KR20050011126A - Finger printer recognition sensor and the fabrication method - Google Patents

Abstract

PURPOSE: A fingerprint recognition sensor using an impedance difference and a manufacturing method thereof are provided to enhance fingerprint recognition of the sensor, and implement slimness and multifunction by maximally enlarging the impedance difference between a ridge and a gully of a fingerprint. CONSTITUTION: A fingerprint recognition array is formed by arranging unit fingerprint recognition sensors(51) in an nXn matrix. A sensor electrode pattern is formed to each unit fingerprint sensor in a predetermined shape. A driving circuit outputs a value according to the impedance detected in the sensor electrode pattern.

Description

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

The present invention relates to a fingerprint sensor and a method of manufacturing the same, and more particularly, to a fingerprint recognition sensor capable of increasing the fingerprint recognition rate of the sensor by minimizing the difference in impedance due to peaks and valleys of the fingerprint, and miniaturizing and multifunctional. .

In general, the fingerprint sensor that has reached the current level of commercialization is largely divided into AC electric field, DC capacitive, thermal swipe, 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, and thus the optical method is significantly different in the application products from the other three types of fingerprint sensors. Flies

In addition, an AC electric field method, a DC capacitive method, and a thermal swappable, which can implement a fingerprint recognition 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 swipe method in terms of the technical aspects, mainly the AC electric field method, the DC capacitive method, and the thermal swipe method will be 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, the contact of the valley of the fingerprint reads the change in capacitance caused by air, which is the medium of e _o , and when the acid part of the fingerprint touches, The change in capacitance caused by the human epidermis 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.

1C is a diagram illustrating a fingerprint sensor using a thermal swipe method. As shown here, 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 swipe fingerprint sensor method has a disadvantage in that it is sensitive to the ambient temperature and needs to be used to swipe to obtain a good fingerprint image.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fingerprint recognition sensor capable of increasing the fingerprint recognition rate of a sensor by minimizing the difference between impedances of peaks and valleys of a fingerprint, and miniaturizing and multifunctioning, and a manufacturing method thereof.

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 view showing a fingerprint sensor using a thermal swipe (Thermal swipe) method.

Figure 2 is a schematic diagram showing the structure of the EID type fingerprint sensor array according to the present invention.

3A to 3C are views illustrating various electrode shapes of the unit fingerprint recognition sensor of FIG. 2.

Figure 4a is a diagram showing a two-port equivalent circuit of the EID fingerprint sensor.

Figure 4b is a view showing an equivalent circuit of the fingerprint when the acid of the fingerprint touches the unit fingerprint recognition sensor.

FIG. 5 is a diagram showing a first embodiment of a sensing circuit of an EID fingerprint sensor; FIG.

FIG. 6 is a diagram illustrating a second embodiment of a sensing circuit of an EID fingerprint sensor. FIG.

7a to 7d is a view showing a manufacturing process of the EID fingerprint sensor according to the present invention.

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

51, 61 --- Unit sensor impedance 52, 62 --- Reference impedance

63 --- Amplifier 71 --- Board

72 --- electrode 73 --- insulation shield

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

A fingerprint array in which unit fingerprint sensors are arranged in n × n;

A sensing electrode pattern part formed in a predetermined form on each unit fingerprint sensor of the fingerprint array;

It is characterized in that it comprises a driving circuit unit for outputting a value according to the impedance sensed by the sensing electrode pattern portion.

In particular, the size of the unit fingerprint recognition sensor is characterized in that it is formed to 50 × 50 ㎛ ² .

In particular, the electrode pattern formed on the sensing electrode pattern portion may include an open comb, a closed comb, and a specifically patterned electrode, and thus impedance according to acid and valley of the fingerprint contacted. The characteristic is to maximize the size of the impedance.

In particular, the driving circuit unit has a characteristic in that the unit sensor and the reference impedance are connected in series, and the output signal V _out is measured between the unit sensor and the reference impedance.

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

Depositing an electrode material for a fingerprint sensor on a substrate;

Patterning the deposited electrode material;

Characterized in that it comprises depositing an insulating protective film on the resultant of the patterned electrode material.

In particular, the electrode material to be deposited is characterized by using poly Si, Al, Cr, Ta, Ti, Pt, Ir, Au, Mo or Pt, Mo, Ir material.

Here, in particular, the insulating protective film is characterized in that it further comprises the step of exposing the electrode to the outside by planarizing the insulating protective film, when the deposited electrode material is formed of Pt, Mo, Ir.

According to the present invention as described above, the fingerprint recognition rate of the sensor can be increased, miniaturization and multifunction can be realized by maximizing the difference between the impedance due to the peak and valley of the fingerprint.

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

2 is a diagram schematically illustrating the structure of an EID fingerprint sensor array according to the present invention. As shown in the drawing, an EID (Enlarged Impedance Difference) fingerprint array has an array in which unit fingerprint sensors are arranged in n × n according to the resolution. In order to maintain a resolution of 500 dpi or more, the size of the unit fingerprint sensor is about 50 × 50 μm ² .

3A to 3C illustrate various electrode shapes of the unit fingerprint recognition sensor of FIG. 2. As shown in Fig. 3a, the open comb form is such that two separate ports 31 and 32 having a plurality of legs face each other and maintain a constant length and spacing of the legs. It is a structure of a form.

As shown in FIG. 3B, a closed comb includes a port 34 having several legs in the direction of the inside of the electrode and a port 33 having several legs outward. And the length and distance of the legs that make up this port are kept constant.

As shown in FIG. 3C, in the form of a specifically patterned electrode, ports 35 and 36 are formed at both sides, and various types of patterns are formed inside a general wide pad. This is the form etched out.

At this time, the pattern (pattern) can be applied in various forms, such as circular, polygonal, linear.

On the other hand, the read-out circuit of the sensor is planted in the lower portion of the fingerprint recognition sensor array formed as described above, the read signal is read by the IC through the wiring and it is possible to perform a specific function through this. .

FIG. 4A is a diagram illustrating a two-port equivalent circuit of an EID fingerprint sensor, and FIG. 4B is a diagram of an equivalent circuit of a fingerprint when the acid of the fingerprint touches the unit fingerprint sensor.

As shown in the figure, the change in the equivalent circuit causes a change in impedance connected in parallel when the acid touches the acid and the bone of the fingerprint to the fingerprint recognition sensor, and when the valley touches, The state of air is maintained.

That is, when the fingerprint is recognized by the above mechanism, the degree of change in impedance becomes a decisive variable of sensor sensitivity of the fingerprint recognition sensor.

Accordingly, the open comb, the closed comb, and the closed comb of the unit fingerprint recognition sensor may be configured to maximize the magnitude of the impedance according to the peaks and valleys of the contact fingerprint. It can be configured as a specially patterned electrode.

FIG. 5 is a diagram illustrating a first embodiment of a sensing circuit of an EID fingerprint sensor. FIG. As shown therein, the sensing circuit of the fingerprint sensor connects the unit sensor 51 and the reference impedance 52 in series, and between the unit sensor 51 and the reference impedance 52. This is a method of measuring the output signal (V _out ).

That is, by comparing the change in the impedance 51 of the unit sensor according to the contact of the acid and the valley of the fingerprint with the reference impedance 52, it is possible to detect whether the valley is in contact with the acid or the acid.

At this time, the output signal (V _out ) is divided between the two impedances (impedance), so the size of the reference impedance (impedance) 52 should be appropriately selected. In general, the reference impedance can be used by making one unit sensor irrespective of the contact of the fingerprint.

In addition, in the case of DC, only resistance should be considered on an equivalent circuit in case of DC, and in case of AC, impedance including a capacitor should be considered.

6 is a diagram illustrating a second embodiment of a sensing circuit of an EID fingerprint sensor. As shown therein, the magnitude of the output signal V _out is also determined by the magnitude of the input signal, the impedance 61 of the unit sensor, and the reference impedance 62.

That is, the impedance 61 of the unit sensor is input to the amplifier 63 and is an output value of the reference impedance 62 ().

In this embodiment as well, the reference impedance may use the unit sensor itself.

7A to 7D are diagrams illustrating a manufacturing process of an EID fingerprint sensor according to the present invention. As shown in FIG. 7A, a port electrode material 72 for a fingerprint sensor is first deposited on a substrate 71.

In this case, as the electrode material 72, an electrode material such as poly Si, Al, Cr, Ta, Ti, Pt, Ir, Au, Mo, or the like is used. If the electrode is in direct contact with the fingerprint, materials such as Pt, Mo, Ir, and the like are used.

Here, the substrate 71 may be a driving circuit or a substrate including a driving circuit and a system IC, or only a sensor may be manufactured, and the driving circuit or the system IC may be an off-chip method. It can be implemented on the PCB.

As shown in FIG. 7B, after depositing the electrode material 72 on the substrate, the deposited electrode material is patterned.

The patterning method is to form an electrode pattern using a dry etching process, a wet etching process, or a lift-off method.

As shown in FIG. 7C, an insulating protective film 73 which maintains insulation between the electrodes of the port and protects the electrode from external foreign substances is deposited on the resultant electrode pattern 72. do.

Finally, as shown in FIG. 7D, the electrode is exposed to the outside by planarizing the deposited insulating protective film 73.

In this case, when the electrode 72 uses an electrode material such as Pt, Mo, Ir, or the like, the insulating protection layer 73 may be planarized to expose the electrode to the outside.

Therefore, the fingerprint recognition sensor manufactured as described above can measure impedance by the method of both AC and DC.

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 recognition sensor and the manufacturing method thereof according to the present invention can increase the fingerprint recognition rate of the sensor by increasing the difference between the impedance due to the peak and valley of the fingerprint, and can realize miniaturization and multifunction.

Claims (7)

A fingerprint array in which unit fingerprint sensors are arranged in n × n; A sensing electrode pattern unit formed in a predetermined form on each unit fingerprint sensor of the fingerprint array; And a driving circuit unit for outputting a value according to the impedance sensed by the sensing electrode pattern unit. The method of claim 1, Fingerprint sensor, characterized in that the size of the unit fingerprint sensor is formed 50 × 50 ㎛ ² . The method of claim 1, The electrode pattern formed on the sensing electrode pattern part may include an open comb, a closed comb, and a specifically patterned electrode to form impedances according to the acid and valley of the contacted fingerprint. Fingerprint sensor, characterized in that to maximize the size. The method of claim 1, The driving circuit unit connects the unit sensor and the reference impedance in series, and measures the output signal (V _out ) between the unit sensor and the reference impedance. Depositing an electrode material for a fingerprint sensor on a substrate; Patterning the deposited electrode material; And depositing an insulating protective film on the resultant of the patterned electrode material. The method of claim 5, As the electrode material to be deposited, a poly Si, Al, Cr, Ta, Ti, Pt, Ir, Au, Mo, ITO, RuO2 single electrode is used or double or more such as ITO / Pt, ITO / Mo, ITO / Ir A method of manufacturing a fingerprint sensor, characterized in that using an electrode material. The method of claim 5, The insulating protective film may further include planarizing the insulating protective film and exposing the electrode to the outside when the deposited electrode material is formed of Pt, Mo, or Ir.