TW202018925A - Optical sensor structure and method for forming the same - Google Patents

Abstract

An optical sensor structure is provided. The optical sensor structure includes a sensor pixel array in a substrate, and the sensor pixel array having a plurality of sensor pixels, a collimating layer on the substrate, and at least a through-substrate via. The at least a through-substrate via extends from a first surface to an opposite second surface of the substrate, and the at least a through-substrate via is in the sensor pixel array and does not vertically overlap with the plurality of sensor pixels.

Description

Optical sensing structure and its forming method

The present invention relates to a sensing structure, in particular to an optical sensing structure and its forming method.

Today's mobile electronic devices (such as mobile phones, tablet computers, notebook computers, etc.) are usually equipped with user identification systems to protect personal data. Since each person's fingerprint is different, the fingerprint sensor is a common and reliable user identification system.

The fingerprint sensors on the market often use optical technology to sense a user's fingerprint. The optical elements of such a fingerprint sensor based on optical technology may include a light collimator, a beam splitter, a focusing lens, and Linear sensors, etc., where a collimator is used to advance light incident on the sensor in parallel to reduce energy loss due to light divergence.

Traditionally, metal wires must be elongated on a flat surface and pass through many different structural layers to connect the fingerprint sensor to other devices, resulting in increased volume, signal attenuation, and increased cost.

Although the existing optical fingerprint sensors generally meet the requirements, they are not satisfactory in all aspects. In particular, the improvement of the connection technology between the optical collimator of the high optical fingerprint sensor and other devices needs further improvement.

An embodiment of the present invention provides an optical sensing structure. The optical sensing structure includes a sensing pixel array in a substrate, wherein the sensing pixel array includes a plurality of sensing pixels, and light collimation on the substrate Layer and at least one via hole, the at least one via hole extends from the first surface of the substrate to the opposite second surface, wherein the at least one via hole is located in the sensing pixel array and is not in contact with the sensing picture The elements overlap vertically.

An embodiment of the present invention further provides a method for forming an optical sensing structure. The method includes forming at least one via hole in a substrate, and forming a sensing pixel array in the substrate, wherein the sensing pixel array includes a plurality of sensing elements Pixels, and wherein the at least one via hole is located in the sensing pixel array and does not vertically overlap the sensing pixel, and a light collimating layer is formed on the substrate.

The optical sensing structure of the embodiments of the present invention can be applied to various types of optical fingerprint recognition systems. In order to make the above objects, features and advantages of the present invention more obvious and understandable, a few embodiments are given below in conjunction with the accompanying drawings The formula is described in detail below.

10‧‧‧Optical sensing structure

90‧‧‧Conductive parts

100‧‧‧ substrate

100A‧‧‧Top surface

100B, 102B‧‧‧Bottom surface

100B'‧‧‧Second surface

102‧‧‧hole

102’‧‧‧through hole

102S‧‧‧Side wall

104‧‧‧Seed layer

106‧‧‧conductive layer

108‧‧‧Guide hole

110‧‧‧via

200‧‧‧sensor pixel array

202‧‧‧sensing pixels

300‧‧‧Transparent column

400‧‧‧shading layer

500‧‧‧Blackout

600‧‧‧Light collimation layer

The embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be noted that according to standard practices in the industry, various features are not drawn to scale and are used for illustration only. In fact, the size of the elements may be arbitrarily enlarged or reduced to clearly show the features of the present disclosure.

Figures 1-7, 8A, 8B, 9, and 10 are schematic cross-sectional views illustrating a method of manufacturing an optical sensing structure according to some embodiments of the present invention.

The following disclosure provides many different embodiments or examples to show the different components of the present disclosure. The following will disclose specific examples of components and arrangements in this specification to simplify the disclosure. Of course, these specific examples are not intended to limit this disclosure. For example, if the following summary of the description of this specification describes the formation of the first component on or above the second component, it means that it includes an embodiment where the formed first and second components are in direct contact, and also includes Additional components can be formed between the first and second components, and the first and second components are embodiments that are not in direct contact. In addition, various examples in this disclosure description may use repeated reference symbols and/or words. The purpose of these repeated symbols or words is to simplify and clarify, not to limit the relationship between the various embodiments and/or the configurations.

Furthermore, in order to conveniently describe the relationship between one element or component and another element(s) in the drawing, relative terms in space may be used, such as "below", "below", "lower", "" "Above", "upper" and the like. In addition to the orientation shown in the drawings, the relative spatial terms also cover different orientations of the device in use or operation. When the device is turned to different orientations (for example, rotated 90 degrees or other orientations), the relative adjectives used in space will also be interpreted according to the turned orientation.

Here, the terms “about”, “approximately” and “approximately” generally mean within 20% of a given value or range, preferably within 10%, and more preferably within 5%, or 3 Within %, or within 2%, or within 1%, or within 0.5%. It should be noted that the quantity provided in the description is an approximate quantity, that is, if there is no specific description of "about", "approximate", "approximately", it can still be implied The meanings of "approximately", "approximately" and "approximately".

The optical sensing device and the forming method thereof according to the embodiments of the present invention are described below. However, it should be understood that the following embodiments are only used to illustrate that the embodiments of the present invention are made and used by a specific method, and are not intended to limit the scope of the present invention. Those of ordinary skill in the art will readily understand that various modifications can be made within the scope of other embodiments. Furthermore, although the method embodiments described below are described in a specific order, other method embodiments may be performed in another logical order, and may include fewer or more steps than discussed herein.

Embodiments of the present invention provide an optical sensing structure and a method for forming the same, in particular, an optical sensing structure including a light collimating layer, which utilizes a through-substrate via (TSV) under the light collimating layer for vertical conduction The stacked device changes the signal transmission method from horizontal to vertical transmission. In this way, the stacking density of the device can be increased, the volume can be reduced, and the electrical performance can be improved. In addition, since there is no need to additionally form metal wires, molding compounds, and packaging substrates for packaging, the thickness of the structure can be further reduced, and defects caused by mismatched thermal expansion coefficients can be reduced.

In addition, the embodiment of the present invention further utilizes the area in the sensing pixel array where no sensing pixel is provided, and sets the via hole in the sensing pixel array. Different from disposing the via hole in the peripheral area of the sensing pixel array, disposing the via hole in the sensing pixel array can further reduce the volume of the optical sensing structure and improve substrate utilization.

FIGS. 1-7, 8A, 8B, 9, and 10 are schematic cross-sectional views of various stages in the process for forming the optical sensing structure 10 of FIG. 10 according to some embodiments of the present invention.

First, please refer to FIG. 1. In some embodiments, a substrate 100 is provided with holes 102. In an embodiment, the substrate 100 may be a silicon substrate, a silicon germanium (SiGe) substrate, a compound semiconductor substrate, a bulk semiconductor substrate, or a semiconductor-on-insulator Insulator (SOI) substrate or similar substrate, which may be doped (for example, using p-type or n-type dopant) or undoped. In general, the semiconductor-on-insulator substrate includes a film layer of semiconductor material formed on the insulator. For example, the insulating layer may be a buried oxide (BOX) layer, a silicon oxide layer, or the like. The above-mentioned insulating layer is provided on the substrate, usually a silicon or glass substrate. Other substrates may also be used, such as multi-layered or gradient substrates. In some embodiments, the semiconductor material of the semiconductor substrate may include elemental semiconductors containing silicon (silicon, Si) or germanium (Ge); including silicon carbide (silicon carbide), gallium arsenic (gallium arsenic), and gallium phosphide (gallium phosphide), indium phosphide, indium arsenide, or indium antimonide compound semiconductors; including SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, or GaInAsP Alloy semiconductor; or a combination of the above.

In some embodiments, the substrate 100 may include various isolation components (not shown) to define active regions and electrically isolate the active region elements in/on the substrate 100. In some embodiments, the isolation features include shallow trench isolation (STI) features, local oxidation of silicon (LOCOS) features, other suitable isolation features, or a combination of the foregoing.

Continuing to refer to FIG. 1, the above-mentioned hole 102 is located in a predetermined area of the sensing pixel array 200 (refer to FIG. 5) to be formed later, and will become a via hole 110 (refer to FIG. 9) in the subsequent manufacturing process, In order to connect the optical sensing device 10 with other devices. The hole 102 extends from the top surface 100A of the substrate 100 toward the bottom surface 100B of the substrate 100, but does not extend to the bottom surface 100B. Although in the illustrated embodiment, the substrate 100 has three holes 102, the embodiments of the present invention are not limited thereto. The above-mentioned substrate 100 may have more or less number of holes 102 according to actual design requirements, such as one Hole 102. In some embodiments, the side wall 102S of the hole 102 may form an angle θ with the bottom surface 102B of the hole 102, and the above-mentioned angle θ ranges from about 90 degrees to 130 degrees. For example, the above-mentioned angle θ may be 90 degrees (that is, the hole 102 has a vertical side wall), or may be 92 degrees (that is, the hole 102 has an inclined side wall). In some embodiments, the depth of the hole 102 is from about 25 microns to about 300 microns, such as about 100 microns. In some embodiments, the diameter of the hole 102 is about 10 microns to about 150 microns, for example, about 50 microns. In some embodiments, the aspect ratio of the hole 102 ranges from about 1 to 20. The above-mentioned holes 102 can be formed by suitable processes, such as lithography and etching processes.

Referring to FIG. 2, according to some embodiments, a seed layer 104 may be conformally formed on the sidewall 102S and bottom surface 102B of the hole 102 and on the top surface 100A of the substrate 100. The seed layer 104 can be used to form the conductive layer 106 (as shown in FIG. 3) in a subsequent process (for example, an electrode plating process). In some embodiments, the material of the seed layer 104 may be a conductive material, such as copper, tungsten, aluminum, similar materials, or a combination thereof, and may be formed by a chemical vapor deposition (CVD) process, Atomic layer The seed layer 104 is formed by an atomic layer deposition (ALD) process, a physical vapor deposition (PVD) process, other suitable processes, or a combination of the foregoing. In some embodiments, the thickness of the seed layer 104 formed by the above method is about 0.1 μm to 3 μm.

Referring to FIG. 3, according to some embodiments, after forming the seed layer 104, a conductive layer 106 may be formed in the hole 102 and the top surface 100A of the substrate 100 by an electroplating process. In the subsequent manufacturing process, the hole 102, the seed layer 104, and the conductive layer 106 will collectively form a via 108 (as shown in FIG. 4). In some embodiments, the conductive layer 106 may include metal or other suitable conductive materials, such as tungsten, copper, nickel, aluminum, polysilicon, or a combination of the foregoing.

FIG. 4 illustrates the formation of the above-mentioned via hole 108. In some embodiments, a first planarization process is performed on the top surface 100A of the substrate 100 to remove excess seed layer 104 and conductive layer 106 outside the holes 102 and expose the top surface 100A of the substrate 100. In some embodiments, the first planarization process may include a chemical mechanical polishing (CMP) process, a grinding process, an etching process, other suitable processes, or a combination of the foregoing.

Please refer to FIG. 5. In some embodiments, a sensing pixel array 200 is formed in the substrate 100, and the sensing pixel array 200 has a plurality of sensing pixels 202. In some embodiments, the substrate 100 may include various device elements. These device components are not shown for simplicity and clarity. These device elements may include transistors, diodes, other suitable elements, or combinations thereof. For example, the transistor may be a metal oxide semiconductor field effect transistor (MOSFET), a complementary metal oxide semiconductor (CMOS) Transistors, bipolar junction transistors (BJT), high voltage transistors, high frequency transistors, p-channel and/or n-channel field effect transistors (PFETs/NFETs), etc.

In some embodiments, the above substrate 100 may include various conductive elements (eg, wires or vias) (not shown). For example, the conductive element may be formed of aluminum, copper, tungsten, other suitable conductive materials, the above alloy, or a combination of the above.

With continued reference to FIG. 5, the via hole 108 is located in the sensing pixel array 200, but does not vertically overlap with the sensing pixel 202. In some embodiments, the sensing pixel 202 may be connected to signal process circuitry (not shown). In some embodiments, the number of sensing pixels 202 in the sensing pixel array 200 depends on the area of the optical sensing area. Each sensing pixel 202 may include one or more photodetectors. In some embodiments, the photodetector may include a photodiode, wherein the photodiode may include a P-type semiconductor layer, an intrinsic layer, and an N-type semiconductor layer. material), the intrinsic layer absorbs light to generate excitons, and the excitons are divided into electrons and holes at the junction of the P-type semiconductor layer and the N-type semiconductor layer, thereby generating a current signal. In other embodiments, the photodetector may also include a charged coupled device (CCD) sensor, a complementary metal-oxide-semiconductor (CMOS) image sensor, and an active sensor Sensors, passive sensors, other suitable sensors, or a combination of the above. In some embodiments, the sensing pixel 202 can convert the received optical signal into an electronic signal by a light detector, and process the electronic signal through a signal processing circuit.

In some embodiments, as shown in FIG. 5, in the schematic cross-sectional view, the sensing pixels 202 in the sensing pixel array 200 are located on the top surface 100A of the substrate 100 and are offset from the above-mentioned via holes 108. It is worth noting that the number and arrangement of the sensing pixel array 200 shown in FIG. 5 are only exemplary, and the embodiment of the present invention is not limited to this. The sensing pixel 202 can be any row and column The number of arrays or other arrangements.

This arrangement method in which the via hole 108 and the sensing pixel 202 are staggered and do not overlap vertically can make full use of the area of the sensing pixel array where the sensing pixel is not provided, so that the via hole to be formed in the subsequent process is set In the sensing pixel array. Different from disposing the via hole in the peripheral area of the sensing pixel array, disposing the via hole in the sensing pixel array can further reduce the volume of the optical sensing structure and improve substrate utilization.

Please refer to FIG. 6 to form a plurality of light-transmitting pillars 300 disposed on the sensing pixel array 200 and corresponding to the sensing pixels 202. In some embodiments, a light-transmitting material layer (not shown) may be blanket formed on the substrate 100 to cover the sensing pixel array 200. In some embodiments, the above light-transmitting material layer may include a light-transmitting material, which has a light transmittance greater than 90% in the wavelength range of 300 nm to 1200 nm, thereby allowing part of incident light to pass through the light-transmitting material layer And arrived at the sensing pixel 202.

In some embodiments, the light-transmitting material layer may include a UV-curable material, a thermosetting material, or a combination thereof. For example, the light-transmitting material may include, for example, poly (methyl methacrylate (PMMA), polyethylene terephthalate (PET), polyethylene naphthalate Polyethylene naphthalate (PEN) polycarbonate (Polycarbonate, PC), perfluorocyclobutyl (PFCB) polymer, polyimide (Polyimide, PI), acrylic resin, epoxy resin (Epoxy resins), polypropylene (Polypropylene, PP), polyethylene (PE), polystyrene (Polystyrene, PS), polyvinyl chloride (Polyvinyl chloride, PVC), other suitable materials, or a combination of the above. Spin-coating, casting, bar coating, blade coating, roller coating, wire bar coating can be used ), dip coating, chemical vapor deposition (CVD), other suitable methods, or a combination of the above, to deposit the above-mentioned light-transmitting material layer on the substrate 100. In some embodiments, the thickness of the light-transmitting material layer formed by the above method is in the range of about 10 to about 300 microns, for example, 100 microns. In other embodiments, the thickness of the light-transmitting material layer is in the range of about 100 to about 500 microns, for example, 300 microns.

Next, the light-transmitting material layer formed on the substrate 100 is selectively removed, as shown in FIG. 6. In some embodiments, since the light-transmitting pillar 300 is correspondingly disposed on the sensing pixel 202, in the schematic cross-sectional view, the light-transmitting pillar 300 and the guide hole 108 are not vertically overlapped, in other words, The light transmission column 300 and the guide hole 108 are staggered. In some embodiments, the light-transmitting column 300 corresponding to the sensing pixel 202 can protect the sensing pixel 202 and reduce or prevent the sensing pixel 202 from being contaminated and/or damaged during the manufacturing process, thereby affecting The sensitivity of the optical sensing structure 10. In some embodiments, each light-transmitting pillar 300 is correspondingly disposed on each sensing pixel 202, as shown in FIG. 6. In other embodiments, at least one light-transmitting column 300 covers more than two sensing pixels 202 (not shown). In some embodiments, in the upper view, the light-transmitting pillar 300 may be circular, rectangular, polygonal, any shape, or a combination of the foregoing, and arranged in an array (not shown).

In some embodiments, a patterning process may be used to selectively remove the light-transmitting material layer to form the light-transmitting pillar 300. In some embodiments in which the light-transmitting material layer is a non-photoresist material, the patterning process may include a lithography process and an etching process. The lithography process may include, for example: photoresist coating (such as spin coating), soft baking, exposure pattern, post-exposure baking, photoresist development, cleaning and drying (such as hard baking), other suitable processes, or the above combination. The etching process may include, for example, a wet etching process, a dry etching process (eg, reactive ion etching (RIE), plasma etching, ion milling), other suitable processes, or a combination thereof.

In other embodiments, the light-transmitting material layer may be a photoresist material. In this case, the light-transmitting material layer may be patterned by a lithography process to directly form a patterned light-transmitting pillar 300 without An additional etching process is required. The aforementioned lithography process is similar to the aforementioned lithography process, so it will not be repeated here.

In some embodiments, the thickness of the light-transmitting pillar 300 formed by the above method is in the range of about 10 to about 300 microns, for example, 100 microns. In other embodiments, the thickness of the light-transmitting pillar 300 is in the range of about 100 to about 500 microns, for example, 300 microns.

Next, referring to FIG. 7, a light-shielding layer 400 is formed on the substrate 100 and filled between the plurality of light-transmitting pillars 300 described above. In some embodiments, the light-shielding layer 400 may include a photoresist (eg, black photoresist or other suitable non-transparent Photoresist), ink (for example: black ink or other suitable non-transparent ink), molding compound (for example: black molding compound or other suitable non-transparent molding compound), solder mask ( solder mask, for example: black solder resist material or other suitable non-transparent solder resist material), other suitable materials or a combination of the above.

In some embodiments, the light-shielding layer 400 may be a photo-curable material, a thermo-curable material, or a combination thereof. In the above embodiment, a light-shielding material (not shown) may be disposed on the substrate 100 and filled between the plurality of light-transmitting pillars 300, and then a curing process is performed to cure the light-shielding material to form the light-shielding layer 400. For example, the above curing process may be a photo curing process, a thermal curing process, or a combination of the above.

In other embodiments, the light shielding layer 400 may include a metal material. In some embodiments where the light-shielding layer 400 includes a metal material, a seed layer (not shown) containing a metal material may be deposited on the substrate 100 before forming the light-transmitting pillar 300, and then the seed crystal The layer is patterned to expose the sensing pixels 202 on the substrate 100 while retaining the seed layer on the via hole 108. In the top view, the shape of the patterned seed layer and the sensing pixel 202 are complementary (not shown). After forming the light-transmitting pillars 300, an electroplating process is performed to form a light-shielding layer 400 filled between the plurality of light-transmitting pillars 300, as shown in FIG. In some embodiments, the thickness of the light-shielding layer 400 generated by the electroplating process or other suitable processes may be higher than, equal to, or lower than that of the light-transmitting pillar 300 described above. In some embodiments, the light shielding layer 400 may include copper, nickel, other suitable metal materials, or a combination of the foregoing.

In addition, some implementations of the above-mentioned light-shielding layer 400 including metallic materials For example, a light-shielding cover 500 may be additionally formed on the light-shielding layer 400. In such an embodiment, the above-mentioned light-shielding cover 500 may include, for example, a resin light-shielding material, which has a light transmittance of less than 1% for a wavelength range of 300 nm to 1200 nm. The light-shielding material may include a photo-curable material, a thermo-curable material, or a combination of the foregoing. In some embodiments, the light-shielding cover 500 formed on the light-shielding layer 400 can prevent the sensing pixels 202 from receiving unnecessary light, and can prevent crosstalk caused by light incident on the optical sensing structure 10 , Thereby improving the performance of the optical sensing structure 10.

In some embodiments, the material of the light-shielding cover may be formed on the light-shielding layer 400 by spin-coating, chemical vapor deposition (CVD), other suitable methods, or a combination thereof, and A curing process (for example, a light curing process, a thermal curing process, or a combination thereof) is performed to cure the light-shielding material, and then a patterning process may be performed to form the light-shielding cover 500 above the light-shielding layer 400. The light-shielding cover 500 after the patterning process only covers the light-shielding layer 400 and does not cover the light-transmitting pillar 300. In some embodiments, the thickness of the light shielding cover 500 formed by the above method is in the range of about 0 nanometers to about 500 nanometers, for example, 100 nanometers. In other embodiments, the thickness of the light shielding cover 500 is in the range of about 10 nanometers to about 500 nanometers, for example, 200 nanometers.

In some embodiments, the material of the light-shielding cover may include non-transparent carbon black, ink, molding compound, solder resist material, other suitable materials, or a combination thereof. In this case, the above-mentioned patterning process may include a lithography process and an etching process. The photolithography process and the etching process here may be similar to the foregoing embodiments regarding the use of non-photoresist materials in FIG. 6 to form the light-transmitting pillars, so they will not be repeated here.

In other embodiments, the material of the shading cover may include non- Transparent photoresist material. In this case, similar to the previous embodiment regarding the use of photoresist materials to form the light-transmitting pillars in FIG. 6, the material of the light-shielding cover can be directly patterned to form the light-shielding cover 500 on the light-shielding layer 400 without additional After the etching process.

In some embodiments, before forming the light-shielding cover 500 over the light-shielding layer 400, a planarization process (such as a chemical mechanical polishing (CMP) process) may be performed to planarize the light-shielding layer 400, so that the light-shielding layer 400 and the light-transmitting pillar 300 The top surface is flush. Next, in the above embodiment, the top surface of the light-shielding cover 500 formed on the light-shielding layer 400 after the planarization process will be slightly higher than the top surface of the light-transmitting pillar 300, as shown in FIG. 8A. For example, the top surface of the light-shielding cover 500 above the light-shielding layer 400 will be slightly higher than the top surface of the light-transmitting pillar 300 by about 10 nm.

In other embodiments, the top surface of the light-shielding layer 400 formed on the patterned seed layer may be slightly lower than the top surface of the light-transmitting pillar 300 (for example, the top surface of the light-shielding layer 400) by controlling the time of the electroplating process (Slightly lower than the top surface of the light-transmitting pillar 300 by about 10 nm to about 10 microns) Higher than the top surface of the transparent pillar 300 (for example, the top surface of the light-shielding cover 500 is slightly higher than the top surface of the transparent pillar 300 by about 10 nanometers), and then a planarization process (for example, chemical mechanical polishing (CMP) process) can be performed The light-shielding cover 500 is planarized so that the light-shielding cover 500 is flush with the top surface of the light-transmitting pillar 300, as shown in FIG. 8B.

According to some embodiments of the present invention, the light-transmitting pillar 300 disposed on the sensing pixel 202, the light-shielding layer 400 filled between the light-transmitting pillars, and the light-shielding cover 500 correspondingly disposed on the light-shielding layer 400 ( If any, the combination of them together constitutes a light collimating layer 600. The function of this optical collimation layer is to collimate (collimate) Light to reduce the energy loss caused by light divergence. In some embodiments, the optical collimating layer may include other optical elements, such as color filters, glass, lenses, etc. (not shown). In some embodiments, the incident light is introduced into the sensing pixel 202 through the optical element above the light collimating layer 600 through the light collimating layer 600. The aspect ratio of the light-transmitting pillar 300 is in the range of 2 to 30, for example, 5, 10, 15, or 20. If the light-transmitting column 700 is too high (that is, the aspect ratio is too large), the light-transmitting column 300 is easily deformed or collapsed, resulting in an increase in the difficulty of the manufacturing process and a relatively high manufacturing cost. If the light transmission column 300 is too wide (that is, the aspect ratio is too small), it is easy to receive unnecessary incident light, and it is difficult to achieve the collimating effect, thus reducing the sensitivity of the optical sensing structure 10.

In some embodiments, a cover layer (not shown) disposed above the light collimating layer may be included above the light collimating layer. The cover plate layer may be a hard light-transmitting material, such as: calcium aluminosilicate glass, soda lime glass, sapphire, transparent polymer, or other suitable materials, so that at least part of The incident light can penetrate and reach the sensing pixel 202, and the hard cover can protect the optical sensing structure 10 and other components under it.

The description of the process for forming the optical sensing structure 10 is continued with the structure of FIG. 8B, but it should be understood that the structure of FIG. 7 or FIG. 8A can also be used to form the optical sensing structure 10. Next, referring to FIG. 9, in some embodiments, a backside thinning process is performed on the bottom surface 100B of the substrate 100 to form a via 110 through the substrate 100. The via hole 110 has a through hole 102' extending from the first surface 100A (also referred to as the top surface 100A) of the substrate 100 to the opposite second surface 100B' of the substrate 100. In addition, the seed layer 104 is located in the through hole 102' and interposed between the substrate 100 and the conductive layer 106 filled in the through hole 102'. In some embodiments, the backside thinning process is performed until the conductive layer 106 is exposed to remove a part of the seed layer 104 under the conductive layer 106, as shown in FIG. 9. In other embodiments, the backside thinning process is performed until the seed layer 104 is exposed, so a part of the seed layer 104 is located under the conductive layer 106 (not shown). The combination of the through hole 102', the seed layer 104, and the conductive layer 106 together constitute the via hole 110. The bottom surface of the via hole 110 is flush with the second surface 100B' of the substrate 100.

Please refer to FIG. 10, in some embodiments, after performing the above second planarization process, a conductive member 90 may be formed on the second surface 100B′ of the substrate 100, and the conductive member 90 is connected to the corresponding via hole 110 to The optical sensing structure 10 is formed. The optical sensing structure 10 can be electrically connected to other devices through the via 110 through the conductive member 90. The conductive member 90 may include conductive pads, conductive bumps, conductive pillars, or a combination of the foregoing, and may be made of aluminum (Al), copper (Cu), tungsten (W), other suitable conductive materials, the above alloys, or The combination of the above.

In the embodiment shown in FIG. 10, the optical sensing structure 10 includes a sensing pixel array 200 in the substrate 100, a light collimating layer 600 on the substrate, and a first surface 100A extending from the substrate 100 The via 110 to the opposite second surface 100B'. The sensing pixel array 200 includes a plurality of sensing pixels 202. The via 110 is located in the sensing pixel array 200 and does not overlap the sensing pixel 202 vertically. Such a configuration in which the via hole 110 is disposed in the sensing pixel array 200 instead of the periphery of the sensing pixel array 200 can further reduce the volume of the optical sensing structure 10 and improve substrate utilization. In addition, although the 10th In the figure, the via hole 110 and the sensing pixel 202 are shown adjacent to each other, but the embodiment of the present invention is not limited thereto. For example, the via hole 110 and the sensing pixel 202 may not be adjacent to each other, for example, the width of the via hole 110 may be smaller than the spacing between adjacent sensing pixels 202.

In this embodiment, the above-mentioned optical sensing structure 10 further includes a conductive member 90. The above-mentioned conductive member 90 is located on the second surface 100B' of the substrate 100 and is connected to the above-mentioned via 110 accordingly. The conductive member 90 includes conductive pads, conductive bumps, conductive pillars, or a combination thereof.

In the embodiment of the present invention, the via 110 includes a through hole 102 ′, a conductive layer 106 filled in the through hole 102 ′, and is disposed in the through hole 102 ′ and interposed between the conductive layer 106 and the substrate 100 Between the seed layer 104.

In the embodiment of the present invention, the light collimating layer 600 includes a plurality of light-transmitting pillars 300 corresponding to the light-sensing pixels 202, and a light-shielding layer located on the substrate 100 and filling the light-transmitting pillars 300. 400. The light-transmitting column 300 can protect the sensing pixel 202 and reduce or avoid the contamination and/or damage of the sensing pixel 202 during the manufacturing process, thereby affecting the sensitivity of the optical sensing structure 10. The light-transmitting pillar 300 is formed of a transparent material, and the light transmittance of the transparent material in the wavelength range of 300 nm to 1200 nm is greater than 90%.

According to the above embodiments, when forming an optical sensing structure with a light collimating layer, a through-substrate via (TSV) device that vertically underlies the light collimating layer can be used to vertically stack the stacked device, so that the signal transmission mode is Horizontal to vertical transmission. Unlike the traditional way of elongated metal wires on a flat surface, the fingerprint sensor can be connected to other devices through many different structural layers. Using via holes to vertically conduct stacked devices can increase the device stack Stack density, reduce volume, and shorten conduction paths to further improve electrical performance. In addition, since there is no need to additionally form metal wires, molding compounds, and packaging substrates for packaging, the thickness of the structure can be further reduced, and defects caused by mismatched thermal expansion coefficients can be reduced.

In addition, the embodiment of the present invention further utilizes the area in the sensing pixel array where no sensing pixel is provided, and sets the via hole in the sensing pixel array. Different from disposing the via hole in the peripheral area of the sensing pixel array, disposing the via hole in the sensing pixel array can further reduce the volume of the optical sensing structure and improve substrate utilization.

It is worth noting that although the exemplary embodiments disclosed in the examples discussed herein are related to fingerprint sensing devices, the technology provided by the present invention can also be applied to other types of sensors, not just applications Sensor device that detects fingerprints. For example, it can also be applied to sensing devices in biosensor, medical-related, and radiation research fields (for example, heartbeat, blood oxygen, etc.), and is not limited to the scope disclosed in the foregoing embodiments.

The above outlines the features of several embodiments of the present disclosure, so that those with ordinary knowledge in the art can more easily understand the present disclosure. Anyone with ordinary knowledge in the technical field should understand that this specification can be easily used as a basis for changes or design of other structures or processes to perform the same purposes and/or obtain the same advantages as the embodiments of the present disclosure. Any person with ordinary knowledge in the technical field can also understand that the structure or process equivalent to the above does not deviate from the spirit and scope of the disclosure, and can be changed or replaced without departing from the spirit and scope of the disclosure With retouch.

10‧‧‧Optical sensing structure

90‧‧‧Conductive parts

100‧‧‧ substrate

100A‧‧‧Top surface (also called the first surface)

100B'‧‧‧Second surface

102’‧‧‧through hole

104‧‧‧Seed layer

106‧‧‧conductive layer

110‧‧‧via

200‧‧‧sensor pixel array

202‧‧‧sensing pixels

300‧‧‧Transparent column

400‧‧‧shading layer

500‧‧‧Blackout

600‧‧‧Light collimation layer

Claims (20)

An optical sensing structure includes: a sensing pixel array located in a substrate, wherein the sensing pixel array includes a plurality of sensing pixels; a light collimating layer on the substrate; and at least one The via hole extends from a first surface of the substrate to an opposite second surface, wherein the at least one via hole is located in the sensing pixel array and does not vertically overlap the sensing pixels. The optical sensing structure as described in item 1 of the patent application scope further includes at least one conductive member located on the second surface and correspondingly connected to the at least one via hole. The optical sensing structure as described in item 2 of the patent application scope, wherein the at least one conductive component comprises a conductive pad, a conductive bump, a conductive pillar, or a combination thereof. The optical sensing structure as described in item 1 of the patent application scope, wherein the at least one via hole includes: a through hole; a conductive layer filled in the through hole; and a seed layer provided in the through hole, And between the conductive layer and the substrate. The optical sensing structure as described in item 1 of the patent application scope, wherein the light collimating layer includes: a plurality of light-transmitting pillars correspondingly disposed on the sensing pixels of the sensing pixel array; and A light-shielding layer is located on the substrate and filled between the light-transmitting pillars. The optical sensing structure as described in item 5 of the patent application scope, wherein the light-transmitting pillars are formed of a transparent material, and the light transmittance of the transparent material in the wavelength range of 300 nm to 1200 nm is greater than 90 %. The optical sensing structure as described in item 5 of the patent application scope, wherein the light-shielding layers are formed of photoresist, ink, molding compound, solder mask, or a combination thereof. The optical sensing structure as described in item 5 of the patent application scope, wherein the light-shielding layers include metal materials. The optical sensing structure as described in item 5 of the patent application scope, wherein the light collimating layer further includes a light-shielding cover located above the light-shielding layer. The optical sensing structure as described in item 9 of the patent application range, wherein the light-shielding cover is a resin light-shielding cover, and the light transmittance of the resin light-shielding cover in the wavelength range of 300 nm to 1200 nm is less than 1%. A method for forming an optical sensing structure includes: forming at least one via hole in a substrate; forming a sensing pixel array in the substrate, wherein the sensing pixel array includes a plurality of sensing pixels, and wherein The at least one via hole is located in the sensing pixel array and does not vertically overlap with the sensing pixels; and a light collimating layer is formed on the substrate. The method for forming an optical sensing structure as described in item 11 of the patent application scope further includes forming at least one conductive component, and the at least one conductive component is electrically connected to the corresponding at least one via hole. The formation method of the optical sensing structure as described in item 12 of the patent application scope Method, wherein the at least one conductive component includes a conductive pad, a conductive bump, a conductive post, or a combination thereof. The method for forming an optical sensing structure as described in item 11 of the patent application range, wherein the at least one via hole includes: a through hole; a conductive layer filled in the through hole; and a seed layer provided in the through hole Inside the hole and between the conductive layer and the substrate. The method for forming an optical sensing structure as described in item 11 of the patent application scope, wherein the step of forming the at least one via hole includes performing a planarization process on the bottom surface of the substrate to remove a portion of the substrate to expose the at least one The bottom surface of a via hole. The method for forming an optical sensing structure as described in item 11 of the patent application range, wherein the light collimating layer includes: a plurality of light-transmitting pillars corresponding to the sensing pixels of the sensing pixel array ; And a light-shielding layer, located on the substrate and filled between the light-transmitting columns. The method for forming an optical sensing structure as described in item 16 of the patent application range, wherein the transparent columns are formed of a transparent material, and the transparent material transmits light in the wavelength range of 300 nm to 1200 nm The rate is greater than 90%. The method for forming an optical sensing structure as described in Item 16 of the patent application range, wherein the light-shielding layers are formed of photoresist, ink, molding compound, solder resist material, or a combination thereof. The method for forming an optical sensing structure as described in item 16 of the patent application scope, wherein the light-shielding layers include metal materials. The method for forming an optical sensing structure as described in item 16 of the patent application scope further includes providing a light-shielding cover on the light-shielding layer, wherein the light-shielding cover is a resin light-shielding cover, and the resin light-shielding cover is at 300 nm The light transmittance in the wavelength range up to 1200 is less than 1%.

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