the first detection circuits;
A second control circuit for controlling a plurality of the second detection circuits;
An overall control circuit for synthesizing outputs of the first control circuit and the second control circuit;
Surface shape recognition sensor, characterized in that it comprises a. A plurality of first detection elements arranged on the same plane of an interlayer insulating layer formed on a semiconductor substrate;
A plurality of second detection elements arranged on the same plane of the interlayer insulating layer;
An integrated circuit provided under the interlayer insulating layer;
With
The integrated circuit comprises:
A detection circuit connected to the first detection element and the second detection element;
A control circuit for controlling the detection circuit;
Including
A sensor for recognizing a surface shape, wherein the first detection element and the second detection element have different detection mechanisms . The surface shape recognition sensor according to claim 3 ,
The detection circuit includes a changeover switch that switches connection between the first detection element and the second detection element . Forming an interlayer insulating film on the semiconductor substrate;
Forming a first metal film on the interlayer insulating film;
Forming a first mask pattern having a plurality of openings on the first metal film;
Forming a first metal pattern by plating on the surface of the first metal film exposed at the bottom of the opening of the first mask pattern;
Forming a second mask pattern having an opening disposed around the first metal pattern on the first metal film and the first metal pattern after removing the first mask pattern;
Forming a second metal pattern thicker than the first metal pattern by plating on the surface of the first metal film exposed at the bottom of the opening of the second mask pattern;
After removing the second mask pattern, the first metal film is etched away using the first metal pattern and the second metal pattern as a mask, and a plurality of lower portions made of the first metal film and the first metal pattern are removed. A step of forming an electrode, a plurality of sensor electrodes, and a support member comprising the first metal film and the second metal pattern;
Forming an insulating film on the interlayer insulating film so as to cover the sensor electrode and the lower electrode and to expose an upper surface of the support member;
Forming an adhesion layer composed of a conductive material on the insulating film;
Forming a seed layer made of a conductive material on the adhesion layer;
Forming a third mask pattern having an opening in an upper region of the lower electrode on the seed layer;
Forming a third metal pattern having an opening by plating on the surface of the seed layer exposed at the bottom of the opening of the third mask pattern;
Removing the third mask pattern and then etching away the seed layer using the third metal pattern as a mask;
Forming a fourth mask pattern covering the adhesion layer in the upper region of the sensor electrode where the third metal pattern is not formed;
Etching the adhesion layer exposed at the bottom of the opening of the third metal pattern using the fourth mask pattern and the third metal pattern as a mask;
Removing the fourth mask pattern;
Etching away the insulating film above the lower electrode through the opening of the third metal pattern to form a space in a region sandwiched between the lower electrode and the third metal pattern;
Removing the adhesion layer covering the surface of the insulating film in the upper region of the sensor electrode, and forming an upper electrode composed of the third metal pattern, the seed layer below the adhesion layer, and the adhesion layer;
With
On the semiconductor substrate,
A plurality of capacitance type capacitance detecting elements comprising the sensor electrode and the insulating film covering the sensor electrode;
A plurality of MEMS capacitive sensing elements comprising the lower electrode and the upper electrode disposed opposite thereto;
A method of manufacturing a surface shape recognition sensor , characterized by comprising : In the manufacturing method of the surface shape recognition sensor according to claim 5 ,
A method for manufacturing a surface shape recognition sensor , comprising: forming a flattening insulating film for flattening a step between the insulating film and the upper electrode on the insulating film and the upper electrode . Forming an interlayer insulating film on the semiconductor substrate;
Forming a first metal film on the interlayer insulating film;
Forming a first mask pattern having openings in a plurality of first regions on the first metal film;
Forming a first metal pattern by plating on the surface of the first metal film exposed at the bottom of the opening of the first mask pattern;
After removing the first mask pattern, an opening disposed at the center of each of the plurality of second regions other than the first region, and an opening disposed around the first region and the second region Forming a second mask pattern having a portion on the first metal film and the first metal pattern;
Forming a second metal pattern thicker than the first metal pattern by plating on the surface of the first metal film exposed at the bottom of the opening of the second mask pattern;
After removing the second mask pattern, the first metal film and the first metal pattern in the first region are removed by etching using the first metal pattern and the second metal pattern as a mask. A plurality of lower electrodes, a plurality of sensor electrodes composed of the first metal film and the second metal pattern disposed in a central portion of the second region, and around the first region and the second region. Forming a support member comprising the first metal film and the second metal pattern disposed;
Forming an insulating film on the interlayer insulating film so as to cover the lower electrode and expose an upper surface of the support member;
Forming an adhesion layer composed of a conductive material on the insulating film;
Forming a seed layer made of a conductive material on the adhesion layer;
Forming a third mask pattern having an opening in an upper region of the lower electrode on the seed layer;
Forming a third metal pattern having an opening by plating on the surface of the seed layer exposed at the bottom of the opening of the third mask pattern;
Removing the third mask pattern and then etching away the seed layer using the third metal pattern as a mask;
Forming a fourth mask pattern covering the adhesion layer in the upper region of the sensor electrode where the third metal pattern is not formed;
Etching the adhesion layer exposed at the bottom of the opening of the third metal pattern using the fourth mask pattern and the third metal pattern as a mask;
Removing the fourth mask pattern;
Etching away the insulating film above the lower electrode through the opening of the third metal pattern to form a space in a region sandwiched between the lower electrode and the third metal pattern;
Removing the adhesion layer in a region other than the third metal pattern, and forming an upper electrode comprising the third metal pattern and the seed layer and the adhesion layer below the third metal pattern;
Forming a planarizing insulating film on the insulating film, the sensor electrode, and the upper electrode to planarize a step due to the insulating film, the sensor electrode, and the upper electrode;
With
On the semiconductor substrate,
A plurality of MEMS capacitive sensing elements, which are arranged in the first region and are composed of the lower electrode and the upper electrode arranged to face the lower electrode;
A plurality of capacitance-type capacitance detecting elements comprising the sensor electrode disposed in the second region and the insulating film covering the sensor electrode;
A method of manufacturing a surface shape recognition sensor, characterized by comprising : In the manufacturing method of the sensor for surface shape recognition of any one of Claims 5-7 ,
A method of manufacturing a sensor for recognizing a surface shape, comprising a step of forming a protrusion on the upper electrode .

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