Method and device for improving responsivity of back incidence high-speed detector

Abstract

The invention provides a method and device for improving the responsivity of a back incidence high-speed detector, and relates to the technical field of infrared photoelectric detectors. The method comprises the following steps: preparing a substrate; a silicon dioxide micro lens is prepared on a substrate, and the silicon dioxide micro lens is used for inhibiting the scattering phenomenon of optical signals in the substrate. According to the method, the silicon dioxide micro lens is prepared on the substrate, scattering of an optical signal in the substrate is inhibited by utilizing the light gathering capability of the silicon dioxide micro lens, and the optical coupling efficiency of the back incidence high-speed detector is improved, so that the responsivity of the back incidence high-speed detector is improved; according to the method, the silicon dioxide micro lens is prepared through the steps of one-time silicon dioxide deposition, one-time photoetching, one-time hot reflux and one-time etching, the preparation process is short, the process requirement is low, and the tape-out cost is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared photoelectric detectors, and in particular to a method and device for improving the responsiveness of a back-incident high-speed detector. Background Art

[0002] III-V semiconductor materials, represented by indium phosphide compounds, are currently one of the mainstream choices for the fabrication of high-speed infrared photodetectors. Bandwidth is a key performance indicator for this type of detector. The bandwidth of a detector is primarily affected by the carrier drift time and the RC constant of the detector chip. To reduce the limitations of the RC constant on the detector bandwidth, detectors with smaller active regions are often designed to reduce junction capacitance. For back-incident high-speed detectors, the optical signal is coupled from the back and scattered during transmission within the substrate, causing the light spot to rapidly expand. Ultimately, the intensity of light entering the active region is much lower than the incident light intensity. However, the substrate, as the foundation of the detector's epitaxial layer, cannot be removed during production processes such as tape-out. Therefore, back-incident high-speed detectors struggle to achieve high responsivity, which poses significant challenges to their application. Therefore, a method for improving responsivity is urgently needed. Summary of the Invention

[0003] In view of the above problems, the present invention provides a method and apparatus for improving the responsiveness of a back-incident high-speed detector.

[0004] According to a first aspect of an embodiment of the present invention, a method for improving the responsiveness of a back-incident high-speed detector is provided, comprising: preparing a substrate; and fabricating a silica microlens on the substrate, wherein the silica microlens is used to suppress scattering of light signals within the substrate.

[0005] According to an embodiment of the present invention, preparing a silicon dioxide microlens on a substrate includes: depositing silicon dioxide on the substrate; uniformly coating a photoresist on the surface of the silicon dioxide and performing a pre-bake treatment; generating a photoresist microlens morphology based on the pre-bake photoresist; and transferring the photoresist microlens morphology to the silicon dioxide to form a silicon dioxide microlens.

[0006] According to an embodiment of the present invention, generating a photoresist microlens morphology based on a pre-baked photoresist includes: rehydrating the pre-baked substrate; exposing and developing the rehydrated substrate using a pre-prepared photomask; and performing a photoresist thermal reflow process on the developed substrate to form a microlens morphology on the photoresist.

[0007] According to an embodiment of the present invention, transferring the photoresist microlens morphology onto silicon dioxide to form the silicon dioxide microlens includes: transferring the photoresist microlens morphology onto silicon dioxide to form the silicon dioxide microlens through a reactive ion etching process.

[0008] According to an embodiment of the present invention, the substrate includes an indium phosphide substrate.

[0009] According to an embodiment of the present invention, the deposition thickness of silicon dioxide is 1.6 μm to 2 μm, and the silicon dioxide is uniformly deposited on the etched side of the substrate.

[0010] According to an embodiment of the present invention, the pattern aperture of the photoresist is 15 μm to 50 μm.

[0011] According to an embodiment of the present invention, the temperature of the thermal reflow treatment is 115° C. to 145° C., and the time of the thermal reflow treatment is 60 seconds to 240 seconds.

[0012] According to an embodiment of the present invention, the etching gases used in the reactive ion etching process are O2 and CF4, and the etching temperature is 15°C to 25°C.

[0013] According to a second aspect of an embodiment of the present invention, a device for improving the responsiveness of a back-incident high-speed detector is provided, comprising: a preparation module for preparing a substrate; and a preparation module for preparing a silica microlens on the substrate, wherein the silica microlens is used to suppress scattering of light signals within the substrate.

[0014] The method for improving the responsivity of a back-incident high-speed detector provided by the present invention has at least the following beneficial effects:

[0015] (1) The method for improving the responsivity of a back-incident high-speed detector provided by the present invention comprises preparing a silicon dioxide microlens on a substrate and utilizing the light-gathering ability of the microlens to suppress the scattering of light signals within the substrate, thereby increasing the light coupling efficiency of the back-incident high-speed detector and achieving an improvement in the responsivity of the back-incident high-speed detector.

[0016] (2) The method provided by the present invention for improving the responsivity of a back-incident high-speed detector realizes the preparation of a silica microlens through the steps of one silica deposition, one photolithography, one thermal reflow and one etching. The method has a short preparation process and low process requirements, which greatly reduces the wafer production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0018] Figure 1 The structure diagram after depositing a silicon dioxide mask on a substrate according to an embodiment of the present invention is schematically shown.

[0019] Figure 2 The structure diagram after photoresist coating is performed on the surface of the silicon dioxide mask according to an embodiment of the present invention is schematically shown.

[0020] Figure 3 The structure diagram after the photoresist is exposed and developed according to an embodiment of the present invention is schematically shown.

[0021] Figure 4 The structure diagram schematically shows the microlens morphology formed after the photoresist is subjected to thermal reflow treatment according to an embodiment of the present invention.

[0022] Figure 5 The structure of a silicon dioxide microlens prepared by RIE etching according to an embodiment of the present invention is schematically shown.

[0023] Figure 6 The longitudinal structure of a silicon dioxide microlens integrated on a back-incident high-speed detector according to an embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. Obviously, the embodiments described are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising", etc. used herein indicate the existence of features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0025] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed or detachable connections, or integration; mechanical or electrical connections, or communication; direct or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0026] In the description of the present invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0027] Throughout the drawings, identical elements are represented by identical or similar reference numerals. Conventional structures or configurations may be omitted when they may obscure the understanding of the present invention. Furthermore, the shapes, sizes, and positional relationships of components in the drawings do not reflect actual size, proportion, or actual positional relationships.

[0028] Similarly, in order to streamline the present invention and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Descriptions with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" and the like mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in an appropriate manner.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0030] When expressions such as "at least one of A, B and C, etc." are used, they should generally be interpreted in accordance with the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0031] An embodiment of the present invention provides a method for improving the responsiveness of a back-incident high-speed detector, including operations S1 to S2:

[0032] In operation S1 , a substrate is prepared.

[0033] In this embodiment, for example, an indium phosphide substrate commonly used in photodetectors may be selected as the substrate.

[0034] In operation S2 , a silicon dioxide microlens is fabricated on the substrate, wherein the silicon dioxide microlens is used to suppress scattering of light signals within the substrate.

[0035] The method for improving the responsiveness of a back-incident high-speed detector provided by the present invention comprises preparing a silicon dioxide microlens on a substrate, utilizing the light-gathering ability of the microlens to suppress the scattering of light signals within the substrate, and increasing the light coupling efficiency of the back-incident high-speed detector, thereby achieving an improvement in the responsiveness of the back-incident high-speed detector.

[0036] Based on the above embodiment, operation S2 further includes:

[0037] Silicon dioxide is deposited on a substrate.

[0038] Figure 1 The structure diagram after depositing a silicon dioxide mask on a substrate according to an embodiment of the present invention is schematically shown.

[0039] like Figure 1 As shown, the deposition thickness of silicon dioxide is 1.6 μm to 2 μm. Preferably, the deposition thickness of silicon dioxide may be, for example, 1.8 μm, and silicon dioxide is uniformly grown on the etched side of the substrate.

[0040] Photoresist is evenly coated on the silicon dioxide surface and pre-baked.

[0041] Figure 2 The structure diagram after photoresist coating is performed on the surface of the silicon dioxide mask according to an embodiment of the present invention is schematically shown.

[0042] like Figure 2 As shown, after the silicon dioxide deposition is completed, the corresponding photoresist is selected according to the designed microlens size and evenly coated on the silicon dioxide surface, and the pre-baking time is selected according to the selected photoresist.

[0043] Based on the photoresist after pre-baking, a photoresist microlens morphology is generated.

[0044] The photoresist microlens morphology is transferred to silicon dioxide to form silicon dioxide microlenses.

[0045] Based on the above embodiment, generating the photoresist microlens morphology based on the pre-baked photoresist may further include:

[0046] The substrate after the pre-baking treatment is subjected to rehydration treatment.

[0047] In this embodiment, after the pre-baking operation is completed, the substrate is placed for rehydration. The rehydration time is generally 20 minutes to 60 minutes, and preferably, the rehydration time is 30 minutes.

[0048] The substrate after the rehydration treatment is exposed and developed using a pre-prepared photomask.

[0049] Figure 3The structure diagram after the photoresist is exposed and developed according to an embodiment of the present invention is schematically shown.

[0050] like Figure 3 As shown, the corresponding exposure dose is selected according to the thickness of the photoresist and the pattern of the photoresist board, and the development process is performed after exposure. The development time is selected according to the ratio of the developer used.

[0051] In this embodiment, the pattern aperture of the photolithography plate is 15 μm to 50 μm. Preferably, the diameter of the photolithography plate can be, for example, 35 μm. The silica microlens prepared with this diameter can converge the back-incident light signal to the active area of ​​the photodetector, thereby improving the responsiveness of the small-diameter back-incident high-speed photodetector.

[0052] The substrate after the development process is subjected to a photoresist heat reflow process to form a microlens morphology on the photoresist.

[0053] Figure 4 The structure diagram schematically shows the microlens morphology formed after the photoresist is subjected to thermal reflow treatment according to an embodiment of the present invention.

[0054] like Figure 4 As shown, the developed substrate is subjected to a photoresist thermal reflow process, and the surface tension of the photoresist is utilized to form a smooth arched microlens morphology.

[0055] In this embodiment, the reflow temperature and time are determined by the size and curvature of the designed microlens. Generally, the reflow temperature is 115°C to 145°C, and the reflow time is 60s to 240s. For microlenses of a certain diameter, a reflow temperature of 130°C and a reflow time of 180s are preferred.

[0056] Based on the above embodiment, transferring the photoresist microlens morphology to silicon dioxide to form the silicon dioxide microlens may further include:

[0057] The photoresist microlens morphology is transferred to silicon dioxide through a reactive ion etching (RIE) process to form a silicon dioxide microlens.

[0058] Reactive ion etching (RIE) is one of the etching processes used in the manufacture of semiconductor integrated circuits. When removing the unnecessary protective film on the integrated circuit board, an ion beam of reactive gas is used to cut the chemical bonds of the protective film material, causing low-molecular substances to evaporate or release from the board surface. This method is called reactive ion etching.

[0059] Ion etching uses high-energy inert gas ions to bombard the surface of the etched object to achieve sputtering etching. Using this method, very small feature sizes and vertical sidewall morphologies can be obtained.

[0060] Figure 5 The structure of a silicon dioxide microlens prepared by RIE etching according to an embodiment of the present invention is schematically shown.

[0061] like Figure 5 As shown, in this embodiment, the microlens morphology is transferred to silicon dioxide by RIE etching, using O2 and CF4 as etching gases. The RIE etching time is determined according to the selection ratio of the photoresist and silicon dioxide materials used in the etching process. In order to avoid etching failure caused by gelatinization of the photoresist due to high temperature during etching, the selected etching temperature is 15°C to 25°C, preferably, the etching temperature is 20°C.

[0062] The method provided by the present invention for improving the responsiveness of back-incident high-speed detectors realizes the preparation of silica microlenses through the steps of one silica deposition, one photolithography, one thermal reflow and one etching. The method has a short preparation process, low process requirements, and greatly reduces the wafer production cost.

[0063] Figure 6 The longitudinal structure of a silicon dioxide microlens integrated on a back-incident high-speed detector according to an embodiment of the present invention is schematically shown.

[0064] like Figure 6 As shown, the structure includes a silicon dioxide microlens, a substrate, a photodetector chip, an N electrode and a P electrode.

[0065] Among them, from Figure 6 Looking in the direction shown, the silicon dioxide microlens and the photodetector chip are respectively arranged on the upper and lower surfaces of the substrate, and the N electrode and the P electrode are arranged on one side of the photodetector chip.

[0066] An embodiment of the present invention further provides a device for improving the responsiveness of a back-incident high-speed detector. The device includes a preparation module and a preparation module.

[0067] The preparation module is used to prepare the substrate.

[0068] The preparation module is used to prepare a silicon dioxide microlens on a substrate, wherein the silicon dioxide microlens is used to suppress the scattering phenomenon of the light signal in the substrate.

[0069] The device provided by the present invention is used to improve the responsiveness of a back-incident high-speed detector. By preparing a silicon dioxide microlens on a substrate and utilizing the light-gathering ability of the microlens, the scattering of light signals within the substrate is suppressed, and the light coupling efficiency of the back-incident high-speed detector is increased, thereby achieving an improvement in the responsiveness of the back-incident high-speed detector.

[0070] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functions and operations that may be implemented according to the systems and methods of various embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the above-mentioned module, program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0071] Those skilled in the art will appreciate that the features described in the various embodiments of the present invention may be combined and / or coupled in various ways, even if such combinations and / or couplings are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention may be combined and / or coupled in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or couplings fall within the scope of the present invention.

[0072] The above describes embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A method for improving the responsivity of a back-incident high-speed detector, the method comprising: preparing the substrate; A silicon dioxide microlens is prepared on the substrate, wherein the silicon dioxide microlens is used to suppress the scattering phenomenon of the light signal in the substrate.

2. The method for improving the responsivity of a back-incident high-speed detector according to claim 1, characterized in that: The step of preparing a silicon dioxide microlens on the substrate comprises: depositing silicon dioxide on the substrate; Uniformly coating photoresist on the surface of the silicon dioxide and performing a pre-baking process; Based on the photoresist after pre-baking, generating a photoresist microlens morphology; The photoresist microlens morphology is transferred to the silicon dioxide to form a silicon dioxide microlens.

3. The method for improving the responsivity of a back-incident high-speed detector according to claim 2, characterized in that: The method of generating a photoresist microlens morphology based on the pre-baked photoresist includes: Rehydrating the substrate after pre-baking; Expose and develop the rehydrated substrate using a pre-prepared photomask; The substrate after the development process is subjected to a photoresist heat reflow process to form a microlens morphology on the photoresist.

4. The method for improving the responsivity of a back-incident high-speed detector according to claim 3, characterized in that: Transferring the photoresist microlens morphology to the silicon dioxide to form the silicon dioxide microlens comprises: The photoresist microlens morphology is transferred to the silicon dioxide through a reactive ion etching process to form a silicon dioxide microlens.

5. The method for improving the responsivity of a back-incident high-speed detector according to claim 1, wherein: The substrate includes an indium phosphide substrate.

6. The method for improving the responsivity of a back-incident high-speed detector according to claim 2, wherein: The deposition thickness of the silicon dioxide is 1.6 μm to 2 μm, and the silicon dioxide is uniformly deposited on the etched side of the substrate.

7. The method for improving the responsivity of a back-incident high-speed detector according to claim 3, characterized in that: The pattern aperture of the photoresist is 15 μm to 50 μm.

8. The method for improving the responsivity of a back-incident high-speed detector according to claim 3, characterized in that: The temperature of the heat reflow treatment is 115° C. to 145° C., and the time of the heat reflow treatment is 60s to 240s.

9. The method for improving the responsivity of a back-incident high-speed detector according to claim 4, characterized in that: The etching gases used in the reactive ion etching process are O2 and CF4, and the etching temperature is 15°C to 25°C.

10. A device for improving the responsiveness of a back-incident high-speed detector, characterized in that: The device comprises: a preparation module for preparing a substrate; A preparation module is used to prepare a silicon dioxide microlens on the substrate, wherein the silicon dioxide microlens is used to suppress the scattering phenomenon of the light signal in the substrate.

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