Photoresist material and use thereof

Abstract

The present application provides a photoresist material and its application. The photoresist material comprises a chemical amplification photoresist and iLine PAC added into the chemical amplification photoresist. The photoresist material is applied to a 193nm or 248nm photoetching process, so that the total amount of photoacid after exposure is increased, acid-base neutralization with a developing solution is realized in a subsequent developing process, the problem of residual developing solution or polymer causing unetching is avoided, and the removal process of the developing solution is not needed, so that the efficiency of the photoetching process and the quality of photoetching are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of photoetching technology, and particularly relates to a photoresist material and application thereof. BACKGROUND

[0002] The semiconductor integrated circuit (IC) industry has experienced rapid growth. The IC material, design, and manufacturing tools have progressed to meet this growing need. Technological advances in IC materials, design, and manufacturing tools have resulted in the development of ICs with increasingly smaller features, higher speeds, and greater capabilities. In these advances, manufacturing processes, tools, and materials have been used to produce increasingly smaller features on ICs.

[0003] The photoetching process is one of the most important process steps in the IC manufacturing industry. Photolithography is the process of transferring geometric patterns on a mask to a thin film material (photoresist) that is sensitive to light radiation and is coated on the surface of a semiconductor substrate. The development of integrated circuits has undergone a development process from g-line (436 nm), i-line (365 nm), KrF (248 nm), ArF (193 nm) to extreme ultraviolet (EUV, 13.5 nm). Different exposure light sources correspond to different photoresists. Among them, the chemical amplification type photoresist occupies a dominant position in the 193 nm and 248 nm photoresist field.

[0004] The chemical amplification type photoresist contains a photo acid generator (PAG), which generates a photo acid after being exposed to a 193 / 248 nm light source of a photoetching agent. However, the generated photo acid is less than the alkaline developing liquid, and a small amount of photo acid cannot completely neutralize the alkaline developing liquid, so that the exposed area is left with developing liquid and polymer residue, resulting in defects (for example, shock effect), and subsequent etching processes cannot be performed. In addition, the existing removal process of residual developing liquid is complex, causing the production process to be cumbersome, and the cost to be high. SUMMARY

[0005] In view of the deficiencies in the related art, the present application provides a photoresist material and application thereof in a photoetching process.

[0006] In one aspect, the present application provides a photoresist material, which comprises a chemical amplification photoresist and iLine PAC added to the chemical amplification photoresist.

[0007] In some embodiments of the application, the weight of the iLine PAC accounts for less than 1% of the total weight of the photoresist material.

[0008] In some embodiments of the invention, the chemically amplified photoresist is a photoresist used under a 193nm or 248nm light source; the iLine PAC is a photoactive compound used under a 365nm light source.

[0009] In some embodiments of the invention, iLine PAC can be converted into photoacid after exposure to a 193nm or 248nm light source.

[0010] In some embodiments of the invention, the chemically amplified photoresist includes a photoacid generator, a polymer resin, a solvent, and additives.

[0011] In some embodiments of the invention, the photoacid generator produces acid after exposure, and the acid can induce the departure of acid-indestructible groups from the polymer resin during the baking process after exposure.

[0012] In some embodiments of the invention, the polymer resin is one or more of poly(p-hydroxystyrene) and its derivatives, polymethyl methacrylate derivatives, cyclic olefin-maleic anhydride copolymers, and cyclic polymers.

[0013] Another aspect of the present invention provides the application of any of the above photoresist materials in a 193nm or 248nm photolithography process.

[0014] In some embodiments of the invention, the application of the above photoresist material includes the following steps:

[0015] Provide the target substrate;

[0016] Photoresist coating: A photoresist layer is formed on top of the target substrate using a photoresist material;

[0017] Exposure: Selectively exposing the photoresist layer to a 193nm or 248nm light beam to form a potential pattern;

[0018] Development: Applying developer to the exposed photoresist layer to reveal the underlying pattern;

[0019] After exposure, the photoacid generator and iLine PAC in the photoresist layer are converted into photoacid. During the development process, the photoacid can neutralize the acid and alkali of the developer.

[0020] In some embodiments of the invention, a pre-baking step is included before exposure, and a post-baking step is included after exposure.

[0021] Compared with the prior art, the advantages and positive effects of the present invention are as follows: The photoresist material provided in at least one embodiment of the present invention adds iLine PAC to the chemically amplified photoresist. When applied to the 193nm or 248nm photolithography process, it can increase the total amount of photoacid after exposure, achieve acid-base neutralization with the developer in the subsequent development process, avoid the problem of etching failure caused by developer or polymer residue, and eliminate the need for developer removal process, thereby improving the efficiency and quality of the photolithography process. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of the photolithography process in an embodiment of the present invention;

[0024] Figure 2 This is a flowchart illustrating the application of the photoresist material provided in the photolithography process according to an embodiment of the present invention.

[0025] In the picture:

[0026] 100, Photolithography system; 101, Photomask; 101a, Transparent area; 101b, Opaque area; 102, Beam; 200, Photoresist layer; 200a, Exposure area; 200b, Unexposed area; 300, Target substrate. Detailed Implementation

[0027] The technical solutions in 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 a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0029] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0030] It is understood that although the accompanying drawings may show a specific order of method steps, the order of the steps may differ from the depicted order. Furthermore, two or more steps may be performed simultaneously or partially simultaneously. Such variations will depend on the chosen software and hardware, as well as the designer's choices. All such variations are within the scope of this disclosure.

[0031] Semiconductor manufacturing is a process that involves depositing thin films, photolithography, etching, ion implantation, and planarization on bare wafers to create complete integrated circuits. Among these processes, photolithography is crucial for forming the circuit pattern of the integrated circuit onto photoresist, defining the areas for etching and ion implantation. Therefore, as the foundation for subsequent patterning processes such as etching, the quality of photolithography directly impacts the quality and yield of the final semiconductor integrated circuit.

[0032] Figure 1 This is a schematic diagram of the photolithography process. (For example...) Figure 1 As shown, the photolithography system 100 includes a photomask 101 and a downward-incident light beam 102 located above the photomask 101. A target substrate 300 for forming an integrated circuit is provided below the photomask 101, and a photoresist layer 200 is formed above the target substrate 300. A transparent region 101a and an opaque region 101b corresponding to the circuit pattern of the integrated circuit are formed on the photomask 101. The transparent region 101a allows the upper light beam 102 to pass through this region and be projected onto the lower photoresist layer 200, while the opaque region 101b blocks the incident light beam 102, thereby projecting the circuit pattern on the photomask 101 onto the photoresist layer 200.

[0033] In some embodiments, the photomask 101 may include silica, fused silica, calcium fluoride (CaF2), silicon carbide, silicon oxide-titanium oxide alloy, or other suitable materials known in the art. The beam 102 may be an ultraviolet light source, such as deep ultraviolet light: krypton fluoride (KrF, 248 nm), argon fluoride (ArF, 193 nm), F2 (157 nm), and far ultraviolet light (EUV, 13.5 nm). The beam 102 is incident on the photomask 101, patterned by the transparent areas 101a and opaque areas 101b on the photomask 101, and then incident on the photoresist layer 200 above the target substrate 300.

[0034] In some embodiments, the target substrate 300 is a bulk silicon substrate. Alternatively, it may be a semiconductor-on-insulator (SOI) substrate, a silicon-germanium-on-insulator (SGOI) substrate, or a germanium-on-insulator (GOI) substrate. P-type or N-type dopant is doped into the target substrate 300 to form a well region. For example, in some embodiments, to form an NMOS, a P-type dopant, such as boron (B or BF2), indium, or other P-type dopant, is doped into the target substrate 300 to form a P-type well region; in other embodiments, to form a PMOS, an N-type dopant, such as phosphorus, arsenic, or other N-type dopant, is doped into the target substrate 300 to form an N-type well region.

[0035] The photoresist layer 200 provided on the target substrate 300 is made of photosensitive material. After the incident beam 102 passes through the light-transmitting area 101a on the mask 101, an exposed area 200a and an unexposed area 200b are formed on the photoresist layer 200.

[0036] Photoresists can be classified into positive photoresists and negative photoresists according to their display effect. For positive photoresists, the exposed areas become soluble in the developer, while the unexposed areas remain insoluble in the developer; for negative photoresists, the exposed areas become insoluble in the developer, while the unexposed areas are soluble in the developer.

[0037] Photoresists are classified according to their exposure wavelength into gLine (436nm) photoresists, iLine (365nm) photoresists, KrF (248nm) photoresists, and ArF (193nm) photoresists, among others. After the adoption of deep ultraviolet light sources in lithography machines, the photoresists used with 193nm and 248nm light sources are completely different systems from gLine and iLine photoresists; this type of photoresist is called Chemically Amplified Resist (CAR).

[0038] Chemically amplified photoresist (CAR) is a type of photoresist based on the principle of chemical amplification. Its main components include polymer resin, photoacid generator (PAG), and corresponding additives and solvents.

[0039] Photoacid generators are photosensitizing compounds that decompose under light to produce acids (H+). +During post-exposure baking (PEB), these acids act as catalysts, causing unstable acid groups suspended on the polymer resin to detach and generate new acids. The detachment of these suspended groups alters the polarity of the polymer resin, and once enough suspended groups have detached, the photoresist can dissolve in the developer.

[0040] In some embodiments, photoacid-generating agents include α-(trifluoromethanesulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide (MDT), N-hydroxy-naphthaleneimide (DDSN), benzoin toluenesulfonate, tert-butylphenyl-α-(p-toluenesulfonyloxy)-acetate and tert-butyl-α-(p-toluenesulfonyloxy)-acetate, triarylsulfonium and diaryliodonium hexafluoroantimonate, hexafluoroarsenate, trifluoromethanesulfonate, N-pentafluorobenzenesulfonyloxynaphthaleneimide, perfluoroalkane sulfonates (e.g., perfluoropentanesulfonate, perfluorooctanesulfonate, perfluoromethanesulfonate), aryl (e.g., phenyl or benzyl) trifluoromethanesulfonates (e.g., triphenylsulfonium trifluoromethanesulfonate or bis-(tert-butylphenyl)iodonium trifluoromethanesulfonate), etc.

[0041] In some embodiments, the polymer resin is one or more of poly(p-hydroxystyrene) and its derivatives, polymethacrylate derivatives, cyclic olefin-maleic anhydride copolymers, and cyclic polymers.

[0042] In some embodiments, the solvents include, but are not limited to, PGMEA (propylene glycol monomethyl ether acetate) (2-methoxy-1-methylethyl acetate), PGME (propylene glycol monomethyl ether), GBL (γ-butyrolactone), cyclohexanone, n-butyl acetate, and 2-heptanone.

[0043] Chemically amplified photoresist produces photoacids after exposure to a light source. However, due to the small amount of photoacids produced, they cannot be completely neutralized with the developer, resulting in uneven acid-base neutralization. This causes developer and polymer residues in the exposed area, leading to defects and making subsequent etching processes impossible.

[0044] To address the aforementioned problems, this application provides a novel photoresist material, comprising a chemically amplified photoresist and iLine PAC incorporated into the chemically amplified photoresist. The iLine PAC is a photoactive compound used in photoresists under a 365nm light source. After exposure to a 193nm or 248nm light beam, it does not dissociate. When added to the chemically amplified photoresist, it is retained and converted into photoacids under 193nm or 248nm light irradiation, thereby increasing the total amount of photoacids in the photoresist after exposure. This allows the developer to be neutralized, preventing the formation of developer or polymer residues and eliminating the need for residual developer removal processes, thus improving the efficiency and quality of the photolithography process.

[0045] In some embodiments, PAC includes one or more of the following: n-phenylglycine, aromatic ketones (e.g., benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, etc.), anthraquinones (e.g., 2-ethylanthraquinone), benzoin derivatives (e.g., benzoin, benzoin methyl ether, benzoin isopropyl ether, benzoin n-butyl ether, etc.), and acetophenones (e.g., 1,1-dichloroacetophenone, p-tert-butyldichloroacetophenone, etc.).

[0046] The amount of iLine PAC added is determined based on its ability to neutralize the developer. Those skilled in the art can determine the amount of iLine PAC to add through multiple experiments. For example, in some embodiments, the weight of iLine PAC is less than 1% of the total weight of the photoresist material. Those skilled in the art can adjust the specific amount of iLine PAC to add according to actual needs.

[0047] In the production process of the above photoresist materials, the required materials are mixed as raw materials and produced using existing production processes. For example, in some embodiments, photoacid generators, iLine PAC, polymer resins, solvents, and additives are mixed in a clean room with constant temperature and humidity in the yellow light zone. The proportions of each component can be determined by those skilled in the art based on experience and a limited number of experiments. Then, the mixture is thoroughly stirred under nitrogen protection to form a homogeneous liquid. After multiple filtrations and product inspection, the product is packaged, marked, and stored under nitrogen protection, completing the entire production process.

[0048] Another aspect of this application provides the application of the above-mentioned photoresist material in 193nm or 248nm photolithography processes. When the chemically amplified photoresist containing iLine PAC is applied to a 193nm or 248nm light source photolithography process, the total amount of photoacid generated after illumination can be increased, effectively neutralizing the developer, avoiding photolithography defects caused by developer or polymer residues, improving the quality of photolithography, and thus increasing the yield of the final product.

[0049] In some embodiments, the application of the above-mentioned photoresist material includes the following steps:

[0050] Provide target substrate 300;

[0051] Photoresist coating: A photoresist layer 200 is formed on the target substrate 300 using the photoresist material described above;

[0052] Exposure: The photoresist layer 200 is selectively exposed to a 193nm or 248nm light beam 102 to form a potential pattern;

[0053] Development: Apply developer to the exposed photoresist layer 200 to reveal the potential pattern;

[0054] After exposure, the photoacid generator and iLine PAC in the photoresist layer 200 are converted into photoacid. During the development process, the photoacid can be completely neutralized with the developer.

[0055] Figure 2 This is a flowchart illustrating the application of the aforementioned photoresist material in a photolithography process, provided as an embodiment of this application. The following will be combined with... Figure 2 Each step in the application process is explained in detail.

[0056] First, in step S1, a target substrate 300 is provided. The target substrate 300 is configured as a bulk silicon substrate as described above. Alternatively, it can be a semiconductor-on-insulator (SOI) substrate, a silicon-germanium-on-insulator (SGOI) substrate, or a germanium-on-insulator (GOI) substrate. P-type or N-type dopant is doped into the target substrate 300 to form a well region. For example, in some embodiments, to form an NMOS, a P-type dopant, such as boron (B or BF2), indium, or other P-type dopant, is doped into the target substrate 300 to form a P-type well region; in other embodiments, to form a PMOS, an N-type dopant, such as phosphorus, arsenic, or other N-type dopant, is doped into the target substrate 300 to form an N-type well region.

[0057] Step S2: A photoresist layer 200 is formed on the target substrate 300 using the photoresist material provided in the above embodiments. This can be achieved using methods such as spin coating, dip coating, air knife coating, wire rod coating, lamination, and extrusion coating, which can be determined by those skilled in the art based on the specific circumstances. Spin coating can be further divided into static spin coating and dynamic spray coating.

[0058] Following the S2 photoresist coating process but before exposure, a S3 pre-baking step is included. In the S3 pre-baking step, a pre-baking process is performed on the target substrate 300 on which the photoresist layer 200 has been formed, allowing the photoresist layer 200 to cure and dry before being exposed to the light beam. After pre-baking, the solvent components in the photoresist layer 200 are removed, while the iLine PAC, PAG polymer resin, and additives are retained. In some embodiments, the pre-baking temperature and time are designed to facilitate solvent evaporation; for example, the pre-baking temperature can be 40°C to 120°C, and the pre-baking time can be 10 seconds to 10 minutes. The specific pre-baking temperature and time depend on the material of the photoresist layer.

[0059] During the S4 exposure process, a 193nm or 248nm light beam 102 is used to selectively irradiate the photoresist layer 200 covering the surface of the target substrate 300, creating an exposed region 200a (corresponding to the light-transmitting region 101a in the mask 101) and an unexposed region 200b (corresponding to the opaque region 101b in the mask 101) in the photoresist layer 200. After being irradiated by the light beam 102, the photoacid generator and iLine PAC in the exposed region 200a of the photoresist layer 200 are converted into photoacid under illumination.

[0060] After exposure in S4, the post-bake (PEB) process in S5 is performed to heat the photoresist layer 200 and the target substrate 300, which can help decompose the polymer in the photoresist layer 200.

[0061] Following baking in step S5, a development process in step S6 is performed, where a developer is applied to the exposed photoresist layer 200 to reveal the potential pattern. For example, in some embodiments, the target substrate 300, along with the photoresist layer 200, can be immersed in the developer for a certain period. During this process, the photoacids generated by PAG in the exposed region 200a of the photoresist layer 200 after exposure, as well as the iLine PAC, are neutralized and removed by the developer, eliminating the need for an additional developer removal process. The composition of the developer depends on the composition of the photoresist. After the development process, a pattern is formed in the photoresist layer 200, which serves as a masking element for subsequent further processing (e.g., etching) of the target substrate 300. In other embodiments, processes such as spin coating or spray coating can also be used to coat the surface of the photoresist layer 200 with the developer.

[0062] After passing through the above steps S1 to S6, the circuit pattern is successfully transferred from the mask 101 to the photoresist layer 200. Subsequently, the target substrate 300 can be etched by dry etching or wet etching to transfer the pattern of the photoresist layer 200 to the target substrate 300 below.

[0063] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A photoresist material for 193 nm or 248 nm photolithography processes, characterized in that, include: Chemically amplified photoresist, and iLine PAC added to the chemically amplified photoresist; The chemically amplified photoresist is a photoresist used under a 193 nm or 248 nm light source; the iLine PAC is a photoactive compound used under a 365 nm light source. After exposure to a 193 nm or 248 nm light source, the iLine PAC can be converted into a photoacid, achieving acid-base neutralization with the developer during subsequent development. The iLine PAC includes one or more of the following: n-phenylglycine, benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-ethylanthraquinone, benzoin, benzoin methyl ether, benzoin isopropyl ether, benzoin n-butyl ether, 1,1-dichloroacetophenone, and p-tert-butyldichloroacetophenone. The chemically amplified photoresist includes a photoacid generator, a polymer resin, a solvent, and additives.

2. The photoresist material according to claim 1, characterized in that, The iLine PAC accounts for less than 1% of the total weight of the photoresist material.

3. The photoresist material according to claim 1, characterized in that, The photoacid-generating agent produces acid after exposure, and the acid can induce the departure of acid-indestructible groups from the polymer resin during the baking process after exposure.

4. The photoresist material according to claim 1, characterized in that, The polymer resin is one or more of poly(p-hydroxystyrene) and its derivatives, polymethyl methacrylate derivatives, cyclic olefin-maleic anhydride copolymers, and cyclic polymers.

5. The application of a photoresist material as described in any one of claims 1-4 in a 193 nm or 248 nm photolithography process.

6. The application according to claim 5, characterized in that, Includes the following steps: Provide the target substrate; Photoresist coating: A photoresist layer is formed on the target substrate using the photoresist material; Exposure: The photoresist layer is selectively exposed to a 193 nm or 248 nm light beam to form a potential pattern; Development: Applying a developer to the exposed photoresist layer to reveal the underlying pattern; After exposure, the photoacid generator and iLine PAC in the photoresist layer are converted into photoacid. During the development process, the photoacid can be neutralized with the acid-base of the developer.

7. The application according to claim 6, characterized in that, The process includes a pre-baking step before exposure and a post-baking step after exposure.

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