TWM518367U - Capacitive fingerprint sensor with improved electrostatic protection - Google Patents

Description

Capacitive fingerprint sensor with enhanced electrostatic protection

The present invention relates to a capacitive fingerprint sensor, and more particularly to a capacitive fingerprint sensor with electrostatic protection.

The fingerprint is the irregular concave and convex lines on the skin epidermis, and each person has its own fingerprint according to the different genetic characteristics. In other words, the fingerprint can be used as the identification biometric of the personal identity, so that the fingerprint is widely used at present. Personal identification.

With the rapid development of the semiconductor industry, capacitive fingerprint sensors made of semiconductor wafers have been gradually applied to a wide variety of mobile electronic devices to reduce the risk of theft of the mobile electronic device. Since the capacitive sensing element in the capacitive fingerprint sensor has a surface for contact with a finger for detection, it must be exposed to an external environment over a large area, but any charged object may generate static electricity. The capacitive sensing component is damaged, and therefore, the antistatic structure in the capacitive fingerprint sensor is becoming more and more important.

For example, in the Chinese Patent Publication No. CN102682271, an electrostatic damage protection structure of a capacitive fingerprint integrated circuit is disclosed, which comprises a plurality of sensing plates, forming a sensing plate array to define a sensing region; a first passivation a layer overlying the sensing plate; a patterned electrostatic damage protective metal layer deposited on the first passivation layer and having a fish-bone-like structure; a common conductive layer Connected to the fishbone structure and surrounding the sensing region and used to conduct electrostatic charge to the outside; an associated signal processing circuit is located below the sensing plate and electrically connected to the sensing plate And a second passivation layer disposed between the sensing board and the signal processing circuit. Accordingly, the sensing board and the signal processing circuit can be protected from electrostatic damage.

However, in the above-mentioned electrostatic damage protection structure, the fishbone structure extends laterally so that the electric field concentration effect generated by the tip thereof may directly discharge electricity to the sensing plate for static electricity generated from the surface downward. On the other hand, the damage of the integrated circuit is caused, and there is still room for improvement in the guidance, and there is an improved demand.

The main purpose of the novel is to solve the problem of the conventional capacitive fingerprint sensor, in which the electrostatic damage protection structure is still insufficient in guiding the static electricity, which may cause damage to the integrated circuit.

To achieve the above objective, the present invention provides a capacitive fingerprint sensor with electrostatic protection, comprising a sensing substrate, a plurality of capacitive sensing plates, a first dielectric layer, a second dielectric layer, and a third A dielectric layer and an electrostatic protection structure.

The sensing substrate includes a substrate and a sensing circuit disposed on the substrate; the capacitive sensing plate is disposed on the sensing circuit and electrically connected to the sensing circuit; the first dielectric layer is disposed on the Between the capacitive sensing plate and the sensing circuit; the second dielectric layer is disposed on the first dielectric layer to cover the capacitive sensing plate; the third dielectric layer is disposed on the second dielectric layer And the static electricity protection structure is disposed on the third dielectric layer and penetrates the third dielectric layer, the static electricity protection structure includes a conductive mesh exposed on the uppermost layer, the conductive mesh includes a plurality of positions corresponding to the capacitor A space area of the sensing board and a plurality of interlaced grid lines, and the conductive grid extends through the third dielectric layer.

Accordingly, the present invention allows the conductive mesh to directly contact the human body by allowing the conductive mesh of the electrostatic protection structure to penetrate the third dielectric layer, so that the static electricity adsorbed by the electrostatic protection structure can be discharged through the finger. Avoid damage to the integrated circuit due to electrostatic damage to enhance the effect of static electricity protection.

The detailed description and technical content of this new model are described below with the following diagram:

Please refer to FIG. 1 to FIG. 3, FIG. 1 is a schematic cross-sectional view showing an embodiment of the present invention, and FIG. 2 is a schematic plan view of the present invention. FIG. 3 is a schematic view of the present invention. A schematic diagram of the leakage of another embodiment, as shown in the figure: the present invention is a capacitive fingerprint sensor with electrostatic protection, comprising a sensing substrate 10, a plurality of capacitive sensing plates 20, and a first dielectric layer. 30. A second dielectric layer 40, a third dielectric layer 50, and an electrostatic protection structure 60.

The sensing substrate 10 includes a substrate 11 and a sensing circuit 12 . The substrate 11 is generally a substrate, and the sensing circuit 12 is disposed on the substrate 11 . The capacitive sensing board 20 is disposed on the sensing circuit 12 and electrically connected to the sensing circuit 12 . The first dielectric layer 30 is disposed between the capacitive sensing board 20 and the sensing circuit 12 . It is made of a polyimine used in an intermetallic dielectric (IMD), and has a dielectric constant of about 2.8 to 3.2. In this embodiment, the capacitive sensing board 20 includes a connecting line 21 extending through the first dielectric layer 30. The capacitive sensing board 20 is electrically connected to the sensing circuit 12 through the connecting line 21.

The second dielectric layer 40 is disposed on the first dielectric layer 30 to cover the capacitive sensing plate 20, and the second dielectric layer has a dielectric constant greater than the first dielectric layer. The second dielectric layer 40 may be made of lanthanum oxynitride (SiON) having a dielectric constant of between about 6.4 and 6.8 and a thickness of about 15 μm to 20 μm. The third dielectric layer 50 is disposed on the second dielectric layer. 40, which may also be made of polyimide, having a thickness of about 3 μm to 4 μm. The third dielectric layer 50 has a sensing surface 51 for contacting a finger 80 away from the second dielectric layer 40. In addition, the first dielectric layer 30, the second dielectric layer 40, and the third dielectric layer 50 may be various passivation layers.

The electrostatic protection structure 60 is disposed in the third dielectric layer 50 and is made of metal. In this embodiment, a conductive mesh 61 and a conductive ring 62 exposed on the uppermost layer are included. The conductive grid 61 includes a plurality of space areas 611 and a plurality of grid lines 612. The spaces area 611 are located above the capacitive sensing board 20, and the grid lines 612 are interlaced with each other. In the region 611, the conductive ring 62 surrounds a periphery of the conductive mesh 61, is electrically connected to the conductive mesh 61 and grounded 70, and the conductive mesh 61 extends through the third dielectric layer 50.

In this way, when the finger 80 (as drawn) or a charged object approaches the sensing surface 51, the conductive mesh 62 is directly contacted, and the grounded wire 70 is discharged through the conductive mesh 62. It is possible to prevent static electricity from leaking to the capacitive sensing board 20, thereby causing damage to the integrated circuit, thereby enhancing electrostatic protection.

In this embodiment, since the third dielectric layer 50 has a lower dielectric constant than the second dielectric layer 40, when the electrostatic discharge occurs in the third dielectric layer 50, it can be reduced. The probability of the static electricity flowing further to the second dielectric layer 40, and in the case of normal fingerprint measurement, the second dielectric layer 40 has a higher dielectric constant and the capacitive sensing plate 20 can be improved. The capacitance value between the sensing surfaces 51 compensates for the capacitance value lost between the capacitive sensing plate 20 and the sensing surface 51 due to the increase in distance, thereby improving the sensing capability.

In summary, the present invention can allow the conductive mesh to directly contact the human body through the conductive mesh of the electrostatic protection structure, and the conductive mesh is discharged from the ground through the conductive mesh. Avoid damage to the integrated circuit due to static electricity to enhance static protection. Furthermore, the present invention further provides that the third dielectric layer has a lower dielectric constant than the second dielectric layer, reducing the probability of the static electricity flowing to the second dielectric layer to protect the capacitance sensing. The board and the sensing circuit can also compensate for the capacitance value lost by the distance between the capacitive sensing board and the sensing surface, and improve the sensing capability. Therefore, the present invention is highly advanced and conforms to the application for a new patent. The requirements of the 爰 提出 提出 提出 提出 提出 提出 提出 。 。 。 。 。 。 。 。 。 。 。 。 。 。

The present invention has been described in detail above, but the above is only a preferred embodiment of the present invention, and the scope of the present invention is not limited. That is, the equal changes and modifications made in accordance with the scope of this new application shall remain within the scope of the patent of this new type.

10‧‧‧Sensing substrate
11‧‧‧Substrate
12‧‧‧Sensor circuit
20‧‧‧Capacitive sensing board
21‧‧‧Connecting line
30‧‧‧First dielectric layer
40‧‧‧Second dielectric layer
50‧‧‧ third dielectric layer
51‧‧‧Sense surface
60‧‧‧Electrostatic protection structure
61‧‧‧ Conductive grid
611‧‧‧Space area
612‧‧ ‧ grid
62‧‧‧ Conductive ring
70‧‧‧ Grounding
80‧‧‧ fingers

Figure 1 is a schematic cross-sectional view showing an embodiment of the present invention. 2 is a top plan view of an embodiment of the present invention. FIG. 3 is a schematic diagram of power leakage according to an embodiment of the present invention.

10‧‧‧Sensing substrate

11‧‧‧Substrate

12‧‧‧Sensor circuit

20‧‧‧Capacitive sensing board

21‧‧‧Connecting line

30‧‧‧First dielectric layer

40‧‧‧Second dielectric layer

50‧‧‧ third dielectric layer

51‧‧‧Sense surface

60‧‧‧Electrostatic protection structure

61‧‧‧ Conductive grid

Claims (5)

A capacitive fingerprint sensor for enhancing electrostatic protection, comprising: a sensing substrate, the sensing substrate comprises a substrate and a sensing circuit disposed on the substrate; a plurality of sensing circuits are disposed on the sensing circuit and a sensing circuit electrically connected to the sensing circuit; a first dielectric layer disposed between the capacitive sensing plate and the sensing circuit; a first dielectric layer disposed on the first dielectric layer to cover the capacitive a second dielectric layer of the test plate; a third dielectric layer disposed on the second dielectric layer; and an electrostatic protection structure extending through the third dielectric layer, the electrostatic protection structure including the exposed uppermost layer And a conductive grid comprising a plurality of locations corresponding to the space area of the capacitive sensing board and a plurality of grid lines interlaced around the space area, and the conductive grid extends through the third dielectric layer. The capacitive fingerprint sensor for enhancing electrostatic protection according to claim 1, wherein the electrostatic protection structure further comprises a conductive ring surrounding the conductive mesh and electrically connected to the conductive mesh and grounded. The capacitive fingerprint sensor for enhancing electrostatic protection according to claim 1, wherein the second dielectric layer has a dielectric constant greater than that of the first dielectric layer. The capacitive fingerprint sensor for enhancing electrostatic protection according to claim 1, wherein the third dielectric layer has a dielectric constant smaller than that of the second dielectric layer. The capacitive fingerprint sensor for enhancing electrostatic protection according to claim 1, wherein the capacitive sensing plate comprises a connecting line electrically connected to the sensing circuit through the first dielectric layer.