JP5247035B2 - Resist protective film material and pattern forming method - Google Patents

Description

  The present invention provides a resist for protecting a photoresist layer in immersion photolithography in which microfabrication in a manufacturing process of a semiconductor element or the like, in particular, 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. The present invention relates to a resist protective film material for use as an upper layer film material, and a resist pattern forming method using the same. The present invention also relates to a polymer compound effective as the resist upper layer film material.

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. Initially, 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 a hard pellicle because the durability of the soft pellicle is extremely low, and a reduction in resist etching resistance 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 or amine compound added to the resist film as a quencher in water, pattern collapse due to swelling, and the like. Therefore, it has been 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) of 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. Examples of the fluorine-based material include perfluoro (2,2-dimethyl-1,3-dioxole) -tetrafluoroethylene copolymer disclosed in JP-A-5-74700 as well as the above-mentioned materials. 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.

  The hexafluoroalcohol group has been studied as a resist protective film for immersion exposure because it has alkali solubility and high water repellency (Non-patent Document 4: Journal of Photopolymer Science and Technology, Vol. 18). , No. 5 (2005) p615-619). Here, Patent Document 7: Japanese Patent Application Laid-Open No. 2003-40840 discloses an acrylate having hexafluoroalcohol, and Patent Document 8: Japanese Patent Application Laid-Open No. 2005-316352 discloses (meth) acrylate and norbornene having a specific hexafluoroalcohol. A resist protective film used has been proposed.

Furthermore, development of a resist protective film having high hydrophobicity and capable of alkali development is desired.
Here, there is a problem that the sensitivity of the resist fluctuates due to being left in a vacuum for a long time in electron beam exposure such as mask drawing. The sensitivity of the resist fluctuates due to evaporation of acid generated during drawing, evaporation of vinyl ether generated by deprotection of the protecting group of the acetal by acid (Patent Document 9: JP-A-2002-99090). The mask blank resist is required to be stable for several months after coating, and the development of a mask blank resist that is stable to the environment has been 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 Journal of Photopolymer Science and Technology, Vol. 18, no. 5 (2005) p615-619 JP-A-62-62520 JP-A-62-62521 JP 60-38821 A JP-A-5-74700 JP-A-6-273926 Japanese Patent No. 2803549 Japanese Patent Laid-Open No. 2003-40840 JP 2005-316352 A JP 2002-99090 A

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. and to provide such a resist protective film material, and forming how a resist pattern using the this.

As a result of intensive studies to achieve the above object, the present inventors have found that the moiety represented by the following general formula (2) includes a polymer compound having a repeating unit represented by the following general formula (1) -1. When a polymer compound film having a structure is formed on a resist film as a resist protective film material, the protective film (resist upper layer film) is water-insoluble and can be dissolved in an alkaline aqueous solution and mixed with the resist layer. Thus, the present invention has been made upon the knowledge that it can be peeled off together with development at the time of development with alkaline water, and the process applicability is considerably widened.

（式中、Ｒ¹、Ｒ²は水素原子、又は炭素数１〜１２の直鎖状、分岐状又は環状のアルキル基で、Ｒ ¹ とＲ ² が結合してこれらが結合する炭素原子と共に環を形成していてもよい。Ｒ³、Ｒ⁶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−Ｒ⁷−Ｃ（＝Ｏ）−Ｏ−である。Ｒ⁷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≦ｃ≦１、０≦ｄ≦１、０＜ｃ＋ｄ≦１の範囲である。）
請求項２：
エーテル化合物が、ジ−ｎ−ペンチルエーテル及び／又はジイソペンチルエーテルである請求項１記載のレジスト保護膜材料。
請求項３：
上記高分子化合物を溶解する溶媒が、炭素数８〜１２のエーテル化合物に加えて、炭素数４〜１０の高級アルコールが０．１〜９０質量％混合された溶媒である請求項１又は２記載のレジスト保護膜材料。
請求項４：
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３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、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３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：
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５記載のパターン形成方法。
請求項７：
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５又は６記載のパターン形成方法。
請求項８：
マスクブランクス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、真空中電子ビームで露光を行った後、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３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。 That is, the present invention provides the following resist protective film material and pattern forming method.
Claim 1 :
Having a repeating unit represented by the following following general formula (3), is dissolved a polymer compound weight average molecular weight in terms of polystyrene by gel permeation chromatography is 1,000 to 500,000, the polymer compound solvent features and, Relais resist protective film material that containing an ether compound having 8 to 12 carbon atoms as.

(In the formula, R ¹ and R ² are a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, and a ring together with the carbon atom to which R ¹ and R ² are bonded to each other) . may form a R ^3, R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group .X 'is -O -, - C (= O ) -O- or -C ( ═O) —O—R ⁷ —C (═O) —O—, wherein R ⁷ is a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms, 0 ≦ c ≦ 1, 0. ≦ d ≦ 1, 0 <c + d ≦ 1.)
Claim 2 :
Ether compound, a resist protective film material of claim 1 wherein the di -n- pentyl ether and / or di-isopentyl ether.
Claim 3 :
The solvent for dissolving the polymer compound, in addition to the ether compound having 8 to 12 carbon atoms, according to claim 1 or 2, wherein the higher alcohol having 4 to 10 carbon atoms is a solvent which is mixed 0.1-90 wt% Resist protective film material.
Claim 4 :
A protective film of a resist upper layer film material is formed on a photoresist layer formed on the wafer, after exposure, the pattern forming method by lithography to perform development, any one of claims 1 to 3 as the resist upper layer film material A pattern forming method comprising using the resist protective film material according to claim 1.
Claim 5 :
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. pattern forming method which comprises using a resist protective film material according to any one of 3.
Claim 6 :
6. The pattern forming method according to claim 5 , wherein the immersion lithography uses an exposure wavelength in a range of 180 to 250 nm and water is inserted between the projection lens and the wafer.
Claim 7 :
The pattern forming method according to claim 5 or 6 , wherein in the developing step performed after exposure, 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.
Claim 8 :
Claims are made as the resist upper layer film material in the 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 mask blank, exposed to an electron beam in vacuum, and then developed. A pattern forming method comprising using the resist protective film material according to any one of 1 to 3 .

  According to the pattern forming method using the resist protective film material of the present invention, the resist protective film formed on the resist film is water-insoluble and can be dissolved in an alkaline aqueous solution (alkaline developer). Since mixing is not performed, satisfactory 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.

（式中、Ｒ¹、Ｒ²は同一又は異種の水素原子、又は炭素数１〜１２の直鎖状、分岐状又は環状のアルキル基で、Ｒ¹とＲ²が結合してこれらが結合する炭素原子と共に、好ましくは炭素数３〜２０、特に３〜１０の環、特に脂環を形成していてもよく、Ｒ³⁰は水素原子又はメチル基である。） The polymer compound of the present invention comprises a repeating unit represented by the following general formula (1).

(In the formula, R ¹ and R ² are the same or different hydrogen atoms, or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, and R ¹ and R ² are bonded to each other. (It may form a ring having 3 to 20 carbon atoms, particularly 3 to 10 carbon atoms, particularly an alicyclic ring, together with a carbon atom, and R ³⁰ is a hydrogen atom or a methyl group.)

（式中、Ｒ¹、Ｒ²は水素原子、又は炭素数１〜１２の直鎖状、分岐状又は環状のアルキル基で、Ｒ¹とＲ²が結合してこれらが結合する炭素原子と共に、好ましくは炭素数３〜２０、特に３〜１０の環、特に脂環を形成していてもよく、Ｒ³⁰、Ｒ⁴⁰は水素原子又はメチル基、Ｒ⁵は炭素数２〜１０の少なくとも１つのフッ素原子で置換された直鎖状又は分岐状のアルキル基である。０＜ａ＜１、０＜ｂ＜１、０＜ａ＋ｂ≦１の範囲である。） In this case, the polymer compound of the present invention may be constituted only by the repeating unit represented by the above formula (1) and may contain other repeating units, but when it contains other repeating units, It preferably has a repeating unit represented by the following formula (1) -1.

(Wherein R ¹ and R ² are a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, together with the carbon atom to which R ¹ and R ² are bonded and to which these are bonded, Preferably, it may form a ring having 3 to 20 carbon atoms, particularly 3 to 10 carbon atoms, particularly an alicyclic ring, R ³⁰ and R ⁴⁰ are hydrogen atoms or methyl groups, and R ⁵ is at least one carbon atom having 2 to 10 carbon atoms. (It is a linear or branched alkyl group substituted with a fluorine atom. The range is 0 <a <1, 0 <b <1, 0 <a + b ≦ 1.)

  In addition, a and b show the abundance ratio of the respective repeating units in the polymer compound, and a + b = 1 means that the total amount of the repeating units a and b is all in the polymer compound containing the repeating units a and b. It shows that it is 100 mol% with respect to the total amount of repeating units, and a + b <1 means that the total amount of repeating units a and b is less than 100 mol% with respect to the total amount of all repeating units, and other than a and b It has other repeating units.

In this case, examples of the ring formed together with the carbon atom to which R ¹ and R ² are bonded together include a cyclopentyl group, a cyclohexyl group, and a norbornyl group.

（Ｒ³⁰は上記と同様である。） Here, the repeating unit of the above formula (1) or the repeating unit a of the above formula (1) -1 can be specifically exemplified below.

(R ³⁰ is the same as above.)

Moreover, as R < ⁵ > of the repeating unit b of said Formula (1) -1, can be specifically illustrated below.

Here, a and b are 0 <a <1, 0 <b <1, and 0 <a + b ≦ 1. In this case, the polymer compound may contain repeating units d, e, f, h, i, which will be described later, as necessary.
However, 0 ≦ d ≦ 1, 0 ≦ e ≦ 0.9, 0 ≦ f ≦ 0.9, 0 ≦ h ≦ 0.9, and 0 ≦ i ≦ 0.9.
Preferably, 0.1 ≦ a ≦ 0.9, 0.1 ≦ b ≦ 0.9, 0.2 ≦ a + b ≦ 1.0, 0 ≦ d ≦ 0.8, 0 ≦ e ≦ 0.6, 0 ≦ f ≦ 0.8, 0 ≦ h ≦ 0.8, 0 ≦ i ≦ 0.8, a + b + d + e + f + h + i = 1.
Note that a + b + d + e + f + h + i = 1 means that in a polymer compound containing repeating units a, b, d, e, f, h, i, the total amount of these repeating units is 100 mol% with respect to the total amount of all repeating units. Indicates that

  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 (2).

（式中、Ｒ¹、Ｒ²は水素原子、又は炭素数１〜１２の直鎖状、分岐状又は環状のアルキル基で、Ｒ¹とＲ²が結合してこれらが結合する炭素原子と共に、好ましくは炭素数３〜２０、特に３〜１０の環を形成していてもよい。Ｘは−Ｏ−又は−Ｃ（＝Ｏ）−Ｏ−である。）

(Wherein R ¹ and R ² are a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, together with the carbon atom to which R ¹ and R ² are bonded and to which these are bonded, Preferably, a ring having 3 to 20 carbon atoms, particularly 3 to 10 carbon atoms may be formed, and X is —O— or —C (═O) —O—.

（式中、Ｒ¹、Ｒ²は前述の通り。Ｒ³、Ｒ⁶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−Ｒ⁷−Ｃ（＝Ｏ）−Ｏ−である。Ｒ⁷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≦ｃ≦１、０≦ｄ≦１、０＜ｃ＋ｄ≦１の範囲である。） As the repeating unit of the polymer compound having the partial structure represented by the general formula (2), those represented by the following general formula (3) are preferable.

(In the formula, R ¹ and R ² are as described above. R ³ and R ⁶ are a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X ′ is —O—, —C (═O) —. O— or —C (═O) —O—R ⁷ —C (═O) —O—, wherein R ⁷ is a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms. ≦ c ≦ 1, 0 ≦ d ≦ 1, 0 <c + d ≦ 1.)

  In this case, as the polymer compound having the partial structure of the formula (2), a polymer having a repeating unit of the formula (3) is preferable. By using the polymer of the repeating unit represented by the general formula (3), 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. A preferable alkali dissolution rate is 1,000 Å / s or more, and a more preferable alkali dissolution rate is 2,000 Å / s or more. If the alkali dissolution rate is too low, undissolved substances are generated in the mixing layer with the resist, bridge-like defects are likely to occur, the resist surface after development becomes hydrophobic, and blob defects are likely to occur. Blob defects occur when droplets are dried in spin dry drying of a hydrophobic resist surface. The contact angle of water droplets on the hydrophobic surface is high, the droplets become smaller and smaller when dried, the internal energy of the water droplets increases, the film surface is peeled off, and additives such as acid generators are agglomerated However, when the water droplet dries, it becomes a blob defect.

  The hexafluoroalcohol group is acidic due to the high electronegativity of the fluorine atom and is dissolved in an alkaline aqueous solution. However, the solubility in an aqueous alkali solution is low, and sufficient alkali solubility could not be provided unless two or more hexafluoroalcohol groups were introduced. In the hexafluoroalcohol group of the present invention, since an ester is bonded to the β-position of the alcohol group, an electron withdrawing effect by the ester group is added, and the acidity is higher than that of the conventional hexafluoroalcohol. For this reason, sufficient alkali solubility can be obtained even with one hexafluoroalcohol group, leading to the present invention.

  Specific examples of the monomer that gives the repeating unit c represented by the general formula (3) include the following.

  Specific examples of the monomer that gives the repeating unit d represented by the general formula (3) include the following.

  As the repeating unit of the resist protective film polymer of the present invention, the unit c and / or d represented by the general formula (3) is essential, but in order to prevent alkali solubility and mixing with the resist film, a carboxyl group is used. The repeating unit e having a group can be copolymerized. Specific examples of the repeating unit e can be given below.

  Moreover, the repeating unit f which has fluoro alcohol other than shown by General formula (3) can be copolymerized. Specific examples of the repeating unit f include the following.

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

  Furthermore, in order to increase the water slidability, the repeating unit h having an alkyl group containing no fluorine can be copolymerized. The repeating unit h can be exemplified below.

  Furthermore, a repeating unit i having both a fluoroalkyl group and an alkyl group shown below can be copolymerized.

  Furthermore, a repeating unit j having a hydroxy group shown below can be copolymerized.

  The ratio of the repeating units c, d, e, f, g, h, i, j is 0 ≦ c ≦ 1.0, 0 ≦ d ≦ 1.0, 0 <c + d ≦ 1.0, 0 ≦ e ≦ 0. .9, 0 ≦ f ≦ 0.9, 0 ≦ g ≦ 0.9, 0 ≦ h ≦ 0.9, 0 ≦ i ≦ 0.9, 0 ≦ j ≦ 0.9, preferably 0 ≦ c ≦ 0 .8, 0 ≦ d ≦ 0.8, 0.1 ≦ c + d ≦ 0.8, 0 ≦ e ≦ 0.6, 0 ≦ f ≦ 0.8, 0 ≦ g ≦ 0.8, 0 ≦ h ≦ 0 0.8, 0 ≦ i ≦ 0.8, 0 ≦ j ≦ 0.8, and c + d + e + f + g + h + i + j = 1.

  Here, c + d + e + f + g + h + i + j = 1 means that in a polymer compound containing repeating units c, d, e, f, g, h, i, repeating units c, d, e, f, g, h, i, j The total amount of is 100 mol% with respect to the total amount of all repeating units.

  The polymer compound according to the present invention has a polystyrene-equivalent 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 each desired repeating unit 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 to 50 to 80 ° C. The reaction time is 2 to 100 hours, preferably 5 to 20 hours. The fluoroalcohol group at the monomer stage is substituted with an acetyl group or an acetal, and may be converted to a fluoroalcohol by alkali treatment or 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. Among these, the most preferred are C8-12 ether compounds, specifically, di-n-butyl ether, di-isobutyl ether, di-secbutyl ether, di-n-pentyl ether, diisopentyl. Examples include ether, di-sec-pentyl ether, di-t-amyl ether, and di-n-hexyl ether. From the viewpoint of flash point, ether compounds having 10 to 12 carbon atoms are preferable, and diisopentyl ether is most preferable. Di-n-pentyl ether. Specific examples of higher alcohols having 4 or more carbon atoms include 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, and 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-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2- Pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl 2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol.

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, perfluorodecalin, Perfluoro (1,2-dimethylcyclohexane), perfluoro (1,3-dimethylcyclohexane), propylene glycol trifluoromethyl ether acetate, propylene glycol methyl ether trifluoromethyl acetate, butyl trifluoromethyl acetate, 3-trifluoromethoxy The Methyl lopionate, 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 mentioned, and one of these can be used alone, or two or more can be mixed and used, but is not limited thereto.

  Moreover, it can also be used as 2 or more types of mixed solvents of the said solvent, and especially the mixed solvent of C8-C12 ether compound and C4 or more, especially 4-10 higher alcohol can be used most preferably. As a mixing ratio, it is preferable that 0.1 to 90% by mass, more preferably 5 to 85% by mass, and still more preferably 7 to 80% by mass of the higher alcohol in the whole solvent.

  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, after spin-coating the resist protective film, the solvent is volatilized by baking at 40 to 130 ° C. for 10 to 300 seconds. Edge cleaning is performed at the time of spin coating in the case of a resist film or dry exposure, 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, which is preferable. Not that. 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 It is necessary to dry or recover (post-soak) 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. The resist material used in KrF exposure is a polyhydroxystyrene or polyhydroxystyrene- (meth) acrylate copolymer as a base resin, in which a part or all of the hydrogen atoms of hydroxy groups or carboxyl groups are substituted with acid labile groups. Coalescence is preferably used.

  The resist material in ArF exposure must have a structure that does not contain an aromatic 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, or ternary 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.

As resist materials for mask blanks, novolak and hydroxystyrene-based resins are mainly used. Those obtained by substituting hydroxy groups of these resins with acid labile groups are used as positive types, and those added with a crosslinking agent are used as negative types. Based on a copolymer of hydroxystyrene and one or more of (meth) acryl derivatives, styrene, vinylnaphthalene, vinylanthracene, vinylpyrene, hydroxyvinylnaphthalene, hydroxyvinylanthracene, indene, hydroxyindene, acenaphthylene, norbornadiene It is good.
When used as a resist protective film for mask blanks, a photoresist is applied on a mask blank substrate such as SiO ₂ , Cr, CrO, CrN, or MoSi to form a resist protective film. A three-layer structure may be formed by forming an SOG film and an organic underlayer film between a photoresist and a blank substrate.
After the resist protective film is formed, exposure is performed with an electron beam drawing machine in a vacuum. After exposure, post-exposure baking (PEB) is performed, and development is performed with an alkali developer for 10 to 300 seconds.

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.
The structural formulas of monomers 1 to 20 used in the synthesis examples are shown below.

[Synthesis Example 1]
29 g of monomer 1 and 40 g of methanol 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 ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 1 was obtained.

[Synthesis Example 2]
32 g of monomer 2 and 40 g of methanol 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, 20.3 g of monomer 1, 4.5 g of monomer 3, 2.3 g of monomer 4 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, 20.3 g of monomer 1, 9.0 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, 24.3 g of monomer 5, 6.3 g of monomer 7, 3.7 g of monomer 8 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 6]
To a 200 mL flask, 24.3 g of monomer 5, 3.7 g of monomer 6, 9.4 g of monomer 9 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]
To a 200 mL flask, 22.5 g of monomer 1, 5.9 g of monomer 12, 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 7 was obtained.

[Synthesis Example 8]
30.8 g of monomer 13 and 40 g of methanol 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 ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 8 was obtained.

[Synthesis Example 9]
33.4 g of monomer 14 and 40 g of methanol 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, the molecular weight was confirmed by GPC, and Example polymer 9 was obtained.

[Synthesis Example 10]
Monomer 1 (14.7 g), monomer 13 (15.4 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 11]
Monomer 1 (14.7 g), monomer 14 (16.7 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 12]
To a 200 mL flask, 20.5 g of monomer 1, 9.7 g of monomer 15 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 13]
To a 200 mL flask, 23.5 g of monomer 1, 6.6 g of monomer 16 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 14]
Monomer 1 (17.6 g), monomer 17 (14.4 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, the molecular weight was confirmed by GPC, and Example polymer 14 was obtained.

[Synthesis Example 15]
23.5 g of monomer 1, 9.7 g of monomer 18 and 40 g of methanol 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 ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 15 was obtained.

[Synthesis Example 16]
In a 200 mL flask, 11.8 g of monomer 1, 14.4 g of monomer 17, 10.0 g of monomer 10 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 16 was obtained.

[Synthesis Example 17]
23.5 g of monomer 1 and 4.2 g of monomer 20 were added to a 200 mL flask, and 40 g of methanol was added as a solvent. 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 18]
In a 200 mL flask, 11.8 g of monomer 1, 14.4 g of monomer 17, 2.6 g of hydroxyethyl methacrylate, 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 18 was obtained.

[Comparative Synthesis Example 1]
35 g of monomer 10 and 40 g of methanol 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, the molecular weight was confirmed by GPC, and Comparative polymer 1 was obtained.

[Comparative Synthesis Example 2]
28 g of monomer 11 and 40 g of methanol 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 ¹ H-NMR, the molecular weight was confirmed by GPC, and the polymer was Comparative Example 2.

[Comparative Synthesis Example 3]
To a 200 mL flask, 27.3 g of monomer 10, 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, the molecular weight was confirmed by GPC, and Comparative polymer 3 was obtained.

[Comparative Synthesis Example 4]
29.4 g of monomer 19 and 40 g of methanol 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, the molecular weight was confirmed by GPC, and a comparative polymer 4 was obtained.

[Examples and Comparative Examples]
Examples Polymers 1 to 18 and Comparative Examples Polymers 1 to 4 used the polymers shown in the above synthesis examples.
Example Polymers 1 to 18 and Comparative Example Polymers 1 to 4 (0.5 g) were dissolved in diisopentyl ether (16 g) and 2-methyl-1-butanol (2 g), and each was filtered through a 0.2 micron polypropylene filter. Protective film solutions (TC-1 to 6, TC-10 to 21, and comparative TC1 to 4) were prepared. Regarding resist protective films (TC-7 to 9, TC-22 to 25), TC-7 is 18 g of diisopentyl ether, TC-8 is 12 g of diisopentyl ether, 8 g of 3-methyl-1-butanol, TC-9 is 18 g of 2,2,2-trifluoroethyl butyrate, TC-22 is 12 g of diisopentyl ether, 8 g of 4-methyl-2-pentanol, TC-23 is 5 g of di-n-butyl ether, 3- Methyl-1-butanol 25g, TC-24 dissolved in di-n-pentyl ether 18g, 2-methyl-1-butanol 2g, TC-25 dissolved in diisopentyl ether 16g, 2-heptanol 2g A membrane solution was prepared.

  After spin-coating a resist protective film solution on a silicon substrate and baking at 100 ° C. for 60 seconds, a resist protective film (TC-1 to 25, comparative TC-1 to 4) having a thickness of 50 nm was prepared. 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 for 60 seconds, and the change in film thickness was observed. The results are shown in Table 3.

  Using an inclination method contact angle meter Drop Master 500 manufactured by Kyowa Interface Science, 50 μL of pure water was dropped on the wafer kept horizontal by forming a resist protective film by the above method to form polka dots. Next, the wafer was gradually tilted, and the wafer angle (falling angle) and receding contact angle at which the polka dots began to fall were determined. The results are shown in Table 4.

In addition, the wafer on which the resist protective film was formed by the above method was dissolved in a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) using a dissolution rate monitor (Model RDA-790) manufactured by Risotech Japan Co., Ltd. The speed was determined. The results are shown in Table 5.

  A small falling angle indicates that water easily flows, and a large receding contact angle indicates that it is difficult for a droplet to remain even in high-speed scanning exposure. In the case of the polymer having an alkali-soluble group according to the present invention, it has a feature that it has a small alkali fall rate, a large receding contact angle, and excellent water slidability while having an alkali dissolution rate as fast as a polymer having two hexafluoroalcohol groups. .

Further, 5 g of a resist polymer shown below, 0.25 g of PAG1, and 0.6 g of tri-n-butylamine as a quencher were dissolved in 55 g of a propylene glycol monomethyl ether acetate (PGMEA) solution to obtain a 0.2 micron size polypropylene. Filtration through a filter produced a resist solution. 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 6.

The resist solution and the protective film solution were prepared by microfiltration three times with a high-density polyethylene filter having a filter size of 0.02 μm.
A resist solution is 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 having a diameter of 200 mm, and baked at 120 ° C. for 60 seconds to produce a resist film having a film thickness of 150 nm. did. A resist protective film was applied thereon and baked at 100 ° C. for 60 seconds. Dry exposure with Nikon ArF scanner S307E (NA0.85 σ0.93 4/5 ring illumination, 6% halftone phase shift mask) and post exposure bake (PEB) at 110 ° C for 60 seconds Development was performed with a 2.38% by mass TMAH developer for 60 seconds to form a 100 nm line and space pattern on the entire wafer surface. Defects were observed with a pixel size of 0.165 μm using a Tokyo Seimitsu defect inspection device Win-Win 50-1400. The results are shown in Table 7. Most of the defects of comparative TC-4 were bridge-like defects that connected the lines.

Electron beam drawing evaluation In the drawing evaluation, 0.2 μm of propylene glycol monomethyl ether acetate (PGMEA) and ethyl lactate (EL) solution dissolved in the composition shown in Table 6 using the following EB polymer synthesized by radical polymerization. A positive resist material was prepared by filtering through a size filter.
The obtained positive resist material was spin-coated on a Si substrate having a diameter of 6 inches φ using a clean track Mark 5 (manufactured by Tokyo Electron Ltd.) and pre-baked on a hot plate at 110 ° C. for 60 seconds to 200 nm. A resist film was prepared. A resist protective film solution was applied thereon and baked at 100 ° C. for 60 seconds to produce a resist protective film having a thickness of 50 nm. To this, drawing in a vacuum chamber was performed at an HV voltage of 50 keV using HL-800D manufactured by Hitachi, Ltd. Thereafter, the sample was left in a vacuum chamber for 20 hours, and drawing was performed by changing the drawing place.
Immediately after drawing, post-exposure baking (PEB) was performed at 90 ° C. for 60 seconds on a hot plate using a clean track Mark 5 (manufactured by Tokyo Electron Ltd.), and paddle development was performed for 30 seconds with a 2.38 mass% TMAH aqueous solution. And a positive pattern was obtained.
The obtained resist pattern was evaluated as follows.
0.12 μm line and space at an exposure amount for resolving 0.12 μm line and space 1: 1 at a place exposed immediately before development using a length measuring SEM (S-7280) manufactured by Hitachi, Ltd. The line dimension of 0.12 μm line-and-space at the same exposure amount at the place exposed 20 hours ago was subtracted to determine the amount of dimensional variation when left in a vacuum. In the dimension fluctuation amount, plus indicates that the resist sensitivity is increased by being left in vacuum, and minus indicates that the sensitivity is decreased.

In ArF exposure, when a pure water rinse 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 conventional protective film having only a hexafluoroalcohol as a soluble group, the resist shape after development is reduced and becomes a tapered shape.
The protective film using a polymer compound having a hexafluoroalcohol group having an ester bonded to the β-position of the alcohol group as a repeating unit according to the present invention has a high alkali dissolution rate, few defects in dry exposure, and lubricity. Therefore, it has a feature that can reduce watermark-like defects in immersion exposure.
In the electron beam exposure, by applying the resist protective film of the present invention, the stability in exposure to vacuum after exposure was improved.

Claims (8)

Having a repeating unit represented by the following following general formula (3), is dissolved a polymer compound weight average molecular weight in terms of polystyrene by gel permeation chromatography is 1,000 to 500,000, the polymer compound solvent features and, Relais resist protective film material that containing an ether compound having 8 to 12 carbon atoms as.

(In the formula, R ¹ and R ² are a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, and a ring together with the carbon atom to which R ¹ and R ² are bonded to each other) . may form a R ^3, R ⁶ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group .X 'is -O -, - C (= O ) -O- or -C ( ═O) —O—R ⁷ —C (═O) —O—, wherein R ⁷ is a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms, 0 ≦ c ≦ 1, 0. ≦ d ≦ 1, 0 <c + d ≦ 1.) Ether compound, a resist protective film material of claim 1 wherein the di -n- pentyl ether and / or di-isopentyl ether. The solvent for dissolving the polymer compound, in addition to the ether compound having 8 to 12 carbon atoms, according to claim 1 or 2, wherein the higher alcohol having 4 to 10 carbon atoms is a solvent which is mixed 0.1-90 wt% Resist protective film material. A protective film of a resist upper layer film material is formed on a photoresist layer formed on the wafer, after exposure, the pattern forming method by lithography to perform development, any one of claims 1 to 3 as the resist upper layer film material A pattern forming method comprising using the resist protective film material according to claim 1. 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. pattern forming method which comprises using a resist protective film material according to any one of 3. 6. The pattern forming method according to claim 5 , wherein the immersion lithography uses an exposure wavelength in a range of 180 to 250 nm and water is inserted between the projection lens and the wafer. The pattern forming method according to claim 5 or 6 , wherein in the developing step performed after exposure, 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. Claims are made as the resist upper layer film material in the 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 mask blank, exposed to an electron beam in vacuum, and then developed. A pattern forming method comprising using the resist protective film material according to any one of 1 to 3 .