Photoresist pattern processing method

Abstract

A photoresist pattern processing method comprises the following steps: providing a semiconductor substrate, and depositing a high-reflection alloy film on the semiconductor substrate; spin-coating photoresist with the thickness of 1.8-2.2 microns, adjusting exposure, and developing to form a photoresist pattern; and processing the developed photoresist pattern to obtain the required photoresist line width. According to the photoresist pattern processing method provided by the invention, by adjusting the thickness of the photoresist covering the surface of the high-reflection alloy film and the exposure amount in the exposure process, the influence of the reflection light intensity of the surface of the alloy film on the morphology of the photoresist pattern formed by developing is reduced to the minimum, and the yield of the photoresist pattern is improved. A better photoresist morphology can be observed through an electron microscope; and processing the developed photoresist pattern through oxygen plasma to obtain the high aspect ratio photoresist pattern with the target line width.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a method for processing photoresist patterns. Background Art

[0002] Aluminum-titanium-silicon thin film is a highly reflective alloy film deposited using doped targets. It is widely used in special MEMS products due to its excellent low stress and low resistivity performance.

[0003] Highly reflective alloy films (metal films such as AL / ALCU / Ta / Ti / Au / Ag and PT materials) have strong mirror reflection characteristics, with a reflectivity (output ratio to incident ratio) > 80%. In the subsequent photolithography process, even if the best exposure conditions are used, a good photoresist morphology cannot be obtained. Summary of the invention

[0004] The present application provides a method for processing a photoresist pattern. By adjusting the thickness of the photoresist covering the surface of a high-reflective alloy film and the exposure amount during the exposure process, the influence of the reflected light intensity on the surface of the alloy film on the morphology of the photoresist pattern formed by development is minimized, and a better photoresist morphology can be observed through an electron microscope; and the developed photoresist pattern is processed by oxygen plasma to obtain a high aspect ratio photoresist pattern with a target line width.

[0005] Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

[0006] To achieve one, part, or all of the above purposes or other purposes, the present invention provides a method for processing a photoresist pattern.

[0007] A method for processing a photoresist pattern, comprising:

[0008] Providing a semiconductor substrate, and depositing a high-reflection alloy thin film on the semiconductor substrate;

[0009] Spin-coat a photoresist with a thickness of 1.8-2.2um, adjust the exposure and then develop to form a photoresist pattern;

[0010] The developed photoresist pattern is processed to obtain the required photoresist line width.

[0011] A highly reflective alloy film is deposited on the semiconductor substrate by a metal sputtering process.

[0012] The high-reflection alloy film is an aluminum-titanium-silicon film.

[0013] The deposition thickness of the high-reflection alloy film is 65±5 nm.

[0014] The thickness of the photoresist is changed by adjusting the film-leveling speed during the photoresist spin coating process.

[0015] The developed photoresist pattern is treated by oxygen plasma until the desired photoresist line width is obtained.

[0016] When the developed photoresist pattern is treated with oxygen plasma, the flow rate is 1000-5000sccm, the power is 700-900W, the pressure is 0.7-1.1Torr, and the duration is 60-70s.

[0017] When the developed photoresist pattern is processed, the lateral consumption rate of the photoresist pattern is greater than the longitudinal consumption rate.

[0018] The line width reduction value of the photoresist pattern is greater than the thickness reduction value, and the processed photoresist pattern is a photoresist pattern with a high aspect ratio.

[0019] The ratio of thickness to line width of the high aspect ratio photoresist pattern is not less than 3:1.

[0020] Compared with the prior art, the beneficial effects of the present invention mainly include:

[0021] The present application provides a method for processing a photoresist pattern. By adjusting the thickness of the photoresist covering the surface of a high-reflective alloy film and the exposure amount during the exposure process, the influence of the reflected light intensity on the surface of the alloy film on the morphology of the photoresist pattern formed by development is minimized, and a better photoresist morphology can be observed through an electron microscope; and the developed photoresist pattern is processed by oxygen plasma to obtain a high aspect ratio photoresist pattern with a target line width.

[0022] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic flow chart of a method for processing a photoresist pattern provided in an embodiment of the present application.

[0025] Figure 2 A schematic diagram of the photoresist morphology corresponding to the experimental condition that the photoresist thickness is 2.0 um provided in the embodiment of the present application.

[0026] Figure 3 A schematic diagram of the corresponding photoresist morphology after descum treatment for 70 seconds under the experimental conditions of a photoresist thickness of 2.0 um provided in an embodiment of the present application.

[0027] Figure 4 A schematic diagram of the photoresist morphology corresponding to the experimental conditions where the photoresist thickness is greater than 2.2um provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The above and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention.

[0029] The present application provides a method for processing a photoresist pattern. By adjusting the thickness of the photoresist covering the surface of a high-reflective alloy film and the exposure amount during the exposure process, the influence of the reflected light intensity on the surface of the alloy film on the morphology of the photoresist pattern formed by development is minimized, and a better photoresist morphology can be observed through an electron microscope; and the developed photoresist pattern is processed by oxygen plasma to obtain a high aspect ratio photoresist pattern with a target line width.

[0030] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.

[0031] Example

[0032] Figure 1 Shown is a schematic flow chart of a method for processing a photoresist pattern provided in an embodiment of the present application.

[0033] like Figure 1 As shown, a method for processing a photoresist pattern comprises:

[0034] Providing a semiconductor substrate, and depositing a high-reflection alloy film on the semiconductor substrate by a metal sputtering process;

[0035] By adjusting the film uniformity speed during the photoresist spin coating process, the photoresist with a thickness of 1.8-2.2um is spin coated, and the development after exposure is adjusted to form a photoresist pattern;

[0036] Performing descum processing on the developed photoresist pattern to obtain the required photoresist line width;

[0037] Specifically, according to the normal process, the wafers are unloaded in the lower cargo hold of the metal sputtering machine, the machine button is triggered to start production, and an aluminum-titanium-silicon film with a thickness of 65±5nm is deposited on the silicon wafer and then taken out;

[0038] Spin-coat the silicon wafer with the aluminum-titanium-silicon thin film already sputtered with photoresist, adjust the film-leveling speed during the photoresist spin-coating process to achieve different photoresist thicknesses of 1.8-2.2um, and adjust the development after exposure to form a photoresist pattern;

[0039] Table 1 shows the film-leveling speed and exposure amount corresponding to different photoresist thicknesses provided in the embodiments of the present application.

[0040]

[0041]

[0042] Table 1

[0043] Figure 2 Shown is a schematic diagram of the corresponding photoresist morphology under the experimental conditions of a photoresist thickness of 2.0 um provided in an embodiment of the present application.

[0044] Figure 4 Shown is a schematic diagram of the corresponding photoresist morphology under the experimental conditions provided in the embodiment of the present application where the photoresist thickness is greater than 2.2um.

[0045] After the silicon wafers with different photoresist thickness conditions are exposed and developed, they are placed under an electron microscope to observe the morphology of the photoresist under the corresponding experimental conditions and measure the line width of the photoresist pattern;

[0046] Under the experimental condition that the photoresist thickness is 2.0um, the corresponding photoresist pattern line width is 0.73um.

[0047] Under the experimental condition that the photoresist thickness is greater than 2.2um, the corresponding MASK line width used in lithography is 0.566um, the actual photoresist pattern line width after lithography is 0.56um, and the photoresist thickness is 1.2um.

[0048] As a preferred embodiment of the present invention, the thickness of the photoresist in this embodiment can be adjusted between 1.2um and 2.8um. ​​However, when the thickness of the photoresist is between 1.8um and 2.2um, the morphology of the corresponding photoresist pattern is the best.

[0049] When oxygen plasma is used to descum the developed photoresist pattern, the flow rate is 1000-5000sccm, the power is 700-900W, the gas pressure is 0.7-1.1Torr, the duration is 60-70s, the rate at which the photoresist thickness is consumed by descum is 0.1um / min, and the lateral consumption rate of the photoresist pattern is greater than the longitudinal consumption rate; that is, for the same processing time, the line width reduction value of the photoresist pattern is greater than the photoresist thickness reduction value, and the processed photoresist pattern is a high aspect ratio photoresist pattern.

[0050] After the developed photoresist pattern is descummed for a period of time, it is placed under an electron microscope to measure the line width of the photoresist pattern.

[0051] Table 2 shows the line width of the photoresist pattern corresponding to different descum processing times under the experimental conditions of a photoresist thickness of 2.0 um provided in an embodiment of the present application. The descum processing time of 30 s is taken as the starting time, and the photoresist line width is confirmed after each increase of 10 s.

[0052] condition Descum processing time (S) Photoresist pattern line width (um) Condition 1 40 0.62 Condition 2 50 0.60 Condition 3 60 0.58 Condition 4 70 0.56 Condition 5 80 0.54

[0053] Table 2

[0054] Figure 3 The figure shows the corresponding photoresist morphology after descum treatment for 70 seconds under the experimental condition that the photoresist thickness is 2.0 um provided in the embodiment of the present application.

[0055] Under the experimental condition that the photoresist thickness is 2.0um, the line width of the photoresist pattern is 0.56um after descum treatment for 70S, the thickness of the photoresist is 1.89um, and the aspect ratio (photoresist thickness to line width) is 3.375:1.

[0056] As a preferred embodiment of the present invention, the ratio of thickness to line width of the high aspect ratio photoresist pattern in this embodiment is not less than 3:1.

[0057] The present application provides a method for processing a photoresist pattern. By adjusting the thickness of the photoresist covering the surface of a high-reflective alloy film and the exposure amount during the exposure process, the influence of the reflected light intensity on the surface of the alloy film on the morphology of the photoresist pattern formed by development is minimized, and a better photoresist morphology can be observed through an electron microscope; and the developed photoresist pattern is processed by oxygen plasma to obtain a high aspect ratio photoresist pattern with a target line width.

[0058] In order to facilitate the description, some common English nouns or letters used in the present invention are only used for exemplary reference rather than restrictive interpretation or specific usage, and the protection scope of the present invention should not be limited by their possible Chinese translations or specific letters.

[0059] It should also be noted that, in this document, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

Claims

1. A method for processing a photoresist pattern, characterized in that: include: Providing a semiconductor substrate, and depositing a high-reflection alloy thin film on the semiconductor substrate; Spin-coat a photoresist with a thickness of 1.8-2.2um, adjust the exposure and then develop to form a photoresist pattern; The developed photoresist pattern is processed to obtain the required photoresist line width.

2. A method for processing a photoresist pattern according to claim 1, characterized in that: A highly reflective alloy film is deposited on the semiconductor substrate by a metal sputtering process.

3. A method for processing a photoresist pattern according to claim 2, characterized in that: The high-reflection alloy film is an aluminum-titanium-silicon film.

4. A method for processing a photoresist pattern according to claim 2, characterized in that: The deposition thickness of the high-reflection alloy film is 65±5 nm.

5. A method for processing a photoresist pattern according to claim 1, characterized in that: The thickness of the photoresist is changed by adjusting the film-leveling speed during the photoresist spin coating process.

6. A method for processing a photoresist pattern according to claim 1, characterized in that: The developed photoresist pattern is treated by oxygen plasma until the desired photoresist line width is obtained.

7. A method for processing a photoresist pattern according to claim 6, characterized in that: When the developed photoresist pattern is treated with oxygen plasma, the flow rate is 1000-5000sccm, the power is 700-900W, the pressure is 0.7-1.1Torr, and the duration is 60-70s.

8. A method for processing a photoresist pattern according to claim 6, characterized in that: When the developed photoresist pattern is processed, the lateral consumption rate of the photoresist pattern is greater than the longitudinal consumption rate.

9. A method for processing a photoresist pattern according to claim 8, characterized in that: The line width reduction value of the photoresist pattern is greater than the thickness reduction value, and the processed photoresist pattern is a photoresist pattern with a high aspect ratio.

10. A method for processing a photoresist pattern according to claim 9, characterized in that: The ratio of thickness to line width of the high aspect ratio photoresist pattern is not less than 3:1.

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