Method for verifying a photoresist layer residue

Abstract

The application provides a method for verifying photoresist layer residue, comprising the following steps: providing a plurality of substrates and forming a diagnostic film layer covering the surface of each of the substrates; forming a photoresist layer covering the surface of the diagnostic film layer; exposing the photoresist layer; developing and etching the photoresist layer and the diagnostic film layer on different substrates respectively by using a plurality of different combinations of lithography process parameters; judging the residue of the photoresist layer corresponding to different combinations of process parameters according to the residue of the diagnostic film layer on different substrates; and selecting the optimal lithography process parameters suitable for the current lithography process from the plurality of combinations of lithography process parameters based on the residue of the photoresist layer. The application verifies the residue of the photoresist layer under different lithography process parameters through parallel experiments, and selects the optimal lithography process parameters accordingly. The method is widely applicable and low in cost.

Description

Methods for verifying photoresist layer residue Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method for verifying photoresist layer residue. Background Technology

[0002] In the manufacturing process of semiconductor devices, especially high-performance cooled infrared detectors, it is often necessary to perform fine patterning on the surface of sensitive materials such as mercury cadmium telluride. This process generally employs a combination of photolithography and wet etching. Specifically, a patterned thin film is first grown on a substrate material, then photoresist is spin-coated onto the surface of the film. The patterned photoresist layer is obtained through exposure and development, and wet etching is used to perform processes such as opening holes or metallization on the semiconductor device.

[0003] However, the aforementioned existing technologies suffer from a long-standing and unresolved problem: after the development process is completed, due to fluctuations in the photolithography window and limitations in detection methods, it is difficult to effectively detect and determine whether an extremely thin and invisible photoresist layer remains at the bottom of the patterned area. When a residual photoresist layer is present, it acts as an unintended barrier layer, hindering the contact between the etching solution and the underlying film, resulting in incomplete etching.

[0004] This problem can trigger a series of serious device performance failures. For example, in the aperture opening process, it can lead to partial aperture blockage, resulting in poor contact; in the metallization process, it can cause poor contact between the metal electrode and the underlying material, leading to a significant increase in contact resistance, ultimately affecting the overall performance and yield of the detector. When etching blockage occurs, those skilled in the art find it difficult to quickly and accurately determine the root cause of the problem, and cannot distinguish whether it is due to incomplete development or improper settings of parameters such as etching solution concentration, temperature, or time. Summary of the Invention

[0005] The purpose of this invention is to provide a method for verifying photoresist layer residue, comprising the following steps:

[0006] A plurality of substrates are provided, and a diagnostic film layer is formed covering the surface of each of the substrates;

[0007] A photoresist layer is formed, which covers the surface of the diagnostic film layer;

[0008] The photoresist layer is exposed;

[0009] Multiple sets of different photolithography process parameters were used to develop and etch the photoresist layer and the diagnostic film layer on different substrates, respectively.

[0010] Based on the residual status of the diagnostic film layer on different substrates, determine the residual status of the photoresist layer corresponding to different combinations of process parameters; and,

[0011] Based on the residual condition of the photoresist layer, the optimal photolithography process parameters suitable for the current photolithography process are selected from multiple combinations of photolithography process parameters.

[0012] Optionally, the combination of process parameters includes the development time for developing the photoresist layer and the etching conditions for etching the diagnostic film layer.

[0013] Optionally, the multiple sets of different process parameter combinations are set by fixing the etching conditions and gradually increasing the development time.

[0014] Optionally, the diagnostic film layer is a different color from the substrate so that the two can be visually distinguished.

[0015] Optionally, determining the residual status of the photoresist layer corresponding to different combinations of process parameters based on the residual status of the diagnostic film layer on different substrates includes:

[0016] Observe the bottom color of the diagnostic film pattern after etching each combination to determine the residue of the diagnostic film; if the bottom of the etched diagnostic film pattern shows the substrate color, it is determined that there is no residue of the photoresist layer; if the bottom of the diagnostic film pattern does not show the substrate color, extend the etching time for a second observation; if the substrate color is still not shown, it is determined that there is residue of the photoresist layer.

[0017] Optionally, selecting the optimal photolithography process parameters suitable for the current photolithography process from multiple combinations of photolithography process parameters based on the residual condition of the photoresist layer includes:

[0018] The shortest development time that leaves no residue in the photoresist layer is determined, and the shortest development time is defined as the optimal photolithography process parameter.

[0019] Optionally, the diagnostic membrane layer includes a silicon dioxide layer.

[0020] Optionally, the method for forming the diagnostic film includes plasma-enhanced chemical vapor deposition.

[0021] Optionally, the etching solution used in the etching includes a buffered oxide etching solution.

[0022] Optionally, the method is used to optimize the photolithography process window on the surface of mercury cadmium telluride material in the manufacturing process of a cooled infrared detector.

[0023] In summary, the present invention provides a method for verifying photoresist layer residue, comprising the following steps: providing multiple substrates and forming a diagnostic film layer covering the surface of each substrate; forming a photoresist layer covering the surface of the diagnostic film layer; exposing the photoresist layer; developing and etching the photoresist layer and the diagnostic film layer on different substrates using multiple different combinations of photolithography process parameters; determining the residue status of the photoresist layer corresponding to different combinations of process parameters based on the residue status of the diagnostic film layer on different substrates; and selecting the optimal photolithography process parameters suitable for the current photolithography process from multiple combinations of photolithography process parameters based on the residue status of the photoresist layer.

[0024] Compared with existing technologies, it has the following advantages:

[0025] This invention systematically verifies the photoresist residue under different photolithography process parameters by designing multiple sets of parallel experiments with different photolithography process parameters, providing direct and quantitative data support for determining the optimal photolithography process parameters. The method is highly universal and inexpensive, and can use common and low-cost materials in semiconductor processes as diagnostic films. The obtained optimal photolithography process parameters are applicable to various process flows. Attached Figure Description

[0026] Figure 1 is a flowchart of the method for verifying photoresist layer residue provided in an embodiment of the present invention;

[0027] Figures 2 to 6 are schematic diagrams of the semiconductor structures corresponding to each step in Figure 1;

[0028] Figures 7 to 9 are semiconductor structure morphology images corresponding to each group in step S5 of Figure 1;

[0029] Figures 10-12 are semiconductor structure morphology images corresponding to each group in step S6 of Figure 1;

[0030] The labels in the attached figures are explained as follows:

[0031] 100 - Substrate; 110 - Diagnostic film layer; 120 - Photoresist layer. Detailed Implementation

[0032] The method for verifying photoresist layer residue proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, used only to facilitate and clarify the illustration of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structure. In particular, different proportions may be used in different drawings to show different emphases. It should be understood that relative terms such as "above," "below," "top," and "bottom" shown in the drawings can be used to describe the relationships between various elements. These relative terms are intended to cover different orientations of elements other than those depicted in the drawings. For example, if the device is inverted relative to the view in the drawings, an element described as "above" another element will now be below that element. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish various components, elements, steps, etc., in the specification, and are not used to indicate logical or sequential relationships between various components, elements, steps, etc.

[0033] Referring to Figure 1, an embodiment of the present invention provides a method for verifying photoresist layer residue, comprising the following steps:

[0034] S1, providing a plurality of substrates and forming a diagnostic film layer covering the surface of each of the substrates;

[0035] S2, forming a photoresist layer that covers the surface of the diagnostic film layer;

[0036] S3, expose the photoresist layer;

[0037] S4, using multiple different combinations of photolithography process parameters, the photoresist layer and the diagnostic film layer on different substrates are respectively developed and etched;

[0038] S5, based on the residual status of the diagnostic film layer on different substrates, determine the residual status of the photoresist layer corresponding to different combinations of process parameters;

[0039] S6. Based on the residual condition of the photoresist layer, select the optimal photolithography process parameters suitable for the current photolithography process from multiple combinations of photolithography process parameters.

[0040] Using the method proposed in this invention, parallel experiments are conducted through multiple combinations of different photolithography process parameters to verify the residual status of the photoresist layer under different photolithography process parameters. This provides direct and quantitative data support for screening the optimal photolithography process parameters. Furthermore, this method is highly universal and inexpensive, and can use common and low-cost materials in semiconductor processes as diagnostic films. The obtained optimal photolithography process parameters can be applied to various process flows.

[0041] The method for verifying photoresist layer residue provided in the embodiments of the present invention will be further described below with reference to Figures 2-12.

[0042] Referring to Figure 2, step S1 is performed by providing multiple substrates 100, each of which may be a silicon substrate with a silver-gray surface. Preferably, a diagnostic film layer 110 is deposited on the surface of the substrate 100 using plasma-enhanced chemical vapor deposition. To reduce costs, the material of the diagnostic film layer 110 is preferably silicon dioxide, and the deposition thickness of the diagnostic film layer 110 is 2500 Å to 20000 Å. In this embodiment, to make the color of the diagnostic film layer 110 different from that of the substrate 100 so that they can be visually distinguished, the thickness of the diagnostic film layer 110 is preferably 5000 Å. By controlling the thickness of the silicon dioxide film layer, i.e., the diagnostic film layer 110, it is made to appear red under the influence of optical interference. The color of the diagnostic film layer 110 is different from that of the substrate 100, and the red diagnostic film layer 110 contrasts sharply with the silver-gray substrate 100 so that they can be visually distinguished. In other embodiments, when the material of the substrate 100 changes, causing its color to change, the diagnostic film layer 110 may also use other colors that are more clearly distinguishable from it.

[0043] Referring to Figure 3, step S2 is performed to spin-coat photoresist on the surface of the diagnostic film layer 110 to form a photoresist layer 120, which covers the surface of the diagnostic film layer 110; then step S3 is performed to expose the photoresist layer 120.

[0044] Referring to Figures 4 and 5, step S4 is performed by using multiple sets of different photolithography process parameter combinations to develop and etch the photoresist layer 120 and the diagnostic film layer 110 on different substrates, respectively. Preferably, in this embodiment, the process parameter combination includes the development time for developing the photoresist layer 120 and the etching conditions for etching the diagnostic film layer 110. More preferably, the multiple sets of different process parameter combinations are set by fixing the etching conditions and increasing the development time in a stepwise manner.

[0045] In this embodiment of the invention, three different combinations of process parameters are used. The etching conditions for the three combinations of process parameters are set as follows: etching is performed using a 10% buffered oxide etching solution (BOE). The development conditions for the first, second, and third combinations of process parameters are set to 30s, 1min, and 2min, respectively.

[0046] It should be noted that the silicon substrate, silicon dioxide diagnostic film, and 10% buffered oxidation etching solution used in the embodiments of the present invention are merely preferred examples and do not constitute a limitation of the present invention. In other embodiments, other substrates, diagnostic films, and corresponding etching solutions may also be used, such as silicon substrates, silicon nitride diagnostic films, and hot phosphoric acid etching solutions. However, it is still necessary to ensure that the substrate and the diagnostic film are different in color so that the etching results can be distinguished.

[0047] Referring to Figures 7-9, step S5 is performed to observe the residual condition of the diagnostic film layer 110 after each group of etching. Based on the residual condition of the diagnostic film layer 110 in each group, the residual condition of the photoresist layer 120 is determined. An optical microscope is used to observe the morphology images obtained after developing and etching the photoresist layer 120 and the diagnostic film layer 110 respectively using the first, second, and third group of process parameter combinations. The morphology images of each group are analyzed, and the color of the bottom of the pattern of the diagnostic film layer 110 after etching in each combination is observed. The residual condition of the diagnostic film layer 110 is determined in sequence.

[0048] Preferably, referring to Figure 7, the first group used a development time of 30 seconds. After etching, the bottom of the pattern of the diagnostic film layer 110 showed a slight red color and did not show the color of the substrate 100. Based on this, it was determined that there was residue in the diagnostic film layer 110 and it was not completely etched. This situation may be due to insufficient etching time. Preferably, in this embodiment, the etching time of the first group is extended and etched for another 1 minute before a second observation. After observation, it was found that the bottom of the pattern of the diagnostic film layer 110 still showed a slight red color and did not show the color of the substrate 100. Therefore, it was determined that the photoresist layer 120 was not fully developed and there was residue, which caused the diagnostic film layer 110 to be poorly etched.

[0049] Referring to Figure 8, the second group used a development time of 1 minute. Compared with the first group, the bottom of the diagnostic film layer 110 pattern after etching in the second group showed a slight red color, indicating that there was a small amount of residue in the diagnostic film layer 110 and it was not completely etched. The etching time of the second group was extended and etched for another minute before a second observation was performed. It was found that the bottom of the diagnostic film layer 110 pattern still showed a slight red color and did not show the color of the substrate 100. Therefore, it was determined that the photoresist layer 120 was not fully developed and there was a small amount of residue, which caused the diagnostic film layer 110 to be poorly etched.

[0050] Referring to Figure 9, the third group used a development time of 2 minutes. The bottom of the pattern of the etched diagnostic film layer 110 was silver-gray. The diagnostic film layer 110 was cleanly etched without any residue. Based on this, it was determined that the photoresist layer 120 was fully developed without any residue.

[0051] Referring to Figure 6, the photoresist layer is removed. Figures 10 to 12 are the morphology images of the first, second, and third sets of process parameters after removing the photoresist layer 120, respectively. Analysis of the images shows that as the development time increases, the red color at the bottom of the pattern of the diagnostic film layer 110 gradually disappears. When the development time is increased to 2 minutes, the bottom of the pattern of the diagnostic film layer 110 completely reveals the color of the substrate 100.

[0052] In step S6, based on the residual condition of the photoresist layer 120, the optimal photoresist parameters suitable for the current photoresist process are selected from multiple combinations of photoresist process parameters. In step S5, the first and second combinations of photoresist process parameters used development times of 30s and 1min, respectively. After extending the etching time, the diagnostic film layer 110 still had residue, so it was determined that the photoresist layer 120 had residue. The third combination of photoresist process parameters used a development time of 2min, and the diagnostic film layer 110 had no residue, so it was determined that the development was sufficient and the photoresist layer 120 had no residue. In this embodiment, different combinations of photoresist process parameters verified that the reason for the residue of the photoresist layer 120 was insufficient development. Therefore, from the three combinations of process parameters, the shortest development time to ensure that the photoresist layer 120 had no residue was determined to be 2min, which was used in the third combination, and this development time was determined as the optimal photoresist process parameter.

[0053] The photolithography process parameters optimized by the method for verifying the residue of photoresist layer 120 provided by the present invention are only for photoresist layer 120. The optimal photolithography process parameters can also be applied to other process flows. Preferably, the method is used to optimize the photolithography process window on the surface of mercury cadmium telluride material in the manufacturing process of cooled infrared detectors. The optimized development time is obtained by selecting silicon substrate 100 and silicon dioxide for experiments, which greatly reduces the optimization cost of photolithography process window.

[0054] In summary, this invention provides a method for verifying photoresist layer residue, comprising the following steps: providing multiple substrates and forming a diagnostic film layer covering the surface of each substrate; forming a photoresist layer covering the surface of the diagnostic film layer; exposing the photoresist layer; developing and etching the photoresist layer and the diagnostic film layer on different substrates using multiple different combinations of photolithography process parameters; determining the residue status of the photoresist layer corresponding to different combinations of process parameters based on the residue status of the diagnostic film layer on different substrates; and selecting the optimal photolithography process parameters suitable for the current photolithography process from multiple combinations of photolithography process parameters based on the residue status of the photoresist layer. By designing multiple sets of parallel experiments with different photolithography process parameters, the residue status of photoresist under different photolithography process parameters is systematically verified, providing direct and quantitative data support for determining the optimal photolithography process parameters; the method is highly universal and low-cost, and can use common and low-cost materials in semiconductor processes as the diagnostic film layer; the obtained optimal photolithography process parameters are applicable to various process flows.

[0055] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for verifying photoresist layer residue, characterized in that, The method includes the following steps: providing multiple substrates and forming a diagnostic film layer covering the surface of each substrate; controlling the thickness of the diagnostic film layer so that the color of the diagnostic film layer is different from the color of the substrate so that the two can be visually distinguished; forming a photoresist layer covering the surface of the diagnostic film layer; and exposing the photoresist layer. Multiple combinations of photolithography process parameters are used to develop and etch the photoresist layer and the diagnostic film layer on different substrates. Based on the residual condition of the diagnostic film layer on different substrates, the residual condition of the photoresist layer corresponding to different combinations of process parameters is determined. Specifically, this includes the following steps: observing the bottom color of the diagnostic film layer pattern after etching for each combination to determine the residual condition; if the bottom of the etched diagnostic film layer pattern shows the substrate color, it is determined that there is no photoresist residue; if the bottom of the diagnostic film layer pattern does not show the substrate color, the etching time is extended for a second observation; if the substrate color is still not shown, it is determined that there is photoresist residue; based on the residual condition of the photoresist layer, the optimal photolithography process parameters suitable for the current photolithography process are selected from multiple combinations of photolithography process parameters.

2. The method for verifying photoresist layer residue according to claim 1, characterized in that, The process parameter combination includes the development time for developing the photoresist layer and the etching conditions for etching the diagnostic film layer.

3. The method for verifying photoresist layer residue according to claim 2, characterized in that, The various combinations of process parameters are set by fixing the etching conditions and gradually increasing the development time.

4. The method for verifying photoresist layer residue according to claim 3, characterized in that, Selecting the optimal photolithography process parameter suitable for the current photolithography process from multiple combinations of photolithography process parameters based on the residual condition of the photoresist layer includes: determining the shortest development time that leaves no residue on the photoresist layer from multiple combinations of process parameters, and determining the shortest development time as the optimal photolithography process parameter.

5. The method for verifying photoresist layer residue according to claim 1, characterized in that, The diagnostic membrane layer includes a silicon dioxide layer.

6. The method for verifying photoresist layer residue according to claim 5, characterized in that, The method for forming the diagnostic film includes plasma-enhanced chemical vapor deposition.

7. The method for verifying photoresist layer residue according to claim 5, characterized in that, The etching solution used includes a buffered oxide etching solution.

8. The method for verifying photoresist layer residue according to claim 1, characterized in that, The method is used to optimize the photolithography window on the surface of mercury cadmium telluride material in the manufacturing process of cooled infrared detectors.

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