Method for improving indium skin residue after indium stripping

Abstract

The invention provides a method for improving indium skin residue after indium stripping, which comprises the following steps: providing a substrate, forming a photoresist layer which covers the exposed surface of the substrate, and patterning the photoresist layer to form an indium column positioning hole; forming an indium layer which is deposited in the indium column positioning hole and covers the surface of the photoresist layer; the substrate is soaked in an alcohol solvent; soaking the substrate with a ketone solvent; blowing the surface of the substrate; and carrying out ultrasonic cleaning on the substrate. By introducing the purging and ultrasonic cleaning steps and combining with the traditional wet etching, the defects of the traditional wet etching are overcome, and the problem of indium skin residue after indium stripping is solved, so that the reliability of indium column interconnection is guaranteed, and the yield and the performance stability of the device are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a method for improving indium skin residue after indium stripping. BACKGROUND

[0002] Indium pillar interconnection structure plays a core role of electrical conduction, mechanical buffering and thermal matching in tellurium cadmium mercury refrigeration infrared detector, and its performance directly determines the imaging quality and reliability of the detector. As a key link for electrical connection between the detector chip and the readout circuit, high-quality indium pillar array is the premise to ensure the refrigeration infrared detector to realize high resolution, high sensitivity and long-term reliable operation.

[0003] The prior art generally uses a wet stripping process for indium stripping. The process usually includes: defining an indium pillar pattern by photolithography, evaporating or sputtering an indium film on the surface of the tellurium cadmium mercury chip, using photoresist as a mask, soaking in organic solvents such as acetone and anhydrous ethanol, dissolving and removing the indium layer (i.e. "indium skin") on the surface of the photoresist, thereby forming an independent indium pillar structure. Subsequently, through low-temperature flip welding process, the indium pillars on the chip are pressed with the corresponding indium pillars on the readout circuit to form a complete circuit conduction structure.

[0004] The existing process flow is prone to cause indium skin residue after indium stripping due to swelling of the solvent to the edge of the photoresist, mask failure, uneven solvent penetration, and incomplete stripping of the weak adhesion area between the indium layer and the substrate. The residual indium skin, if present between the indium pillars or in the non-conduction area, may cause short circuit between adjacent indium pillars, or hinder the full contact of the indium pillars with the circuit during flip welding, resulting in local conduction failure or even open circuit, affecting the yield and performance stability of the device.

[0005] Therefore, it is urgent to develop a new and more reliable process method to effectively solve the problem of indium skin residue after indium stripping, so as to ensure the reliability of the indium pillar interconnection and improve the yield and performance stability of the device. SUMMARY

[0006] The purpose of the present application is to provide a method for improving indium skin residue after indium stripping to solve the problem of indium skin residue after indium stripping.

[0007] To solve the above technical problems, the present application provides a method for improving indium skin residue after indium stripping, comprising:

[0008] providing a substrate, forming a photoresist layer covering the exposed surface of the substrate, and patterning the photoresist layer to form an indium pillar positioning hole;

[0009] forming an indium layer deposited in the indium pillar positioning hole and covering the surface of the photoresist layer;

[0010] immersing the substrate in an alcohol solvent;

[0011] immersing the substrate in a ketone solvent;

[0012] blowing the surface of the substrate;

[0013] ultrasonically cleaning the substrate.

[0014] Optionally, the frequency of the ultrasonic cleaning ranges from 20 kHz to 40 kHz, the current of the ultrasonic cleaning ranges from 0.6 A to 1 A, and the cleaning time ranges from 1 min to 2 min.

[0015] Optionally, after the blowing of the surface of the substrate and before the ultrasonic cleaning of the substrate, the method for improving the residue of indium skin after indium stripping further comprises:

[0016] maintaining the wet state of the surface of the substrate.

[0017] Optionally, the ultrasonic cleaning of the substrate is performed in the ketone solvent environment used in the immersing step.

[0018] Optionally, the time for immersing in the alcohol solvent ranges from 2 min to 60 min.

[0019] Optionally, the time for immersing in the ketone solvent ranges from 2 min to 60 min.

[0020] Optionally, the alcohol solvent comprises anhydrous ethanol.

[0021] Optionally, the ketone solvent comprises acetone.

[0022] Optionally, the method for forming the indium layer comprises a vacuum evaporation process.

[0023] Optionally, the substrate comprises a mercury cadmium telluride material.

[0024] In summary, the present application provides a method for improving the residue of indium skin after indium stripping, which comprises: providing a substrate, forming a photoresist layer covering the exposed surface of the substrate, patterning the photoresist layer to form an indium column positioning hole, forming an indium layer deposited in the indium column positioning hole and covering the surface of the photoresist layer, immersing the substrate in an alcohol solvent, immersing the substrate in a ketone solvent, blowing the surface of the substrate, and ultrasonically cleaning the substrate.

[0025] Compared with the prior art, the technical solution provided by the present application has the following beneficial effects:

[0026] The introduction of the blowing and ultrasonic cleaning steps greatly improves the removal rate of residual indium skin, ensures the reliability of the indium column interconnection, and thus improves the yield and performance stability of the device. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A flowchart of the method for improving the residual indium skin after indium stripping provided by the embodiment of the present application is shown in the figure.

[0028] Figures 2 to 7 For Figure 1 A structural schematic diagram of the indium stripping process corresponding to each step

[0029] In the figures, the reference signs are explained as follows:

[0030] 100 - substrate; 110 - indium layer; 120 - residual indium skin; 200 - photoresist layer; 300 - indium column positioning hole. DETAILED DESCRIPTION

[0031] The method for improving the residual indium skin after indium stripping provided by the present application is further described in detail below in combination with the drawings and specific embodiments. It should be noted that the drawings are all very simplified and use non-precise proportions, only to facilitate and clearly assist the purpose of explaining the embodiment of the present application. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing needs to be different, sometimes different proportions are used. It should be recognized that relative terms such as "above", "below", "top", "bottom" shown in the drawings can be used to describe the relationship between various elements. These relative terms are intended to cover different orientations of the elements in addition to the orientation depicted in the drawings. For example, if the device is inverted with respect to the view in the drawing, the element described as "above" another element will now be below the element.

[0032] Referring to Figure 1 The embodiment of the present application provides a method for improving the residual indium skin after indium stripping, which comprises:

[0033] providing a substrate, forming a photoresist layer covering the exposed surface of the substrate, patterning the photoresist layer to form an indium column positioning hole;

[0034] forming an indium layer deposited in the indium column positioning hole and covering the surface of the photoresist layer;

[0035] immersing the substrate in an alcohol solvent;

[0036] immersing the substrate in a ketone solvent;

[0037] blowing the surface of the substrate;

[0038] ultrasonic cleaning is performed on the substrate.

[0039] The method for improving indium skin residue after indium stripping provided by the embodiment of the application, by introducing the blowing and ultrasonic cleaning steps, combining with the traditional wet etching, makes up for the defects of the traditional wet etching, solves the problem of indium skin residue after indium stripping, thereby guaranteeing the reliability of the indium column interconnection, and improving the yield and performance stability of the device.

[0040] The following will be described in combination with the accompanying Figures 2 to 7 The method for improving indium skin residue after indium stripping provided by the embodiment of the application will be further described.

[0041] Reference Figure 2 As shown in FIG. 1, step S1 is performed to provide a substrate 100, the substrate 100 provided by the embodiment of the application is used in the manufacturing process of the refrigeration type infrared detector, in order to improve the adaptability of the substrate 100 and the refrigeration type infrared detector, the material of the substrate 100 includes tellurium mercury cadmium, the tellurium mercury cadmium is used as the preferred material for manufacturing the refrigeration type infrared detector due to its unique physical and optical characteristics (such as adjustable band gap, high quantum efficiency and excellent electron transport performance); a photoresist layer 200 is formed by spin coating photoresist, the photoresist layer 200 covers the exposed surface of the substrate 100, and then the photoresist layer 200 is patterned by an exposure process and a development process to form an indium column positioning hole 300, the indium column positioning hole 300 is used to fill indium to form an indium column in the subsequent process.

[0042] Reference Figure 3 As shown in FIG. 2, step S2 is performed to form an indium layer 110 on the surface of the substrate 100, the embodiment of the application can use a vacuum evaporation process to form the indium layer 110, the indium layer 110 is deposited in the indium column positioning hole 300 to form an indium column structure, and covers the surface of the photoresist layer 200; wherein,

[0043] The indium layer 110 includes the indium layer 110 deposited in the indium column positioning hole 300 to form the indium column structure, and the redundant indium layer 110 covering the surface of the photoresist layer 200 to be stripped in the subsequent step.

[0044] It should be noted that the vacuum evaporation process is used to form the indium layer 110 in the embodiment only as an example, and does not constitute a limitation to the present application, and in some other embodiments, some other processes such as electroplating, sputtering, etc. can also be used to form the indium layer 110.

[0045] Reference Figure 4, execute step S3, using alcohol solvent to soak the substrate 100; the present embodiment uses the alcohol solvent to soak the substrate 100, swells the photoresist layer 200, thereby softening, loosening and lifting the redundant indium layer 110 covering the surface of the photoresist layer 200. The hydroxyl (-OH) in the alcohol solvent forms hydrogen bond with the polar group in the photoresist, so that the volume of the photoresist layer 200 expands, the binding force between the photoresist layer 200 and the substrate 100 is destroyed, and the edge of the photoresist layer 200 is lifted, and the edge of the redundant indium layer 110 covering the surface of the photoresist layer 200 is also lifted, generating a small gap, so that the overall adhesion of the indium layer 110 is reduced, and the indium layer 110 becomes easy to peel off.

[0046] As a preferred solution, the present embodiment uses highly volatile anhydrous ethanol to soak the substrate 100, which is easy to volatilize and remove to avoid affecting subsequent process steps. Also as a preferred solution, the time for soaking the substrate 100 is 2 min to 60 min, and the present embodiment selects 8 min for soaking.

[0047] Referring to FIGS. 1, 2 and 3, Figure 4 and Figure 5 As shown in FIGS. 1, 2 and 3, execute step S4, using ketone solvent to soak the substrate 100; using the ketone solvent to soak the substrate 100 to dissolve the photoresist layer 200 and separate the indium layer 110 covering the surface of the photoresist layer 200. Using the ketone solvent to soak the substrate 100 causes the photoresist layer 200 to chemically break and dissolve in the ketone solvent, and the redundant indium layer 110 covering the surface of the photoresist layer 200 loses support, most of the redundant indium layer 110 separates from the substrate 100, and a small part of the redundant indium layer 110 adheres to the surface of the substrate 100 to form a residual indium skin 120.

[0048] Further, to improve the dissolution effect of the photoresist layer 200 and prevent damage to the substrate 100, preferably, the present embodiment selects acetone with high dissolution efficiency for the photoresist to soak the substrate 100, the acetone has high volatility and is easy to volatilize and remove to avoid affecting subsequent process steps, and the soaking time is preferably 2 min to 60 min, and the present embodiment selects 8 min for soaking.

[0049] It should be noted that the selection of anhydrous ethanol and acetone and the soaking time of the substrate 100 using anhydrous ethanol and acetone in the present embodiment are only preferred examples and do not constitute a limitation on the present application. In other embodiments, other alcohol solvents and ketone solvents can also be selected, and correspondingly, the soaking time using alcohol solvents and ketone solvents also needs to be adaptively adjusted according to the selected solvents.

[0050] Referring to FIGS. 1, 2 and 3, Figure 6 andFigure 7 As shown in FIG. 6, after step S5, the surface of the substrate 100 is blown to remove the residual indium sheet 120 adhered to the surface of the substrate 100 by introducing physical intervention. To prevent the removed residual indium sheet 120 from being re-adsorbed to the surface of the substrate 100 due to electrostatic effect after the surface of the substrate 100 is dried, preferably, after the surface of the substrate 100 is blown, and before the substrate 100 is ultrasonically cleaned, the method for improving residual indium sheet after indium stripping provided by the embodiment of the present application further comprises:

[0051] maintaining the wet state of the surface of the substrate 100.

[0052] Continuing to refer to Figure 6 and Figure 7 As shown in FIG. 6, after step S5, the surface of the substrate 100 is blown to remove the residual indium sheet 120 adhered to the surface of the substrate 100 by introducing physical intervention. To prevent the removed residual indium sheet 120 from being re-adsorbed to the surface of the substrate 100 due to electrostatic effect after the surface of the substrate 100 is dried, preferably, after the surface of the substrate 100 is blown, and before the substrate 100 is ultrasonically cleaned, the method for improving residual indium sheet after indium stripping provided by the embodiment of the present application further comprises:

[0053] To improve the effect of ultrasonic cleaning, as a preferred solution, the ultrasonic cleaning of the substrate 100 in the embodiment of the present application is performed in the ketone solvent environment in the soaking step, that is, when the ultrasonic cleaning is performed, the substrate 100 is placed in a container filled with acetone solvent, and the container is placed in the water tank of an ultrasonic cleaning machine. In this way, the chemical dissolution effect of the acetone solvent can be continued, the residue of the photoresist layer 200 can be dissolved, the adhesion of the residual indium sheet 120 can be weakened, and the re-adsorption of the residual indium sheet 120 that has been stripped during the ultrasonic cleaning process can be prevented.

[0054] To improve the effect of ultrasonic cleaning and avoid damaging the substrate 100, as a preferred solution, the frequency range of the ultrasonic cleaning in the embodiment of the present application is 20 kHz to 40 kHz, to avoid damage to the substrate 100 caused by a too high cleaning frequency. Preferably, the current of the ultrasonic cleaning is 0.6 A to 1 A, and the cleaning time is 1 min to 2 min. In this embodiment, the substrate 100 is ultrasonically cleaned at a cleaning frequency of 40 kHz and a current of 0.6 A for 1 min. Through the combination of low frequency, low current, and short time, efficient cleaning is achieved while damage to the substrate 100 is avoided.

[0055] In summary, the embodiment of the present application provides a method for improving indium residue after indium stripping, comprising: providing a substrate, forming a photoresist layer covering the exposed surface of the substrate, patterning the photoresist layer to form an indium pillar positioning hole; forming an indium layer deposited in the indium pillar positioning hole and covering the surface of the photoresist layer; soaking the substrate with an alcohol solvent; soaking the substrate with a ketone solvent; purging the surface of the substrate; and ultrasonic cleaning the substrate. By introducing the purging and ultrasonic cleaning steps, the defects of traditional wet etching are compensated for, the problem of indium residue after indium stripping is solved, and the reliability of the indium pillar interconnection is ensured, thereby improving the yield and performance stability of the device.

[0056] The above description is only a description of the preferred embodiments of the present application, and is not any limitation on the scope of the present application. Any modification or change made by a person of ordinary skill in the art based on the above disclosure is within the protection scope of the claims.

Claims

1. A method for improving indium residue after indium stripping, characterized in that, include: A substrate is provided, a photoresist layer is formed covering the exposed surface of the substrate, and the photoresist layer is patterned to form indium pillar positioning holes; An indium layer is formed, which is deposited inside the indium pillar positioning hole and covers the surface of the photoresist layer; The substrate was immersed in an alcohol solvent; The substrate was immersed in a ketone solvent; The substrate surface is purged; The substrate is ultrasonically cleaned.

2. The method for improving indium residue after indium stripping according to claim 1, characterized in that, The ultrasonic cleaning frequency range is 20kHz to 40kHz, the ultrasonic cleaning current is 0.6A to 1A, and the cleaning time is 1min to 2min.

3. The method for improving indium residue after indium stripping according to claim 1, characterized in that, After purging the substrate surface and before ultrasonic cleaning the substrate, the method for improving indium residue after indium stripping further includes: Maintain the substrate surface in a moist state.

4. The method for improving indium residue after indium stripping according to claim 1, characterized in that, The substrate is ultrasonically cleaned in the same ketone solvent environment used in the immersion step.

5. The method for improving indium residue after indium stripping according to claim 1, characterized in that, The soaking time using the alcohol solvent is 2 min to 60 min.

6. The method for improving indium residue after indium stripping according to claim 1, characterized in that, The soaking time using the ketone solvent is 2 min to 60 min.

7. The method for improving indium residue after indium stripping according to claim 1, characterized in that, The alcohol solvents include anhydrous ethanol.

8. The method for improving indium residue after indium stripping according to claim 1, characterized in that, The ketone solvents include acetone.

9. The method for improving indium residue after indium stripping according to claim 1, characterized in that, The method for forming the indium layer includes a vacuum evaporation process.

10. The method for improving indium residue after indium stripping according to claim 1, characterized in that, The substrate comprises mercury cadmium telluride material.

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