An EUV photoresist, its preparation method and application

Abstract

This invention discloses an EUV photoresist, its preparation method, and its applications. The EUV photoresist composition of this invention comprises the following components: 55-75 parts by weight of compound A, a photoacid-generating agent, an organic base, and an organic solvent. This EUV photoresist composition exhibits low exposure dose, high resolution, and low LER value, showing promising application prospects. Wherein L: R′: n-butyl (n-Bu).

Description

Technical Field

[0001] This invention belongs to the field of photoresist technology, specifically relating to an EUV photoresist, its preparation method, and its application. Background Technology

[0002] With the continuous development of modern semiconductor technology and its widespread application in electronic devices, communication equipment, information security, and entertainment devices, it has become one of the most dynamic technological fields in the world today, permeating all aspects of our work and life. Integrated circuit manufacturing is the core area of ​​the semiconductor industry. Every upgrade of integrated circuits is inseparable from the evolution of photolithography technology; the history of photolithography technology is the history of integrated circuit development, and the level of photolithography technology determines the manufacturing level of integrated circuits.

[0003] The principle of photolithography is to coat the surface of a silicon wafer with a layer of highly photosensitive photoresist, and then shine light (usually ultraviolet, deep ultraviolet, or extreme ultraviolet light) through a mask onto the silicon wafer surface. The photoresist exposed to the light reacts. Afterwards, the exposed / unexposed photoresist is washed away with a specific solvent, thus transferring the circuit pattern from the mask to the silicon wafer. Photolithography technology has undergone transformations in exposure methods, from contact / proximity, equal-magnification projection, shrinkage step projection, and scanning step projection. Exposure wavelengths have evolved from full-spectrum exposure (300-450nm), to 436nm G-lines, 365nm I-lines, 248nm KrF lasers, to the most widely used 193nm ArF lasers, and now to the widely researched 13.5nm extreme ultraviolet light, electron beams, and X-rays. Manufacturing nodes have progressed from 0.5mm, 0.1mm, 90nm to 30nm, and even lower. Extreme ultraviolet lithography differs from traditional optical lithography in that it uses extremely low wavelengths. However, most elements strongly absorb extreme ultraviolet (EUV) light, making traditional long-wavelength photoresists unsuitable for EUV lithography. Therefore, the development of new EUV photoresist systems is necessary. Each new generation of photoresist technology drives significant progress in related fields. Photolithography is one of the most critical technologies in integrated circuit manufacturing. The successful application of each generation of photolithography technology has greatly promoted the development of integrated circuits, leading to higher integration density and lower costs. Photolithography involves exposing photoresist material coated on the surface of a semiconductor substrate, transferring the intricate geometric patterns from the mask onto the semiconductor substrate. Increasingly higher resolution photolithographic patterns mean higher integration density and smaller critical dimensions in integrated circuits.

[0004] The semiconductor industry currently agrees that extreme ultraviolet (EUV) lithography (13.5nm) is the most likely next-generation lithography technology to be realized. With an exposure wavelength of 13.5nm, the final resolution will only be limited by the material properties of the photoresist. EUV lithography can produce higher-resolution circuit patterns, significantly improving the integration density of integrated circuits and the performance of electronic devices. Researching photoresists and lithography processes suitable for EUV lithography has become both a hot topic and a challenge in lithography research.

[0005] EUV photoresists must possess low absorbance, high transparency, high etch resistance, high resolution (less than 22nm), high sensitivity, and low exposure dose (less than 10mJ / cm²). 2 EUV photoresists possess characteristics such as high environmental stability, low gas generation, and low line edge roughness (less than 1.5 nm). The development of EUV photoresists has always been limited by three factors: resolution, line edge roughness, and photosensitivity, which generally have an interdependent relationship. In early photolithography technologies, polymer photoresists were the most widely used, thus polymer photoresist systems were initially applied to EUV lithography. However, due to their large molecular volume, the resolution of the lithographic pattern cannot be less than the volume of the molecules, resulting in high line edge roughness and low resolution. To achieve higher resolution, the development of small-molecule photoresist systems, especially molecular glass systems, has received widespread attention. Molecular glass is a small-molecule organic compound with a high glass transition temperature, combining the advantages of polymers and small molecules. It has a monodisperse molecular weight, exhibits an amorphous morphology, and possesses high thermal stability. In recent years, molecular glass-based photoresist substrate materials have achieved certain results, and it has been proven that EUV photoresist materials based on this type of material have great development potential. Therefore, it is necessary to develop different types of molecular glass-based photoresist substrate materials. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the deficiency of limited types of EUV photoresists, thereby providing an EUV photoresist, its preparation method, and its applications. The EUV photoresist provided by this invention can be applied to extreme ultraviolet lithography technology, and has the characteristics of low exposure dose, high resolution, and low LER value, thus possessing broad application prospects.

[0007] This invention provides an EUV photoresist composition comprising the following components: 55-75 parts by weight of a compound of formula A, a photoacid generator, an organic base, and an organic solvent;

[0008] The compound of formula A is shown below:

[0009]

[0010] In the formula, L:

[0011]

[0012] R': n-Butyl(n-Bu).

[0013] In this invention, the compound of formula A can be 55-75 parts by weight, preferably 55-65 parts.

[0014] In this invention, the photoacid generator can be a conventional photoacid generator in the EUV photoresist field, and may be:

[0015]

[0016] In this invention, the photo-induced acid-producing agent can be in the conventional amount by weight, preferably 1.0-12 parts, more preferably 8-10 parts.

[0017] In this invention, the organic solvent can be a conventional organic solvent in the field of EUV photoresist, preferably an ester solvent, such as ethyl lactate.

[0018] In this invention, the organic solvent can be in the conventional parts by weight, preferably 1500-2500 parts, more preferably 1700-2000 parts.

[0019] In this invention, the organic base can be a conventional organic base in the field of EUV photoresist, preferably a weak organic base, such as trioctylamine.

[0020] In this invention, the organic base can be in the conventional parts by weight, preferably 0.2-1.0 parts, more preferably 0.5 parts.

[0021] In this invention, the photoacid-producing agent is preferably 1.0-12 parts by weight.

[0022] The organic base is preferably 0.2-1.0 parts by weight of trioctylamine;

[0023] The organic solvent is preferably ethyl lactate in parts by weight of 1500-2500.

[0024] The components of the EUV photoresist are preferably composed of the following: the compound of formula A above, the photoacid generator above, the organic solvent above, and the organic base above.

[0025] The EUV photoresist composition comprises components from any of the following groups;

[0026] EUV photoresist composition: 1:65 parts of compound A, 9 parts of... 2000 parts ethyl lactate and 0.5 parts trioctylamine;

[0027] EUV photoresist composition 2: 55 parts of compound A, 3 parts of... 1500 parts ethyl lactate and 0.5 parts trioctylamine;

[0028] EUV photoresist composition: 3: 60 parts of compound A, 5 parts of... 1700 parts ethyl lactate and 0.5 parts trioctylamine;

[0029] EUV photoresist composition: 4: 70 parts of compound A, 7 parts of... 2100 parts of ethyl lactate and 0.5 parts of trioctylamine;

[0030] EUV photoresist composition: 5 parts of compound A (75 parts), 12 parts of... 2500 parts of ethyl lactate and 0.5 parts of trioctylamine;

[0031] EUV photoresist composition: 6 parts of Formula A compound, 71 parts of [unclear text - possibly a typo, should be 6 parts], 9 parts of [unclear text - possibly a typo, should be 9 parts] 2000 parts ethyl lactate and 0.5 parts trioctylamine;

[0032] EUV photoresist composition: 7:67 parts of compound A, 9 parts of... 2000 parts ethyl lactate and 0.5 parts trioctylamine;

[0033] EUV photoresist composition: 8:55 parts of compound A, 9 parts of... 2000 parts of ethyl lactate and 0.5 parts of trioctylamine.

[0034] The present invention also provides a method for preparing an EUV photoresist composition, which includes the following steps: mixing the components of the EUV photoresist composition.

[0035] The mixing process may further include a filtration step. The filtration can be a conventional method, preferably using an ultra-high molecular weight polyethylene (UHMWPE) membrane. The UHMWPE membrane preferably has a pore size of 0.2 μm.

[0036] The present invention also provides a method for forming patterns using extreme ultraviolet lithography, which includes the following steps:

[0037] Step 1: Coat the above EUV photoresist composition onto the substrate surface and bake to obtain a photoresist layer;

[0038] Step 2: Expose, bake, and develop the EUV photoresist layer obtained in Step 1 to obtain the photoresist pattern.

[0039] In step 1, the substrate can be a conventional substrate in the art, preferably a silicon wafer. The silicon wafer used is preferably an 8-inch silicon wafer.

[0040] In step 1, the coating method can be a conventional method in the art, preferably spin coating with a rotary coater.

[0041] In step 1, the thickness of the EUV photoresist layer can be a conventional thickness in the art, preferably 80 nm.

[0042] In step 1, the baking temperature can be a conventional baking temperature in the art, preferably 100-130°C, for example 120°C.

[0043] In step 1, the baking time is preferably 50-70 seconds, for example, 60 seconds.

[0044] In step 2, the baking temperature can be a conventional baking temperature in the art, preferably 100-130°C, for example 120°C.

[0045] In step 2, the baking time is preferably 50-70 seconds, for example, 60 seconds.

[0046] In step 2, the development can be a conventional operation in the art, and the developer generally used is an aqueous solution of tetramethylammonium hydroxide (TMAH), such as a 2.38% TMAH aqueous solution by mass.

[0047] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0048] The reagents and raw materials used in this invention are all commercially available.

[0049] The positive and progressive effects of this invention are as follows: This invention provides a new EUV photoresist composition, which has low exposure dose, high resolution and low LER value, and has good application prospects. Detailed Implementation

[0050] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0051] Preparation of compound A

[0052]

[0053] In the formula, L:

[0054]

[0055] R': n-Butyl(n-Bu)

[0056] The preparation method of compound A is based on the synthesis of [BuSnO(OOCL)]6 in the synthesis of organotin oxide clusters in patent CN102093431B.

[0057] In the following examples or comparative examples, the EUV photoresist compositions were prepared according to the following methods.

[0058] Sample testing: EUV photoresist compositions 1-8 and comparative samples 1-6 were coated onto 8-inch silicon wafers using a spin coater, followed by baking at 120°C for 60 seconds, yielding a film thickness of 80 nm. EUV exposure was then performed, followed by baking at 120°C for another 60 seconds. The silicon wafers were then immersed in a 2.38% tetramethylammonium hydroxide (TMAH) aqueous solution for development.

[0059] Optimal exposure (Eop) is defined as the exposure dose (μC / cm) that provides 1:1 resolution at the top and bottom of a 200nm 1:1 line-and-space pattern. 2 ).

[0060] The maximum resolution of a resist is defined as the minimum linewidth of the line-space pattern that can be resolved and separated under optimal exposure.

[0061] LER determination: 100 nm line-space pattern was measured under SEM.

[0062] Based on the observation results of the cross-section of the resist pattern under SEM, the visual judgment is made as to whether the pattern outline is right-angled.

[0063] Examples 1-8 and Comparative Examples 1-6

[0064] Preparation method of EUV photoresist composition: After mixing the components of EUV photoresist according to the proportions in Table 1, the mixture is filtered through a 0.2 μm UPE filter membrane to obtain the corresponding positive EUV photoresist, wherein the photoacid generator is... The organic solvent is ethyl lactate; the organic base is trioctylamine.

[0065] Table 1

[0066]

[0067]

[0068] As shown in the table, the exposure dose of the prepared EUV photoresist is 30-40 μC / cm. 2 The maximum resolution of the resist is 35nm-45nm, the LER value is 3.0-4.0, and the resulting pattern is rectangular.

Claims

1. An EUV photoresist composition comprising the following components: 55-75 parts by weight of a compound of formula A, a photoacid generator, an organic base, and an organic solvent; The compound of formula A is shown below: Where L: R': n-Butyl.

2. The EUV photoresist composition as described in claim 1, characterized in that, The EUV photoresist composition satisfies one or more of the following conditions: (1) The photo-induced acid-producing agent is (2) The organic solvent is an ester solvent; and (3) The organic base mentioned is a weak organic base.

3. The EUV photoresist composition as described in claim 2, characterized in that, The EUV photoresist composition satisfies one or more of the following conditions: (1) The organic solvent is ethyl lactate; and (2) The organic base mentioned is trioctylamine.

4. The EUV photoresist composition as described in claim 1, characterized in that, The EUV photoresist composition satisfies one or more of the following conditions: (1) The compound of formula A is 55-75 parts by weight; (2) The photo-induced acid-producing agent is 1.0-12 parts by weight; (3) The organic solvent is 1500-2500 parts by weight; and (4) The organic base is 0.2-1.0 parts by weight.

5. The EUV photoresist composition as described in claim 4, characterized in that, The EUV photoresist composition satisfies one or more of the following conditions: (1) The compound of formula A is 55-65 parts by weight; (2) The photo-induced acid-producing agent is 8-10 parts by weight; (3) The organic solvent is 1700-2000 parts by weight; and (4) The organic base is 0.5 parts by weight.

6. The EUV photoresist composition as claimed in claim 1, characterized in that, The EUV photoresist composition satisfies one or more of the following conditions: (1) The photo-induced acid-producing agent is 1.0-12 parts by weight. (2) The organic base is 0.2-1.0 parts by weight of trioctylamine; and (3) The organic solvent is ethyl lactate in parts by weight of 1,500-2,500.

7. The EUV photoresist composition according to any one of claims 1-6, characterized in that, It consists of the following components: the compound of formula A, the photoacid-producing agent, the organic solvent, and the organic base.

8. The EUV photoresist composition as claimed in claim 1, characterized in that, It is composed of any of the following groups of components; EUV photoresist composition: 1:65 parts of compound A, 9 parts of... 2000 parts ethyl lactate and 0.5 parts trioctylamine; EUV photoresist composition 2: 55 parts of compound A, 3 parts of... 1500 parts ethyl lactate and 0.5 parts trioctylamine; EUV photoresist composition: 3: 60 parts of compound A, 5 parts of... 1700 parts ethyl lactate and 0.5 parts trioctylamine; EUV photoresist composition: 4: 70 parts of compound A, 7 parts of... 2100 parts of ethyl lactate and 0.5 parts of trioctylamine; EUV photoresist composition: 5 parts of compound A (75 parts), 12 parts of... 2500 parts of ethyl lactate and 0.5 parts of trioctylamine; EUV photoresist composition: 6 parts of Formula A compound, 71 parts of [unclear text - possibly a typo, should be 6 parts], 9 parts of [unclear text - possibly a typo, should be 9 parts] 2000 parts ethyl lactate and 0.5 parts trioctylamine; EUV photoresist composition: 7:67 parts of compound A, 9 parts of... 2000 parts ethyl lactate and 0.5 parts trioctylamine; EUV photoresist composition: 8:55 parts of compound A, 9 parts of... 2000 parts of ethyl lactate and 0.5 parts of trioctylamine.

9. A method for preparing an EUV photoresist composition, characterized in that, It includes the following steps: The components of the EUV photoresist composition as described in any one of claims 1-8 are mixed together.

10. The method for preparing the EUV photoresist composition according to claim 9, characterized in that, The mixing process further includes a filtration step; the filtration method employs an ultra-high molecular weight polyethylene (UHMWPE) filter membrane; the UHMWPE filter membrane has a pore size of 0.2 μm.

11. A method for forming patterns using extreme ultraviolet lithography, characterized in that, It includes the following steps: Step 1: Coat the EUV photoresist composition as described in any one of claims 1-8 onto the surface of a substrate, and bake to obtain a photoresist layer; Step 2: Expose, bake, and develop the EUV photoresist layer obtained in Step 1 to obtain the photoresist pattern.

12. The method for forming a pattern using extreme ultraviolet lithography as described in claim 11, characterized in that, The method described satisfies one or more of the following conditions: (1) In step 1, the substrate is a silicon wafer; (2) In step 1, the coating method is spin coating with a rotary coater; (3) In step 1, the thickness of the photoresist layer is 80 nm; (4) In step 1, the baking temperature is 100-130℃; (5) In step 1, the baking time is 50-70 seconds; (6) In step 2, the baking temperature is 100-130℃; (7) In step 2, the baking time is 50-70 seconds; and (8) In step 2, the developing agent used in the developing process is an aqueous solution of tetramethylammonium hydroxide.

13. The method for forming a pattern using extreme ultraviolet lithography as described in claim 12, characterized in that, The method described satisfies one or more of the following conditions: (1) In step 1, the substrate is an 8-inch silicon wafer; (2) In step 1, the baking temperature is 120°C; (3) In step 1, the baking time is 60 seconds; (4) In step 2, the baking temperature is 120℃; (5) In step 2, the baking time is 60 seconds; and (6) In step 2, the tetramethylammonium hydroxide aqueous solution is a tetramethylammonium hydroxide aqueous solution with a mass fraction of 2.38%.

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