JP2007025634A - Resist protective coating material and patterning process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective coating material effective for liquid immersion lithography, the material which facilitates preferable liquid immersion lithography, can be removed simultaneously with a photoresist layer during development, and has excellent process compatibility, and to provide a patterning process using the material. <P>SOLUTION: The resist protective coating material comprises a polymer compound having a partial structure expressed by general formula (1). In formula (1), R<SP>0</SP>represents a hydrogen atom, a fluorine atom, or a 1-8C alkyl group or alkylene group; and R<SP>1</SP>represents a 1-6C straight chain or branched alkyl group or alkylene group and containing at least one fluorine atom. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to microfabrication in a manufacturing process of a semiconductor device or the like, particularly in immersion photolithography in which an ArF excimer laser having a wavelength of 193 nm is used as a light source and water is inserted between a projection lens and a wafer to protect the photoresist. The present invention relates to a resist protective film material used as a material and a resist pattern forming method using the same.

In recent years, with the higher integration and higher speed of LSIs, there is a demand for finer pattern rules. In light exposure currently used as a general-purpose technology, the intrinsic resolution limit derived from the wavelength of the light source Is approaching. As exposure light used for forming a resist pattern, light exposure using a g-ray (436 nm) or i-line (365 nm) of a mercury lamp as a light source has been widely used. As a means for further miniaturization, a method of shortening the exposure wavelength is effective, and for mass production processes after 64 Mbit (process size is 0.25 μm or less) DRAM (Dynamic Random Access Memory). As a light source for exposure, a short wavelength KrF excimer laser (248 nm) was used in place of i-line (365 nm). However, in order to manufacture DRAMs with a density of 256M and 1G or more that require finer processing technology (processing dimensions of 0.2 μm or less), a light source with a shorter wavelength is required, and an ArF excimer has been used for about 10 years. Photography using a laser (193 nm) has been studied in earnest. At first, ArF lithography was supposed to be applied from the device fabrication of the 180 nm node, but KrF excimer lithography was extended to 130 nm node device mass production, and full-scale application of ArF lithography is from the 90 nm node. Further, a 65 nm node device is being studied in combination with a lens whose NA is increased to 0.9. For the next 45 nm node device, the exposure wavelength has been shortened, and F ₂ lithography with a wavelength of 157 nm was nominated. However, various factors such as an increase in the cost of the scanner by using a large amount of expensive CaF ₂ single crystal for the projection lens, a change in the optical system due to the introduction of the hard pellicle because the durability of the soft pellicle is extremely low, and a decrease in resist etching resistance, etc. Because of this problem, it was proposed to postpone F ₂ lithography and early introduction of ArF immersion lithography (Non-patent Document 1: Proc. SPIE Vol. 4690 xxix).

  In ArF immersion lithography, it has been proposed to impregnate water between the projection lens and the wafer. The refractive index of water at 193 nm is 1.44, and it is possible to form a pattern using a lens having an NA of 1.0 or more. Theoretically, the NA can be increased to 1.44. The resolution is improved by the improvement of NA, and the possibility of a 45 nm node is shown by a combination of a lens of NA 1.2 or higher and strong super-resolution technology (Non-patent Document 2: Proc. SPIE Vol. 5040 p724).

  Here, various problems due to the presence of water on the resist film have been pointed out. This includes shape change caused by dissolution of the generated acid and an amine compound added to the resist film as a quencher in water, and pattern collapse due to swelling. Therefore, it is proposed that it is effective to provide a protective film between the resist film and water (Non-patent Document 3: 2nd Immersion Work Shop, July 11, 2003, Resist and Cover Material Investigation Lithography). .

  The protective film on the resist upper layer has been studied as an antireflection film until now. Examples thereof include the ARCOR method disclosed in Patent Documents 1 to 3, Japanese Patent Application Laid-Open Nos. 62-62520, 62-62521, and 60-38821. The ARCOR method is a method including a step of forming a transparent antireflection film on a resist film and peeling off after exposure, and is a method of forming a fine pattern with high accuracy and high alignment accuracy by the simple method. When a perfluoroalkyl compound (perfluoroalkyl polyether, perfluoroalkylamine), which is a low refractive index material, is used as the antireflection film, the reflected light at the resist-antireflection film interface is greatly reduced, and the dimensional accuracy is improved. As the fluorine-based material, in addition to the aforementioned materials, perfluoro (2,2-dimethyl-1,3-dioxole) -tetrafluoroethylene copolymer disclosed in JP-A-5-74700 can be used. Amorphous polymers such as cyclized polymers of fluoro (allyl vinyl ether) and perfluorobutenyl vinyl ether have been proposed.

  However, since the perfluoroalkyl compound has low compatibility with organic substances, chlorofluorocarbon is used as a diluent for controlling the coating film thickness. Therefore, its use has become a problem. Moreover, the said compound had a problem in uniform film formability, and it could not be said that it was enough as an antireflection film. Further, before developing the photoresist film, the antireflection film had to be peeled off with chlorofluorocarbon. For this reason, there have been significant demerits in practical use, such as the need to add a system for removing the antireflection film to the conventional apparatus and the considerable cost of the fluorocarbon solvent.

  When the antireflection film is peeled off without adding to the conventional apparatus, it is most desirable to peel off using the developing unit. Since the solution used in the photoresist developing unit is an alkaline aqueous solution as a developer and pure water as a rinse solution, it can be said that an antireflection film material that can be easily peeled off with these solutions is desirable. Therefore, many water-soluble antireflection film materials and pattern forming methods using these have been proposed. For example, Patent Documents 5 and 6: JP-A-6-273926, Patent 2803549, and the like.

  However, since the water-soluble protective film is dissolved in water during exposure, it cannot be used for immersion lithography. On the other hand, water-insoluble fluorine-based polymers have the problems that a special fluorocarbon-based release agent is required and that a special cup for fluorocarbon solvents is required. There was a need for a protective film.

Since the hexafluoroalcohol group has alkali solubility and high water repellency, it has been studied as a resist protective film for immersion exposure (Non-patent Document 4: Proc. SPIE Vol. 5753-05 (2005). )).
Furthermore, development of a resist protective film having high hydrophobicity and capable of alkali development is desired.

Proc. SPIE Vol. 4690 xxix Proc. SPIE Vol. 5040 p724 2nd Immersion Work Shop, July 11, 2003, Resist and Cover Material Investing for Immersion Lithography Proc. SPIE Vol. 5753-05 (2005) JP-A-62-62520 JP-A-62-62521 JP 60-38821 A JP-A-5-74700 JP-A-6-273926 Japanese Patent No. 2803549

  The present invention has been made in view of the above circumstances, and enables good immersion lithography and can be removed at the same time as development of a photoresist layer, and is effective for immersion lithography having excellent process applicability. An object of the present invention is to provide a protective film material and a pattern forming method using such a material.

  As a result of intensive studies to achieve the above object, the present inventors have formed a film of a polymer compound having a partial structure represented by the following general formula (1) on a resist film as a resist protective film material In addition, this protective film (resist upper layer film) is water-insoluble and can be dissolved in an alkaline aqueous solution, and does not mix with the resist layer, and can be peeled off together with development during development with alkaline water. It has been found that process applicability is considerably widened, and the present invention has been made.

（式中、Ｒ⁰は水素原子、フッ素原子、又は炭素数１〜８のアルキル基又はアルキレン基であり、Ｒ¹は炭素数１〜６の直鎖状又は分岐状のアルキル基又はアルキレン基で、少なくとも１個以上のフッ素原子を含む。）

(In the formula, R ⁰ is a hydrogen atom, a fluorine atom, an alkyl group or alkylene group having 1 to 8 carbon atoms, and R ¹ is a linear or branched alkyl group or alkylene group having 1 to 6 carbon atoms. And at least one fluorine atom.)

（式中、Ｒ⁰は水素原子、フッ素原子、又は炭素数１〜８のアルキル基又はアルキレン基であり、Ｒ¹は炭素数１〜６の直鎖状又は分岐状のアルキル基又はアルキレン基で、少なくとも１個以上のフッ素原子を含む。）
請求項２：
下記一般式（２）で示される繰り返し単位を有する高分子化合物を含むことを特徴とするレジスト保護膜材料。

（式中、Ｒ⁰は水素原子、フッ素原子、又は炭素数１〜８のアルキル基又はアルキレン基であり、Ｒ¹は炭素数１〜６の直鎖状又は分岐状のアルキル基又はアルキレン基で、少なくとも１個以上のフッ素原子を含む。Ｒ²は炭素数１〜１０の直鎖状、分岐状又は環状のアルキレン基又はアルキリジン基で、フッ素原子を有していてもよく、Ｒ⁰又はＲ¹と結合して環を形成してもよい。Ｒ⁰又はＲ¹とＲ²が結合してこれらが結合する炭素原子と共に環を形成する場合、Ｒ⁰は炭素数１〜８のアルキレン基又はＲ¹は炭素数１〜６の直鎖状又は分岐状のアルキレン基、Ｒ²は炭素数１〜１０の直鎖状又は分岐状のアルキリジン基を示す。又は、Ｒ¹とＲ²が結合してこれらが結合している炭素原子と共に環を形成していてもよく、環を形成する場合、Ｒ¹は炭素数１〜６の直鎖状又は分岐状のアルキレン基、Ｒ²は炭素数１〜１０の直鎖状又は分岐状のアルキリジン基を示す。Ｒ³、Ｒ⁴は水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｘは−Ｏ−、−Ｃ（＝Ｏ）−Ｏ−又は−Ｃ（＝Ｏ）−Ｏ−Ｒ⁵−Ｃ（＝Ｏ）−Ｏ−である。Ｒ⁵は炭素数１〜１０の直鎖状、分岐状又は環状のアルキレン基である。０≦ａ≦１、０≦ｂ≦１、０＜ａ＋ｂ≦１の範囲である。）
請求項３：
更に、高分子化合物が、カルボキシル基を有する繰り返し単位、一般式（２）で示される以外のフルオロアルコールを有する繰り返し単位、及びパーフルオロアルキル基を有する繰り返し単位から選ばれる１種又は２種以上の繰り返し単位を有する請求項２記載のレジスト保護膜材料。
請求項４：
更に、上記高分子化合物を溶解する溶媒を含有する請求項１、２又は３記載のレジスト保護膜材料。
請求項５：
ウエハーに形成したフォトレジスト層上にレジスト上層膜材料による保護膜を形成し、露光を行った後、現像を行うリソグラフィーによるパターン形成方法において、上記レジスト上層膜材料として請求項１乃至４のいずれか１項記載のレジスト保護膜材料を用いることを特徴とするパターン形成方法。
請求項６：
ウエハーに形成したフォトレジスト層上にレジスト上層膜材料による保護膜を形成し、水中で露光を行った後、現像を行う液浸リソグラフィーによるパターン形成方法において、上記レジスト上層膜材料として請求項１乃至４のいずれか１項記載のレジスト保護膜材料を用いることを特徴とするパターン形成方法。
請求項７：
液浸リソグラフィーが、１８０〜２５０ｎｍの範囲の露光波長を用い、投影レンズとウエハーの間に水を挿入させたものである請求項６記載のパターン形成方法。
請求項８：
露光後に行う現像工程において、アルカリ現像液によりフォトレジスト層の現像とレジスト上層膜材料の保護膜の剥離とを同時に行う請求項６又は７記載のパターン形成方法。 That is, the present invention provides the following resist protective film material and pattern forming method.
Claim 1:
A resist protective film material comprising a polymer compound having a partial structure represented by the following general formula (1).

(In the formula, R ⁰ is a hydrogen atom, a fluorine atom, an alkyl group or alkylene group having 1 to 8 carbon atoms, and R ¹ is a linear or branched alkyl group or alkylene group having 1 to 6 carbon atoms. And at least one fluorine atom.)
Claim 2:
A resist protective film material comprising a polymer compound having a repeating unit represented by the following general formula (2).

(In the formula, R ⁰ is a hydrogen atom, a fluorine atom, an alkyl group or alkylene group having 1 to 8 carbon atoms, and R ¹ is a linear or branched alkyl group or alkylene group having 1 to 6 carbon atoms. R ² is a linear, branched or cyclic alkylene group or alkylidene group having 1 to 10 carbon atoms, which may have a fluorine atom, R ⁰ or R ^A ring may be formed by bonding to ^{1. When} R ⁰ or R ¹ and R ² are bonded to form a ring together with the carbon atom to which these are bonded, R ⁰ is an alkylene group having 1 to 8 carbon atoms or R ¹ represents a linear or branched alkylene group having 1 to 6 carbon atoms, and R ² represents a linear or branched alkylidine group having 1 to 10 carbon atoms, or R ¹ and R ² are bonded to each other. May form a ring together with the carbon atom to which they are bonded, and when forming a ring, ¹ is a linear or branched alkylene groups having 1 to 6 carbon atoms, R ² is a straight or branched alkylidine group having 1 to 10 carbon atoms .R ^3, R ⁴ is a hydrogen atom, a fluorine atom X is —O—, —C (═O) —O—, or —C (═O) —O—R ⁵ —C (═O) —O—. R ⁵ is a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms in the range of 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 <a + b ≦ 1.
Claim 3:
Furthermore, the polymer compound is one or more selected from a repeating unit having a carboxyl group, a repeating unit having a fluoroalcohol other than that represented by the general formula (2), and a repeating unit having a perfluoroalkyl group. The resist protective film material of Claim 2 which has a repeating unit.
Claim 4:
Furthermore, the resist protective film material of Claim 1, 2, or 3 containing the solvent which melt | dissolves the said high molecular compound.
Claim 5:
5. A lithography pattern forming method in which a protective film made of a resist upper layer film material is formed on a photoresist layer formed on a wafer, exposed and then developed, and the resist upper layer film material is used as the resist upper layer film material. A pattern forming method comprising using the resist protective film material according to claim 1.
Claim 6:
A pattern forming method by immersion lithography in which a protective film made of a resist upper layer film material is formed on a photoresist layer formed on a wafer, exposed in water, and then developed, wherein the resist upper layer film material is used as the resist upper layer film material. 5. A pattern forming method using the resist protective film material according to any one of 4 above.
Claim 7:
The pattern forming method according to claim 6, wherein the immersion lithography uses an exposure wavelength in the range of 180 to 250 nm and water is inserted between the projection lens and the wafer.
Claim 8:
8. The pattern forming method according to claim 6, wherein the development of the photoresist layer and the removal of the protective film of the resist upper layer film material are simultaneously performed with an alkali developer in the development step performed after the exposure.

  According to the pattern forming method of the present invention, the resist protective film formed on the resist film is non-water soluble and can be dissolved in an alkaline aqueous solution (alkaline developer), and does not mix with the resist film. Good immersion lithography can be performed, and development of the resist film and removal of the protective film can be simultaneously performed at the same time during alkali development.

  In particular, the resist protective film material of the present invention is a pattern forming method by immersion lithography in which a protective film made of a resist upper layer film material is formed on a photoresist layer formed on a wafer, exposed in water, and then developed. It is suitably used as the resist upper layer film material, and is characterized by adding a polymer compound having a partial structure represented by the following general formula (1).

（式中、Ｒ⁰は水素原子、フッ素原子、又は炭素数１〜８のアルキル基又はアルキレン基であり、Ｒ¹は炭素数１〜６の直鎖状又は分岐状のアルキル基又はアルキレン基で、少なくとも１個以上のフッ素原子を含む。）
なお、Ｒ⁰又はＲ¹がアルキレン基である場合、式（１）は２価の基となる。但し、Ｒ⁰とＲ¹は同時にアルキレン基にならない。

(In the formula, R ⁰ is a hydrogen atom, a fluorine atom, an alkyl group or alkylene group having 1 to 8 carbon atoms, and R ¹ is a linear or branched alkyl group or alkylene group having 1 to 6 carbon atoms. And at least one fluorine atom.)
When R ⁰ or R ¹ is an alkylene group, the formula (1) is a divalent group. However, R ⁰ and R ¹ are not an alkylene group at the same time.

（式中、Ｒ⁰は水素原子、フッ素原子、又は炭素数１〜８のアルキル基又はアルキレン基であり、Ｒ¹は炭素数１〜６の直鎖状又は分岐状のアルキル基又はアルキレン基で、少なくとも１個以上のフッ素原子を含む。Ｒ²は炭素数１〜１０の直鎖状、分岐状又は環状のアルキレン基又はアルキリジン基で、フッ素原子を有していてもよく、Ｒ⁰又はＲ¹と結合して環を形成してもよい。Ｒ⁰又はＲ¹とＲ²が結合してこれらが結合する炭素原子と共に環を形成する場合、Ｒ⁰は炭素数１〜８のアルキレン基又はＲ¹は炭素数１〜６の直鎖状又は分岐状のアルキレン基、Ｒ²は炭素数１〜１０の直鎖状又は分岐状のアルキリジン基を示す。又は、Ｒ¹とＲ²が結合してこれらが結合している炭素原子と共に環を形成していてもよく、環を形成する場合、Ｒ¹は炭素数１〜６の直鎖状又は分岐状のアルキレン基、Ｒ²は炭素数１〜１０の直鎖状又は分岐状のアルキリジン基を示す。Ｒ³、Ｒ⁴は水素原子、フッ素原子、メチル基又はトリフルオロメチル基である。Ｘは−Ｏ−、−Ｃ（＝Ｏ）−Ｏ−又は−Ｃ（＝Ｏ）−Ｏ−Ｒ⁵−Ｃ（＝Ｏ）−Ｏ−である。Ｒ⁵は炭素数１〜１０の直鎖状、分岐状又は環状のアルキレン基である。０≦ａ≦１、０≦ｂ≦１、０＜ａ＋ｂ≦１の範囲である。） As the repeating unit of the polymer compound having the partial structure represented by the general formula (1), those represented by the following general formula (2) are preferable.

(In the formula, R ⁰ is a hydrogen atom, a fluorine atom, an alkyl group or alkylene group having 1 to 8 carbon atoms, and R ¹ is a linear or branched alkyl group or alkylene group having 1 to 6 carbon atoms. R ² is a linear, branched or cyclic alkylene group or alkylidene group having 1 to 10 carbon atoms, which may have a fluorine atom, R ⁰ or R ^A ring may be formed by bonding to ^{1. When} R ⁰ or R ¹ and R ² are bonded to form a ring together with the carbon atom to which these are bonded, R ⁰ is an alkylene group having 1 to 8 carbon atoms or R ¹ represents a linear or branched alkylene group having 1 to 6 carbon atoms, and R ² represents a linear or branched alkylidine group having 1 to 10 carbon atoms, or R ¹ and R ² are bonded to each other. May form a ring together with the carbon atom to which they are bonded, and when forming a ring, ¹ is a linear or branched alkylene groups having 1 to 6 carbon atoms, R ² is a straight or branched alkylidine group having 1 to 10 carbon atoms .R ^3, R ⁴ is a hydrogen atom, a fluorine atom X is —O—, —C (═O) —O—, or —C (═O) —O—R ⁵ —C (═O) —O—. R ⁵ is a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms in the range of 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 <a + b ≦ 1.

  In this case, the polymer having the partial structure of the formula (1) is preferably a polymer having a repeating unit of the formula (2), and the polymer having the repeating unit represented by the general formula (2) can be used. And a resist protective film having a dissolution rate of a developing solution of 2.38 mass% tetramethylammonium hydroxide aqueous solution of 300 Å / s or more can be formed.

  Specific examples of the monomer that gives the repeating unit a represented by the general formula (2) include the following.

  Specific examples of the monomer that gives the repeating unit b represented by the general formula (2) include the following.

  As the repeating unit of the resist protective film polymer of the present invention, the unit a and / or b represented by the general formula (2) is essential, but in order to prevent alkali solubility and mixing with the resist film, The repeating unit c having a group can be copolymerized. Specific examples of the repeating unit c include the following.

  Moreover, the repeating unit d which has fluoro alcohol other than shown by General formula (2) can be copolymerized. Specific examples of the repeating unit d can be given below.

  Furthermore, in order to prevent mixing with the resist film, a repeating unit e having a perfluoroalkyl group can be copolymerized. The repeating unit e can be exemplified below.

  The ratio of the repeating units a, b, c, d, e is 0 ≦ a ≦ 1.0, 0 ≦ b ≦ 1.0, 0 <a + b ≦ 1.0, 0 ≦ c ≦ 0.9, 0 ≦ d. ≦ 0.9, 0 ≦ e ≦ 0.9, preferably 0 ≦ a ≦ 0.8, 0 ≦ b ≦ 0.8, 0.1 ≦ a + b ≦ 0.8, 0 ≦ c ≦ 0.6, 0 ≦ d ≦ 0.8, 0 ≦ e ≦ 0.8, and a + b + c + d + e = 1.

  Here, a + b + c + d + e = 1 means that in a polymer compound containing repeating units a, b, c, d and e, the total amount of repeating units a, b, c, d and e is the total amount of all repeating units. It shows that it is 100 mol%.

  The polymer compound of the present invention has a polystyrene-reduced weight average molecular weight of 1,000 to 500,000, preferably 2,000 to 30,000, as determined by gel permeation chromatography (GPC). If the weight average molecular weight is too small, mixing with the resist material occurs, or it becomes easy to dissolve in water. If it is too large, there may be a problem in film formability after spin coating, or the alkali solubility may be lowered.

  In order to synthesize these polymer compounds, as one method, a monomer having an unsaturated bond for obtaining repeating units a to e is added to a radical initiator in an organic solvent, and heat polymerization is performed to obtain a polymer. A compound can be obtained. Examples of the organic solvent used at the time of polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane, methanol, ethanol, isopropanol and the like. As polymerization initiators, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2-azobis (2-methylpropio) Nate), benzoyl peroxide, lauroyl peroxide, and the like, preferably polymerized by heating from 50 ° C to 80 ° C. The reaction time is 2 to 100 hours, preferably 5 to 20 hours. The sulfo group in the monomer stage is an alkali metal salt and may be converted to a sulfonic acid residue by acid treatment after polymerization.

  The resist protective film material of the present invention is preferably used by dissolving the polymer compound in a solvent. In this case, it is preferable to use a solvent so that the concentration of the polymer compound is 0.1 to 20% by mass, particularly 0.5 to 10% by mass, from the viewpoint of film formability by spin coating.

  The solvent used is not particularly limited, but a solvent that dissolves the resist layer is not preferable. For example, ketones such as cyclohexanone and methyl-2-n-amyl ketone used as a resist solvent, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol Alcohols such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether and diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate , Ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, 3-ethoxy Ethyl propionate, acetate tert- butyl, tert- butyl propionate, and esters such as propylene glycol monobutyl -tert- butyl ether acetate is not preferable.

  Examples of the solvent that does not dissolve the resist layer include non-polar solvents such as higher alcohols having 4 or more carbon atoms, toluene, xylene, anisole, hexane, cyclohexane, and ether. In particular, higher alcohols having 4 or more carbon atoms are preferably used. Specifically, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-amyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-diethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl 2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentane 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol , Diisopropyl ether, diisobutyl ether, methylcyclopentyl ether, and methylcyclohexyl ether.

On the other hand, a fluorine-based solvent can be preferably used because it does not dissolve the resist layer.
Examples of such fluorine-substituted solvents include 2-fluoroanisole, 3-fluoroanisole, 4-fluoroanisole, 2,3-difluoroanisole, 2,4-difluoroanisole, 2,5-difluoroanisole, 5, 8-difluoro-1,4-benzodioxane, 2,3-difluorobenzyl alcohol, 1,3-difluoro-2-propanol, 2 ′, 4′-difluoropropiophenone, 2,4-difluorotoluene, trifluoroacetaldehyde Ethyl hemiacetal, trifluoroacetamide, trifluoroethanol, 2,2,2-trifluoroethyl butyrate, ethyl heptafluorobutyrate, ethyl heptafluorobutyl acetate, ethyl hexafluoroglutaryl methyl, ethyl-3-hydroxy 4,4,4-trifluorobutyrate, ethyl-2-methyl-4,4,4-trifluoroacetoacetate, ethyl pentafluorobenzoate, ethyl pentafluoropropionate, ethyl pentafluoropropynyl acetate, ethyl perfluoroocta Noate, ethyl-4,4,4-trifluoroacetoacetate, ethyl-4,4,4-trifluorobutyrate, ethyl-4,4,4-trifluorocrotonate, ethyltrifluorosulfonate, ethyl-3 -(Trifluoromethyl) butyrate, ethyl trifluoropyruvate, S-ethyl trifluoroacetate, fluorocyclohexane, 2,2,3,3,4,4,4-heptafluoro-1-butanol, 1,1,1 , 2,2,3,3-heptafluoro-7,7-dimethyl Til-4,6-octanedione, 1,1,1,3,5,5,5-heptafluoropentane-2,4-dione, 3,3,4,4,5,5,5-heptafluoro- 2-pentanol, 3,3,4,4,5,5,5-heptafluoro-2-pentanone, isopropyl 4,4,4-trifluoroacetoacetate, methyl perfluorodenanoate, methyl perfluoro (2 -Methyl-3-oxahexanoate), methyl perfluorononanoate, methyl perfluorooctanoate, methyl-2,3,3,3-tetrafluoropropionate, methyl trifluoroacetoacetate, 1,1, 1,2,2,6,6,6-octafluoro-2,4-hexanedione, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 1H, H, 2H, 2H-perfluoro-1-decanol, perfluoro (2,5-dimethyl-3,6-dioxane anionic) acid methyl ester, 2H-perfluoro-5-methyl-3,6-dioxanonane, 1H 1H, 2H, 3H, 3H-perfluorononane-1,2-diol, 1H, 1H, 9H-perfluoro-1-nonanol, 1H, 1H-perfluorooctanol, 1H, 1H, 2H, 2H-perfluoro Octanol, 2H-perfluoro-5,8,11,14-tetramethyl-3,6,9,12,15-pentaoxaoctadecane, perfluorotributylamine, perfluorotrihexylamine, perfluoro-2,5 8-trimethyl-3,6,9-trioxadodecanoic acid methyl ester, perfluorotripentyl Min, perfluorotripropylamine, 1H, 1H, 2H, 3H, 3H-perfluoroundecane-1,2-diol, trifluorobutanol 1,1,1-trifluoro-5-methyl-2,4-hexanedione 1,1,1-trifluoro-2-propanol, 3,3,3-trifluoro-1-propanol, 1,1,1-trifluoro-2-propyl acetate, perfluorobutyltetrahydrofuran, perfluoro (butyl Tetrahydrofuran), perfluorodecalin, perfluoro (1,2-dimethylcyclohexane), perfluoro (1,3-dimethylcyclohexane), propylene glycol trifluoromethyl ether acetate, propylene glycol methyl ether trifluoromethyl acetate, trifluorome Butyl butyl acetate, methyl 3-trifluoromethoxypropionate, perfluorocyclohexanone, propylene glycol trifluoromethyl ether, butyl trifluoroacetate, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione 1,1,1,3,3,3-hexafluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 2,2,3,4 , 4,4-hexafluoro-1-butanol, 2-trifluoromethyl-2-propanol, 2,2,3,3-tetrafluoro-1-propanol, 3,3,3-trifluoro-1-propanol, 4,4,4-trifluoro-1-butanol and the like can be used, and one of these can be used alone or in admixture of two or more. But it is not limited thereto.

The pattern forming method using the water-insoluble and alkali-soluble resist protective film (upper layer film) material of the present invention will be described.
First, a water-insoluble and alkali-soluble resist protective film (upper film) material is formed on the photoresist layer by spin coating or the like. The film thickness is preferably in the range of 10 to 500 nm. The exposure method may be dry exposure in which the space between the resist protective film and the projection lens is a gas such as air or nitrogen, but may be immersion exposure in which the space between the resist protective film and the projection lens is filled with liquid. Water is preferably used in the immersion exposure. In immersion exposure, the presence or absence of cleaning of the wafer edge and back surface and the cleaning method are important in order to prevent water from flowing around the wafer back surface and elution from the substrate. For example, the solvent is volatilized by baking the resist protective film in the range of 40 to 130 ° C. for 10 to 300 seconds after spin coating. In the case of resist layer formation and dry exposure, edge cleaning is performed at the time of spin coating, but in the case of immersion exposure, when a highly hydrophilic substrate surface comes into contact with water, water may remain on the substrate surface of the edge portion, It is not preferable. Therefore, there is a method in which edge cleaning is not performed during spin coating of the resist protective film.

  After forming the resist protective film, exposure is performed in water by KrF or ArF immersion lithography. After exposure, post-exposure baking (PEB) is performed, and development is performed with an alkali developer for 10 to 300 seconds. 2.38 mass% tetramethylammonium hydroxide aqueous solution is generally widely used as the alkali developer, and the resist protective film is peeled off and the resist film is developed simultaneously. Before PEB, water may remain on the resist protective film. If PEB is carried out with water remaining, the water passes through the protective film and sucks out the acid in the resist, so that the pattern cannot be formed. In order to completely remove water on the protective film before PEB, spin dry before PEB, purge with dry air or nitrogen on the surface of the protective film, or optimization of the water recovery nozzle shape and water recovery process on the stage after exposure For example, it is necessary to dry or recover the water on the protective film. Furthermore, the resist protective film having high water repellency shown in the present invention is characterized by excellent water recoverability.

  The type of resist material is not particularly limited. It may be a positive type or a negative type, and may be an ordinary hydrocarbon-based single layer resist material or a bilayer resist material containing silicon atoms. As a resist material in KrF exposure, a polymer in which a hydrogen atom of a hydroxy group or a carboxyl group of a polyhydroxystyrene or polyhydroxystyrene- (meth) acrylate copolymer is substituted with an acid labile group is preferably used as a base resin. .

  The resist material in ArF exposure must have a structure that does not contain aromatics as a base resin. Specifically, polyacrylic acid and its derivatives, norbornene derivative-maleic anhydride alternating polymer, and polyacrylic acid or its derivatives. Tri- or quaternary copolymer, tetracyclododecene derivative-maleic anhydride alternating polymer and polyacrylic acid or a derivative thereof, ternary or quaternary copolymer, norbornene derivative-maleimide alternating polymer and polyacrylic acid or the like Tri- or quaternary copolymers with derivatives, tetracyclododecene derivative-maleimide alternating polymers and ternary or quaternary copolymers with polyacrylic acid or its derivatives, and two or more of these, or polynorbornene and One or more polymer polymerizations selected from metathesis ring-opening polymers It is preferably used.

EXAMPLES Hereinafter, although a synthesis example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the examples, GPC is gel permeation chromatography, and the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were determined.
Moreover, the structural formula of the monomers 1-8 used by the synthesis example is shown below.

[Synthesis Example 1]
To a 200 mL flask, 36 g of monomer 1 and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 1 was obtained.

[Synthesis Example 2]
Monomer 1 (25.6 g), monomer 3 (9 g), and methanol (40 g) as a solvent were added to a 200 mL flask. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 3]
To a 200 mL flask, 26.9 g of monomer 2, 9 g of monomer 3 and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 4]
To a 200 mL flask, 12.8 g of monomer 1, 1.3 g of methacrylic acid, 15 g of monomer 3 and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 5]
To a 200 mL flask, 9.2 g of monomer 1, 7.5 g of monomer 4, 15 g of monomer 3 and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 6]
To a 200 mL flask, 31.5 g of monomer 5, 4.2 g of monomer 6, 7.2 g of monomer 7 and 20 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 85 ° C. and reacted for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 7]
In a 200 mL flask, 21.5 g of monomer 5, 3.0 g of α-trifluoromethylacrylic acid, 10.5 g of monomer 7 and 20 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 85 ° C. and reacted for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 7 was obtained.

[Comparative Synthesis Example 1]
To a 200 mL flask, 35 g of monomer 8 and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, the molecular weight was confirmed by GPC, and Comparative polymer 1 was obtained.

  Examples Polymers 1 to 7 and Comparative Example Polymer 1 used the polymers shown in the above synthesis examples. Example Polymers 1 to 7 and Comparative Example Polymer 1 (0.5 g) were dissolved in isobutyl alcohol (25 g) and filtered through a 0.2 micron polypropylene filter to prepare a resist protective film solution.

  After spin-coating a resist protective film on a silicon substrate and baking at 100 ° C. for 60 seconds, a 50 nm thick protective film was produced. A. The refractive index of the protective film at a wavelength of 193 nm was determined using spectroscopic ellipsometry manufactured by Woollam. The results are shown in Table 1.

  Next, the wafer on which the resist protective film was formed by the above method was rinsed with pure water for 5 minutes, and the change in film thickness was observed. The results are shown in Table 2.

  Further, the wafer on which the resist protective film was formed by the above method was developed with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution, and the change in film thickness was observed. The results are shown in Table 3.

  50 μL of pure water was dropped onto a wafer that was kept horizontal by forming a resist protective film by the above method to form polka dots. Next, this wafer was gradually tilted, and the angle (falling angle) of the wafer at which the polka dots began to fall was determined. The results are shown in Table 4.

  A small sliding angle indicates that water easily flows and indicates that the scanning speed in scanning exposure can be increased. The polymer having an alkali-soluble group according to the present invention has a feature that the falling angle is smaller than that of a polymer having a hexafluoroalcohol group.

Furthermore, 5 g of resist polymer shown below, 0.25 g of PAG, and 0.6 g of tri-n-butylamine as a quencher were dissolved in 55 g of a propylene glycol monoethyl ether acetate (PGMEA) solution to obtain a 0.2 micron size polypropylene filter. And a resist solution was prepared. A resist solution was applied on an 87 nm film thickness of an anti-reflective film ARC-29A manufactured by Nissan Chemical Industries, Ltd. produced on a Si substrate, and baked at 120 ° C. for 60 seconds to prepare a resist film having a film thickness of 150 nm. A resist protective film was applied thereon and baked at 100 ° C. for 60 seconds. In order to reproduce the simulated immersion exposure, the exposed film was rinsed with pure water for 5 minutes. Expose with Nikon ArF scanner S307E (NA0.85 σ0.93 4/5 annular illumination, 6% halftone phase shift mask), rinse for 5 minutes while applying pure water, post-exposure at 110 ° C for 60 seconds Arbake (PEB) was performed, and development was performed for 60 seconds with a 2.38 mass% TMAH developer.
A normal process without exposure, pure water rinsing, PEB, development, and post-exposure pure water rinsing was also performed without a protective film.
The wafer was cleaved, and the pattern shape and sensitivity of the 75 nm line and space were compared. The results are shown in Table 5.

  When pure water rinsing was performed after exposure without a protective film, a T-top shape was obtained. This is probably because the generated acid was dissolved in water. On the other hand, when the protective film of the present invention was used, the shape did not change. In the case of a protective film containing only hexafluoroalcohol as a soluble group, the resist shape after development was reduced and became a tapered shape.

Claims (8)

A resist protective film material comprising a polymer compound having a partial structure represented by the following general formula (1).

(In the formula, R ⁰ is a hydrogen atom, a fluorine atom, an alkyl group or alkylene group having 1 to 8 carbon atoms, and R ¹ is a linear or branched alkyl group or alkylene group having 1 to 6 carbon atoms. And at least one fluorine atom.) A resist protective film material comprising a polymer compound having a repeating unit represented by the following general formula (2).

(In the formula, R ⁰ is a hydrogen atom, a fluorine atom, an alkyl group or alkylene group having 1 to 8 carbon atoms, and R ¹ is a linear or branched alkyl group or alkylene group having 1 to 6 carbon atoms. R ² is a linear, branched or cyclic alkylene group or alkylidene group having 1 to 10 carbon atoms, which may have a fluorine atom, R ⁰ or R ^A ring may be formed by bonding to ^{1. When} R ⁰ or R ¹ and R ² are bonded to form a ring together with the carbon atom to which these are bonded, R ⁰ is an alkylene group having 1 to 8 carbon atoms or R ¹ represents a linear or branched alkylene group having 1 to 6 carbon atoms, and R ² represents a linear or branched alkylidine group having 1 to 10 carbon atoms, or R ¹ and R ² are bonded to each other. May form a ring together with the carbon atom to which they are bonded, and when forming a ring, ¹ is a linear or branched alkylene groups having 1 to 6 carbon atoms, R ² is a straight or branched alkylidine group having 1 to 10 carbon atoms .R ^3, R ⁴ is a hydrogen atom, a fluorine atom X is —O—, —C (═O) —O—, or —C (═O) —O—R ⁵ —C (═O) —O—. R ⁵ is a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms in the range of 0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 <a + b ≦ 1.   Furthermore, the polymer compound is one or more selected from a repeating unit having a carboxyl group, a repeating unit having a fluoroalcohol other than that represented by the general formula (2), and a repeating unit having a perfluoroalkyl group. The resist protective film material of Claim 2 which has a repeating unit.   Furthermore, the resist protective film material of Claim 1, 2, or 3 containing the solvent which melt | dissolves the said high molecular compound.   5. A lithography pattern forming method in which a protective film made of a resist upper layer film material is formed on a photoresist layer formed on a wafer, exposed and then developed, and the resist upper layer film material is used as the resist upper layer film material. A pattern forming method comprising using the resist protective film material according to claim 1.   A pattern formation method by immersion lithography in which a protective film made of a resist upper layer film material is formed on a photoresist layer formed on a wafer, exposed in water, and then developed, wherein the resist upper layer film material is used as the resist upper layer film material. 5. A pattern forming method using the resist protective film material according to any one of 4 above.   The pattern forming method according to claim 6, wherein the immersion lithography uses an exposure wavelength in the range of 180 to 250 nm and water is inserted between the projection lens and the wafer.   8. The pattern forming method according to claim 6, wherein the development of the photoresist layer and the removal of the protective film of the resist upper layer film material are simultaneously performed with an alkali developer in the development step performed after the exposure.