A thinning and polishing method suitable for photoresist and micro-nano device

Abstract

The application discloses a thinning and polishing processing method suitable for photoresist and a micro-nano device. The application can realize photoresist with a very high aspect ratio by spin coating on a substrate, and solidifies the photoresist. A low-pressure and low-rotation-speed CMP technology is adopted to modify the form of the surface of the photoresist, so that the height difference of the surface of the photoresist is less than 5 microns. A high-pressure and high-rotation-speed CMP technology is adopted to coarsely polish the surface of the photoresist to a preset thickness. The photoresist after processing is cleaned. Compared with a dry etching method in the related art, the application can effectively solve the problems of slow speed, large roughness and unevenness.

Description

Technical Field

[0001] This invention belongs to the field of photoresist thinning and polishing processing technology, specifically relating to a thinning and polishing processing method for photoresist and micro / nano devices. Background Technology

[0002] Photoresist, also known as photoresist, is a thin-film etching material whose solubility changes upon irradiation or radiation such as ultraviolet light, electron beams, ion beams, and X-rays. It can be used for etching and electroplating of various materials, is suitable for high aspect ratio processes, has high transparency and good verticality, and is widely used in the fabrication of micro and nano devices. However, its application is limited due to the difficulty in removing the photoresist; currently, the main treatment method is to thin it to a certain thickness to serve as a dielectric layer without affecting subsequent processes.

[0003] In related technologies, the main method for thinning and polishing photoresist on substrate surfaces relies on dry etching. Commonly used etching equipment includes ICP (Inductively Coupled Plasma) etching, RIE (Reactive Ion Etching), and IBE (Ion Beam Etching). ICP and RIE equipment mainly use fluorine-based gases in combination with oxygen for reactive ion etching, but their etching rates are relatively slow, and the surface height difference after etching exceeds 2µm. The high energy density during etching can easily lead to photoresist denaturation, causing etching to stop. IBE, using single argon ion bombardment, has a slower surface removal rate than ICP / RIE, but the height difference after etching is smaller. In other words, the current mainstream etching methods suffer from drawbacks such as long etching times and large height differences after etching, which limits the photoresist thinning and polishing process and greatly restricts the application of high aspect ratio photoresists.

[0004] Therefore, given the shortcomings of the current mainstream etching methods, such as long etching time and large height difference after etching, which limit the photoresist thinning and polishing process and greatly restrict the application of high aspect ratio photoresists, there is an urgent need to design and develop a thinning and polishing method suitable for photoresists. Summary of the Invention

[0005] To overcome the shortcomings and difficulties of the existing technology, the purpose of this invention is to provide a thinning and polishing method for photoresist and micro / nano devices; aiming to solve the problem of thinning and polishing process for photoresist with extremely high aspect ratio.

[0006] The first objective of this invention is to provide a thinning and polishing method suitable for photoresist; the second objective of this invention is to provide a micro / nano device.

[0007] The first objective of this invention is achieved as follows: the method comprises:

[0008] Photoresist with extremely high aspect ratio can be achieved by spin-coating onto a substrate and then curing the photoresist.

[0009] The surface of the photoresist is morphologically modified using low-pressure, low-speed CMP technology, so that the height difference of the photoresist surface is less than 5μm;

[0010] The photoresist surface is polished to a preset thickness using high-pressure, high-speed CMP technology.

[0011] The processed photoresist is then cleaned.

[0012] Furthermore, the method of curing the photoresist includes the following steps:

[0013] The photoresist is subjected to a pre-exposure baking process;

[0014] The baked photoresist is exposed using a photomask and a preset exposure dose, and then the pattern on the photomask is transferred to the substrate surface using a developing solution.

[0015] After development, the substrate is baked and the photoresist is cured.

[0016] Furthermore, the baking temperature for the pre-exposure baking treatment is 65℃~120℃, and the time is 30min~90min.

[0017] Furthermore, the baking temperature of the post-baking is 90℃~120℃ and the time is 10min~30min. Preferably, the baking temperature of the heat treatment is 90℃ and the time is 30min.

[0018] Furthermore, in the morphological finishing process, the rough polishing pressure is 2 psi; the polishing fluid flow rate is 220 ml / min; the polishing disc rotation speed is 93 R / min, the polishing head rotation speed is 87 R / min; the polishing rate is 4 μm; the polishing fluid is selected as an alumina-based polishing fluid, and the abrasive particle size is 1 μm.

[0019] Furthermore, the height difference of the photoresist surface after morphological modification is less than 3 μm.

[0020] Furthermore, the polishing pressure in the thinning and polishing process is 1.5psi to 2psi; the polishing fluid flow rate is 90ml / min to 220mL / min; the polishing disc speed is 63R / min to 93R / min; the polishing head speed is 60R / min to 87R / min; and the polishing rate is 4um to 200um.

[0021] Furthermore, after morphological trimming, the photoresist was subjected to large-area thinning and rough polishing, wherein the polishing pressure was 2 psi; the polishing fluid flow rate was 120 mL / min; the polishing disc speed was 93 R / min; the polishing head speed was 87 R / min; and the polishing rate was 4 μm.

[0022] The polishing fluid is selected from alumina-based polishing fluids, and the abrasive particle size is 1µm.

[0023] Furthermore, before cleaning the processed photoresist, the following step is also included: fine polishing the surface of the photoresist;

[0024] The fine polishing pressure is 1.5 psi; the polishing fluid flow rate is 120 mL / min; the polishing disc speed is 63 R / min, the polishing head speed is 60 R / min; the polishing rate is 200 μm; and the polishing fluid is a silica sol type with an abrasive particle size of 80 μm.

[0025] The second objective of this invention is achieved as follows: the micro / nano device is fabricated using the aforementioned thinning and polishing method suitable for photoresist;

[0026] The micro / nano devices utilize photoresist thinning and polishing to expose the metal circuitry, requiring some photoresist to be retained for dielectric layer support.

[0027] This invention achieves extremely high aspect ratio photoresist by spin-coating onto a substrate and then curing the photoresist. Low-pressure, low-speed CMP technology is used to morphologically refine the surface of the photoresist, resulting in a height difference of less than 5 μm. High-pressure, high-speed CMP technology is then used for rough polishing to reduce the surface of the photoresist to a predetermined thickness. Finally, the processed photoresist is cleaned. Compared to dry etching methods in related technologies, this invention effectively solves the problems of slow etching rate, high roughness, and poor uniformity. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0029] Figure 1 This is a schematic diagram of a thinning and polishing process for photoresist according to the present invention;

[0030] Figure 2 This is a schematic diagram of the preparation process of an embodiment of a thinning and polishing method for photoresist according to the present invention;

[0031] Figure 3 This is a schematic diagram of the preparation process of an embodiment of the thinning and polishing method for photoresist according to the present invention. Detailed Implementation

[0032] To enable those skilled in the art to better understand the purpose, technical solution, and advantages of this application, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] Many specific details are set forth in the following description in order to provide a full understanding of the invention. Those skilled in the art can easily understand other advantages and effects of the invention from the content disclosed in this specification. However, the invention may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0034] As described in the background section, traditional etching methods have drawbacks such as long etching time and large height difference after etching, which limits the photoresist thinning and polishing process and greatly restricts the application of high aspect ratio photoresists.

[0035] In view of this, such as Figures 1-3 As shown, the present invention provides a thinning and polishing method suitable for photoresist, the method comprising:

[0036] S01. Spin-coat a photoresist capable of achieving an extremely high aspect ratio onto a substrate and then cure the photoresist. Specifically, the substrate is generally selected from silicon, quartz, or other materials as required. The substrate should be cleaned according to actual needs before use. Photoresists capable of achieving an extremely high aspect ratio generally refer to photoresists made of materials such as SU8, PI, and THB, and their specific use can be selected according to actual conditions.

[0037] The photoresist can be applied by spin coating or spray coating, with spin coating being the preferred method. After the photoresist is applied, it should be cured. The curing process can be adjusted according to the actual properties and requirements of the photoresist; no single specific limitation is made here.

[0038] When SU8 and PI are selected as photoresists, the preferred curing steps are as follows:

[0039] ① Photoresist with extremely high aspect ratio can be achieved by spin-coating on a clean substrate. That is, a photoresist with extremely high aspect ratio can be achieved by spinning on a clean silicon / quartz substrate (such as SU8 / PI). A heating stage is used for pre-exposure baking. The working temperature is adjusted according to the material and thickness, generally 65℃-120℃, and the time is 30min-90min. Then, mask exposure can be performed according to actual needs. The designed mask is used for exposure, and then the pattern is transferred to the substrate surface using a suitable developer.

[0040] ② After the mask is exposed, the post-exposure baking work can be carried out on the heating stage, that is, the substrate after development is subjected to appropriate heat treatment to remove residual moisture and volatile organic compounds on the surface; the working temperature is generally selected as 90℃-120℃, and the time is 10min-30min, so that the photoresist is completely cured.

[0041] The mask exposure method is as follows: the designed mask is exposed at an appropriate exposure dose, and then a suitable developer is used to develop the mask and transfer the designed pattern on the mask to the substrate surface.

[0042] S02. The surface of the photoresist is morphologically modified using low-pressure, low-speed CMP technology, resulting in a surface height difference of less than 5μm. This morphological modification is achieved through a low-pressure, low-speed CMP polishing process, which modifies the surface of the photoresist to avoid large undulations and defects. This overcomes the problem that conventional photoresist homogenization methods often result in large surface height differences, leading to significant frictional resistance and easy fragmentation during CMP operation. Specifically, by selecting appropriate working disc and polishing head speeds, and matching pressure with a suitable polishing slurry flow rate, and properly combining the polishing pad, the photoresist is polished and thinned to achieve the desired thickness and roughness.

[0043] During the morphological trimming, a low-pressure, low-speed method is used. Specifically, the substrate is mounted on the CMP equipment and polished by vacuum adsorption using a black airbag silicone pad. The main polishing parameters are set as follows: pressure of 1.5psi to 2psi, polishing fluid flow rate of 90mL / min to 220mL / min, polishing disc speed of 63R / min to 93R / min, and polishing head speed of 60R / min to 87R / min.

[0044] The material, polishing pressure, and rotation speed of the polishing pad mentioned above need to be adjusted according to actual needs to achieve a surface height difference of less than 5 micrometers and to prevent fragmentation during CMP polishing. That is, after using low pressure and low speed to homogenize the photoresist on the substrate surface, the large height difference is shaped and trimmed to achieve a basically flat photoresist surface with a height difference of <1um-5um.

[0045] Preferably, the surface of the photoresist after morphological correction is substantially flat, with a height difference maintained between 1 micrometer and 5 micrometers. More preferably, the height of the photoresist should be less than 3 micrometers.

[0046] S03. After surface trimming, the substrate is subjected to rough polishing using high-pressure, high-speed CMP technology to remove surface defects and actual thickness of the photoresist over a large area, enabling the photoresist to reach the preset thickness. The specific rough polishing process is as follows: a double-layer polyurethane pad is used; an alumina-based polishing slurry is selected; the abrasive particle size is 1µm; the thinning polishing pressure is 2.0 psi; the polishing slurry flow rate is 220 ml / min; the polishing disc rotation speed is 93 R / min; and the polishing head rotation speed is 87 R / min.

[0047] The material, polishing pressure, and rotation speed of the polishing pad mentioned above need to be adjusted according to actual needs to meet the requirement of quickly polishing to the preset thickness.

[0048] Depending on the actual needs, if there are higher requirements for the flatness of the processed photoresist surface, further fine polishing can be performed to improve roughness and flatness. Preferably, the fine polishing process can refer to the following: the fine polishing pad is a black damping cloth, the polishing fluid is a silica sol type, the abrasive particle size of the polishing fluid is 80nm, the thinning polishing pressure is 1.5psi, the polishing fluid flow rate is 120ml / min, the polishing disc rotation speed is 63R / min, and the polishing head rotation speed is 60R / min.

[0049] The specific parameters can be adjusted according to the actual situation and the required flatness; no single specific limit is set here.

[0050] S04. Clean the processed photoresist. A CMP post-cleaning machine is used to directly clean the surface of the photoresist to remove residual debris and other contaminants, ensuring a smooth surface.

[0051] CMP technology is generally used for grinding and polishing equipment. This application innovatively uses CMP technology to thin and polish photoresist. Compared with conventional thinning methods in the prior art, it has the effect of faster thinning speed and better uniformity.

[0052] In the prior art, since CMP technology is generally used to polish hard metal materials, directly polishing photoresist with CMP technology can easily lead to extremely high frictional resistance, which can cause the entire substrate to break. This application avoids the problem of fragmentation by pre-treating the surface of the photoresist and controlling the CMP parameters, and can ensure the uniformity of the thickness of the entire photoresist surface.

[0053] The advantages and technical effects of the photoresist thinning and polishing preparation method of this invention are as follows: Compared with the dry etching method in related technologies, the CMP thinning and polishing photoresist preparation method can effectively solve the problems of slow speed, large roughness, and poor uniformity. Furthermore, the preparation process of this invention is stable, has a short processing time, high personnel efficiency, can use various different structures at low cost, and has high production efficiency, effectively ensuring the preparation of photoresist thinning and polishing at a low cost; and the production process has no harmful emissions, making it green and environmentally friendly.

[0054] Example 1

[0055] This invention provides a method for photoresist polishing and thinning, comprising the following steps:

[0056] S1. Preparation of spin coating sample: A spin coating machine (such as SU8 / PI, etc.) can be used to spin a clean silicon / quartz substrate to achieve a photoresist with an extremely high aspect ratio. A heating stage is used for pre-exposure baking at a working temperature of 65℃~105℃ for 30min~60min.

[0057] S2, Exposure pairs such as SU8 / PI can achieve extremely high aspect ratio photoresists, and exposure is performed using a well-designed mask at an appropriate exposure dose;

[0058] S3. After development, use a suitable developing solution to transfer the pattern designed on the mask to the surface of the substrate.

[0059] S4. Post-baking: Select a post-baking temperature of 90℃~120℃ and a time of 10min~30min; cure the photoresist.

[0060] S5. Sample loading: Manually load the sample into the fixture of the polishing head. The equipment uses a black airbag silicone pad for vacuum adsorption. Polishing slurry transfer method: Open the outer packaging of the appropriate polishing slurry and transfer it to the polishing pad position through the peristaltic pump soft tube. Set the peristaltic pump polishing slurry flow rate to 220ml / min.

[0061] S6. Equipment Parameter Settings and Operation: Turn on the equipment power, mechanical pump, and gas. Select the photoresist polishing program and set the parameters as follows: main polishing pressure 1.5psi~2psi, polishing disc speed 88R / min~93R / min, polishing head speed 87R / min. Perform rough polishing to thin to the required thickness. Change to a silica sol-based polishing slurry with an abrasive particle size of approximately 80nm, pressure 1.5PSI, slurry flow rate 120ml / min, polishing disc speed 63R / min, and polishing head speed 60R / min. Perform fine polishing to improve the surface roughness and flatness of the substrate and reduce step differences. Thickness Monitoring: Some CMP equipment has end-point monitoring functions. In practice, a step meter is used to test the actual removed resist thickness and rate.

[0062] S7. End of Thinning and Polishing: After thinning and polishing, the wafer source needs to be cleaned thoroughly using a CMP post-cleaning machine. Specific residual contamination can be addressed by using a wet organic solution. Clean the polishing pads, polishing heads, polishing discs, peristaltic pump pipes, and keep the polishing pads moist. Turn off the power to the equipment and shut off any gas from the mechanical pumps.

[0063] Table 1: Thickness of adhesive before and after thinning and polishing in the preparation method of Example 1, with different parameters and rates.

[0064]

[0065] The thickness and roughness of the photoresist prepared by the method of Example 1 after thinning and polishing were tested at at least 10 different locations on the same photoresist surface. The results showed that the thickness was within the range of 35um ± 20nm, and the actual thickness value had a small error compared with the target thickness of 35um. The roughness at 10 different locations was within 1nm ± 1nm, indicating that the preparation method of Example 1 produced good uniformity, high flatness, and low roughness.

[0066] In addition, by observing the appearance of the photoresist prepared by the preparation method of Example 1, no appearance defects such as orange peel, damage, or burrs were found.

[0067] Example 2

[0068] Based on Example 1 above, in step S1, the substrate is a silicon wafer, the photoresist is SU8 negative photoresist with a thickness of 70 μm, the pre-baking temperature is 65°C, and the time is 30 min. In step S2, the photoresist surface is exposed using a photolithography machine through a pre-designed mask, and then immersed in developing solution for pattern transfer. In step S3, the developed substrate is post-baked at 90°C for 10 min. In step S4, in the CMP equipment, the coarse polishing pad is a double-layer polyurethane, the polishing slurry is an alumina-based slurry with a large abrasive particle size of approximately 1 μm, the pressure is 2 Psi, the slurry flow rate is 220 ml / min, the polishing disc speed is 93 R / min, and the polishing head speed is 87 R / min. In the CMP equipment, the fine polishing pad is a black damping cloth, the polishing slurry is a silica sol-based slurry with an abrasive particle size of approximately 80 nm, the pressure is 1.5 psi, the slurry flow rate is 120 ml / min, the polishing disc speed is 63 R / min, and the polishing head speed is 60 R / min. The rough polishing rate is 4 μm / min, and the fine polishing rate is 200 nm / min. The actual thinning thickness is 35 μm to 40 μm. In step S5, the substrate surface with large height differences after photoresist homogenization is first shaped using low pressure and low speed. After shaped shaping, the height difference of the photoresist surface is less than 4 μm. In step S6, the substrate with the pre-shaped photoresist surface is rough polished using a high-pressure, high-speed rough polishing pad to remove surface defects and the actual thickness of the photoresist over a large area. A fine polishing pad is used to finely polish the photoresist surface with appropriate pressure, speed, and polishing fluid flow rate to improve roughness and flatness. After completion, a CMP post-cleaning machine is used for cleaning. Compared with the preparation methods in related technologies, the photoresist surface morphology of the thinned and polished photoresist of this invention is better, with faster speed, higher flatness, better uniformity, and no obvious appearance defects.

[0069] Example 3

[0070] Based on Example 1 above, in step S1, the substrate is a silicon wafer, the photoresist is SU8 negative photoresist with a thickness of 70 μm, and the pre-baking temperature is 120°C for 90 min. In step S2, the substrate is exposed to the photoresist surface using a photolithography machine through a pre-designed mask, and then immersed in a developing solution for pattern transfer. In step S3, the developed substrate is post-baked at 90°C for 30 min. In step S4, in the CMP equipment, the coarse polishing pad is a double-layer polyurethane, the polishing slurry is an alumina-based slurry with a large abrasive particle size of approximately 1 μm, the pressure is 2 psi, the slurry flow rate is 90 ml / min, the polishing disc speed is 63 R / min, and the polishing head speed is 60 R / min. In the CMP equipment, the fine polishing pad is a black damping cloth, the polishing slurry is a silica sol-based slurry with a generally 80 nm abrasive particle size, the pressure is 2 psi, the slurry flow rate is 90 ml / min, the polishing disc speed is 93 R / min, and the polishing head speed is 60 R / min. The rough polishing rate is 4 μm / min, and the fine polishing rate is 200 nm / min. The actual thinning thickness is 35 μm. In step S5, the substrate surface with large height differences after photoresist homogenization is first shaped using low pressure and low speed, and the height difference of the photoresist surface after shaped shaping is less than 1 μm. In step S6, the substrate with the pre-shaped photoresist surface is rough polished using a high-pressure, high-speed rough polishing pad to remove photoresist surface defects and the actual thickness removed over a large area. A fine polishing pad is used to finely polish the photoresist surface with appropriate pressure, speed, and polishing fluid flow rate to improve roughness and flatness. After completion, a CMP post-cleaning machine is used for cleaning. Compared with the preparation methods in related technologies, the photoresist surface morphology of the thinned and polished photoresist of this invention is better, with faster speed, higher flatness, better uniformity, and no obvious appearance defects.

[0071] Example 4

[0072] Based on Example 1 above, in step S1, the substrate is a silicon wafer, the photoresist is SU8 negative photoresist with a thickness of 70 μm, and the pre-baking temperature is 100°C for 80 min. In step S2, the substrate is exposed to the photoresist surface using a photolithography machine through a pre-designed mask, and then immersed in a developing solution for pattern transfer. In step S3, the developed substrate is post-baked at 70°C for 20 min. In step S4, in the CMP equipment, the coarse polishing pad is a double-layer polyurethane, the polishing slurry is an alumina-based slurry with a large abrasive particle size of approximately 1 μm, the pressure is 1.8 psi, the slurry flow rate is 120 ml / min, the polishing disc speed is 75 R / min, and the polishing head speed is 70 R / min. In the CMP equipment, the fine polishing pad is a black damping cloth, the polishing slurry is a silica sol-based slurry with an abrasive particle size of approximately 80 nm, the pressure is 1.5 psi, the slurry flow rate is 100 ml / min, the polishing disc speed is 83 R / min, and the polishing head speed is 70 R / min. In step (4), the rough polishing rate is 5 μm / min, and the fine polishing rate is 150 nm / min. The actual thinning thickness is 40 μm. In step S5, the substrate surface with large height differences after photoresist homogenization is first trimmed using low pressure and low speed. After trimming, the height difference of the photoresist surface is less than 4 μm. In step S6, the substrate with the pre-trimmed photoresist surface is rough polished using a high-pressure, high-speed rough polishing pad to remove photoresist surface defects and the actual thickness removal over a large area. A fine polishing pad is used to finely polish the photoresist surface with appropriate pressure, speed, and polishing fluid flow rate to improve roughness and flatness. After completion, a CMP cleaning machine is used for cleaning. Compared with the preparation methods in related technologies, the photoresist surface morphology of the thinned and polished photoresist of this invention is better, with faster speed, higher flatness, better uniformity, and no obvious appearance defects.

[0073] Current etching methods suffer from long etching times and large height differences after etching, limiting photoresist thinning and polishing processes and severely restricting the application of high aspect ratio photoresists. The primary method for photoresist thinning and polishing on substrate surfaces relies on dry etching. Common etching equipment includes ICP (Inductively Coupled Plasma) etching, RIE (Reactive Ion Etching), and IBE (Ion Beam Etching). ICP and RIE primarily use fluorine-based gases combined with oxygen for reactive ion etching. However, traditional methods suffer from slow etching rates and surface height differences exceeding 2µm after etching. The high energy density during etching can easily lead to photoresist denaturation and etching cessation. IBE, using single argon ion bombardment, has an even slower surface removal rate than ICP / RIE, resulting in smaller height differences after etching. Specifically, traditional thinning and polishing processes, such as chemical mechanical polishing (a highly complex process with many influencing factors), require adjustments to parameters based on traditional etching equipment (e.g., simplifying the operation and reducing influencing factors).

[0074] In addition, because the spin coating method of photoresist can easily lead to a large difference in surface height, the CMP machine is prone to generating large frictional resistance during operation, which can cause it to break easily. It is necessary to strictly control the uniformity and height difference of the spin coating, and to reduce the degree of large differences in the surface height of the photoresist on the substrate by adjusting the spin coating time, speed and amount of photoresist.

[0075] In other words, using CMP technology and specific technical parameters to thin and polish photoresist is something those skilled in the art would not easily conceive of compared to traditional preparation methods. The present invention's approach, employing CMP to thin and polish photoresist, offers superior removal rates and an extremely high aspect ratio. Furthermore, it is difficult to imagine using an alkaline silica sol polishing solution with small abrasive particles, low pressure, and low rotation speed to improve the morphology of the photoresist on the substrate surface, reduce roughness and flatness, and minimize the structural differences between the photoresist and the substrate.

[0076] To achieve the objective of this invention, this invention also provides a micro / nano device, which is applied to the aforementioned photoresist thinning and polishing method; the micro / nano device utilizes photoresist thinning and polishing to expose the metal circuitry, while some photoresist needs to be retained for dielectric layer support.

[0077] In other words, this invention also provides a process for exposing metal circuitry in micro / nano devices through photoresist polishing and thinning, requiring some photoresist to be retained as a dielectric layer support, facilitating better subsequent processes. The advantages and technical effects of this invention in micro / nano device manufacturing are: fast photoresist removal rate, high flatness, and low roughness; and the ability to achieve extremely high aspect ratio processes.

[0078] This invention achieves extremely high aspect ratio photoresist by spin-coating onto a substrate and curing the photoresist; it employs low-pressure, low-speed CMP technology to morphologically refine the surface of the photoresist, ensuring a height difference of less than 5 μm; it then uses high-pressure, high-speed CMP technology for rough polishing, significantly removing surface defects and reducing the actual thickness removed; finally, it cleans the processed photoresist, i.e., spin-coating the photoresist onto the substrate and then baking it before exposure; wherein the substrate is a cleaned silicon / quartz substrate; a photomask is used in conjunction with... The photoresist after baking is exposed to a preset exposure dose, and then the pattern on the photomask is transferred to the substrate surface using a developer solution. The substrate is then heat-treated and developed, and the photoresist is cured. Based on polishing parameters, the photoresist is thinned and polished to a preset thickness and roughness, and then cleaned using a CMP post-cleaning machine. The polishing parameters include polishing disc rotation speed, thinning polishing pressure, polishing fluid flow rate, and polishing head rotation speed. Compared to dry etching methods in related technologies, this method effectively solves the problems of slow etching rate, high roughness, and poor uniformity.

[0079] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for thinning and polishing photoresist, characterized in that, The method includes: Photoresist with extremely high aspect ratio can be achieved by spin-coating onto a substrate and then curing the photoresist. The surface of the photoresist is morphologically modified using low-pressure, low-speed chemical mechanical polishing (CMP) technology, so that the height difference of the photoresist surface is less than 5 μm. The parameters for morphological modification are: polishing pressure 1.5 psi to 2.0 psi, polishing fluid flow rate 90 ml / min to 220 ml / min, polishing disc speed 63 R / min to 93 R / min, and polishing head speed 60 R / min to 87 R / min. High-pressure, high-speed chemical mechanical polishing (CMP) is used for rough polishing to grind the surface of the photoresist to a preset thickness. The parameters for rough polishing are: polishing pressure 2.0 psi, polishing fluid flow rate 220 ml / min, polishing disc rotation speed 93 R / min, and polishing head rotation speed 87 R / min. The processed photoresist is cleaned and retained; The method of curing the photoresist includes the following steps: The photoresist is subjected to a pre-exposure baking process; The baked photoresist is exposed using a photomask and a preset exposure dose, and then the pattern on the photomask is transferred to the substrate surface using a developing solution. The substrate after development is then baked and the photoresist is cured; wherein the baking temperature of the post-baking is 90℃~120℃ and the time is 10min~30min.

2. The thinning and polishing method for photoresist according to claim 1, characterized in that, The baking temperature for the pre-exposure baking treatment is 65℃~120℃, and the time is 30min~90min.

3. The thinning and polishing method for photoresist according to claim 1, characterized in that, The post-baking temperature is 90℃ and the time is 30 minutes.

4. A thinning and polishing method for photoresist according to any one of claims 1 to 3, characterized in that, The polishing fluid used in the morphological trimming is an alumina-based polishing fluid with an abrasive particle size of 1 μm.

5. The thinning and polishing method for photoresist according to claim 4, characterized in that, The height difference of the photoresist surface after morphological modification is less than 3 μm.

6. A thinning and polishing method for photoresist according to any one of claims 1 to 3, characterized in that, The coarse polishing rate is 4 μm / min.

7. The thinning and polishing method for photoresist according to claim 6, characterized in that, The polishing fluid used for rough polishing is an alumina-based polishing fluid with an abrasive particle size of 1μm.

8. The thinning and polishing method for photoresist according to claim 6, characterized in that, The rough polishing is followed by a fine polishing step: The parameters for fine polishing are as follows: polishing pressure is 1.5 psi; polishing fluid flow rate is 120 ml / min; polishing disc speed is 63 R / min; polishing head speed is 60 R / min; the polishing fluid is a silica sol-based polishing fluid; and the abrasive particle size is 80 nm.

9. A micro / nano device, characterized in that, The micro / nano device is fabricated using the thinning and polishing process described in any one of claims 1 to 8; wherein the photoresist portion is retained as a dielectric layer support structure, and the metal circuit portion is exposed through thinning and polishing.

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