TW201937401A - Optical fingerprint sensing module - Google Patents

Abstract

An optical fingerprint sensing module includes a substrate, a semiconductor layer and an optical channel structure layer, wherein the semiconductor layer and the optical channel structure layer are stacked on the substrate in sequence. The substrate includes a plurality of light sensing elements formed at intervals in the substrate; and further, the optical channel structure layer set on the semiconductor layer to form a plurality of optical channel. The optical channel structure includes a first combined-type photoresist layer having a first photoresist layer; a micro lens structure are set at least one of the two position: on the first photoresist layer, and under the first photoresist layer; and the optical channel are formed by the micro lens structure. The above-mentioned optical fingerprint sensing module is disclosed to converge the light by the micro lens structure; and further, the angle light can be effectively filtered by the opaque photoresist layer so as to improve the quality of the sensing image.

Description

Optical fingerprint sensor module

The invention relates to an optical fingerprint sensing technology, in particular to an optical fingerprint sensing module with a light channel.

The so-called fingerprint identification, as the name implies, uses the unique fingerprint information on the human finger for identification. A common fingerprint recognition device can be composed of two elements. One is the Fingerprint Sensor, whose main purpose is to collect a complete fingerprint image. Another element is the Fingerprint Algorithm. After the front-end fingerprint sensor collects the fingerprint image, it is followed by an algorithm for fingerprint image processing and fingerprint feature point extraction. After generating a fingerprint template, the original fingerprint image is discarded, and finally fingerprint comparison is performed. According to different sensing methods, fingerprint recognition devices can be divided into optical (Optical) and capacitive (Capacity). Capacitive fingerprint recognition device, its principle is to integrate high-density capacitive sensors or pressure sensors such as miniaturized sensors into a chip. When a finger presses on the surface of the chip, the internal miniature capacitive sensor will Fingerprint images are formed based on the different charge amounts (or temperature differences) generated by the peak and trough accumulation of the fingerprint. Capacitive sensors have the advantages of thinness and miniaturization and can be widely used in handheld devices, but their disadvantages are high cost and durability. The optical fingerprint recognition device includes a light source, an image capturing (sensing) element and a light transmitting element. The light source is used to emit a light beam to irradiate a finger pressed on the light-transmitting element, and the peaks and troughs of the fingerprint absorb and destroy the total reflection of the light, thereby obtaining a fingerprint image, and then the image is charged by a charge coupled element (CCD). Capture and output. Because the optical fingerprint sensor's collection method is the non-contact chip itself, that is, the fingerprint pressing part is composed of optical elements such as acrylic or glass, so the biggest advantage of the optical type is that it is cheap and durable. However, in the above-mentioned image capturing process, the light beam reflected by the fingerprint is easily scattered to the image capturing element, resulting in poor image capturing quality and affecting the identification result.

In view of this, how to improve the image capturing quality of the photoelectric fingerprint identification device is a goal that needs to be worked hard at present.

The present invention provides an optical fingerprint sensing module. The fingerprint sensing module uses a micro-lens structure to collect light and effectively filter angular light through an opaque photoresist layer to increase the quality of a sensing image.

An optical fingerprint sensing module according to an embodiment of the present invention includes a substrate, a semiconductor layer, and an optical channel structure layer. The substrate includes a plurality of light sensing modules arranged at intervals. The semiconductor layer is disposed on the substrate. The optical channel structure layer is disposed on the semiconductor layer to form a plurality of optical channels. The optical channel structure layer includes a first composite photoresist layer and a plurality of microlens structures. The first composite photoresist layer is disposed on the semiconductor layer, and the first composite photoresist layer includes a first photoresist layer. Any micro-lens structure is disposed above any one of the first composite photoresist layers and at least one of the first composite photoresist layers, wherein the micro-lens structure forms the light channel.

In the following, detailed description will be given through specific embodiments in conjunction with the accompanying drawings to make it easier to understand the purpose, technical content, characteristics and effects achieved by the present invention.

Hereinafter, the embodiments of the present invention will be described in detail, and illustrated with drawings. In addition to these detailed descriptions, the present invention can also be widely implemented in other embodiments, and easy replacements, modifications, equivalent changes of any of the embodiments are included in the scope of the present invention, and the scope of the patent application is quasi. In the description of the specification, in order to make the reader have a more complete understanding of the present invention, many specific details are provided; however, the present invention may be implemented without omitting some or all of the specific details. In addition, well-known steps or elements have not been described in detail to avoid unnecessarily limiting the invention. The same or similar elements in the drawings will be represented by the same or similar symbols. It is particularly noted that the drawings are for illustration purposes only and do not represent the actual size or number of components. Some details may not be fully drawn in order to make the drawings concise.

Please refer to FIG. 1A, which is a schematic cross-sectional view of an optical fingerprint sensor module according to an embodiment of the present invention. The optical fingerprint sensing module 100 includes a substrate 110, a semiconductor layer 120, and an optical channel structure layer 130. As shown in the figure, the substrate 110 includes a plurality of light-sensing modules 111 spaced apart. The substrate 110 includes, but is not limited to, a silicon substrate. In this embodiment, any one of the light-sensing modules 111 may include only one light-sensing element 1111. The semiconductor layer 120 is disposed on the substrate 110. Please continue to refer to FIG. 1A, an optical channel structure layer 130 is disposed on the semiconductor layer 120 to form a plurality of optical channels. The optical channel structure layer 130 includes a first composite photoresist layer 131 and a plurality of microlens structures 133. As shown in FIG. 1A, the first composite photoresist layer 131 is disposed on the semiconductor layer 120. Any one of the micro lens structures 133 is disposed above the first composite photoresist layer 131 and at least one of the first composite photoresist layers 131 (as shown in FIGS. 1A, 1B, and 1C), wherein the plurality of microlens structures form the A plurality of optical channels. In an embodiment, please refer to FIG. 2A. The first composite photoresist layer 131 includes a first photoresist layer 1311 and a first opaque photoresist layer 1312 stacked on the first photoresist layer 1311. An opaque photoresist layer 1312 has a plurality of first openings 1313. In yet another embodiment, the first opaque photoresist layer 1312 is made of a low-reflectivity material, and its reflectance is less than 30%. For example, preferably, the first opaque photoresist layer 1312 is Black photoresist layer (Black Matrix) or color photoresist layer. In this embodiment, the size of the micro-lens structure 133 is larger than the size of the opening of the first opening 1313 corresponding thereto. It can be understood that the size of the micro-lens structure 133 may also happen to be equal to the size of the first opening 1313. In addition, any micro-lens structure 133 is not limited to the plano-convex lens structure shown in FIG. 2A, but may also be a bi-convex lens structure (as shown in FIG. 2B), a plano-concave lens structure (as shown in FIG. 2C), or a bi-concave lens structure ( (As shown in FIG. 2D). In addition, according to different lens structures, the micro-lens structure 133 may be provided above the first opening 1313 (as shown in FIG. 2A) and below the first opening 1313 (as shown in FIG. 2E, 2F and 2G), or disposed in the first opening 1313 (as shown in FIG. 2C). Furthermore, the micro-lens structure 133 may be arranged below the first opening 1313 and extended into the opening according to the design (as shown in FIG. 2B). (Shown in Figure 2D). As shown in FIG. 2E, FIG. 2F, and FIG. 2G, in the embodiment provided below the first opening 1313, it is possible to form a desired shape groove on the first photoresist layer 1311 by using an appropriate method, and then The lens structure 133 is disposed therein, and its manufacturing method is not repeated here. In the above structure, light is incident from the light channel structure layer 130 and enters the light sensing module 111 of the substrate 110 through the micro lens structure 133 and the first opening 1313. Among them, the reflectivity of the opaque photoresist layer is low, for example In other words, the reflectivity of the black photoresist is only about 6%, so it can effectively absorb light or prevent the continued reflection of invalid light, and the micro-lens structure 133 helps the light to focus on the light-sensing module 111. Therefore, the fingerprint sensing mode of the present invention In addition to effectively converging light, the angular light is effectively filtered by the light absorption effect of the opaque photoresist layer, which can increase the quality of the induced image. In the following embodiments, the micro-lens structure 133 uses a plano-convex lens structure as the main implementation example, and the changes of the remaining lenses will not be described again.

In an embodiment, please refer to FIGS. 3 and 4. FIGS. 3 and 4 are schematic cross-sectional views of an optical fingerprint sensor module according to different embodiments of the present invention. Please refer to FIG. 3 first. In this embodiment, the semiconductor layer 120 further includes at least one metal layer 121, and the metal layer 121 has a plurality of second openings 1211. The positions of the second openings 1211 correspond to the positions of the light sensing module 111. . That is, in the optical fingerprint sensor module according to the embodiment of the present invention, the positions of the first opening 1313, the second opening 1211, and the light sensing module 111 correspond to each other from top to bottom. In one embodiment, the semiconductor layer 120 includes, but is not limited to, a 1-Poly-Five-Metal (P5M) structure. The metal layer structure of the semiconductor layer 120 can reflect invalid light again. In still another embodiment, the opening size of any one of the second openings 1211 is smaller than the opening size of the first opening 1313 corresponding to it; or the opening size of any one of the second openings is smaller than the opening size of the fourth opening 1323 corresponding thereto. Opening size. In yet another embodiment, the metal layer 121 in the semiconductor layer 120 is a plurality of layers, and the position of the second opening 1211 at least partially overlaps in the axial position. That is, the positions of the second openings 1211 of the upper and lower metal layers may be as shown in FIG. 3, and all the opening positions are completely overlapped, or, as shown in the embodiment of FIG. 4, all the opening positions are not completely overlapped. In this way, the size of the opening may be the smallest due to the limitation of the process technology. The position of the light entering the light-sensing module 111 can be controlled by the incomplete alignment of the opening positions of the upper and lower metal layers.

In another embodiment, as shown in FIG. 5, FIG. 5 is a schematic cross-sectional view of an optical fingerprint sensor module according to another embodiment of the present invention. In this embodiment, at least one third opaque photoresist layer 1314 is further disposed in the first photoresist layer 1311, wherein each third opaque photoresist layer 1314 has a third opening 1315, and the first The position of the three openings 1315 and the position of the first opening 1313 correspond to the position of the light sensing module 111. In an embodiment, the third opaque photoresist layer 1314 is a plurality of layers, and the position of the third opening 1315 at least partially overlaps in the axial position (as shown in FIG. 6). The reason is as described above. More details. In an embodiment, the third opaque photoresist layer 1314 may be a black photoresist or a color photoresist. Preferably, the third opaque photoresist layer is a black photoresist to effectively absorb ineffective light.

Please refer to FIG. 7. In an embodiment, the optical channel structure layer 130 includes a second composite photoresist layer 132, and the second composite photoresist layer 132 is stacked on the first composite photoresist layer 131, and the second composite The photoresist layer 132 includes a second photoresist layer 1321 and a second opaque photoresist layer 1322 stacked on the second photoresist layer 1321. The second opaque photoresist layer 1322 has a plurality of fourth openings. 1323. In the embodiment of FIG. 6, the structures of the first composite photoresist layer 131 and the second composite photoresist layer 132 may be the same or different. In yet another embodiment, the second opaque photoresist layer 1322 may also be made of a low-reflectivity material with a reflectance of less than 10%, which includes but is not limited to a black photoresist layer or a color photoresist layer. In an embodiment, the plurality of through holes 134 penetrate the second photoresist layer 1321 from the fourth opening 1323 and expose at least part of the plurality of micro lens structures 133. The fourth opening 1323, the through holes 134, and the micro lens structure 133 are exposed. And the first opening 1313 forms the light channel. In an embodiment, a low-refractive-index material is further filled at least in the through-hole 134 to form a low-refractive-index layer 135, that is, a low-refractive-index material can be filled into the fourth opening 1323, and further, a low-refractive index The material can be filled to be flush with the second opaque photoresist layer 1322. In another embodiment, the through hole 134 may not be filled with any substance. In the above structure, light is incident through the optical channel structure layer 130, and enters the light sensing module 111 of the substrate 110 through the fourth opening 1323, the through hole 134 (low refractive index layer 135), the micro lens structure 133, and the first opening 1313. on.

Following the above, the role of the microlens structure 133 and the opaque photoresist layer is further explained here. For example, if the focal length of the microlens structure 133 itself is f, the image distance of the microlens structure 133 to the light sensing module 111 is v, and the object distance of the microlens structure 133 to the imaging object is u, according to the lens imaging formula: , You can control f and v to image fingerprints at distance u clearly, but the images at other distances will be more blurred. If the focal length f of the microlens structure 133 is fixed, whether the imaging of the fingerprint distance u is clear or not is determined by the depth of field. Therefore, the structure of the present invention can determine the depth of field by controlling the opening size of the fourth opening 1323. That is, in addition to filtering the angle light, the opening of the second opaque photoresist layer 1322 of the second composite photoresist layer 132 determines the depth of field, which is one of the main keys for whether the imaging is clear.

In still another embodiment, please refer to FIGS. 8 and 9. FIGS. 8 and 9 are schematic cross-sectional views of an optical fingerprint sensor module according to another embodiment of the present invention. As shown in the figure, at least one fourth opaque photoresist layer 1324 is further disposed in the second photoresist layer 132, wherein each fourth opaque photoresist layer 1324 has a fifth opening 1325, and the fifth The position of the opening 1325 corresponds to the position of the first opening 1313, the position of the fourth opening 1323, and the position of the light sensor module 111. In one embodiment, the fourth opaque photoresist layer 1324 is a plurality of layers, and The position of the fifth opening 1325 at least partially overlaps in the axial position (FIG. 7 illustrates a complete overlap; FIG. 8 illustrates a partial overlap).

In yet another embodiment, please refer to FIG. 10, which is a schematic cross-sectional view of an optical fingerprint sensor module according to another embodiment of the present invention. As shown in the figure, the light-sensing module 111 may also include a plurality of light-sensing elements 1111. The light-sensing element 1111 includes, but is not limited to, an array disposed on the substrate 110. The light-sensing elements 1111 arranged in multiple arrays can be used to collect light at different angles, and the quality of the sensing image can be increased.

It should be noted that, in the foregoing embodiment, the optical fingerprint sensing module 100 is applied to an optical fingerprint recognition system, and the complete structure of the optical fingerprint recognition system is not shown. Other functional elements of the optical fingerprint recognition system, such as a light source structure and a glass cover structure, are well known to those of ordinary skill in the technical field to which the present invention pertains, and are not the main technical features of the present invention, so they will not be repeated here.

To sum up, the fingerprint sensor module of the present invention uses a micro-lens structure to effectively focus light on the light sensor module. In addition, it effectively filters angular light through an opaque photoresist layer, thereby reducing invalid reflection. Furthermore, according to the thickness design of different fingerprint recognition systems, the opening size of the opaque photoresist layer can be flexibly designed to control the depth of field to improve the quality of imaging. Furthermore, the light-sensing module can be designed to include a light-sensing element or a plurality of light-sensing elements according to requirements to effectively collect light at different angles. Furthermore, in order to avoid the limitation of the process technology, the opaque photoresist layer and the metal layer mentioned in the present invention can be designed to completely overlap or partially overlap the upper and lower opening positions according to requirements, so as to meet the required light channel.

The above-mentioned embodiments are only for explaining the technical ideas and characteristics of the present invention. The purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. When the scope of the patent of the present invention cannot be limited, That is, any equivalent changes or modifications made in accordance with the spirit disclosed in the present invention should still be covered by the patent scope of the present invention.

100‧‧‧optical fingerprint sensor module

110‧‧‧ substrate

111‧‧‧light sensor module

1111‧‧‧Light sensor

120‧‧‧Semiconductor layer

121‧‧‧ metal layer

1211‧‧‧Second opening

130‧‧‧Optical channel structure layer

131‧‧‧The first composite photoresist layer

1311‧‧‧First photoresist layer

1312‧‧‧First opaque photoresist layer

1313‧‧‧First opening

1314‧‧‧Third opaque photoresist layer

1315‧‧‧ Third opening

132‧‧‧Second composite photoresist layer

1321‧‧‧Second photoresist layer

1322‧‧‧Second opaque photoresist layer

1323‧‧‧fourth opening

1324‧‧‧ Fourth opaque photoresist layer

1325‧‧‧Fifth opening

133‧‧‧Micro lens structure

134‧‧‧through hole

135‧‧‧Low refractive index layer

FIG. 1A is a schematic cross-sectional view showing a structure of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 1B is a schematic cross-sectional view showing a structure of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 1C is a schematic cross-sectional view showing a structure of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 2A is a schematic cross-sectional view showing a structure of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 2B is a schematic cross-sectional view showing the structure of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 2C is a schematic cross-sectional view showing a structure of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 2D is a schematic cross-sectional view showing the structure of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 2E is a schematic cross-sectional view showing the structure of an optical fingerprint sensor module according to an embodiment of the present invention. 2F is a schematic cross-sectional view showing the structure of an optical fingerprint sensor module according to an embodiment of the present invention. 2G is a schematic cross-sectional view showing the structure of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a structure of an optical fingerprint sensor module according to another embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a structure of an optical fingerprint sensor module according to still another embodiment of the present invention. 5 is a schematic cross-sectional view showing a cross-sectional view of an optical fingerprint sensor module according to an embodiment of the present invention. 6 is a schematic cross-sectional view showing a cross-sectional view of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing a schematic cross-sectional view of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 8 is a schematic cross-sectional view showing a schematic cross-sectional view of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 9 is a schematic cross-sectional view showing a schematic cross-sectional view of an optical fingerprint sensor module according to an embodiment of the present invention. FIG. 10 is a schematic cross-sectional view showing a schematic cross-sectional view of an optical fingerprint sensor module according to an embodiment of the present invention.

Claims (18)

An optical fingerprint sensing module includes: a substrate including a plurality of light sensing modules disposed on the substrate at intervals; a semiconductor layer disposed on the substrate; and an optical channel structure layer disposed on the semiconductor layer, To form a plurality of optical channels, the optical channel structure layer includes: a first composite photoresist layer disposed on the semiconductor layer; and a plurality of microlens structures, any of which is arranged on the first composite light Above the resist layer and at least one of the first composite photoresist layer, the plurality of micro-lens structures form the plurality of optical channels. The optical fingerprint sensing module according to claim 1, wherein the first composite photoresist layer includes a first photoresist layer and a first opaque photoresist layer stacked on the first photoresist layer, and The first composite photoresist layer has a plurality of first openings, and the plurality of first openings and the plurality of microlens structures form the plurality of optical channels. The optical fingerprint sensor module according to claim 2, wherein the first opaque photoresist layer is made of a low reflectivity material. The optical fingerprint sensor module according to claim 3, wherein the first opaque photoresist layer is a black photoresist layer or a color photoresist. The optical fingerprint sensing module according to claim 1, wherein the semiconductor layer further comprises at least one metal layer, and the metal layer has a plurality of first openings, the plurality of first openings and the plurality of microlens structures form the plurality of Light channels. The optical fingerprint sensor module according to claim 5, wherein the metal layer is a plurality of layers, and the positions of the plurality of first openings at least partially overlap in the axial position. The optical fingerprint sensor module according to claim 1, further comprising at least a second opaque photoresist layer disposed in the first photoresist layer, wherein each of the second opaque photoresist layers has a first Three openings, the plurality of third openings and the plurality of microlens structures form the plurality of light channels. The optical fingerprint sensor module according to claim 7, wherein the third opaque photoresist layer is a plurality of layers, and the positions of the plurality of third openings at least partially overlap in the axial position. The optical fingerprint sensor module according to claim 1, wherein the optical channel structure layer includes a second composite photoresist layer, which is stacked on the first composite photoresist layer, and the second composite photoresist layer includes a first Two photoresist layers and a second opaque photoresist layer are stacked on the second photoresist layer, wherein the second opaque photoresist layer has a plurality of fourth openings; and the plurality of fourth openings and The plurality of micro-lens structures form the plurality of light channels. The optical fingerprint sensor module according to claim 9, wherein a plurality of through holes penetrate the second photoresist layer downward from the fourth opening, and expose at least part of the plurality of microlens structures, wherein the plurality of fourth openings, The plurality of through holes and the plurality of microlenses are structured into the plurality of optical channels. The optical fingerprint sensor module according to claim 10, further comprising a low refractive index layer filled at least in the plurality of through holes. The optical fingerprint sensor module according to claim 9, wherein the second opaque photoresist layer is made of a low reflectivity material. The optical fingerprint sensor module according to claim 12, wherein the second opaque photoresist layer is a black photoresist layer or a color photoresist. The optical fingerprint sensing module according to claim 9, further comprising at least a fourth opaque photoresist layer disposed in the second photoresist layer, wherein each of the fourth opaque photoresist layers has a first Five openings, and the fifth opening, the plurality of fourth openings, and the plurality of microlens structures form the plurality of light channels. The optical fingerprint sensor module according to claim 14, wherein the fourth opaque photoresist layer is a plurality of layers, and the positions of the plurality of fifth openings at least partially overlap in the axial position. The optical fingerprint sensor module according to claim 1, wherein any one of the light sensor modules includes a light sensor element. The optical fingerprint sensor module according to claim 1, wherein any one of the light sensor modules includes a plurality of light sensor elements. The optical fingerprint sensor module according to claim 1, wherein the micro lens structure is a plano-convex lens structure, a biconvex lens structure, a plano-concave lens structure, or a bi-concave lens structure.