Method for controlling height of bottom filling colloid around infrared detector and detector

Abstract

The invention provides a method for controlling the height of filling colloid at the bottom of the periphery of an infrared detector and the detector. The method comprises the steps that a prepared tellurium-cadmium-mercury infrared detector chip wafer is placed on a working platform of a grinding wheel scribing machine and fixed through vacuum adsorption; a grinding wheel scribing machine is used for scribing along the outer edge of the tellurium-cadmium-mercury infrared detector chip wafer ground wire, and a circle of scribing groove is formed in the edge of the tellurium-cadmium-mercury infrared detector chip wafer; the scribed tellurium-cadmium-mercury infrared detector chip wafer and a corresponding reading circuit are connected in an inverted mode; and filling colloid between the scribed mercury-cadmium-telluride infrared detector chip wafer and the reading circuit until the periphery of the mercury-cadmium-telluride infrared detector chip wafer overflows, and forming a glue wall at the periphery of the mercury-cadmium-telluride infrared detector chip wafer, wherein at least part of the height of the glue wall is equal to the depth of the scribing groove. According to the invention, the influence of the glue walls stacked around the hybrid chip on the stress of the device can be effectively solved, the overall performance of the device is improved, and the yield and reliability of the hybrid chip are improved.

Description

Technical Field

[0001] The invention relates to the technical field of infrared focal plane detector preparation, and in particular to a method for controlling the height of a colloid filled at the bottom around an infrared detector and an infrared detector. Background Art

[0002] As an important part of modern photoelectric detection technology, the performance and reliability of infrared focal plane detectors are directly related to the application effects of various infrared imaging systems. The hybrid chip of infrared focal plane detector is a focal plane device that uses indium pillars to tightly combine high-performance infrared detector chips with dedicated readout circuits through advanced flip-chip interconnection technology. This structure not only improves the integration of the detector, but also significantly enhances its signal processing capabilities.

[0003] However, with the continuous development of infrared imaging technology, large-area and long-line infrared focal plane detectors have gradually become the mainstream demand of the market. The size of such devices is large, and extremely high requirements are placed on the long-term stability and reliability of their interconnection coupling, especially in an environment that experiences high and low temperature shocks: hybrid chips usually work at liquid nitrogen temperature (77K), and this extremely low temperature environment has a more prominent impact on the material and structural design of the device.

[0004] In the process of cooling the device from room temperature to liquid nitrogen temperature, due to the significant difference in thermal expansion coefficient between the infrared detector material and the readout circuit Si, the indium column, as a key component connecting the two, will be subjected to huge shear stress. After multiple high and low temperature cycles, this stress will cause the indium column, especially the indium column near the periphery of the device, to suffer from fatigue and desoldering due to multiple shear deformations, thus affecting the overall performance and reliability of the device.

[0005] In order to address this problem, the related art uses epoxy resin for bottom filling to solidify the coupling device and perform back thinning. This method enhances the mechanical strength of the device to a certain extent and improves its ability to resist high and low temperature impact. However, after filling the back thinning, a high glue wall will be formed around the device. Since the thermal expansion coefficient of epoxy resin at liquid nitrogen temperature is much higher than that of the detector material and silicon material, these glue walls will produce large tensile stress on the edge of the device. After multiple high and low temperature cycles, this stress may cause the performance of the device, especially the surrounding pixels, to deteriorate, thereby affecting the quality of the entire infrared imaging system. Summary of the invention

[0006] The present invention provides a method for controlling the height of colloid filling around the bottom of an infrared detector and an infrared detector, which solves the problem in the related art that the glue wall generates tensile stress on the edge of the device under high and low temperature cycles, affecting the performance of surrounding pixels and the device.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions:

[0008] In a first aspect, a method for controlling the height of a colloid filling around the bottom of an infrared detector is provided, comprising:

[0009] The prepared mercury cadmium telluride infrared detector chip wafer is placed on the working platform of the grinding wheel dicing machine and fixed by vacuum adsorption;

[0010] Using a grinding wheel dicing machine to scribing along the outer edge of the ground line of the mercury cadmium telluride infrared detector chip wafer, a circle of scribing grooves is formed on the edge of the mercury cadmium telluride infrared detector chip wafer;

[0011] Flip-chip interconnecting the diced mercury cadmium telluride infrared detector chip wafer and the corresponding readout circuit;

[0012] The colloid is filled between the diced HgCdTe infrared detector chip wafer and the readout circuit until it overflows around the HgCdTe infrared detector chip wafer, and a glue wall having at least a partial height equal to the depth of the dicing groove is formed around the HgCdTe infrared detector chip wafer.

[0013] In a first possible implementation manner of the first aspect, the depth of the scribe line is not less than the thickness of the mercury cadmium telluride film.

[0014] Based on the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, the scribe line depth is 10-15 μm.

[0015] In a third possible implementation manner of the first aspect, the colloid is epoxy resin.

[0016] In a second aspect, an infrared detector is provided, comprising:

[0017] A mercury cadmium telluride infrared detector chip, an indium column and a readout circuit, wherein a colloid is filled between the mercury cadmium telluride infrared detector chip and the readout circuit;

[0018] A circle of scribing grooves is arranged on the edge of the mercury cadmium telluride infrared detector chip, and the scribing grooves are used to limit the flow of colloid;

[0019] The colloid forms a glue wall around the mercury cadmium telluride infrared detector chip, at least a portion of which has a height equal to the depth of the scribe line.

[0020] In a first possible implementation manner of the second aspect, the depth of the scribe line is not less than the thickness of the mercury cadmium telluride film.

[0021] Based on the first possible implementation manner of the second aspect, in a second possible implementation manner of the second aspect, the scribe line depth is 10-15 μm.

[0022] In a third possible implementation manner of the second aspect, the colloid is epoxy resin.

[0023] The present application can effectively solve the influence of the glue wall piled around the infrared detector hybrid chip on the device stress, so that the overall performance of the device is greatly improved, and the yield and reliability of the infrared detector hybrid chip are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic flow chart of a method for controlling the height of a colloid filling around the bottom of an infrared detector provided in an embodiment of the present application;

[0025] Figure 2 A schematic diagram of the surface of a mercury cadmium telluride infrared detector chip wafer after dicing provided in an embodiment of the present application;

[0026] Figure 3 A schematic cross-sectional view of a mercury cadmium telluride infrared detector chip wafer after dicing provided in an embodiment of the present application;

[0027] Figure 4 A schematic diagram of a hybrid chip glue wall overflow after flip-chip interconnection, bottom filling, and back thinning process of a mercury cadmium telluride infrared detector provided in an embodiment of the present application;

[0028] Figure 5 A cross-sectional schematic diagram of a hybrid chip with glue wall overflow after flip-chip interconnection, bottom filling, and back thinning processes of a mercury cadmium telluride infrared detector provided in an embodiment of the present application.

[0029] Reference numerals:

[0030] Mercury cadmium telluride infrared detector chip 1; indium column 2; readout circuit 3; scribe groove 4; glue wall 5. DETAILED DESCRIPTION

[0031] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose, the technical solutions in the embodiments of the present application are clearly described. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0032] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0033] The description of the method flow in the specification of the present application and the steps of the flowchart in the drawings of the present specification do not have to be strictly executed according to the step numbers, and the method steps can be executed in a different order. Moreover, some steps can be omitted, multiple steps can be combined into one step, and / or one step can be decomposed into multiple steps.

[0034] The following is a detailed description of the method for controlling the height of the bottom filling colloid around the infrared detector and the infrared detector provided in the embodiment of the present application in conjunction with the accompanying drawings and preferred embodiments.

[0035] First, the application scenario of the method for controlling the height of the bottom filling colloid around the infrared detector according to the embodiment of the present application is described in detail.

[0036] In the related art, in order to solve the problem of fatigue debonding of the indium column between the coupling detector and the readout circuit, epoxy resin is used for bottom filling to solidify the coupling device and perform back thinning. After filling and back thinning, there will be a high glue wall around the device. Since the thermal expansion coefficient of epoxy resin at liquid nitrogen temperature is usually more than ten times that of the detector material and silicon material, the glue wall around the device will produce a large tensile stress on the edge of the device. After multiple high and low temperature cycles, the performance of the device, especially the surrounding pixels, may deteriorate.

[0037] Therefore, it is necessary to control the height of the glue wall filled at the bottom of the infrared detector to reduce the thermal stress of the glue wall accumulated around the hybrid chip and improve the performance and reliability of the device. The grinding wheel scribing process used in this application can accurately control the height of the glue wall filled at the bottom of the infrared detector hybrid chip, reduce the thermal stress of the glue wall accumulated around the hybrid chip and improve the performance and reliability of the device.

[0038] See also Figure 1 , the embodiment of the present application provides a method for controlling the height of the bottom filling colloid around the infrared detector, such as Figure 1 As shown, the control method of the embodiment of the present application includes the following steps:

[0039] Step S1, placing the prepared mercury cadmium telluride infrared detector chip wafer on the working platform of a grinding wheel dicing machine and fixing it by vacuum adsorption.

[0040] Step S2, use a grinding wheel dicing machine to scribing along the outer edge of the ground line of the mercury cadmium telluride infrared detector chip wafer, and form a circle of scribing grooves on the edge of the mercury cadmium telluride infrared detector chip wafer. The depth of the scribing groove is not less than the thickness of the mercury cadmium telluride film. Figure 2-3 .

[0041] Step S3, flip-chip interconnecting the diced mercury cadmium telluride infrared detector chip wafer and the corresponding readout circuit.

[0042] Step S4, filling the space between the diced HgCdTe infrared detector chip wafer and the readout circuit with colloid until it overflows around the HgCdTe infrared detector chip wafer, and forming a glue wall around the HgCdTe infrared detector chip wafer, at least part of which has a height equal to the depth of the dicing groove. Figure 4-5 .

[0043] The principles of this application are:

[0044] Slicing is performed on the mercury cadmium telluride infrared detector chip wafer, that is, a thin groove is cut in a specific area of ​​the chip wafer. The function of this thin groove is to form a boundary in the subsequent process of filling the colloid, which is used to limit the flow range of the bottom filling glue, thereby forming a highly controlled "glue wall" around the chip. In the actual operation of filling the colloid, in order to ensure that the colloid is completely filled between the mercury cadmium telluride infrared detector chip and the readout circuit, the filling glue usually needs to ensure a certain degree of overflow. After the back reduction, there will be a high glue wall around the device. The present application can form a boundary for the flow of colloid in the process of filling the colloid. After the colloid flows into the scribe groove and solidifies, a circle of regular glue wall equal to the depth of the scribe groove is formed on the edge of the chip. By accurately controlling the depth and position of the scribe, the height of the glue wall of the bottom filling glue around the infrared detector chip can be directly controlled, thereby reducing its thermal stress effect on the hybrid chip, that is, the focal plane detector, and improving the performance and reliability of the device.

[0045] In some possible implementations, the scribe line depth is 10-15 μm.

[0046] Use a grinding wheel scriber to scribing along the edge of the ground wire of the HgCdTe infrared detector chip. The position is along the outer edge of the chip ground wire. As long as the position does not touch the edge ground wire of the device, try to get close to the center of the HgCdTe infrared detector chip and scribing near the ground wire around the chip. In addition, the depth cannot be less than the thickness of the HgCdTe film. The specific depth can be determined according to the required height of the glue wall. In specific implementation, the height of the glue wall is generally controlled as small as possible, and the glue wall must be exposed after the chip flip-chip interconnection, bottom filling and back reduction process, so the depth is controlled at 10-15μm.

[0047] In some possible embodiments, the colloid is an epoxy resin.

[0048] For example, in the specific implementation process of preparing the scribe line, the operation process is as follows:

[0049] Step 1: Place the wafer with the prepared mercury cadmium telluride infrared detector chip on the working platform of the grinding wheel dicing machine for vacuum adsorption to ensure that the wafer chip will not move at all.

[0050] Step 2: Use a grinding wheel scriber to scribe along the edge of the ground wire of the mercury cadmium telluride infrared detector chip. The position is along the outer edge of the chip ground wire. The depth cannot be less than the thickness of the mercury cadmium telluride film. The specific depth can be determined according to the required height of the glue wall. The depth of the scribe groove is the height of the glue wall on the outer edge of the infrared detector.

[0051] Step 3, remove the diced mercury cadmium telluride infrared detector chip, clean it with an anhydrous ethanol spray gun, and clean the residue and protective glue sputtered on the surface of the device during dicing.

[0052] The present application can effectively solve the influence of the glue wall piled around the infrared detector hybrid chip on the device stress, so that the overall performance of the device is greatly improved, and the yield and reliability of the infrared detector hybrid chip are improved.

[0053] See also Figure 5 , corresponding to the above-mentioned method embodiment for controlling the height of the bottom filling colloid around the infrared detector, the embodiment of the present application provides an infrared detector, which includes:

[0054] A mercury cadmium telluride infrared detector chip 1, an indium column 2 and a readout circuit 3, wherein a colloid is filled between the mercury cadmium telluride infrared detector chip 1 and the readout circuit 3;

[0055] A circle of scribing grooves 4 is arranged on the edge of the mercury cadmium telluride infrared detector chip, and the scribing grooves 4 are used to limit the flow of colloid;

[0056] The colloid forms a glue wall 5 around the mercury cadmium telluride infrared detector chip 1 , at least a portion of which has a height equal to the depth of the scribe groove 4 .

[0057] In some possible implementations, the depth of the scribe line 4 is 10-15 μm.

[0058] In some possible embodiments, the colloid is an epoxy resin.

[0059] The preparation process of the infrared detector implements the steps and processes of the above-mentioned method embodiment for controlling the height of the bottom filling colloid around the infrared detector, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0060] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0061] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for controlling the height of the bottom filling colloid around the infrared detector, characterized in that: include: The prepared mercury cadmium telluride infrared detector chip wafer is placed on the working platform of the grinding wheel dicing machine and fixed by vacuum adsorption; Using a grinding wheel dicing machine to scribing along the outer edge of the ground line of the mercury cadmium telluride infrared detector chip wafer, a circle of scribing grooves is formed on the edge of the mercury cadmium telluride infrared detector chip wafer; Flip-chip interconnecting the diced mercury cadmium telluride infrared detector chip wafer and the corresponding readout circuit; The colloid is filled between the diced HgCdTe infrared detector chip wafer and the readout circuit until it overflows around the HgCdTe infrared detector chip wafer, and a glue wall having at least a partial height equal to the depth of the dicing groove is formed around the HgCdTe infrared detector chip wafer.

2. The method for controlling the height of the bottom filling colloid around the infrared detector according to claim 1, characterized in that: The depth of the scribe groove is not less than the thickness of the mercury cadmium telluride film.

3. The method for controlling the height of the bottom filling colloid around the infrared detector according to claim 2, characterized in that: The scribe line depth is 10-15 μm.

4. The method for controlling the height of the bottom filling colloid around the infrared detector according to claim 1, characterized in that: The colloid is epoxy resin.

5. An infrared detector, characterized in that: include: A mercury cadmium telluride infrared detector chip, an indium column and a readout circuit, wherein a colloid is filled between the mercury cadmium telluride infrared detector chip and the readout circuit; A circle of scribing grooves is arranged on the edge of the mercury cadmium telluride infrared detector chip, and the scribing grooves are used to limit the flow of colloid; The colloid forms a glue wall around the mercury cadmium telluride infrared detector chip, at least a portion of which has a height equal to the depth of the scribe line.

6. The infrared detector according to claim 5, characterized in that: The depth of the scribe groove is not less than the thickness of the mercury cadmium telluride film.

7. The infrared detector according to claim 6, characterized in that: The scribe line depth is 10-15 μm.

8. The infrared detector according to claim 5, characterized in that: The colloid is epoxy resin.

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