A photoresist etching method for a wafer

Abstract

The application discloses a glue etching method for a wafer and relates to the etching technical field. The glue etching method comprises the following steps: placing the wafer in a preset cavity; adjusting the temperature of the preset cavity to a preset temperature and filling inert gas into the preset cavity; adopting a first preset radio frequency wave to bombard the wafer, and adopting a second preset radio frequency wave to cooperate with the first preset radio frequency wave to form downward traction so as to remove the shielding layer. Through the application, the uniformity of etching can be improved.

Description

Technical Field

[0001] This invention relates to the field of etching technology, and in particular to a photoresist etching method for wafers. Background Technology

[0002] Existing semiconductor etching methods all use high-frequency microwave bombardment to remove resist. Such etching methods cannot guarantee the uniformity of resist etching across the entire wafer. In addition, due to the isotropic nature of high-frequency microwaves, it is impossible to guarantee the image morphology after resist etching under image conditions, resulting in severe side etching, serious damage to the microlens at the edge of the pattern, and direct impact on the performance of the finished product.

[0003] Therefore, how to improve the etching method to enhance the uniformity of etching is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a photoresist etching method for wafers that can improve etching uniformity.

[0005] This invention provides the following solution:

[0006] A method for resist etching of a wafer, wherein a resist etching layer and a masking layer are sequentially covered from bottom to top on the wafer, the resist etching method comprising:

[0007] The wafer is placed in a preset cavity;

[0008] The temperature of the preset cavity is adjusted to the preset temperature, and inert gas is introduced into the preset cavity;

[0009] The wafer is bombarded with a first preset radio frequency wave, while a second preset radio frequency wave is used in conjunction with the first preset radio frequency wave to form a downward pull, thereby removing the shielding layer.

[0010] Optionally, the first preset radio frequency wave is a radio frequency wave of 15-50MHz, and the second preset radio frequency wave is a radio frequency wave of 0.5-10MHz.

[0011] Optionally, the first preset radio frequency wave is a 27MHz radio frequency wave, and the second preset radio frequency wave is a 2MHz radio frequency wave.

[0012] Optionally, filling the preset cavity with inert gas includes:

[0013] The inert gas is blown toward the first surface of the wafer;

[0014] The step of bombarding the wafer with a first preset radio frequency wave, and simultaneously using a second preset radio frequency wave in conjunction with the first preset radio frequency wave to form a downward traction layer, includes:

[0015] The first preset radio frequency wave is used to bombard the second surface of the wafer, and the second preset radio frequency wave is used in conjunction with the first preset radio frequency wave to form a downward pull from the second surface;

[0016] The first surface and the second surface are arranged opposite to each other.

[0017] Optionally, the inert gas includes helium.

[0018] Optionally, the preset temperature is any value less than 50°C.

[0019] Optionally, the preset temperature is 30°C.

[0020] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0021] The photoresist etching method provided by this invention uses the first preset radio frequency wave to replace the high microwave in the prior art for photoresist etching. While the first preset radio frequency wave is bombarding, the second preset radio frequency wave cooperates with the first preset radio frequency wave to form a downward pull, so that the radio frequency wave bombards downward in the photoresist etching process, thereby effectively preventing the occurrence of side etching phenomenon and ensuring that the Micro Lens at the edge of the image is not damaged.

[0022] Furthermore, by combining temperature control and helium, the temperature distribution of the wafer can be made more uniform. Compared with traditional equipment that only heats the Chuck, the etching uniformity of the resist is significantly improved. In some embodiments, the uniformity is optimized from 9% to 3%.

[0023] Of course, the embodiments of the present invention do not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 These are before-and-after comparison images of etching using traditional methods;

[0026] Figure 2 This is a flowchart of a photoresist etching method for wafers provided in one embodiment of the present invention;

[0027] Figure 3 These are comparison images before and after etching using the method provided by this invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0029] As described in the background section above, existing resist etching methods, such as the etching of Micro Lens P resist, use the principle of high-frequency microwave bombardment to remove the resist. The direction of the high-frequency microwave bombardment is as follows: Figure 1 As indicated by the arrow, uneven etching of the resist on the wafer can easily occur, and part of the sidewalls of the etched grooves will be etched away simultaneously, resulting in an uneven morphology after etching, which affects product performance and yield. To address this, the present invention provides a resist etching method for wafers, wherein the wafer 10 is sequentially covered from bottom to top with a resist etching layer 20 and a shielding layer 30. Figure 2 This is a flowchart of a photoresist etching method for wafers provided in one embodiment of the present invention, as shown below. Figure 2 As shown, the photoresist etching method includes:

[0030] S10: Place the wafer in a preset cavity;

[0031] S20: Adjust the temperature of the preset cavity to the preset temperature, and fill the preset cavity with inert gas;

[0032] S30: The wafer is bombarded with a first preset radio frequency wave, while a second preset radio frequency wave is used in conjunction with the first preset radio frequency wave to form a downward pull, so as to remove the shielding layer.

[0033] The first preset radio frequency wave and the second preset radio frequency wave are not equal, and both are less than a preset value, such as 60MHz.

[0034] In the above method, the preset cavity is a sealed cavity, and its built-in structure can simultaneously provide the first preset radio frequency wave and the second preset radio frequency wave. The first preset radio frequency wave is used instead of the high-frequency microwaves used in the prior art for photoresist etching. While the first preset radio frequency wave bombards the photoresist, the second preset radio frequency wave works in conjunction with the first preset radio frequency wave to form a downward pull. This ensures that the radio frequency waves bombard downwards during the photoresist etching process, effectively preventing lateral etching and ensuring that the Micro Lens at the image edge is not damaged.

[0035] The etching method provided by this invention forms a downward pull under the wafer, ensuring a downward radio frequency wave is maintained throughout the process. The wafer state after the method is completed is as follows. Figure 3 As shown, from Figure 3 It can be seen that the side-marking phenomenon can be avoided, and the product performance is greatly improved, making it more competitive in the market.

[0036] In one embodiment, the preset cavity is a Lam Flex cavity, which is the cavity possessed by a Flex device. Preferably, the first preset radio frequency wave is a 15-50MHz radio frequency wave, and the second preset radio frequency wave is a 0.5-10MHz radio frequency wave. More preferably, the first preset radio frequency wave is a 27MHz radio frequency wave, and the second preset radio frequency wave is a 2MHz radio frequency wave. Of course, those skilled in the art will understand that the first preset radio frequency wave and the second preset radio frequency wave can also be radio frequency waves of other frequencies within the above-mentioned respective ranges, which will not be detailed here due to space limitations.

[0037] In a preferred embodiment, filling the preset cavity with inert gas includes:

[0038] The inert gas is blown toward the first surface of the wafer 10;

[0039] The step of bombarding the wafer with a first preset radio frequency wave, while simultaneously using a second preset radio frequency wave in conjunction with the first preset radio frequency wave to form a downward pull, includes:

[0040] The first preset radio frequency wave is used to bombard the second surface of the wafer, and the second preset radio frequency wave is used in conjunction with the first preset radio frequency wave to form a downward pull from the second surface;

[0041] The first surface and the second surface are arranged opposite to each other.

[0042] Preferably, the first surface is the back side of the wafer 10, and the second surface is the front side of the wafer 20.

[0043] Specifically, the inert gas includes helium.

[0044] Specifically, the preset temperature is any value less than 50°C. More specifically, the preset temperature is 30°C.

[0045] The Ceramic ESC configured via the Flex device has an independent heat exchange device for temperature control during the process, with a control accuracy of 0.1 degrees Celsius, and helium is filled into the back side of the wafer 10. The combined effect of temperature control and helium gas results in a more uniform temperature distribution on the wafer 10, significantly improving the etching uniformity of the resist compared to traditional devices that rely solely on heating the Chuck. In some embodiments, the uniformity is optimized from 9% to 3%.

[0046] To better illustrate this application, the following embodiments and comparative examples are described.

[0047] Example 1

[0048] Wafer 1 was selected, with its resist etching layer 20 being a P-resist etching layer and its masking layer 30 being a PR masking layer. The etching was performed using the method of this application, and the method parameters and method data are shown in Table 1 below.

[0049] Example 2

[0050] Wafer 2 was selected, with its resist etching layer 20 being a P-resist etching layer and its masking layer 30 being a PR masking layer. The etching was performed using the method of this application, and the method parameters and method data are shown in Table 1 below.

[0051] Table 1

[0052]

[0053] Comparative Example 1

[0054] Wafer 3 was selected, with its resist etching layer 20 being a P-resist etching layer and its masking layer 30 being a PR masking layer. The etching was performed using a traditional method, and the method parameters and data are shown in Table 2 below.

[0055] Comparative Example 2

[0056] Wafer 4 was selected, with its resist etching layer 20 being a P-resist etching layer and its masking layer 30 being a PR masking layer. The etching was performed using a traditional method, and the method parameters and data are shown in Table 2 below.

[0057] Table 2

[0058]

[0059] As can be seen from Tables 1 and 2 above:

[0060] First, compared with traditional methods, this application can complete etching at low temperatures, which can increase the selectivity of the masking layer PR, eliminating the need for a high-temperature resistant PR layer. Furthermore, the method of this application has achieved significant improvements in etching rate (ER) and uniformity (UNIF), greatly increasing the product yield. It can reduce the performance differences of products in different areas on the same wafer, thereby increasing the product yield and effectively improving production capacity.

[0061] Secondly, although the wafers used in Examples 1 and 2 are different, the difference in method data (ER and Unif) between the two is not large when the method parameters are the same. However, Comparative Examples 1 and 2, which use the same method parameters for etching using the conventional method, have a large difference in the final method data. This shows that compared with the conventional method, the method of this application is more stable and superior not only in terms of repeatability stability but also in terms of etching rate uniformity.

[0062] The technical solution provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for resist etching on a wafer, wherein the wafer is sequentially covered from bottom to top with a resist etching layer and a masking layer, characterized in that, The glue etching method comprises the following steps: placing the wafer in a preset cavity; adjusting the temperature of the preset cavity to a preset temperature, and filling inert gas into the preset cavity; using a first preset radio frequency wave to bombard the wafer, and using a second preset radio frequency wave to cooperate with the first preset radio frequency wave to form a downward traction to remove the shielding layer; wherein the step of filling inert gas into the preset cavity comprises: blowing the inert gas towards a first surface of the wafer; the step of using a first preset radio frequency wave to bombard the wafer, and using a second preset radio frequency wave to cooperate with the first preset radio frequency wave to form a downward traction comprises: using the first preset radio frequency wave to bombard a second surface of the wafer, and using the second preset radio frequency wave to cooperate with the first preset radio frequency wave to form a downward traction from the second surface; the first surface and the second surface are oppositely arranged, the first surface is the back surface of the wafer, and the second surface is the front surface of the wafer; 2. The gum etching method of claim 1, wherein, the first preset radio frequency wave is a radio frequency wave of 15-50 MHz, and the second preset radio frequency wave is a radio frequency wave of 0.5-10 MHz.

3. The gum etching method of claim 1, wherein, the first preset radio frequency wave is a radio frequency wave of 27 MHz, and the second preset radio frequency wave is a radio frequency wave of 2 MHz.

4. The gel lithography method according to any one of claims 1 to 3, wherein the inert gas comprises helium.

5. The gel lithography method of claim 4, wherein, the preset temperature is any value less than 50℃. the preset temperature is 30℃.

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