Photosensitive crystal grain and manufacturing method thereof

Abstract

The invention provides a photosensitive crystal grain and a manufacturing method thereof. The manufacturing method comprises the following steps. Firstly, a wafer is cut to form a plurality of photosensitive crystal grains, and secondly, the photosensitive crystal grains are adhered to an adhesive film. Then, the adhesive film is stretched to increase the distance between the photosensitive crystal grains. Finally, at least one optical film is provided to cover the surface of the photosensitive crystal grain.

Description

Technical Field

[0001] This invention relates to a photosensitive grain and its manufacturing method, and particularly to a photosensitive grain with a sidewall optical coating and its manufacturing method. Background Technology

[0002] A photodiode is an electronic component that converts external light signals into electrical signals. Its core function is to absorb external light, allowing it to detect the light signal and convert it into a measurable current. This conversion is crucial for various applications, such as optical communication, optical measurement, and imaging.

[0003] The way photodiodes absorb external light is by utilizing the semiconductor material (such as silicon) inside the diode. When a photon enters the photodiode and is absorbed, the photon's energy causes an electron in the valence band to jump to the conduction band, thus generating an electron-hole pair. These photogenerated carriers separate under the influence of the diode's built-in electric field and generate a current.

[0004] However, traditional photodiodes are inefficient at absorbing external light in practical applications, affecting the accuracy of photoelectric conversion. To overcome these problems, the industry urgently needs an innovative photodiode architecture to improve the aforementioned issue of poor photoelectric conversion efficiency. Summary of the Invention

[0005] The main objective of this invention is to provide an innovative photosensitive chip and its manufacturing method. Compared to traditional photosensitive chips of the same size, the photosensitive chip of this invention has a larger area and angle for absorbing external light, thereby improving photosensitivity. Its innovative manufacturing method also solves the problem of false signals caused by external light interference on the edge sidewalls of traditional photosensitive chips.

[0006] To achieve the above objectives, the present invention provides a method for manufacturing photosensitive chips, the method comprising the following steps: First, a wafer is diced to form a plurality of photosensitive chips; second, the photosensitive chips are adhered to an adhesive film; next, the adhesive film is stretched to increase the distance between the photosensitive chips; finally, at least one optical film is provided to cover the surface of the photosensitive chips.

[0007] In the method for manufacturing photosensitive chips of the present invention, the step of cutting a wafer to form a plurality of photosensitive chips is to cut a wafer to form a plurality of flip-chip photosensitive chips.

[0008] In the method for manufacturing photosensitive chips of the present invention, the step of providing at least one optical film to cover the surface of the photosensitive chip is to provide at least one optical film that allows only light of a specific wavelength to pass through to cover the upper surface and edge sidewalls of the photosensitive chip.

[0009] In the manufacturing method of the photosensitive chip of the present invention, the step of providing at least one optical film to cover the surface of the photosensitive chip is to deposit at least one optical film by vapor deposition to cover the upper surface and edge sidewalls of the photosensitive chip.

[0010] In the manufacturing method of the photosensitive chip of the present invention, the step of providing an adhesive film is to provide a high-temperature resistant adhesive film, which has a protective film and an adhesive layer, the adhesive layer being formed on the protective film for attaching the photosensitive chip.

[0011] In the method for manufacturing photosensitive crystals of the present invention, the protective film is a polyester fiber film and the adhesive layer is an acrylic layer.

[0012] The method for manufacturing photosensitive grains of the present invention further includes the step of irradiating the adhesive film with ultraviolet light to reduce the viscosity of the adhesive layer, and then separating the photosensitive grains from the adhesive film.

[0013] To achieve the above objectives, the present invention provides a photosensitive chip, comprising a flip-chip photosensitive chip body and at least one optical film. The optical film directly covers the upper surface and edge sidewalls of the flip-chip photosensitive chip body, wherein the at least one optical film only allows light with a specific wavelength range to pass through to enter the flip-chip photosensitive chip body, so that the flip-chip photosensitive chip body generates an electrical signal accordingly after receiving the light.

[0014] In one embodiment of the photosensitive chip of the present invention, the photosensitive chip is one of a photodiode, a phototransistor, or an optical coupling chip.

[0015] In one embodiment of the photosensitive chip of the present invention, the photosensitive chip further has a pair of positive and negative electrodes disposed on the side of the flip-chip photosensitive chip body not covered by the optical film.

[0016] Other objects of the present invention, as well as the technical means and implementation methods of the present invention, will be understood by those skilled in the art upon referring to the accompanying drawings and the embodiments described below. Attached Figure Description

[0017] Figure 1 This diagram shows a wafer containing multiple dicing channels and multiple photosensitive grains according to an embodiment of the present invention.

[0018] Figure 2 This diagram illustrates a method for attaching multiple photosensitive crystals to an adhesive film according to one embodiment of the present invention.

[0019] Figure 3 This is a side view schematic diagram showing the bonding of flip-chip photosensitive particles onto an adhesive film according to an embodiment of the present invention;

[0020] Figure 4 A schematic diagram showing a flip-chip photosensitive die with complete optical thin film coverage in one embodiment of the present invention; and

[0021] Figure 5 This diagram illustrates the process steps of the photosensitive grains of the present invention.

[0022] Explanation of reference numerals in the attached figures

[0023] 10 wafers

[0024] 20 Cutting Tracks

[0025] 30 photosensitive grains

[0026] 32 Flip-chip photosensitive chip body

[0027] 34 Positive and negative electrodes

[0028] 36 Optical Thin Films

[0029] 40 film

[0030] 42 Adhesive layer

[0031] 44. Protective film. Detailed Implementation

[0032] The following embodiments will explain the content of this invention. These embodiments are not intended to limit the implementation of this invention to any specific environment, application, or special method described in the embodiments. Therefore, the descriptions of the embodiments are merely illustrative of the invention and not intended to limit it. It should be noted that in the following embodiments and drawings, elements not directly related to this invention have been omitted and are not shown, and the dimensional relationships between the elements in the drawings are for ease of understanding only and are not intended to limit the actual scale.

[0033] Please see Figure 1 As shown, a wafer 10 is displayed, which has multiple dicing channels 20 and multiple uncut photosensitive dies 30 between each dicing channel. In this embodiment, these photosensitive dies 30 can receive external light and correspondingly generate an electrical signal. Specifically, the photosensitive dies 30 can be, but are not limited to, photosensitive elements such as photodiodes, phototransistors, and optically coupled electrodes. Taking a photodiode as an example, the photosensitive die 30 in one embodiment of the present invention can be a flip-chip photodiode, which has a flip-chip photosensitive die body 32 and a pair of positive and negative electrodes 34 (e.g., ...). Figure 3(As shown). Both positive and negative electrodes 34 are identically disposed on a bottom side of the flip-chip photosensitive chip body 32. Specifically, the flip-chip photosensitive chip body 32 primarily has a PN junction (not shown) composed of P-type and N-type compound semiconductor layers as the light-acting region. This PN junction is a depletion region formed at the junction of the P-type and N-type compound semiconductor layers. No free carriers exist in this region, and it possesses a built-in electric field. When external light enters the flip-chip photosensitive chip body 32 with sufficient energy, it excites electrons to jump to the conduction band, forming electron-hole pairs. These electron-hole pairs are separated by the built-in electric field; electrons move to the N-type region, and holes move to the P-type region, thereby generating an electrical signal that is proportional to the intensity of the incident external light.

[0034] After the wafer 10 completes the growth process of the P-type and N-type compound semiconductor layers in the aforementioned photosensitive die 30, in the conventional photosensitive element process, the entire wafer 10 is placed in a coating machine to perform a vapor deposition process of related optical thin films on the wafer surface. The function of this optical thin film is to allow only light of a specific wavelength to pass through into the light-receiving region of the photosensitive die, while blocking light of other wavelengths from passing through. After the wafer 10 completes the optical coating, it is then diced using the dicing channel 20 to form multiple photosensitive dies 30. However, this optical coating process can only form an optical thin film on the upper surface of the photosensitive die 30. The edge sidewalls of the photosensitive die, because no optical thin film is formed, cannot absorb light effectively, or even allow external natural light to enter the die interior through the edge sidewalls, causing interference to the element and generating incorrect electrical signals. Therefore, how to increase the area and angle of light reception to improve the photosensitivity of the photosensitive element and eliminate unexpected interference from external light is the effect that this invention aims to achieve.

[0035] Please refer to both together. Figure 2 , Figure 3 Unlike the aforementioned traditional processes, in this invention, after the growth process of each compound semiconductor layer is completed, the wafer 10 does not undergo an optical thin film deposition process. Instead, it directly performs die cutting. The wafer 10 is cut using the dicing channel 20 to form multiple photosensitive granules 30. These photosensitive granules 30 are then individually adhered to an adhesive film 40 and arranged in an appropriate array. Figure 2 As shown, the photosensitive grains 30 on the adhesive film 40 are spaced at an appropriate distance. In a preferred embodiment, the adhesive film 40 has the characteristics of high temperature resistance and acid and alkali resistance, and has an adhesive layer 42 and a protective film 44. The adhesive layer 42 is formed on the protective film 44 for attaching the photosensitive grains 30, such as... Figure 3As shown. Specifically, the adhesive layer 42 can be an acrylic layer, which can reduce its viscosity after being exposed to ultraviolet light, facilitating the subsequent separation of the photosensitive grains and the adhesive film. On the other hand, the protective film 44 can be a polyester film, used to provide protection against high temperatures and acid and alkalis.

[0036] Please see Figure 4 Next, an optical coating process is performed. Unlike traditional processes, in this invention, a whole sheet of adhesive film 40 with multiple photosensitive grains 30 attached is fed into a coating machine for optical coating, and the adhesive film 40 is appropriately stretched to increase the distance between the photosensitive grains 30. As mentioned earlier, since the photosensitive grains 30 on the adhesive film 40 have been cut and spaced appropriately, the coating process performed in the coating machine allows one or more layers of optical thin film 36 to completely cover the surface of each photosensitive grain 30 by vapor deposition. That is, except for the bottom side of the flip-chip photosensitive grain body 32, the optical thin film 36 can completely cover the upper surface and edge sidewalls of the flip-chip photosensitive grain body 32.

[0037] The manufacturing method disclosed in this invention can form one or more optical thin films 36 on the upper surface and edge sidewalls of the photosensitive chip 30 according to actual needs, so as to precisely control the wavelength range of light that can enter the light-acting region inside the photosensitive chip. For example, the optical thin film 36 can be a band-pass filter (BPF) composite layer composed of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) to selectively allow light of a specific wavelength, such as ultraviolet light in the range of 100 to 400 nanometers (nm), to pass through and be received by the light-acting region inside the flip-chip photosensitive chip body 32, while blocking the passage of other wavelengths of light, such as visible light and far-infrared light. As mentioned above, the flip-chip photosensitive die manufactured using the method of this invention can improve the coverage of the optical coating layer on the flip-chip photosensitive die, allowing the sidewalls of the die, which were originally unsuitable for coating, to be effectively utilized. This results in the flip-chip photosensitive die of this invention having a larger side light-receiving area and a larger side light-sensing angle compared to conventional dies of the same size, thus giving the photosensitive die of this invention better photocurrent gain. Moreover, the edge sidewalls of the flip-chip photosensitive die of this invention are completely covered by an optical thin film, thus avoiding the problem of erroneous signals caused by external light interference on the edge sidewalls of conventional photosensitive dies.

[0038] Please see Figure 5This diagram illustrates the process steps of the photosensitive grains of the present invention. First, in step S01, a wafer is diced to form a plurality of photosensitive grains. Second, in step S02, the photosensitive grains are adhered to an adhesive film. Next, in step S03, the adhesive film is stretched to increase the distance between the photosensitive grains. Finally, in step S04, at least one optical film is provided to cover the surface of the photosensitive grains. The descriptions of the relevant components are as described above and will not be repeated here.

[0039] The above embodiments are merely illustrative of implementation schemes of the present invention and to explain the technical features of the present invention, and are not intended to limit the scope of protection of the present invention. Any changes or equivalent arrangements that can be easily made by those skilled in the art are within the scope of the present invention, and the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for manufacturing a photosensitive chip, comprising: Cut a wafer to form multiple photosensitive grains; Adhere the photosensitive crystal onto an adhesive film; Stretch the film to increase the distance between the photosensitive grains; and At least one optical film is provided to cover the surface of the photosensitive grain.

2. The manufacturing method of claim 1, wherein the step of dicing a wafer to form a plurality of photosensitive chips is to dicing a wafer to form a plurality of flip-chip photosensitive chips.

3. The manufacturing method of claim 1, wherein the step of providing at least one optical film to cover the surface of the photosensitive grain is to provide at least one optical film that allows only light of a specific wavelength to pass through to cover the upper surface and edge sidewalls of the photosensitive grain.

4. The manufacturing method of claim 1, wherein the step of providing at least one optical film to cover the surface of the photosensitive grain is to deposit at least one optical film by vapor deposition to cover the upper surface and edge sidewalls of the photosensitive grain.

5. The manufacturing method of claim 1, wherein the step of providing an adhesive film comprises providing a high-temperature resistant adhesive film having a protective film and an adhesive layer formed on the protective film for attaching the photosensitive grains.

6. The manufacturing method of claim 5, wherein the protective film is a polyester fiber film and the adhesive layer is an acrylic layer.

7. The manufacturing method of claim 6 further includes the step of separating the photosensitive grains from the adhesive film after irradiating the film with ultraviolet light to reduce the viscosity of the adhesive layer.

8. A photosensitive grain, comprising: A flip-chip photosensitive chip body; and At least one optical thin film directly covers the upper surface and edge sidewalls of the flip-chip photosensitive die body. The at least one optical film allows light with a specific wavelength range to pass through and enter the flip-chip photosensitive chip body, so that the flip-chip photosensitive chip body generates an electrical signal after receiving the light.

9. The photosensitive chip as claimed in claim 8, wherein the photosensitive chip is one of a photodiode, a phototransistor, or an optically coupled chip.

10. The photosensitive chip of claim 8, wherein the photosensitive chip further has a pair of positive and negative electrodes disposed on a side of the flip-chip photosensitive chip body not covered by the at least one optical film.

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