Method for preparing tin-glycol dry photoresist by using molecular layer deposition

Abstract

The invention relates to a method for preparing a tin-diol dry photoresist by using molecular layer deposition, which comprises the following steps of: preparing a tin-based mixed film by using a tetradimethylamine tin (tin tetrachloride) metal source and a diol organic source as raw materials through a molecular layer deposition (MLD) technology, and taking the tin-based mixed film as a high-resolution dry positive photoresist. The tin-based photoresist can be used in electron beam lithography (EBL), extreme ultraviolet lithography (EUVL) and beyond extreme ultraviolet lithography (BEUVL). Under 50 kilovolt electron beam exposure, the resolution ratio can reach 7 nanometers at 2000 [mu] C / cm < 2 >; under extreme ultraviolet exposure, the resolution ratio can reach at least 18 nanometers at 22 mj / cm < 2 >; under exposure beyond extreme ultraviolet, the resolution ratio at 520 mj / cm < 2 > reaches at least 32 nanometers. The tin-based mixed photoresist disclosed by the invention has a wide application prospect, and a new technical scheme is provided for developing a semiconductor dry photoresist with higher performance.

Description

Technical Field

[0001] This invention relates to the field of photoresist preparation technology, and in particular to a universal method for preparing tin-diol-based dry photoresist using molecular layer deposition. Background Technology

[0002] With the continuous advancement of photolithography technology, photoresists, a key material in the field, are also constantly evolving. However, when process nodes shrink to below 3 nanometers, traditional organic molecular photoresists face numerous limitations, including excessively high line edge roughness and insufficient extreme ultraviolet (EUV) photon absorption efficiency. This severely hinders the application of extreme ultraviolet lithography (EUVL) and high-resolution electron beam lithography. Organic photoresists, composed of light elements such as C, H, and O, have very weak absorption of EUV light, resulting in a significant decrease in their photosensitivity. Due to its high absorption efficiency for EUV, tin-based photoresists represent an important direction for developing novel high-performance photoresists.

[0003] However, with the advent of high numerical aperture (NA) EUV lithography machines, the thickness of the photoresist needs to be below 20 or even 10 nanometers. Current physical spin-coating methods for both organic and metal-based photoresists struggle to address this issue. Therefore, there is an urgent need for a method to prepare tin-based photoresists with precisely controllable thickness and high uniformity. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing tin-diol-based dry photoresist using molecular layer deposition (MLD). The thickness of the dry photoresist using MLD is precisely controllable, down to the angstrom (Å) level (0.1 nm). A novel type of tin-based dry positive photoresist is developed by using electron beam, EUV, or BEUV lithography, followed by post-baking at 70-150°C for 50-600 s, wet development using an ammonia solution, or dry development using plasma etching. The pattern on the photoresist is then transferred to a substrate via dry etching.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing tin-diol-based dry photoresist using molecular layer deposition (MLD) involves using metallic tin and an organic diol source as precursors for molecular layer deposition, resulting in a dry photoresist. The specific steps of the molecular layer deposition are as follows: The tin source is kept at its evaporation temperature and the source bottle containing the diol organic source is heated to a certain temperature. The temperature of the reactor is kept at 90-180℃ and the reaction is purged with 15 sccm of dry nitrogen. Each cycle consists of two half cycles: (1) tin source is introduced and nitrogen is purged; (2) diol organic source is introduced and nitrogen is purged. The deposition thickness is controlled according to the number of deposition cycles.

[0006] The sources of metallic tin include either tin tetrachloride or tetradimethylamine tin.

[0007] Diol organic source precursors include one of the following: ethylene glycol, propylene glycol, butanediol and its isomers, butenyl glycol and its isomers, pentenyl glycol and its isomers, hexenyl glycol and its isomers, heptenyl glycol and its isomers, and octenyl glycol and its isomers.

[0008] The specific steps of the molecular layer deposition are as follows: The thin film was deposited in a self-built 8-inch MLD device. The tin source was kept at its evaporation temperature (room temperature or 70°C), and the source bottle containing the diol organic source was heated to a certain temperature (70-180°C). The reactor temperature was kept at 90-180°C, and the reaction was purged with 15 sccm of dry nitrogen. Each cycle consisted of two half cycles: (1) tin source was introduced and nitrogen was purged; (2) diol organic source was introduced and nitrogen was purged. The deposition thickness was controlled according to the number of deposition cycles.

[0009] Specifically, when tetradimethylamine tin and 1,4-butenediol are used as precursors, the growth thickness per cycle is 0.05 nm; when tin tetrachloride and ethylene glycol are used as precursors, the growth thickness per cycle is 0.15 nm.

[0010] Furthermore, the molecular layer is deposited on a silicon, silicon dioxide, mica, or gold substrate.

[0011] Furthermore, each complete cycle of the tin source ligand combines with the hydroxyl bonds on the diol organic source ligand, and the final thin film is obtained through multiple cycles of growth.

[0012] The technical advantages are: This invention allows for precise film thickness control; the desired thickness can be obtained by controlling the number of cycles, which is difficult to achieve with traditional spin coating methods. Furthermore, under 50 kV electron beam exposure, it maintains a film thickness of 2000 μC / cm. 2 The time resolution can reach 7 nanometers; under extreme ultraviolet exposure, it achieves a speed of 22 mJ / cm². 2 The temporal resolution can reach at least 18 nanometers; under exposure beyond extreme ultraviolet light, it achieves a speed of 158 mJ / cm². 2 The time resolution is at least 25 nanometers. Attached Figure Description

[0013] Figure 1 a is a schematic diagram illustrating the growth principle of this type of photoresist prepared using tin tetrachloride and ethylene glycol in Example 1. Figure 1 b is a schematic diagram of the growth of this photoresist prepared using tetradimethylamine tin and 1,4-butenediol in Example 2.

[0014] Figure 2 The XPS spectra are of tetradimethylaminetin and 1,4-butenediol.

[0015] Figure 3 SEM images with HP=50nm, L / S=1 / 2; SEM images with HP=50nm, L / S=1 / 3; SEM images with HP=40nm, L / S=1 / 2; SEM images with HP=40nm, L / S=1 / 4; SEM images with HP=30nm, L / S=1 / 4; and SEM images with HP=25nm, L / S=1 / 4. The exposure voltage was 50kV, and the exposure dose was 2000μC / cm². 2 Bake at 70℃ for 60 seconds, then develop with 15 wt% ammonia for 15 seconds.

[0016] Figure 4 The SEM images are for the following patterns: HP=12.17nm, HP=8.18nm, and HP=7.00nm. The exposure voltage was 50kV, and the exposure dose was 2000μC / cm. 2 Bake at 70℃ for 60 seconds, then develop with 15 wt% ammonia for 15 seconds.

[0017] Figure 5 After EUV exposure at 70°C, bake for 60 seconds, and develop with 15 wt% ammonia solution for 15 seconds. The dose is 22 mJ / cm². 2 SEM image with HP=50nm and L / S=1 / 1; dose 44mj / cm 2 SEM image of HP=50nm, L / S=1 / 1; dose 22mj / cm 2 SEM image of HP=18nm, L / S=1 / 3; dose 22mj / cm 2 SEM images of HP=40nm, L / S=1,2.

[0018] Figure 6 For ultraviolet (BEUV) exposure, the product was exposed at 70°C and baked for 60 seconds, followed by development with 15 wt% ammonia solution for 15 seconds. The dose was 520 mJ / cm². 2 SEM image with HP=35nm and L / S=1 / 1; dose 520mj / cm 2 SEM image of HP=32nm, L / S=1 / 1; Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the methods described are conventional methods. Unless otherwise specified, the raw materials can be obtained from publicly available commercial sources. Tin-based diol photoresists were prepared using molecular layer deposition. In each complete cycle, the tin source ligand binds to the hydroxyl bonds on the diol organic source, and the final thin film is obtained through multiple cycles of growth. The film thickness can be precisely controlled by the number of cycles. A schematic diagram of the principle of the dry photoresist molecular layer deposition method of the present invention is shown below. Figure 1 As shown.

[0020] Example 1: This photoresist was prepared using tetradimethylamine tin and 1,4-butenediol.

[0021] Silicon wafers were placed in a self-built 8-inch MLD apparatus for deposition. A source vial containing tetramethylamine tin was maintained at 70°C, and a source vial containing 1,4-butenediol was heated to 85°C. The reactor temperature was maintained at 110°C, and the reaction was purged with 15 sccm of dry nitrogen. Each cycle consisted of two half-cycles: (1) a 150 ms tin source was introduced, followed by a 30 s purging with nitrogen; (2) a 450 ms 1,4-butenediol was introduced, followed by a 50 s purging with nitrogen. The system pressure was 10 Pa, and 800 cycles were deposited, resulting in a film thickness of 40 nm. The XPS spectra of tetramethylamine tin and 1,4-butenediol in this embodiment are attached. Figure 2 As shown. The effects of electron beam exposure, extreme ultraviolet exposure, and beyond-extreme ultraviolet exposure of this photoresist are shown in [the image / description]. Figures 3 to 6 .

[0022] Example 2: This photoresist was prepared using tin tetrachloride and ethylene glycol.

[0023] Silicon wafers were placed in a self-built 8-inch MLD apparatus for deposition. A source vial containing tin tetrachloride was kept at room temperature, while a source vial containing ethylene glycol was heated to 80°C. The reactor temperature was maintained at 90°C, and the reaction was purged with 15 sccm of dry nitrogen. Each cycle consisted of two half-cycles: (1) a 50 ms tin source was introduced, followed by 40 s purging with nitrogen; (2) a 150 ms ethylene glycol was introduced, followed by 50 s purging with nitrogen. The system pressure was 10 Pa. Performance testing was performed as in Example 1.

[0024] Example 3: This photoresist was prepared using tetradimethylamine tin and propylene glycol.

[0025] Silica wafers were placed in a self-made MLD apparatus for deposition. A source vial containing tetra(dimethylamino)tin was heated to 70°C, and a source vial containing propylene glycol was heated to 90°C. The reactor temperature was maintained at 120°C, and the reaction was purged with 15 sccm of dry nitrogen. Each cycle consisted of two half-cycles: (1) 150 ms of tin source was introduced, followed by 50 s purging with nitrogen; (2) 450 ms of propylene glycol was introduced, followed by 50 s purging with nitrogen. The system pressure was 10 Pa. Performance testing was performed as in Example 1.

[0026] Example 4: This photoresist was prepared using tin tetrachloride and 1,5-pentanediol.

[0027] A 100 nm gold-coated silicon wafer was placed in a homemade MLD apparatus for deposition. Tin tetrachloride was maintained at room temperature, and the source vial containing 1,5-pentanediol was heated to 120 °C. The reactor temperature was maintained at 150 °C, and the reaction was purged with 15 sccm of dry nitrogen. Each cycle consisted of two half-cycles: (1) 50 ms of tin source was introduced, followed by 25 seconds of nitrogen purging; (2) 450 ms of 1,5-pentanediol was introduced, followed by 40 seconds of nitrogen purging. The system pressure was 10 Pa. Performance testing was performed as in Example 1.

[0028] Comparative Example 1: Polymethyl methacrylate (PMMA) photoresist (positive photoresist) was spin-coated at 8000 rpm for 60 seconds and pre-baked at 180°C for 3 minutes. The thickness was about 100 nanometers, which did not allow for good control of the film thickness. At the same time, its resolution under a 50 kV electron beam was only 30 nanometers, which is significantly different from the 7 nanometer resolution of this tin-based photoresist.

[0029] Comparative Example 2: Hydrogen silsesquioxane polymer (HSQ) photoresist, using spin coating, 4000 rpm for 60 seconds, pre-baking at 120°C for 5 minutes, with a thickness of about 90 nanometers. The film thickness cannot be well controlled. At the same time, its extreme ultraviolet sensitivity is 150 mj / cm2, which is significantly different from the 22 mj / cm2 of this tin-based photoresist.

[0030] By comparing with comparative examples, it can be seen that the method of preparing tin-diol-based dry photoresist using molecular layer deposition of the present invention can precisely control the photoresist film thickness, while its resolution is better than that of traditional photoresists, its extreme ultraviolet lithography sensitivity is high, and it can perform exposure beyond extreme ultraviolet light.

Claims

1. A method for preparing tin-diol-based dry photoresist using molecular layer deposition, characterized in that: Using metallic tin and diol organic sources as precursors, molecular layer deposition is performed to obtain tin-based dry photoresist. The specific steps of molecular layer deposition are as follows: The tin source is kept at its evaporation temperature and the source bottle containing the diol organic source is heated to a certain temperature. The temperature of the reactor is kept at 90-180℃ and the reaction is purged with 15 sccm of dry nitrogen. Each cycle consists of two half cycles: (1) tin source is introduced and nitrogen is purged; (2) diol organic source is introduced and nitrogen is purged. The deposition thickness is controlled according to the number of deposition cycles.

2. The method for preparing tin-diol-based dry photoresist using molecular layer deposition according to claim 1, characterized in that: The tin source includes either tin tetrachloride or tetradimethylamine tin metal precursor.

3. The method for preparing tin-diol-based dry photoresist using molecular layer deposition according to claim 1, characterized in that: Diol organic source precursors include one of the following: ethylene glycol, propylene glycol, butanediol and its isomers, butenyl glycol and its isomers, pentenyl glycol and its isomers, hexenyl glycol and its isomers, heptenyl glycol and its isomers, and octenyl glycol and its isomers.

4. The method for preparing tin-diol-based dry photoresist using molecular layer deposition according to claim 1, characterized in that: The molecular layer is deposited on a silicon, silicon dioxide, mica, or gold substrate.

5. The method for preparing tin-diol-based dry photoresist using molecular layer deposition according to claim 1, characterized in that: Each complete cycle of the tin source ligand binds to the hydroxyl bonds on the diol organic source ligand, and the final thin film is obtained through multiple cycles of growth.

6. The method for preparing tin-diol-based dry photoresist using molecular layer deposition according to claim 1, characterized in that: The resulting photoresist is suitable for electron beam lithography, extreme ultraviolet lithography, or beyond extreme ultraviolet lithography.

7. The method for preparing tin-diol-based dry photoresist using molecular layer deposition according to claim 1, characterized in that: The aforementioned maintenance of the tin metal source at its evaporation temperature means maintaining it at room temperature or 70°C.

8. The method for preparing tin-diol-based dry photoresist using molecular layer deposition according to claim 1, characterized in that: The heating of the source bottle containing the diol organic source to a certain temperature refers to heating it to 70-180℃.

Images