JP-7856592-B2 - Pattern formation method

JP7856592B2JP 7856592 B2JP7856592 B2JP 7856592B2JP-7856592-B2

Inventors

小林直貴
岩森頌平
郡大佑
石綿健汰

Assignees

信越化学工業株式会社

Dates

Publication Date: 20260511
Application Date: 20230215

Claims (6)

A method for forming a pattern on a substrate to be processed, (i-1) A step of forming an organic underlayer film on a substrate to be processed, forming a tin-containing interlayer film on the organic underlayer film, and further forming an upper resist film on the tin-containing interlayer film. (i-2) A step of pattern exposure of the upper resist film, and then developing it to form an upper resist pattern. (i-3) A step of transferring the upper resist pattern to the tin-containing interlayer by dry etching the tin-containing interlayer using the upper resist pattern as a mask, and further forming an organic underlayer pattern in which a portion of the tin-containing interlayer remains on the upper part of the pattern by dry etching the organic underlayer using the tin-containing interlayer on which the upper resist pattern has been transferred as a mask. (i-4) A step of removing the portion of the tin-containing interlayer remaining on the upper part of the organic underlayer pattern by dry etching. (i-5) A step of forming an inorganic silicon-containing film made of polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxidnitride, silicon carbide, or a composite material thereof, by CVD or ALD, so as to cover the organic underlayer film pattern. (i-6) A step of removing a portion of the inorganic silicon-containing film by dry etching to expose the upper part of the organic underlayer film pattern. (i-7) A step of removing the organic underlayer film pattern to form an inorganic silicon-containing film pattern whose pattern pitch is half that of the upper resist pattern, and (i-8) A step of processing the substrate to be processed using the inorganic silicon-containing film pattern as a mask to form a pattern on the substrate to be processed, The tin-containing interlayer is formed from a tin-containing interlayer-forming composition containing a compound having a crosslinkable organic structure . A pattern-forming method characterized by using the compound having one or more organic groups selected from the group consisting of any of the following general formulas (a-1) to (a-3) and (b-1) to (b-4) as the crosslinkable organic structure . (In the general formulas (a-1) to (a-3) above, R1 is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, q represents 0 or 1, and * represents a bond.) (In the above general formulas (b-1) and (b-3), R1 ' is a hydrogen atom or a methyl group, and they may be the same or different from each other within the same formula. In (b-3) to (b-4), R2 is a hydrogen atom, a substituted or unsubstituted saturated or unsaturated monovalent organic group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted arylalkyl group having 7 to 31 carbon atoms. * represents a bond.)
A method for forming a pattern on a substrate to be processed, (ii-1) A step of forming an organic underlayer film on a substrate to be processed, forming a tin-containing interlayer film on the organic underlayer film, and further forming an upper resist film on the tin-containing interlayer film. (ii-2) A step of pattern exposure of the upper resist film, and then developing it to form an upper resist pattern, (ii-3) A step of transferring the upper layer resist pattern to the tin-containing interlayer by dry etching the tin-containing interlayer using the upper layer resist pattern as a mask, and further forming an organic underlayer pattern in which a portion of the tin-containing interlayer remains on the upper part of the pattern by dry etching the organic underlayer using the tin-containing interlayer on which the upper layer resist pattern has been transferred as a mask. (ii-4) A step of forming an inorganic silicon-containing film made of polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxidnitride, silicon carbide, or a composite material thereof, by CVD or ALD, so as to cover the part of the tin-containing interlayer film and the organic underlayer film pattern. (ii-5) A step of removing a portion of the inorganic silicon-containing film by dry etching to expose the upper part of the portion of the tin-containing interlayer film. (ii-6) A step of removing the portion of the tin-containing interlayer remaining on the upper part of the organic underlayer pattern by dry etching. (ii-7) A step of removing the organic underlayer film pattern by dry etching to form an inorganic silicon-containing film pattern whose pattern pitch is half that of the upper resist pattern, (ii-8) The process includes a step of processing the substrate to be processed using the inorganic silicon-containing film pattern as a mask to form a pattern on the substrate to be processed, The tin-containing interlayer is formed from a tin-containing interlayer-forming composition containing a compound having a crosslinkable organic structure . A pattern-forming method characterized by using the compound having one or more organic groups selected from the group consisting of any of the following general formulas (a-1) to (a-3) and (b-1) to (b-4) as the crosslinkable organic structure . (In the general formulas (a-1) to (a-3) above, R1 is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, q represents 0 or 1, and * represents a bond.) (In the above general formulas (b-1) and (b-3), R1 ' is a hydrogen atom or a methyl group, and they may be the same or different from each other within the same formula. In (b-3) to (b-4), R2 is a hydrogen atom, a substituted or unsubstituted saturated or unsaturated monovalent organic group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted arylalkyl group having 7 to 31 carbon atoms. * represents a bond.)
The pattern forming method according to claim 1 or 2, characterized in that step (i-4) or (ii-6) includes etching the tin-containing interlayer with plasma formed in an H2- containing gas.
The pattern formation method according to claim 1 or 2, characterized in that the tin-containing interlayer is formed by a spin-coating method using a tin-containing interlayer-forming composition.
The pattern forming method according to claim 1 or 2, characterized in that a water-repellent coating film is further formed on the upper resist film in step (i-1) or (ii-1).
The pattern forming method according to claim 1 or 2, characterized in that an organic adhesion film is formed between the tin-containing interlayer film and the upper resist film in step (i-1) or (ii-1).

Description

This invention relates to a pattern formation method using a sidewall spacer method. In the 1980s, light exposure using mercury lamps with g-line (436 nm) or i-line (365 nm) wavelengths as the light source for resist pattern formation was widely used. As a means of further miniaturization, shortening the exposure wavelength was considered effective, and in mass production processes for 64Mbit (processing dimensions of 0.25 μm or less) DRAM (Dynamic Random Access Memory) from the 1990s onward, a short-wavelength KrF excimer laser (248 nm) was used as the exposure light source, replacing the i-line (365 nm). However, the manufacturing of DRAMs with integration density of 256M and 1G or higher, which require even finer processing technology (processing dimensions of 0.2 μm or less), necessitates shorter wavelength light sources, and photography using ArF excimer lasers (193 nm) has been seriously considered for about 10 years. Initially, ArF lithography was supposed to be applied to the fabrication of 180 nm node devices, but KrF excimer lithography was extended to the mass production of 130 nm node devices, and the full-scale application of ArF lithography began at the 90 nm node. Furthermore, mass production of 65 nm node devices is being carried out by combining it with lenses that have increased the NA to 0.9. For the next 45 nm node devices, the exposure wavelength is being shortened, and F2 lithography with a wavelength of 157 nm has been nominated as a candidate. However, due to various problems such as increased scanner costs resulting from the large use of expensive CaF2 single crystals in the projection lens, changes to the optical system due to the introduction of hard pellicles because of the extremely low durability of soft pellicles, and a decrease in the etching resistance of the resist film, the development of F2 lithography was discontinued and ArF immersion lithography was introduced. In ArF immersion lithography, water with a refractive index of 1.44 is inserted between the projection lens and the wafer using a partial-fill method. This enables high-speed scanning, and mass production of 45 nm node devices is being carried out using lenses with an NA of 1.3. While vacuum ultraviolet (EUV) lithography at a wavelength of 13.5 nm has been put into practical use as a lithography technology at the 32 nm node, the optical exposure techniques used as a general-purpose technology are approaching the intrinsic resolution limit inherent in the wavelength of the light source. Therefore, one of the miniaturization technologies that has attracted attention in recent years is the double patterning process (Non-Patent Literature 1), in which a pattern is formed in the first exposure and development, and a second exposure forms a pattern exactly between the first pattern. Many processes have been proposed for double patterning. For example, (1) a photoresist pattern with a line-to-space ratio of 1:3 is formed in the first exposure and development, the underlying hard mask is processed by dry etching, another hard mask is laid on top, a line pattern is formed in the space areas of the first exposure by exposure and development of the photoresist film, and the hard mask is processed by dry etching to form a line-and-space pattern with half the pitch of the initial pattern. Also, (2) a photoresist pattern with a space-to-line ratio of 1:3 is formed in the first exposure and development, the underlying hard mask is processed by dry etching, a photoresist film is applied on top, a second space pattern is exposed to the remaining hard mask area, and the hard mask is processed by dry etching. In both cases, the hard mask is processed by two dry etchings. The former method requires two hard mask layers, while the latter method requires only one hard mask layer, but it requires the formation of trench patterns, which are more difficult to resolve than line patterns. Furthermore, the latter method includes using negative resist material to form the trench patterns. This method allows the use of the same high-contrast light as when forming lines with positive-developed patterns, but the dissolution contrast of negative resist material is lower than that of positive-developed resist material. Therefore, comparing the formation of lines with positive-developed resist material and the formation of trench patterns of the same size with negative-developed resist material, the negative-developed resist material results in lower resolution. In the latter method, it is conceivable to apply thermal flow methods, where a wide trench pattern is formed using positive-developed resist material and then the substrate is heated to shrink the trench pattern, or the RELACS method, where a water-soluble film is coated onto the developed trench pattern and then heated to crosslink the resist film surface and shrink the trenches. However, these methods suffer from drawbacks such as a deterioration of proximity bias and increased process