Method for thinning multicolor detector
By combining alcohol reagents with hydrofluoric acid-based and nitric acid-based corrosion liquid, the multi-color detector chip is corroded and thinned, which solves the problems of poor chip surface quality and low efficiency of mechanical chemical polishing caused by mechanical polishing, and achieves a high-efficiency and low damage thinning process, improving imaging quality and process efficiency.
Patent Information
- Application Number
- CN202510024650.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-08
- Publication Date
- 2025-05-13
AI Technical Summary
In the thinning process of multi-color detectors, pure mechanical polishing leads to poor surface quality of the chip and poor imaging quality; the process of combining mechanical chemical polishing and chemical corrosion is low efficiency and yield is low.
After cleaning with alcohol reagents, the multi-color detector chip is corroded by combining hydrofluoric acid-based corrosion liquid and nitric acid-based corrosion liquid, and the substrate is gradually removed until the HgCdTe surface is exposed, and multiple cleanings and drying are carried out.
Effectively replace traditional mechanical and mechanical chemical polishing processes, reduce the probability of chip surface damage, improve imaging quality, and improve process efficiency and yield.
Smart Images
Figure CN119997637A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of photoelectric detectors and semiconductor technology, and in particular to a method for thinning a multi-color detector. Background Art
[0002] A multicolor detector is a high-tech optoelectronic device that can respond to radiation in two or more different infrared bands at the same time. This detector improves the integration of device functions by realizing simultaneous detection of two or more bands of light on a single photosensitive element. It reduces the burden on the entire detection system. A multicolor detector can provide radiation information of a target in two or more bands, which can not only suppress background interference and extract the absolute temperature of the target, but also greatly improve the detection rate. Compared with traditional monochromatic detectors, it has better imaging performance.
[0003] The thinning process is the most important and challenging part of the device process flow of multi-color detectors. This process mainly removes the substrate of the detector and reduces its thickness to improve the response sensitivity to infrared radiation. For example, for a two-color detector made of HgCdTe material, thinning to about 20um can significantly improve the quantum efficiency and signal quality of the detector, but in actual process, in order to avoid the reliability of the packaging process in subsequent steps, the CdZnTe substrate needs to be completely removed. The thinning methods for multi-color detectors mainly include mechanical polishing and chemical corrosion. Mechanical polishing may introduce material surface defects and mechanical damage, which may lead to loss of imaging quality. Summary of the invention
[0004] The embodiment of the present application provides a method for thinning a multi-color detector to solve the problem of poor chip surface quality caused by pure mechanical polishing, which in turn leads to poor imaging quality, as well as the problem of low process efficiency and low yield rate caused by the combination of mechanical chemical polishing and chemical etching.
[0005] The embodiment of the present application provides a method for thinning a multi-color detector. In the thinning process of the multi-color detector, the following steps are adopted:
[0006] Use alcohol reagent to clean the bonded multi-color detector chip;
[0007] Protect the circuits and pads of the multi-color detector chip;
[0008] The protected multi-color detector chip is corroded by a first corrosive liquid until color stripes appear around the short-wave chip and then taken out, wherein the first corrosive liquid is a hydrofluoric acid-based corrosive liquid;
[0009] placing the multi-color detector chip after removal into a second etching solution, and taking it out after the HgCdTe surface is completely exposed, wherein the second etching solution is a nitric acid-based etching solution;
[0010] Clean the chip until there is no organic residue on the surface of the multi-color detector chip and dry it.
[0011] Optionally, protecting the circuits and pads of the multi-color detector chip includes: protecting the circuits and pads of the multi-color detector chip by using a photolithography process.
[0012] Optionally, the first etching solution is a hydrofluoric acid-based etching solution, whose components include hydrofluoric acid, nitric acid compounds, lactic acid complexes and water. The first etching solution has different etching rates for HgCdTe materials in different bands, and the etching rate for short-wave HgCdTe materials is the highest.
[0013] Optionally, the second etching solution is a nitric acid-based etching solution, components of which include nitric acid, potassium complexes and water. The second etching solution makes the etching rates of HgCdTe materials in different bands roughly the same.
[0014] Optionally, cleaning the chip includes: using an alcohol reagent or a ketone reagent to clean the chip.
[0015] Optionally, the method further includes: repeating the thinning step according to circumstances until the thinning requirement of the multi-color detector is met.
[0016] The embodiment of the present application abandons the traditional mechanical polishing and mechanical chemical polishing process methods to reduce the problem of poor chip surface quality caused by mechanical damage. By utilizing two etching solutions for rapid thinning of CdZnTe-based HgCdTe multi-color detectors, the problem of poor chip surface quality caused by pure mechanical polishing and the resulting poor imaging quality is solved, as well as the problem of low process efficiency and low yield rate of the combination of mechanical chemical polishing and chemical etching.
[0017] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:
[0019] Figure 1 The thinning process flow diagram of the multi-color detector in the embodiment of the present application is shown;
[0020] Figure 2This is a cross-sectional view of a multi-color detector chip in an embodiment of the present application (taking dual-color as an example);
[0021] Figure 3 This is a top view of a multi-color detector chip in an embodiment of the present application (taking dual-color as an example);
[0022] Figure 4 This is a 3D side view of the multi-color detector before and after thinning in an embodiment of the present application (taking two colors as an example);
[0023] Figure 5 This is a cross-sectional view of the multi-color detector before and after thinning in an embodiment of the present application (taking a two-color detector as an example). DETAILED DESCRIPTION
[0024] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.
[0025] The present application embodiment provides a method for thinning a multi-color detector. In the process of thinning a multi-color detector, Figure 1 As shown, the following steps are taken:
[0026] In step S100, the bonded multi-color detector chip is cleaned using an alcohol reagent.
[0027] In step S200, the circuits and pads of the multi-color detector chip are protected. For example, in some embodiments, protecting the circuits and pads of the multi-color detector chip includes: protecting the circuits and pads of the multi-color detector chip by using a photolithography process.
[0028] In step S300, the protected multi-color detector chip is corroded by a first corrosive solution until color stripes appear around the short-wave chip and then taken out. The first corrosive solution is a hydrofluoric acid-based corrosive solution.
[0029] In step S400, the multi-color detector chip is placed in a second etching solution after being taken out, and is taken out after the HgCdTe surface is completely exposed, wherein the second etching solution is a nitric acid-based etching solution.
[0030] In step S500, the chip is cleaned until there is no organic residue on the surface of the multi-color detector chip, and then dried, for example, by baking or drying.
[0031] In some embodiments, the first etching solution is a hydrofluoric acid-based etching solution, and its components include hydrofluoric acid, nitric acid compounds, lactic acid complexes and water. The first etching solution has different rates for HgCdTe materials in different bands, and the etching rate for short-wave HgCdTe materials is the highest. Specifically, the first etching solution is used for HgCdTe materials in different bands, and its etching rate is quite different. For example, for short-wave HgCdTe materials, the rate can be as high as 2um / min; while for HgCdTe materials in medium-wave, long-wave, and very long-wave bands, the removal rate is only 0.5um / min.
[0032] In some specific examples, the first etching solution ratio may be, for example, 1:n:1:n for hydrofluoric acid, nitric acid compounds, lactic acid compounds, and water, and this ratio may achieve faster etching efficiency and etching quality. For example, when the ratios are 1:2:1:2, 1:1:1:1, and 1:3:1:3, the removal rates of short-wave materials are 2um / min, 1um / min, and 5um / min, respectively.
[0033] In some embodiments, the second etching solution is a nitric acid-based etching solution, the main components of which are nitric acid, potassium complexes, and water. The second etching solution makes the etching rate of HgCdTe materials in different bands roughly the same. In a specific example, the second etching solution has roughly the same etching rate for HgCdTe materials in different bands, and its corrosion effect is almost negligible, that is, selective corrosion. In a specific example, the second etching solution can slowly remove the CdZnTe substrate, with a maximum rate of only 1um / min, and the corrosion effect on the HgCdTe material in a short time is almost negligible, that is, selective corrosion.
[0034] In some specific examples, the second etching solution may have a ratio of nitric acid, potassium complex and water that is a multiple of 1:3:3, which can fully exert the performance of the etching solution. For example, when the ratio is 1:3:6, better etching efficiency and selective etching performance can be achieved.
[0035] In some embodiments, cleaning the chip includes: using an alcohol reagent or a ketone reagent to clean the chip.
[0036] In some embodiments, the process further includes: repeating the thinning step according to the situation until the multi-color detector thinning requirement is met, that is, repeating steps S101 to S105 until the multi-color detector thinning process standard is met.
[0037] Figure 2 shows a cross-sectional view of a multi-color detector chip, Figure 2Taking dual-color as an example, two or more detector chips with different bands are integrated on a readout circuit, the chip and circuit are interconnected with indium columns, and the gap between the two is filled with filling glue to increase the overall strength of the hybrid chip. Figure 3 The top view of the multi-color detector chip is shown, where chips with different wavelength bands are placed parallel to each other.
[0038] Figure 4 The 3D side view of the multi-color detector of the present application before and after thinning is shown, still taking the two-color detector as an example, Figure 5 The cross-sectional view of the multi-color detector before and after thinning in the embodiment of the present application is shown. The specific process flow is as follows: 1) Use alcohol reagents to clean the bonded multi-color detector chip; 2) Use photolithography to protect the exposed circuits and pads around the chip; 3) Place the protected chip in the prepared first etching solution and let it stand until color stripes appear on the four sides of the short-wave chip and then take it out immediately; 4) Place the chip in the prepared second etching solution and let it stand for a period of time, and take it out after the HgCdTe surface is completely exposed; 5) Use alcohol reagents and ketone reagents to clean the chip until there is no organic residue on the chip surface, and then dry the chip. Repeat steps 1)-5) according to the actual process conditions until the multi-color detector thinning process standard is reached.
[0039] The embodiment of the present application abandons the traditional mechanical polishing and mechanical chemical polishing process methods to reduce the problem of poor chip surface quality caused by mechanical damage. By utilizing two etching solutions for rapid thinning of CdZnTe-based HgCdTe multi-color detectors, the problem of poor chip surface quality caused by pure mechanical polishing and the resulting poor imaging quality is solved, as well as the problem of low process efficiency and low yield rate of the combination of mechanical chemical polishing and chemical etching.
[0040] The method of the present application can replace traditional mechanical and mechanical chemical polishing processes and reduce the probability of chip surface damage.
[0041] It should be noted that in the various embodiments of the present application, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a 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, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.
[0042] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.
[0043] 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 thinning a multi-color detector, characterized in that: In the thinning process of the multi-color detector, the following steps are used: Use alcohol reagent to clean the bonded multi-color detector chip; Protect the circuits and pads of the multi-color detector chip; The protected multi-color detector chip is corroded by a first corrosive liquid until color stripes appear around the short-wave chip and then taken out, wherein the first corrosive liquid is a hydrofluoric acid-based corrosive liquid; placing the multi-color detector chip after removal into a second etching solution, and taking it out after the HgCdTe surface is completely exposed, wherein the second etching solution is a nitric acid-based etching solution; Clean the chip until there is no organic residue on the surface of the multi-color detector chip and dry it.
2. The method for thinning a multi-color detector according to claim 1, characterized in that: Protecting the circuit and pads of the multi-color detector chip includes: protecting the circuit and pads of the multi-color detector chip by using a photolithography process.
3. The method for thinning a multi-color detector according to claim 1, characterized in that: The first etching solution is a hydrofluoric acid-based etching solution, and its components include hydrofluoric acid, nitric acid compounds, lactic acid complexes and water. The first etching solution has different etching rates for HgCdTe materials in different bands, and the etching rate for short-wave HgCdTe materials is the highest.
4. The method for thinning a multi-color detector as claimed in claim 3, characterized in that: The second etching solution is a nitric acid-based etching solution, and its components include nitric acid, potassium complex and water. The second etching solution makes the etching rates of HgCdTe materials in different bands roughly the same.
5. The method for thinning a multi-color detector according to claim 1, characterized in that: Cleaning the chip includes: using alcohol reagents and ketone reagents to clean the chip.
6. The method for thinning a multi-color detector according to claim 1, characterized in that: Also includes: Repeat the thinning steps as needed until the multi-color detector thinning requirements are met.