KR100641103B1 - Fingerprint sensor of impedance conversion type and fabricating method thereof - Google Patents

Abstract

A fingerprint recognition sensor of an impedance changing mode and a manufacturing method thereof are provided to form a flat surface protecting layer without any polishing process by etching the second insulation layer formed to an upper part of a metal feed layer, forming a sensor metal layer to an etched part, and forming the surface protecting layer to an upper part of the formed structure. The second insulation layer(20) is formed to the upper part of the metal feed layer(3) and is etched as much as height of the sensor metal layer(5) by being patterned in a shape of the sensor metal layer. The sensor metal layer is formed to the etched part of the second insulation layer. The surface protecting layer(30) is formed to the upper part of the formed structure. The metal feed layer is formed to the upper part of the first insulation layer(10). The first insulation layer formed to the upper part of a lower substrate(1).

Description

Impedance conversion type fingerprint sensor and manufacturing method {FINGERPRINT SENSOR OF IMPEDANCE CONVERSION TYPE AND FABRICATING METHOD THEREOF}

1 is an exemplary diagram of an optical fingerprint recognition sensor using a prism.

2A to 2D are exemplary diagrams of respective fingerprint recognition sensors according to a non-optical measurement scheme.

Figure 3 is a structure for a conventional impedance conversion fingerprint recognition sensor.

Figures 4a to 4c is a cross-sectional view of the manufacturing process of the fingerprint sensor shown in FIG.

Figure 5 is a cross-sectional view of an embodiment of the present invention impedance conversion fingerprint sensor.

Figure 6a to 6e is a cross-sectional view of the manufacturing process of the fingerprint recognition sensor of the present invention shown in FIG.

Figure 7 is a cross-sectional view of yet another embodiment of the present invention impedance conversion fingerprint sensor.

** Description of the symbols for the main parts of the drawings **

1: lower substrate 2, 10: first insulating layer

3: metal feed layer 5: sensor metal layer

20: second insulating layer 30: surface protective layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impedance conversion fingerprint recognition sensor and a manufacturing method thereof, and more particularly, to an impedance conversion fingerprint recognition sensor and a method for manufacturing the same, which can improve a recognition rate for a fingerprint.

With the advent of the information age due to the spread of the Internet, it has become easy to collect and process the desired information, and serious problems have been raised that important personal information is easily stolen or destroyed by others. In addition, the development of electronic commerce and the use of mobile electronic devices have highlighted the necessity of restricting access to confidential and personal data. Therefore, as an alternative to token-based recognition methods such as PIN (Personal Identification Number) or password, and resident registration card and driver's license, the biometric technology, that is, technology that recognizes identity based on physiological or behavioral characteristics, is of great interest. Is evoking.

Biometrics are behavioral biometrics based on learning characteristics such as physical / physiological biometrics that measure face, fingerprint, iris, body odor, retina, and branched veins, and signature authentication. biometrics). The oldest and most popular method is fingerprint recognition, and with the development of recent technology, a small fingerprint sensor has been commercialized.

The fingerprint sensor is classified into optical and non-optical methods according to the measurement method of the fingerprint, and the optical method has a great strength in terms of detection reliability, but has a disadvantage in that its size is relatively large because it uses an optical system as a base (Fig. 1). ). The non-optical equations can be classified into four types according to the measurement method: AC electric field method, DC capacitive method, thermal swipe method, and resistive method (FIG. 2). .

As shown in FIG. 2A, the AC electric field fingerprint sensor uses one terminal of the conducting portion existing inside the fingerprint, and uses another terminal present in the fingerprint sensor. After generating a and array a metal pattern array (antenna pattern) acting as an antenna on the surface of the fingerprint sensor to obtain a fingerprint image by measuring the difference of the AC electric field (detected according to the acid and valley of the fingerprint). In this case, the metal pattern array is protected by an insulating film, and the insulating film serves to prevent damage to the sensor that may be caused by contact of external foreign matter. The AC electric field fingerprint sensor has a strong advantage against contamination by foreign matters because it does not become a problem at all if the foreign matter gets on the surface of the sensor if the AC electric field can penetrate well. In addition, by using AC instead of DC, it is relatively strong in ESD (Electro Static Discharge), and it is a fingerprint recognition mechanism that recognizes the conducting part existing inside the human skin. Or it can be distinguished by counterfeit goods. However, in order to increase the electric field change caused by the peaks and valleys of the fingerprint, the applied AC electric field must be large and additional circuits for signal processing are complicated.

The DC capacitive fingerprint sensor differs from the alternating current electric field method in that the patterned metal electrodes are arranged in an array, as shown in FIG. 2B. However, when the fingerprint touches the surface of the sensor, the capacitive fingerprint sensor is different. The contact area of the bone with the reading of the capacitance change caused by air with dielectric constant ε ₀ , and the change of capacitance caused by the epidermis of human with dielectric constant ε when the acid part of the fingerprint touches. At this time, the change of capacitance caused by acid and valley occurs about tens to hundreds [pF], and the driving circuit which reads the change of capacitance is possible in various ways. The DC capacitive fingerprint sensor has to clean the surface of the fingerprint sensor periodically and is very vulnerable to ESD (electrical state discharge) because of the contamination of the sensor by human hands, resulting in afterimage. There is a disadvantage in that it is indistinguishable from the fingerprint of a real person even using.

In the thermal swipe fingerprint sensor, the unit sensors are arranged in a linear array form as shown in FIG. 2C, and the unit sensors are arranged according to the valleys and mountains of the fingerprint when a human fingerprint is touched. Fingerprints are recognized by reading the difference in radiated heat. At this time, the method of sensing the heat is generally used pyroelectric, because the pyroelectric heat sensing method can implement the unit sensor structure in a stable state. If a temperature sensor of a method such as bolometric or thermopile is used, it is difficult to implement a mechanically stable fingerprint sensor because a membrane must be formed. Thermal Swapping fingerprint sensors are sensitive to ambient temperatures and have the disadvantage of being accustomed to swiping to obtain a good fingerprint image, while being relatively resistant to contaminants.

The resistive fingerprint sensor reads the resistance value of the human skin, which is a medium having a very high resistivity, as shown in FIG. 2D. The resistance value of the human skin is 500 [dpi]. In order to read, since the distance between the two terminals is very short and the effective cross-sectional area should be as wide as possible, it has the form of electrodes of IDC (inter digit comb) structure. This method measures resistance, which is the simplest electrical property to read fingerprint images, and has the advantage of evaluating the condition of the skin according to the resistance of the human skin. On the other hand, there is a problem that the electrode material must be exposed to external physical shocks and contact with human skin. Such exposure has a problem that requires the premise that the development of highly reliable electrode materials capable of withstanding physical shock and chemical reactions must be made.

Conventionally, as shown in FIG. 3, the electrode material is protected by a surface protection layer having excellent physical and chemical resistance to eliminate exposure of the electrode material, which is a problem of the resistive fingerprint sensor.

A manufacturing process for such a conventional resistive fingerprint sensor will be described with reference to FIG.

First, as shown in FIG. 4A, a first insulating layer (Si _x O _y or Si _x N _z ) 2 and a metal feed layer 3 are sequentially formed on the lower substrate 1.

Next, as shown in FIG. 4B, a second insulating layer (Si _x O _y or Si _x N _z ) 4 is formed on the structure, and a portion of the formed second insulating layer 4 is photo-etched. After etching through a method to expose a portion of the metal feed layer 3, a metal layer is applied and patterned on the structure to form a sensor metal layer 5 having an IDC structure.

Then, as shown in FIG. 4C, an insulating layer (Si _x N _z ) is deposited on the structure to a predetermined thickness (about 5000 [mm]) and then polished to polish the surface to about 1000 [mm]. The protective layer 6 is formed. That is, the surface protection layer 6 is bent by the sensor metal layer 5 formed at the bottom, and the surface protection layer 6 is made flat by a polishing process to eliminate the bending.

Through this manufacturing process, a conventional resistive (impedance conversion) fingerprint sensor is manufactured. In order to obtain a more accurate and reliable signal in manufacturing the sensor, the surface protective layer formed on the sensor metal layer is not curved. It must have a flat surface.

However, there is a problem in that a sensor manufacturing technique using a conventional polishing process has a very large technical difficulty to implement a thin and uniform surface protection layer.

Therefore, the present invention was created to solve the above-mentioned conventional problems, and etching the second insulating layer formed on the metal feed layer to the sensor metal layer height to be formed by patterning the sensor metal layer shape, the etched portion After forming a sensor metal layer on the structure to form a surface protective layer for protecting the sensor metal layer on the structure, thereby providing an impedance conversion fingerprint recognition sensor that can form a flat surface protective layer without a polishing process and a method of manufacturing the same. Its purpose is to.

The impedance conversion type fingerprint recognition sensor of the present invention for achieving the above object is formed on the metal feed layer, the second insulating layer patterned in the shape of a sensor metal layer to be described later and etched by the height of the sensor metal layer; A sensor metal layer formed on an etched portion of the second insulating layer; It characterized in that it comprises a surface protective layer formed on the structure.

The metal feed layer may be formed on the lower substrate, and may be formed on the etched portion of the first insulating layer etched by the height of the metal feed layer by patterning the metal feed layer.

In order to achieve the above object, the present invention provides a method of manufacturing an impedance conversion fingerprint recognition sensor, wherein a second insulating layer is formed on a metal feed layer, and a portion of the second insulating layer is etched to expose a portion of the metal feed layer. Steps; Patterning the second insulating layer into a shape of a sensor metal layer to be described later and etching the substrate by the height of the sensor metal layer; Forming a sensor metal layer on the etched portion of the second insulating layer; Forming a surface protective layer for protecting the sensor metal layer on the structure, characterized in that made.

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

First of all, in adding reference numerals to the components of each drawing, it should be noted that the same components have the same reference numerals as much as possible even if displayed on different drawings.

In addition, detailed description of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

FIG. 5 is a cross-sectional view of an exemplary embodiment of the impedance conversion fingerprint sensor according to the present invention, wherein the first insulating layer 10 is etched by the height of the metal feed layer in the shape of a metal feed layer, and a metal feed on the etched portion. It can be seen that the layer 3 is formed, and the second insulating layer 20 is etched in the shape of the sensor metal layer by the height of the sensor metal layer to form the sensor metal layer 5 on the etched portion.

That is, the first insulating layer 10 formed on the lower substrate 1 and etched by the height of the metal feed layer in the shape of the metal feed layer, and the metal feed layer formed on the etched portion of the first insulating layer 10. (3) and a second insulating layer 20 formed on the structure and etched by the height of the sensor metal layer in the shape of a sensor metal layer, and partially etched to expose a portion of the metal feed layer 3, and The sensor metal layer 5 formed on the etched portion of the second insulating layer 20 and the surface protection layer 30 formed on the structure to protect the sensor metal layer 5.

Here, the sensor metal layer 5 has an IDC (inter digit comb) structure, the first insulating layer 10 and the second insulating layer 20 is formed of Si _x O _y or Si _x N _z , The metal feed layer 3 is formed on the etched portion of the first insulating layer 10, and the sensor metal layer 5 is formed on the etched portion of the second insulating layer 20 so that the sensor metal layer 5 may be formed. Since the heights of the second insulating layers 20 are the same, the top surface of the structure on which the sensor metal layer 5 is formed is flat so that the surface protection layer 30 is flat, and thus, without performing a polishing process as in the prior art. The surface protection layer 30 can be formed flat to about 1000 [mm] thickness.

Then, the manufacturing process of the fingerprint sensor for the present invention having the structure as described above will be described with reference to FIG.

As shown in FIG. 6A, the first insulating layer 10 composed of Si _x O _y or Si _x N _z is formed on the lower substrate 1 by using a predetermined method, for example, vapor deposition, sputtering, or the like. The first insulating layer 10 is then patterned into the shape of the metal feed layer 3 to be formed later, and then etched by the height of the metal feed layer 3. That is, the first insulating layer 10 is patterned into the shape of the metal feed layer 3 to be formed later using a photolithography process, and then etched by the height of the metal feed layer 3.

Next, as shown in FIG. 6B, a metal feed layer 3 is formed on the etched portion of the first insulating layer 10 by using metal such as Pt and Mo, and Si _x O is formed on the structure. A second insulating layer 20 composed of _y or Si _x N _z is formed. In this case, since the metal feed layer 3 and the first insulating layer 10 are formed at the same height, and the upper portion of the structure has a flat surface, the second insulating layer 20 formed on the upper surface also has a flat surface.

Next, as shown in FIG. 6C, a portion of the second insulating layer 20 is etched to expose a portion of the metal feed layer 3, and patterned into a shape of a sensor metal layer 5 to be formed later. The metal layer 5 is etched by the height. That is, the second insulating layer 20 is patterned into a shape of a sensor metal layer to be formed later using a photolithography process, and then etched by the height of the sensor metal layer.

Next, as shown in FIG. 6D, the sensor metal layer 5 is formed on the etched portion of the second insulating layer 20 by using metal. In this case, the part of the metal feed layer 3 exposed in the second insulating layer 20 is filled with metal in the process of forming the sensor metal layer 5, so that the sensor metal layer 5 and the metal feed layer 3 are filled. ) Is connected. In addition, the cross-sectional view of the second insulating layer 20 and the sensor metal layer 5 shown in the drawing shows that the sensor is rotated 90 degrees, and the sensor metal layer 5 has an IDC structure.

When the sensor metal layer 5 is formed, as shown in FIG. 6E, an insulating layer Si _x N _z is coated on the structure by about 1000 [Å] to form the surface protective layer 30. Here, the surface protective layer 30 is formed at the same height as the sensor metal layer 5 and the second insulating layer 20, so that the surface on which the surface protective layer 30 is formed is flat. There is no need to go through a polishing process after deposition by a predetermined thickness (about 5000 [mm]), thus reducing the number of processes for manufacturing the sensor and having the advantage of forming a surface protection layer having excellent uniformity.

In this process, the metal feed layer 3 and the sensor metal layer 5 are formed on the etched portions of the first insulating layer 10 and the second insulating layer 20, respectively. Sensors can be manufactured.

In addition, the fingerprint sensor of the present invention can be manufactured by mixing with the existing method, an example thereof will be described with reference to FIG.

7 is a cross-sectional view of another embodiment of the fingerprint sensor according to the present invention, in which the metal feed layer 3 is formed on the first non-etched first insulating layer 2 and the sensor metal layer 5. Only the etched portion of the second insulating layer 20 can be seen.

That is, the first insulating layer 2 and the metal feed layer 3 sequentially formed on the lower substrate 1, and are formed on the structure and etched by the shape and height of the sensor metal layer, and the metal feed layer 3. The second insulating layer 20 is partially etched to expose a portion of the), the sensor metal layer 5 formed on the etched portion of the second insulating layer 20, and the sensor metal layer 5 on the structure It is composed of a surface protective layer 30 formed to protect.

As described above, although the metal feed layer 3 does not have a flat surface, the lower structure on which the surface protection layer 30 is formed, that is, the structure on which the sensor metal layer 5 is formed may be formed to have a flat surface. The surface protective layer 30 may be formed to have a uniform thickness with a thin thickness without a polishing process.

As described in detail above, the present invention may be etched to a height of a sensor metal layer to be formed by patterning a second insulating layer formed on the metal feed layer in the shape of a sensor metal layer, and forming a sensor metal layer on the etched portion. By forming a surface protection layer to protect the sensor metal layer on the structure, there is an effect that can form a flat surface protection layer without a polishing process.

Claims (5)

A second insulating layer formed on the metal feed layer and patterned into a shape of a sensor metal layer to be described later and etched by the height of the sensor metal layer; A sensor metal layer formed on an etched portion of the second insulating layer; Impedance conversion type fingerprint recognition sensor comprising a surface protective layer formed on the structure. 2. The fingerprint recognition sensor of claim 1, wherein the metal feed layer is formed on the first insulating layer formed on the lower substrate. The impedance conversion method of claim 1, wherein the metal feed layer is formed on the lower substrate, and is formed on the etched portion of the first insulating layer etched by the height of the metal feed layer by patterning the metal feed layer. Fingerprint sensor. Forming a second insulating layer on the metal feed layer, and etching a portion of the second insulating layer to expose a portion of the metal feed layer; Patterning the second insulating layer into a shape of a sensor metal layer to be described later and etching the substrate by the height of the sensor metal layer; Forming a sensor metal layer on the etched portion of the second insulating layer; And forming a surface protective layer for protecting the sensor metal layer on the structure. The metal feed layer of claim 4, wherein the metal feed layer is formed on an etched portion formed on the first insulating layer formed on the lower substrate or patterned into the metal feed layer shape of the first insulating layer formed on the lower substrate. Impedance conversion method fingerprint recognition sensor manufacturing method.

Images