KR20050032854A - Finger printer recognition sensor and the fabrication method - Google Patents

Abstract

A fingerprint recognition sensor and a fabrication method are provided to increase the corrosion resistance and abrasion resistance of a fingerprint recognition sensor of a DC(Direct Current) restive method so as to increase the reliability. A fingerprint recognition sensor includes a substrate(401), an electrode(402), a passivation conductor layer(403), and an insulated shield(404). The electrode(402) is formed on the substrate(401) in a predetermined pattern. The passivation conductor layer(403) is formed on the electrode(402). The insulated shield(404) is formed on the passivation conductor layer(403) in planarization.

Description

Fingerprint sensor and its manufacturing method {FINGER PRINTER RECOGNITION SENSOR AND THE FABRICATION METHOD}

The present invention relates to a fingerprint recognition sensor and a method for manufacturing the same, and more particularly, to a fingerprint recognition sensor and a method for manufacturing the same, which improve reliability by improving corrosion resistance and wear resistance in a DC resistive fingerprint recognition sensor.

Generally, the fingerprint sensor that has reached the level of commercialization is largely divided into AC electric field, DC capacitive, thermal sweep, and optical methods according to the fingerprint measurement method. It can be divided into branches.

Of these, the optical method has strength in terms of detection reliability, but since the optical system is used as a base, the size of the optical method is relatively large. It makes a difference.

In addition, an AC electric field method, a DC capacitive method, and a thermal sweep capable of implementing a fingerprint sensor unit, a sensor driving circuit, and a fingerprint recognition algorithm processing unit on a single chip. Since the optical method is very different from the technical method in terms of the sweep method, mainly the AC electric field method, the DC capacitive method, and the thermal sweep method will be mainly described. .

FIG. 1A is a diagram schematically illustrating a fingerprint sensor using an AC electric field method. As shown therein, the conducting portion existing inside the fingerprint is used as one terminal, and another terminal existing in the fingerprint sensor is used to generate an AC electric field.

Then, a fingerprint pattern is recognized by arranging a metal pattern array serving as an antenna on the surface of the fingerprint recognition sensor and measuring a difference in an AC electric field sensed according to the acid and valley of the fingerprint.

At this time, the metal pattern (pattern array) is protected by an insulating film and serves to prevent damage to the sensor that may be caused by the contact of the foreign matter by the insulating film.

This AC electric field fingerprint sensor is not a problem if it has capacitance and inductance that the AC field can penetrate well even if foreign matter gets on the surface of the sensor. Because of this, it is relatively resistant to contamination by foreign substances.

However, in the case of the AC electric field method, in order to increase the change of the electric field due to the acid and valley of the fingerprint, the size of the applied AC electric field must be large and additional circuits for signal processing are complicated. Therefore, there is a disadvantage that the power consumption is relatively high.

FIG. 1B schematically illustrates a fingerprint sensor using a DC capacitive method. As shown here, this method is not much different from the AC electric field method in that the patterned metal electrodes are arranged in an array.

However, when the fingerprint touches the surface of the sensor, when the bone region of the fingerprint touches, the change in capacitance caused by air, which is a medium of ε _o , is read. The change in capacitance caused by the epidermis of a person of ε is read.

At this time, the change of capacitance caused by the generated hills and valleys is a change of about tens to hundreds of pF. There are many different ways to drive circuitry that reads this change in capacitance.

Since the DC capacitance fingerprint sensor may cause afterimages due to contamination of the sensor by a human hand, the surface of the fingerprint sensor should be periodically cleaned and prevented from electrostatic discharge (ESD). The disadvantage is that it is very vulnerable.

In addition, even using a simulated fingerprint has a disadvantage that it can not be distinguished from the fingerprint of a real person.

FIG. 1C is a diagram illustrating a fingerprint sensor using a thermal sweep method. As shown therein, the unit sensors are arranged in a linear array, and the unit sensors recognize the fingerprint by reading the difference in heat radiated according to the valley and acid of the fingerprint when the human fingerprint is touched. Done.

At this time, the method of sensing the heat is generally pyroelectric. This pyroelectric thermal sensing method can be used for fingerprint recognition because the structure of the unit sensor can be implemented in a structurally stable state.

The thermal sweep fingerprint sensor method has a disadvantage in that it is sensitive to ambient temperature and needs to be familiar with sweep operation in order to obtain a good fingerprint image.

Therefore, the recent fingerprint recognition sensor is applied to the DC resistive method for measuring the resistance of the human fingerprint.

2A to 2C illustrate various types of electrodes of a unit fingerprint recognition sensor of a fingerprint sensor according to a conventional DC resistive method. As shown in the drawing, generally, a fingerprint sensor array has a form in which unit fingerprint sensors are arranged in n × n according to the resolution thereof.

In order for the n × n array to maintain a resolution of 500 dpi or more, the size of the unit fingerprint sensor should be about 50 × 50 μm ² . The read-out circuit of the sensor is planted in the lower part of the fingerprint sensor array, and the read signal is read by the IC through the wiring, and it becomes possible to perform a specific function.

In the driving method of the fingerprint recognition sensor composed of two ports, the comb shape as shown in FIGS. 2A and 2B maintains an electrical open in DC when the fingerprint is not contacted.

As shown in FIG. 2C, when the fingerprint is not contacted, the patterned electrode has a very large resistance. When a contact of a fingerprint is made to such an electrode form, a resistance is added in parallel. At this time, the magnitude of the resistance by the fingerprint may vary depending on the moisture state of the fingerprint or the individual, and the magnitude of the resistance is usually about 1-100 kΩ.

Therefore, when the contact of the fingerprint is made, the change in the resistance value according to the fingerprint contact according to the shape of the electrode at the electrically open (open) or very large resistance value has a very large value.

On the other hand, Figure 3 is a cross-sectional view showing a fingerprint recognition sensor by a conventional DC resistive method. As shown therein, the substrate 301; An electrode 302 formed in a predetermined pattern on the substrate 301; The insulating protective film 303 is formed between the predetermined pattern of the electrode 302.

Therefore, the fingerprint can be detected by reading a change in the resistance value of the unit fingerprint recognition sensor according to whether or not the contact of the fingerprint to the electrode 302 formed as described above.

However, when the fingerprint sensor is configured, a metal material must be formed in contact with the fingerprint to measure the resistance of the human fingerprint, and the metal material has corrosion resistance and wear resistance that can withstand an environment in which long-term contact with the human fingerprint occurs. The lack of this good enough metallic material creates problems in terms of long-term reliability of the fingerprint sensor.

It is an object of the present invention to provide a fingerprint recognition sensor and a method of manufacturing the same which can improve reliability by improving corrosion resistance and wear resistance of a DC resistive fingerprint recognition sensor.

Fingerprint recognition sensor according to the present invention to achieve the above object,

A substrate;

An electrode formed in a predetermined pattern on the substrate;

A passivation conductor layer formed on said electrode layer;

It is characterized in that it comprises an insulating protective film formed between the electrode and the predetermined pattern of the passivation.

In addition, the manufacturing method of the fingerprint sensor according to the present invention in order to achieve the above object,

Depositing a metal film on the substrate;

Depositing a passivation conductor layer on the deposited metal film;

Forming an electrode on the passivation conductor layer and the metal film in a predetermined pattern;

Forming an insulating protective film on the formed electrode pattern;

It is characterized in that it comprises the step of planarizing the formed insulating protective film.

Here, in particular, the insulating protective film is characterized in that it is formed on the passivation conductor layer formed in the predetermined pattern and the removed portion of the metal film.

Here, in particular, the electrode is characterized in that it is formed of a material such as Poly Si, Al, Cr, Ta, Ti, Pt, Ir, Au, Mo.

In particular, the passivation conductor layer is characterized in that it is formed of indium tin oxide (ITO), RuO ₂ , IrO ₂ materials.

In particular, the insulating protective film is characterized in that it is formed of a material such as Oxide, SiO ₂ , SiN _x .

According to the present invention as described above, the DC resistive fingerprint sensor can be improved in reliability by improving corrosion resistance and wear resistance.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a cross-sectional view showing the structure of a fingerprint sensor according to the present invention. As shown therein, the substrate 401; An electrode 402 formed on the substrate 401 in a predetermined pattern; A passivation conductor layer (403) formed on the electrode (402); It is characterized in that it includes an insulating protective film 404 formed to be planarized on the passivation conductor layer 403.

The electrode 402 is formed of a material such as Poly Si, Al, Cr, Ta, Ti, Pt, Ir, Au, Mo, or the like.

The passivation conductor layer 403 is formed of indium tin oxide (ITO), RuO ₂ , or IrO ₂ material.

The insulating protective film 404 is formed of a material such as oxide, SiO ₂ , SiN _x, or the like.

5A through 5E are flowcharts illustrating a method of manufacturing a fingerprint recognition sensor according to the present invention. First, as shown in FIG. 5A, a step of depositing a metal film 402 on a substrate 401 is performed.

In more detail, the substrate 401 may be a substrate including a driving circuit or a driving circuit and a system IC since the manufacturing process of the fingerprint sensor is a process applicable to a general semiconductor process. Do.

Alternatively, only the sensor can be manufactured, and the driving circuit or system IC can be implemented on the PCB in an off-chip manner. A port electrode material for a fingerprint sensor is deposited on the substrate 401.

In this case, the material of the sensor electrode 402 of the fingerprint sensor used is a metal conductor or Na + ion such as Al, Cr, Ta, Ti, Pt, Ir, Au, Mo, or the like. Polysilicon (Poly Si) with a wide variation in electrical characteristics.

As shown in FIG. 5B, the passivation conductor layer 403 is deposited on the deposited metal film 402.

The passivation conductor layer 403 is deposited to protect the metal film 402. In this case, a ceramic passivation conductor layer 403 that may protect the metal electrode 402 may be indium tin oxide (ITO), RuO ₂ , IrO _2, or the like. There is this.

Subsequently, as illustrated in FIG. 5C, the passivation conductor layer 403 and the metal layer 402 are patterned in a predetermined pattern to form an electrode 402.

The metal layer 402, which is the fingerprint sensor electrode, is patterned, and the patterning method is a dry etching process, a wet etching process, or a lift-off method.

Next, as shown in FIG. 5D, a step of forming an insulating protective film 404 on the formed electrode 402 pattern is performed.

More specifically, an insulating protective film 404 is deposited to maintain insulation between the electrodes of the patterned port and to protect the side of the electrode from external foreign matter.

At this time, oxide, SiO ₂ , SiN _x, or the like is used as the insulating protective film 404.

Finally, as shown in FIG. 5E, the step of planarizing the formed insulating protective film 404 is performed.

The insulating protective layer 404 is planarized to expose the patterned electrode to the outside.

This may prevent the electrode 402 material from being directly exposed to a poor fingerprint recognition environment, and may be kept constant without deterioration of electrical characteristics of the DC resistive fingerprint sensor.

Therefore, the fingerprint recognition sensor according to the above method can continuously maintain the performance of the fingerprint recognition sensor by contact with the fingerprint even in a fingerprint recognition environment in which a large amount of metallic negative material such as human fingerprint is in contact.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the fingerprint sensor and the manufacturing method thereof according to the present invention can improve reliability by improving the corrosion resistance and wear resistance of the DC resistive fingerprint sensor.

FIG. 1A schematically illustrates a fingerprint sensor using an AC electric field scheme. FIG.

FIG. 1B schematically illustrates a fingerprint sensor using a DC capacitive scheme. FIG.

Figure 1c is a diagram showing a fingerprint sensor using a thermal sweep (Thermal sweep) method.

2A to 2C are views illustrating various electrode shapes of a unit fingerprint recognition sensor of a fingerprint sensor according to a conventional DC resistive method.

Figure 3 is a cross-sectional view showing a fingerprint recognition sensor according to the conventional DC resistive method.

Figure 4 is a cross-sectional view showing the structure of the fingerprint sensor according to the present invention.

5a to 5e is a flow chart showing a manufacturing method of the fingerprint sensor according to the present invention.

<Description of the symbols for the main parts of the drawings>

401 --- Substrate 402 --- Electrode

403 --- Passivation Conductor 404 --- Insulation Shield

Claims (6)

A substrate; An electrode formed in a predetermined pattern on the substrate; A passivation conductor layer formed on said electrode layer; And an insulating protective film formed between the electrode and the predetermined pattern of the passivation. Depositing a metal film on the substrate; Depositing a passivation conductor layer on the deposited metal film; Forming an electrode on the passivation conductor layer and the metal film in a predetermined pattern; Forming an insulating protective film on the formed electrode pattern; And planarizing the formed insulating protective film. The method of claim 2, The insulating protective film is a manufacturing method of a fingerprint sensor, characterized in that formed in the removed portion of the passivation layer and the metal film formed in the predetermined pattern. The method of claim 2, The electrode is a method of manufacturing a fingerprint sensor, characterized in that formed of a material such as Poly Si, Al, Cr, Ta, Ti, Pt, Ir, Au, Mo. The method of claim 2, The passivation conductor layer is a method of manufacturing a fingerprint sensor, characterized in that formed of indium tin oxide (ITO), RuO ₂ , IrO ₂ material. The method of claim 2, The insulating protective film is a method of manufacturing a fingerprint sensor, characterized in that formed of a material such as Oxide, SiO ₂ , SiN _x .