JP2013003167A - Method for forming pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a pattern, by which PEB can be carried out in a short time, resulting in improvement in throughput and reduction in an acid diffusion distance, and thereby, improvement in resolution can be achieved.SOLUTION: The method for forming a pattern comprises: forming an underlay film that absorbs light in a wavelength range from 600 to 2000 nm on a substrate to be processed; forming a photoresist film on the underlay film; exposing the photoresist film; then carrying out poste exposure baking (PEB) by irradiating the film with light at a wavelength of 600 to 2000 nm to heat; and then developing the film to form a pattern.

Description

  The present invention relates to a pattern forming method using a photoresist film.

  Chemically amplified resist films are used for fine processing of semiconductors and photomask patterns. The chemically amplified resist film generates an acid upon exposure, and can give a positive or negative pattern after development by deprotection reaction or crosslinking reaction with an acid catalyst. Heating is necessary to advance the acid-catalyzed reaction, and the heating method is the simplest and widely used method of heating the substrate to be processed on a hot plate.

However, with the progress of pattern miniaturization, degradation of resolution due to acid diffusion has become a problem. In order to suppress the diffusion of the acid, a method has been proposed in which an infrared ray emitted from a CO ₂ laser is applied to the resist film and heated in a short time (Non-Patent Document 1). In this method, since heating can be completed in a short time, the diffusion distance of the acid contributing to the reaction can be shortened. Further, if a thick substrate such as a mask substrate is to be heated, a long baking time is required. Thus, it has been proposed to heat the resist film using a halogen lamp (Patent Document 1). Here, the heating temperature by the halogen lamp is sensed by an infrared sensor to control the temperature.

  In addition, a negative resist is proposed that performs baking by irradiating infrared rays onto a photoresist film to which a near-infrared or infrared absorber is added (Patent Document 2).

JP 2001-274109 A JP 2001-133969 A Proc. SPIE Vol. 7639 p76390L-1 (2010)

  However, when baking is performed in a short time by irradiation with near infrared rays or infrared rays, there is a problem that the resolution is deteriorated when a near infrared ray or infrared absorber is added to the resist film material. Further, when no near-infrared and infrared absorbers are added to the resist film material, the rate of increase in the resist film temperature due to light irradiation is slow and there is a problem that the resolution is lowered due to acid diffusion. Although it is conceivable to increase the light irradiation energy in order to increase the film temperature rising speed, if the light irradiation energy is too high, it becomes difficult to control the temperature in the film. Therefore, a pattern forming method that can be heated in a short time in post-exposure baking (PEB) has been desired.

  The present invention has been made in view of such problems, and forms a lower layer film that absorbs light in the wavelength range of 600 to 2000 nm, and heats the lower layer film by performing light irradiation at a wavelength of 600 to 2000 nm. To provide a pattern formation method that can perform PEB by heating a resist film in a short time, thereby improving throughput and improving resolution by shortening an acid diffusion distance. With the goal.

  In order to solve the above problems, in the present invention, a lower layer film that absorbs light in the wavelength range of 600 to 2000 nm is formed on a substrate to be processed, a photoresist film is formed on the lower layer film, and the photoresist film is formed. Provided is a pattern forming method characterized in that after exposure, post-exposure baking (PEB) is performed by irradiating and heating light having a wavelength of 600 to 2000 nm, followed by development to form a pattern.

  In this way, by forming a lower layer film that absorbs light in the wavelength range of 600 to 2000 nm, and performing PEB by irradiating light with a wavelength of 600 to 2000 nm, the lower layer film that absorbs light generates heat and the photoresist film Heating can be performed in a short time. As a result, the pattern formation method can achieve an improvement in throughput and an improvement in resolution due to a reduction in the acid diffusion distance. Further, according to the pattern forming method of the present invention, even a photoresist film formed on a thick substrate to be processed such as a mask substrate can be heated in a short time. Since a film material can be used, resolution degradation due to a change in the resist film material as in Patent Document 2 does not occur.

  Moreover, it is preferable to form a lower layer film including at least one of a cyanine compound, a phthalocyanine compound, a diimonium salt compound, and an aminium salt compound as the lower layer film.

  By including such a compound, it becomes a lower layer film that more easily absorbs light in the wavelength range of 600 to 2000 nm. Therefore, by performing irradiation with light of wavelength 600 to 2000 nm and heating, PEB can be performed in a shorter time. Can do.

  Furthermore, it is preferable to form a lower layer film by forming a lower layer film material on the substrate to be processed by spin coating and then solidifying by cross-linking during baking.

  Thereby, the lower layer film can be easily formed in a short time.

  The post-exposure bake is preferably heated by irradiating with the light having a wavelength of 600 to 2000 nm using a xenon lamp or a halogen lamp.

  By using such a light source, light in the wavelength range of 600 to 2000 nm can be efficiently generated.

  Furthermore, it is preferable that an intermediate layer containing silicon atoms is formed on the lower layer film, and the photoresist film is formed on the intermediate layer.

  By providing the intermediate layer in this manner, a three-layer resist method can be performed.

  In addition, the formation of the photoresist film is a chemically amplified resist film material containing a photoacid generator that generates an acid by exposure, 1 selected from an acid generator by exposure to sulfonic acid, imide acid, or methide acid. Chemically amplified resist film material that generates more than one kind of acid and changes its solubility in the developer due to the deprotection reaction of the protecting group, or sulfonic acid by exposure from an acid generator bonded to the main chain of the base polymer It is preferable to use a chemically amplified resist film material that is generated and changes in solubility in a developer due to the deprotection reaction of the protecting group.

  In the case of a photoresist film using such a chemically amplified resist film material, an acid is generated by exposure, and then an acid-catalyzed reaction proceeds by heating the photoresist film for a short time in PEB. Improvement in resolution can be achieved.

（式中、Ｒ^１、Ｒ^３は水素原子又はメチル基、Ｒ^２、Ｒ^６は酸不安定基を表す。Ｒ^４は単結合、又は炭素数１〜６の直鎖状若しくは分岐状のアルキレン基であり、カルボニル基、エステル基又はエーテル基を含んでいてもよく、Ｒ^５は水素原子、フッ素原子、トリフルオロメチル基、シアノ基、又は炭素数１〜６の直鎖状、分岐状若しくは環状のアルキル基であり、ｐは１又は２であり、ｑは０〜４の整数である。Ｘ_１は単結合、エステル基、エーテル基若しくはラクトン環を有する炭素数１〜１２の連結基、フェニレン基、又はナフチレン基である。Ｘ_２は単結合、−Ｃ（＝Ｏ）−Ｏ−、又は−Ｃ（＝Ｏ）−ＮＨ−である。Ａｒは水素原子がＲ^４、Ｒ^５及びＯＲ^６により置換されたフェニル基又はナフチル基である。） Furthermore, the formation of the photoresist film has at least one repeating unit among the repeating units (a1) and (a2) having the following acid labile groups, and has a weight average molecular weight of 1,000 to 500,000. Range, and the copolymerization ratio of the repeating units (a1) and (a2) is 0 ≦ a1 <1.0, 0 ≦ a2 <1.0, and 0.1 ≦ a1 + a2 <1.0 It is preferable to use a resist film material having a base resin.

(In the formula, R ¹ and R ³ represent a hydrogen atom or a methyl group, R ² and R ⁶ represent an acid labile group. R ⁴ represents a single bond, or a linear or branched alkylene having 1 to 6 carbon atoms. R ⁵ may be a carbonyl group, an ester group or an ether group, and R ⁵ is a hydrogen atom, a fluorine atom, a trifluoromethyl group, a cyano group, or a straight chain, branched or A cyclic alkyl group, p is 1 or 2, and q is an integer of 0 to 4. X ₁ is a single bond, an ester group, an ether group, or a linking group having 1 to 12 carbon atoms having a lactone ring, A phenylene group or a naphthylene group, X ₂ is a single bond, —C (═O) —O—, or —C (═O) —NH—, wherein Ar is a hydrogen atom represented by R ⁴ , R ⁵ and OR; ⁶ is a phenyl group or a naphthyl group substituted by ⁶ .

  In the case of a photoresist film using a resist film material having such an acid labile group, an acid-catalyzed reaction preferably proceeds by heating the photoresist film for a short time in PEB, so that throughput and resolution are improved. Can be achieved.

（式中、Ｒ^７、Ｒ^１１は水素原子又はメチル基、Ｒ^８、Ｒ^９、Ｒ^１０、Ｒ^１２、Ｒ^１３、Ｒ^１４は同一又は異種の炭素数１〜１２の直鎖状、分岐状又は環状のアルキル基であり、カルボニル基、エステル基又はエーテル基を含んでいてもよく、又は炭素数６〜１２のアリール基、炭素数７〜２０のアラルキル基又はチオフェニル基を表し、Ｒ^８とＲ^９、Ｒ^９とＲ^１０、Ｒ^８とＲ^１０がそれぞれ結合して環を形成していても良く、Ｒ^１２とＲ^１３、Ｒ^１２とＲ^１４、Ｒ^１３とＲ^１４がそれぞれ結合して環を形成していても良い。Ｙは単結合、メチレン基、エチレン基、フェニレン基、フッ素化されたフェニレン基、−Ｏ−Ｒ^１５−、又は−Ｃ（＝Ｏ）−Ｚ−Ｒ^１５−である。前記Ｚは酸素原子又はＮＨ、前記Ｒ^１５は炭素数１〜６の直鎖状、分岐状若しくは環状のアルキレン基、アルケニレン基又はフェニレン基であり、カルボニル基、エステル基、エーテル基、ハロゲン原子又はヒドロキシ基を含んでいてもよい。） In addition, the formation of the photoresist film is a resist using the polymer compound as a base resin, the polymer compound having at least one repeating unit of the following sulfonium salt repeating units (b1) and (b2). It is preferable to use a film material.

(Wherein R ⁷ and R ¹¹ are a hydrogen atom or a methyl group, R ⁸ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , and R ¹⁴ are the same or different, linear or branched, having 1 to 12 carbon atoms. Or a cyclic alkyl group, which may contain a carbonyl group, an ester group or an ether group, or an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or a thiophenyl group, and R ⁸ R ⁹ , R ⁹ and R ¹⁰ , R ⁸ and R ¹⁰ may be bonded to form a ring, R ¹² and R ¹³ , R ¹² and R ¹⁴ , R ¹³ and R ¹⁴ are bonded Y may form a ring, Y is a single bond, methylene group, ethylene group, phenylene group, fluorinated phenylene group, —O—R ¹⁵ —, or —C (═O) —Z—R ¹⁵ —. in it. the Z is oxygen atom or NH, wherein ^{R 15} is Prime 1-6 linear, branched or cyclic alkylene group, an alkenylene group or a phenylene group, a carbonyl group, an ester group, an ether group, may contain a halogen atom or a hydroxy group.)

  Thus, a polymer compound having a repeating unit in which the sulfonic acid as the acid generator is bonded to the main chain of the base polymer can maximize the effect of shortening the acid diffusion distance and further improve the resolution. improves.

  Further, the exposure of the photoresist film is preferably performed using an electron beam or soft X-rays having a wavelength in the range of 3 to 15 nm.

  By exposing with such light, a highly accurate pattern can be formed.

  The photoresist film is preferably exposed using an electron beam and a mask blank is used as the substrate to be processed.

  Even if such a relatively thick mask blank is exposed to light, PEB can be performed in a short time according to the present invention, and a highly accurate pattern can be formed.

  As described above, according to the pattern forming method of the present invention, a lower layer film that absorbs light having a wavelength in the range of 600 to 2000 nm is formed, and PEB is performed by irradiating with light having a wavelength of 600 to 2000 nm. The underlayer film that absorbs heat is generated and the photoresist film can be heated in a short time, and PEB can be performed in a short time. As a result, the pattern formation method can achieve an improvement in throughput and an improvement in resolution due to a reduction in the acid diffusion distance. Further, according to the pattern forming method of the present invention, even a photoresist film formed on a thick substrate to be processed such as a mask substrate can be heated in a short time. Since a film material can be used, the pattern forming method does not cause degradation in resolution due to a change in the resist film material, such as when an infrared absorber is added to the resist film material.

It is a flowchart which shows the pattern formation method of this invention.

  Hereinafter, the pattern forming method of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited thereto.

  As described above, it has been desired to develop a pattern forming method capable of efficiently heating in a short time in a post-exposure bake (PEB).

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors formed a lower layer film that absorbs light in the wavelength range of 600 to 2000 nm, and irradiated light with a wavelength of 600 to 2000 nm. The absorption lower layer film generates heat and the photoresist film can be heated in a short time, and PEB can be performed in a short time even in a resist film formed on a thick substrate to be processed such as a mask substrate. The present invention has been completed by finding the headline, and thereby improving the throughput and improving the resolution by shortening the acid diffusion distance. Hereinafter, the present invention will be described in detail.

  That is, the present invention forms a lower layer film that absorbs light in the wavelength range of 600 to 2000 nm on a substrate to be processed, forms a photoresist film on the lower layer film, exposes the photoresist film, In this pattern forming method, post-exposure baking (PEB) is performed by irradiating and heating light of 600 to 2000 nm, followed by development. Therefore, it is not necessary to add a light absorber to the photoresist film itself.

[Formation of lower layer film (FIG. 1A)]
In the present invention, the lower layer film 31 that absorbs light in the wavelength range of 600 to 2000 nm is formed on the substrate 10 to be processed. At this time, the substrate 10 to be processed has the layer 20 to be processed, and the lower layer film 31 can be formed on the layer 20 to be processed (FIG. 1A). The thickness of the lower layer film is preferably in the range of 5 to 500 nm.

  It is preferable to form a lower layer film by forming a lower layer film material on a substrate to be processed by spin coating and then solidifying by cross-linking during baking. Thereby, the lower layer film can be easily formed in a short time. The baking temperature after forming (coating) the lower layer film material is preferably in the range of 100 to 350 ° C. If the baking temperature is too high, the near-infrared absorber is decomposed, and the efficiency of heating by light irradiation may be reduced. If the baking temperature is too low, the crosslinking reaction does not proceed, so that mixing may occur when a silicon-containing intermediate layer is applied thereon. Therefore, it is preferable to set the baking temperature after coating within a temperature range in which the near-infrared absorber does not decompose and the crosslinking reaction proceeds.

  Baking after application of the lower layer film can be performed by heating by near infrared or infrared irradiation. In this case, the thermal decomposition of the infrared absorbent can be minimized by heating in a short time. However, it is preferable to carry out such that bumping occurs by evaporation of the solvent for a short time and pinhole defects do not occur in the lower layer film.

  Cyanine compounds, phthalocyanine compounds, diimonium salt compounds, and aminium salt compounds (hereinafter referred to as near infrared and infrared rays) are used as the lower layer film that absorbs light in the wavelength range of 600 to 2000 nm used in the pattern forming method of the present invention. It is also preferable to form a lower layer film including at least one of the absorbent. By including such near-infrared and infrared absorbers, it becomes a lower layer film that can more easily absorb light in the wavelength range of 600 to 2000 nm. PEB can be performed in time.

  Among these near infrared and infrared absorbers, cyanine compounds are most preferably used from the viewpoint of heat resistance and solvent solubility. Specific examples of the cyanine compound include those described in JP-A Nos. 2001-133969 (0014) to (0019), JP-A 2008-224926 (0021) to (0034), and diimonium compounds and aminium compounds. As the compound described in No.-2552 and the phthalocyanine compound, compounds described in JP-A-2008-224926 (0037) to (0051) can be used.

  As the lower layer film, a phenol base resin described in Patents 4220361, 42522872, 4355543, 4388429, and 4466854, a crosslinking agent, a thermal acid generator, a solvent, and the above-described near infrared and infrared absorbers. What was mixed can be used.

  Increasing the mixing ratio of the near-infrared and infrared absorbers increases the heat generation efficiency by near-infrared and infrared irradiation, but decreases the etching resistance when etching the substrate to be processed using the lower layer film as a mask. Although it is necessary to optimize the mixing ratio of the near infrared and infrared absorbers while balancing the etching resistance and the heat generation efficiency, the preferred addition amount of the near infrared and infrared absorbers is 100 parts by mass of the base resin. It is 5-300 mass parts, Preferably it is 10-200 mass parts.

  In addition, the lower layer film material used in the pattern forming method of the present invention may contain other components such as an organic solvent and a surfactant.

  Specific examples of the organic solvent used for the lower layer film material include cyclohexanone, cyclopentanone, methyl-2-n-amylketone described in paragraphs (0144) to (0145) of JP-A-2008-111103, -Ketones such as heptanone, alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether , Ethers such as propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene Recall monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono tert-butyl ether acetate, etc. Examples include esters, lactones such as γ-butyrolactone, and mixed solvents thereof.

  Specific examples of the surfactant used for the lower layer film material include those described in paragraphs (0165) to (0166) of JP-A-2008-111103.

As the substrate 10 to be processed, a silicon substrate or a mask substrate is generally used. As the layer to be processed _{20, SiO 2, SiN, SiON} , SiOC, p-Si, α-Si, TiN, WSi, BPSG, SOG, Cr, CrO, CrON, MoSi, low dielectric films and etching stopper film Is mentioned.

[Formation of Intermediate Layer (FIG. 1B)]
In the present invention, it is preferable to form an intermediate layer 32 containing silicon atoms on the lower layer film 31 and to form the photoresist film on the intermediate layer 32. By providing the intermediate layer in this way, a three-layer resist method can also be performed.

  The baking temperature of the intermediate layer containing silicon atoms is preferably within a temperature range in which the near-infrared and infrared absorbers in the lower layer film are not decomposed, and is preferably in the range of 100 to 300 ° C. Further, the film thickness of the intermediate layer containing silicon atoms is preferably in the range of 2 to 80 nm.

[Formation of photoresist film (FIG. 1C)]
In the present invention, a photoresist film 33 is formed on the lower layer film 31. Further, when the intermediate layer 32 is formed, the photoresist film 33 can be formed on the intermediate layer 32. After application of the resist film material, baking is performed to produce a resist film. The baking temperature after application of the resist film material is preferably in the range of 50 to 150 ° C. The thickness of the photoresist film is preferably in the range of 2 to 500 nm. In addition, an antistatic film can be formed on the resist film. Hereinafter, although the resist film material which can be used in the pattern formation method of this invention is demonstrated, this invention is not limited to this, Moreover, 1 or 2 or more resist film material can also be used together.

  The resist film material used in the pattern forming method of the present invention may be positive or negative, but is preferably a chemically amplified resist film material. As the chemically amplified resist film material, a chemically amplified resist film material containing a photoacid generator that generates acid upon exposure, one kind selected from sulfonic acid, imide acid, and methide acid from an acid generator upon exposure. Generates the above acids and generates sulfonic acid by exposure from chemically amplified resist film materials whose solubility in the developer changes due to the deprotection reaction of the protecting group, or from the acid generator bonded to the main chain of the base polymer It is preferable to use a chemically amplified resist film material whose solubility in the developer changes due to the deprotection reaction of the protecting group. In the case of a photoresist film using such a chemically amplified resist film material, acid is generated by exposure, and then an acid-catalyzed reaction proceeds by heating the photoresist film for a short time in PEB. Improvement in resolution can be achieved.

（式中、Ｒ^１、Ｒ^３は水素原子又はメチル基、Ｒ^２、Ｒ^６は酸不安定基を表す。Ｒ^４は単結合、又は炭素数１〜６の直鎖状若しくは分岐状のアルキレン基であり、カルボニル基、エステル基又はエーテル基を含んでいてもよく、Ｒ^５は水素原子、フッ素原子、トリフルオロメチル基、シアノ基、又は炭素数１〜６の直鎖状、分岐状若しくは環状のアルキル基であり、ｐは１又は２であり、ｑは０〜４の整数である。Ｘ₁は単結合、エステル基、エーテル基若しくはラクトン環を有する炭素数１〜１２の連結基、フェニレン基、又はナフチレン基である。Ｘ₂は単結合、−Ｃ（＝Ｏ）−Ｏ−、又は−Ｃ（＝Ｏ）−ＮＨ−である。Ａｒは水素原子がＲ^４、Ｒ^５及びＯＲ^６により置換されたフェニル基又はナフチル基である。） Further, in the positive resist film material and the negative resist film material, it has at least one repeating unit among the following repeating units (a1) and (a2) having an acid labile group, and has a weight average molecular weight of 1. The copolymerization ratio of the repeating units (a1) and (a2) is 0 ≦ a1 <1.0, 0 ≦ a2 <1.0, and 0.1 ≦ a1 + a2 <1. A resist film material (positive resist) having a polymer compound of 0.0 as a base resin can be preferably used. In the case of a photoresist film using a resist film material having such an acid labile group, an acid-catalyzed reaction preferably proceeds by heating the photoresist film for a short time in PEB, so that throughput and resolution are improved. Can be achieved.

(In the formula, R ¹ and R ³ represent a hydrogen atom or a methyl group, R ² and R ⁶ represent an acid labile group. R ⁴ represents a single bond, or a linear or branched alkylene having 1 to 6 carbon atoms. R ⁵ may be a carbonyl group, an ester group or an ether group, and R ⁵ is a hydrogen atom, a fluorine atom, a trifluoromethyl group, a cyano group, or a straight chain, branched or A cyclic alkyl group, p is 1 or 2, q is an integer of 0 to 4. X ₁ is a single bond, an ester group, an ether group, or a linking group having 1 to 12 carbon atoms having a lactone ring, A phenylene group or a naphthylene group, X ₂ is a single bond, —C (═O) —O—, or —C (═O) —NH—, wherein Ar is a hydrogen atom represented by R ⁴ , R ⁵ and OR; ⁶ is a phenyl group or a naphthyl group substituted by ⁶ .

（式中、Ｒ^７、Ｒ^１１は水素原子又はメチル基、Ｒ^８、Ｒ^９、Ｒ^１０、Ｒ^１２、Ｒ^１３、Ｒ^１４は同一又は異種の炭素数１〜１２の直鎖状、分岐状又は環状のアルキル基であり、カルボニル基、エステル基又はエーテル基を含んでいてもよく、又は炭素数６〜１２のアリール基、炭素数７〜２０のアラルキル基又はチオフェニル基を表し、Ｒ^８とＲ^９、Ｒ^９とＲ^１０、Ｒ^８とＲ^１０がそれぞれ結合して環を形成していても良く、Ｒ^１２とＲ^１３、Ｒ^１２とＲ^１４、Ｒ^１３とＲ^１４がそれぞれ結合して環を形成していても良い。Ｙは単結合、メチレン基、エチレン基、フェニレン基、フッ素化されたフェニレン基、−Ｏ−Ｒ^１５−、又は−Ｃ（＝Ｏ）−Ｚ−Ｒ^１５−である。前記Ｚは酸素原子又はＮＨ、前記Ｒ^１５は炭素数１〜６の直鎖状、分岐状若しくは環状のアルキレン基、アルケニレン基又はフェニレン基であり、カルボニル基、エステル基、エーテル基、ハロゲン原子又はヒドロキシ基を含んでいてもよい。） In addition, the chemically amplified resist film material may be in a form in which a photoacid generator is added to the base polymer, but in order to maximize the effect of shortening the acid diffusion distance by the pattern forming method of the present invention. The acid generator having a structure in which the sulfonic acid as the acid generator is bonded to the main chain can be preferably used. For example, a polymer compound having at least one repeating unit among the repeating units (a1) and (a2), wherein at least one repeating unit of the following sulfonium salt repeating units (b1) and (b2) A resist film material containing a high molecular compound having a base resin as a base resin can be used.

(Wherein R ⁷ and R ¹¹ are a hydrogen atom or a methyl group, R ⁸ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , and R ¹⁴ are the same or different, linear or branched, having 1 to 12 carbon atoms. Or a cyclic alkyl group, which may contain a carbonyl group, an ester group or an ether group, or an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or a thiophenyl group, and R ⁸ R ⁹ , R ⁹ and R ¹⁰ , R ⁸ and R ¹⁰ may be bonded to form a ring, R ¹² and R ¹³ , R ¹² and R ¹⁴ , R ¹³ and R ¹⁴ are bonded Y may form a ring, Y is a single bond, methylene group, ethylene group, phenylene group, fluorinated phenylene group, —O—R ¹⁵ —, or —C (═O) —Z—R ¹⁵ —. in it. the Z is oxygen atom or NH, wherein ^{R 15} is Prime 1-6 linear, branched or cyclic alkylene group, an alkenylene group or a phenylene group, a carbonyl group, an ester group, an ether group, may contain a halogen atom or a hydroxy group.)

（Ｒ^１、Ｒ^２、Ｘ_１は前述の通りである。） Hereinafter, the repeating units (a1) to (b2) and other repeating units (c) and (d) that can be included will be exemplified. The monomer for obtaining the repeating unit (a1) is a methacrylate or acrylate monomer shown below.

(R ¹ , R ² and X ₁ are as described above.)

Specific examples of the monomer for obtaining the repeating unit (a1) are shown below.

The monomer for obtaining the repeating unit (a2) is specifically shown below.

In the repeating units (a1) and (a2), various acid labile groups represented by R ² and R ⁶ are selected, but those described in (0032) to (0058) of JP-A No. 2011-039315. Can be used.

  As a monomer for obtaining the repeating unit (b1) having the acid generator, as a monomer for obtaining the repeating unit (b2) having the acid generator described in JP-A-2011-039315 (0060) Monomers described in (0063) of JP 2011-039315 A can be used.

Specific examples of the repeating unit (b1) having an acid generator include the following.

Specific examples of the repeating unit (b2) having an acid generator include the following.

In addition to the repeating units (a1) and (a2) having an acid labile group and the repeating units (b1) and (b2) having an acid generator, a lactone ring, a carbonate group, a thiocarbonate group, a carbonyl group, and a cyclic acetal group , A linear ether group, a branched ether group, a cyclic ether group, a cyano group, a hydroxy group, a carboxyl group, an —O—C (═O) —G—, an azide group, a sulfo group, and a sulfonamide group. Can be copolymerized (G is a sulfur atom, NH). The repeating unit (c) is specifically exemplified below. The phenolic hydroxyl group may be protected with an acid labile group or an acyl group at the monomer stage, and may be deprotected with an acid or aqueous alkali solution after polymerization to form a hydroxy group.

  Furthermore, in order to improve etching resistance, the polymer compound that is the base resin of the resist film material is styrene, vinyl chrysene, vinyl naphthacene, vinyl pentacene, vinyl acenaphthene, indene, acenaphthylene, coumarin, chromone, maleic anhydride, It can also have repeating units (d) such as maleimide and vinylcarbazole.

  The polymer compound serving as the base resin for the resist film material used in the pattern forming method of the present invention has a polystyrene-reduced weight average molecular weight of 1,000 to 500,000, particularly 2,000 to 4,000, as determined by gel permeation chromatography (GPC). 30,000 is preferred. If the weight average molecular weight is 1,000 or more, the crosslinking efficiency in the thermal crosslinking after developing the resist material is good, and if it is 500,000 or less, the alkali solubility is lowered, and the trailing phenomenon is less likely to occur after pattern formation.

  Furthermore, in the high molecular compound used as the base resin of the resist film material used in the pattern forming method of the present invention, when the molecular weight distribution (Mw / Mn) is wide, low molecular weight or high molecular weight polymers exist. There is a risk that foreign matter is seen on the pattern or the shape of the pattern is deteriorated. Therefore, since the influence of such molecular weight and molecular weight distribution tends to increase as the pattern rule becomes finer, a multi-component copolymer to be used is used to obtain a resist film material suitably used for fine pattern dimensions. The molecular weight distribution of is preferably 1.0 to 2.0, particularly 1.0 to 1.5, and is narrowly dispersed. It is also possible to blend two or more polymers having different copolymerization ratios, molecular weight distributions, and molecular weights of the polymer compounds.

  One method for synthesizing these polymer compounds is a monomer having an unsaturated bond for obtaining repeating units (a1), (a2), (b1), (b2), (c), and (d). There is a method in which a radical initiator is added in an organic solvent to carry out heat polymerization, whereby a polymer compound can be obtained. Examples of the organic solvent used at the time of polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane and the like. As polymerization initiators, 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2-azobis (2-methylpropionate) ), Benzoyl peroxide, lauroyl peroxide and the like, and preferably polymerized by heating to 50 to 80 ° C. The reaction time is 2 to 100 hours, preferably 5 to 20 hours. As the acid labile group, those introduced into the monomer may be used as they are, or they may be protected or partially protected after polymerization.

  The copolymerization ratio of the polymer compound synthesized in this way is as follows: 0 ≦ a1 <1.0, 0 ≦ a2 <1.0, 0.1 <a1 + a2 <1.0, 0 ≦ b1 <1.0. 0 ≦ b2 <1.0, 0 <b1 + b2 <1.0, 0 <c <1.0, 0 ≦ d <1.0, and a1 + a2 + b1 + b2 + c + d = 1.0, preferably 0 ≦ a1 ≦ 0 .8, 0 ≦ a2 ≦ 0.8, 0.1 ≦ a1 + a2 ≦ 0.8, 0 ≦ b1 ≦ 0.4, 0 ≦ b2 ≦ 0.4, 0.01 ≦ b1 + b2 ≦ 0.4, 0.1 More preferably, ≦ c ≦ 0.8, 0 ≦ d ≦ 0.5, and a1 + a2 + b1 + b2 + c + d = 1.0 are satisfied.

  In addition, the resist film material used in the pattern forming method of the present invention includes an organic solvent, a compound that generates an acid in response to high energy rays (acid generator), a dissolution controller, a basic compound, if necessary, Other components such as a surfactant can be contained.

  The resist film material used in the pattern forming method of the present invention uses an acid generator bonded to a polymer compound having a repeating unit (b1) or (b2), in order to function as a chemically amplified positive resist film material. However, when it does not contain an acid generator bonded to the base polymer, it may contain an additive type acid generator, for example, a compound that generates an acid in response to actinic rays or radiation (photoacid generator) It may contain. In this case, the compounding amount of the photoacid generator is preferably 0.5 to 30 parts by mass, particularly 1 to 20 parts by mass with respect to 100 parts by mass of the base resin. The component of the photoacid generator may be any compound that generates an acid upon irradiation with high energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, oxime-O-sulfonate type acid generators, and the like. These can be used alone or in admixture of two or more.

  Specific examples of the acid generator are described in paragraphs (0122) to (0142) of JP2008-111103A. In the case of the polymer compound having the repeating units (b1) and (b2) having the acid generator, the acid generator is not necessarily added.

  Specific examples of the organic solvent used for the resist film material include cyclohexanone, cyclopentanone, methyl-2-n-amyl ketone, and 2-heptanone described in paragraphs (0144) to (0145) of JP-A-2008-111103. Ketones such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, alcohols such as 1-methoxy-2-propanol, 1-ethoxy-2-propanol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene Glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, ethers such as diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene group Cole monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono tert-butyl ether acetate, etc. Examples include esters, lactones such as γ-butyrolactone, and mixed solvents thereof.

  Basic compounds used as resist film materials include primary, secondary and tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, Examples thereof include nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amide derivatives, imide derivatives, and the like.

  Specifically, as basic compounds, paragraphs (0146) to (0164) of JP-A-2008-111103, surfactants as paragraphs (0165) to (0166), and as dissolution control agents, JP-A-2008-122932. The materials described in paragraphs (0155) to (0178) and acetylene alcohols in paragraphs (0179) to (0182) can be used.

[Exposure (FIG. 1D)]
In the present invention, the photoresist film 33 is exposed (arrow in the figure). For the exposure, high energy rays having a wavelength of 300 nm or less, specifically KrF, ArF, EUV, EB can be used, and in particular, electron beam or soft X-ray having a wavelength in the range of 3 to 15 nm is more preferably used. preferable. By exposing with such light, a highly accurate pattern can be formed. The photoresist film is preferably exposed using an electron beam and a mask blank is used as the substrate to be processed. Even if such a thick mask blank is exposed to light, PEB can be performed in a short time and a highly accurate pattern can be formed.

[Post-exposure bake (Figure 1E)]
In the present invention, post-exposure baking (PEB) is performed by irradiating light with a wavelength of 600 to 2000 nm (arrow in the figure) and heating. This light irradiation preferably does not include a wavelength of 400 nm or less. If the wavelength is 400 nm or less, the resist may be exposed to light and the resist film may be dissolved after development. Therefore, in order to cut a wavelength of 400 nm or less, a filter can be used, or a glass plate can be attached to the outlet of the lamp.

  Light irradiation can be performed with a laser or a lamp, and a lamp capable of irradiating a large area at once can be preferably used. In particular, the post-exposure bake is preferably heated by irradiation with light having a wavelength of 600 to 2000 nm using a xenon lamp or a halogen lamp. By using such a light source, light in the wavelength range of 600 to 2000 nm can be efficiently generated. With this PEB, not only the photoresist but also the lower layer film is irradiated with light of 600 to 2000 nm.

  The output of the lamp is preferably in the range of 10 W to 10000 W. If the output is 10000 W or less, the lamp can be controlled at an appropriate temperature increase rate. If the output is 10 W or more, it can be sufficiently heated by light irradiation. The irradiation time is in the range of 0.01 to 100 seconds. The shorter the irradiation time, the shorter the acid diffusion distance, but the uniformity of irradiation energy decreases. The direction of irradiation may be from the direction of the resist film or from the direction of the substrate surface.

  The surface of the photoresist film during lamp irradiation can be measured with a radiation thermometer to adjust the lamp irradiation energy and irradiation time. When the lamp is used for a long time, the illuminance decreases or the light intensity decreases due to the deposits on the radiation opening surface, so the baking temperature during light irradiation decreases. In order to keep the baking temperature uniform, it is preferable to constantly monitor the photoresist film surface with a radiation thermometer to adjust the lamp irradiation energy and irradiation time.

  In this way, a lower layer film that absorbs light in the wavelength range of 600 to 2000 nm is formed, and irradiation of light with a wavelength of 600 to 2000 nm causes heat generation of the lower layer film that absorbs light, thereby shortening the heating of the photoresist film. It can be done in time and PEB can be done. As a result, the pattern formation method can achieve an improvement in throughput and an improvement in resolution due to a reduction in the acid diffusion distance. Further, as the photoresist, a normal resist to which no infrared absorber or the like is added can be used, so that there is no deterioration in resolution. Further, according to the pattern forming method of the present invention, even a photoresist film formed on a thick substrate such as a mask substrate can be heated in a short time.

[Development (Fig. 1F)]
Finally, in the present invention, a pattern is formed by development. For example, 0.1 to 5% by weight, preferably 2-3% by weight Alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH) or an organic solvent developer is used for 0.1 to 3 minutes, preferably 0. The target pattern is formed on the substrate to be processed by developing by a conventional method such as a dip method, a paddle method, or a spray method for 5 to 2 minutes.

[Etching transfer (FIGS. 1G to I)]
In the present invention, after development, the intermediate layer 32 is etched using the pattern of the photoresist film 33 as a mask, the lower layer film 31 is etched using the intermediate layer 32 as a mask, and the processed layer 20 using the lower layer film 31 as a mask. Is a three-layer resist method in which a photoresist pattern is transferred to a substrate to be processed.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example etc. The weight average molecular weight (Mw) and dispersity (Mw / Mn) are determined by gel permeation chromatograph (GPC) to determine the polystyrene equivalent weight average molecular weight, and the composition of the polymer compound is determined by ¹ H-NMR measurement. It was.

[Composition of resist film material]
Resist polymers (resist polymers 1 to 5), quenchers, surfactants manufactured by Sumitomo 3M; FC-4430, organic solvents; PGMEA (propylene glycol monomethyl ether acetate) and CyH (cyclohexanone) shown in Table 1 below. Resist film materials 1 to 5 and comparative resist film material 1 which were mixed and filtered through a 0.2 μm Teflon (registered trademark) filter were prepared. Here, only the comparative resist film material 1 includes a die.

[Composition of lower layer film material]
Underlayer film polymers (underlayer film polymers 1 to 3), thermal acid generator 1, crosslinker 1, die compound (cyanine die 1, diimonium salt die 1, phthalocyanine die 1, aminium salt die 1), manufactured by Sumitomo 3M, shown below Surfactant; FC-4430, organic solvent; cyclopentanone and γ-butyrolactone mixed in the composition shown in Table 2 and filtered through a 0.2 μm Teflon (registered trademark) filter and lower layer film materials 1 and 6 1 was prepared. Here, only the comparative lower layer film material 1 does not include a die and does not absorb light having a wavelength of 600 to 2000 nm. The lower layer film materials 1 to 6 each include a die and absorb light having a wavelength of 600 to 2000 nm.

[Pattern formation (Examples 1-7, Comparative Examples 1-3)]
Each lower layer material shown in Table 2 was applied to a 6025 quartz mask substrate on which a Cr film having a thickness of 30 nm was formed by sputtering, and baked at 200 ° C. for 300 seconds to produce a lower layer film having a thickness of 150 nm. A silicon-containing intermediate layer material SHB-A940L35 manufactured by Shin-Etsu Chemical Co., Ltd. was applied thereon, and baked at 200 ° C. for 300 seconds to form a silicon-containing intermediate layer having a thickness of 35 nm.

  Next, the positive resist film material shown in Table 1 was spin-coated on the quartz mask substrate, and pre-baked on a hot plate at 110 ° C. for 300 seconds to produce a 100 nm photoresist film. This was exposed with an electron beam (EB) in a vacuum chamber at an HV voltage of 50 keV using an HL-800D manufactured by Hitachi, Ltd. to draw a pattern.

  After the exposure, post-exposure baking (PEB) was performed by irradiating light having a wavelength of 600 to 2000 nm from the upper side of the photoresist film for the time shown in Table 3 using a 400 W xenon lamp. Thereafter, paddle development was performed for 30 seconds with a 2.38 mass% TMAH aqueous solution to obtain a positive pattern. In Comparative Example 3, baking was performed at 90 ° C. for 300 seconds without performing light irradiation after drawing.

  With respect to the obtained resist pattern, the minimum dimension at the exposure amount for resolving 120 nm line and space at 1: 1 was defined as the resolution. Table 3 shows the results of resist film material, lower layer film material, irradiation time of light having a wavelength of 600 to 2000 nm, sensitivity in electron beam exposure, and resolution.

  As described above, in Comparative Example 1 and Comparative Example 2 using a resist film material that absorbs light having a wavelength of 600 to 2000 nm and a lower layer film material that does not absorb light, the resolution is achieved even when PEB is performed by irradiating light having a wavelength of 600 to 2000 nm. I know it ’s bad. In particular, as shown in Comparative Example 1, when the irradiation time of light having a wavelength of 600 to 2000 nm is short, the sensitivity is bad and the resolution is worst, and as shown in Comparative Example 2, the sensitivity is improved when the irradiation time is lengthened. However, it was shown that the throughput decreases and the resolution deteriorates due to the longer acid diffusion distance as the irradiation time is extended. On the other hand, with the pattern forming method of the present invention, it was shown that both sensitivity and resolution are good even if the irradiation time of light with a wavelength of 600 to 2000 nm is short.

  As described above, according to the pattern forming method of the present invention, a lower layer film that absorbs light having a wavelength in the range of 600 to 2000 nm is formed, and the mask substrate is irradiated with the light having a wavelength of 600 to 2000 nm and heated. PEB can be performed in a short time even on a resist film formed on a thick substrate to be processed, thereby improving throughput and improving resolution by shortening the acid diffusion distance. It was shown that the pattern forming method can be performed. Furthermore, since a normal resist can be used as the resist, resolution does not deteriorate.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

10: Substrate to be processed,
20 ... Work layer,
31 ... Under film,
32: Intermediate layer 33: Photoresist film.

Claims (12)

  A lower layer film that absorbs light in the wavelength range of 600 to 2000 nm is formed on the substrate to be processed, a photoresist film is formed on the lower layer film, the photoresist film is exposed, and then light having a wavelength of 600 to 2000 nm is emitted. A pattern forming method comprising performing post-exposure baking (PEB) by irradiation and heating, and then forming a pattern by development.   2. The pattern forming method according to claim 1, wherein an underlayer film including at least one of a cyanine compound, a phthalocyanine compound, a diimonium salt compound, and an aminium salt compound is formed as the lower layer film.   The pattern forming method according to claim 1, wherein a lower layer film material is formed on the substrate to be processed by spin coating and then solidified by cross-linking during baking to form the lower layer film. .   The post-exposure bake is performed by irradiating and heating the light having a wavelength of 600 to 2000 nm using a xenon lamp or a halogen lamp. The pattern formation method as described.   5. The pattern formation according to claim 1, wherein an intermediate layer containing silicon atoms is formed on the lower layer film, and the photoresist film is formed on the intermediate layer. Method.   6. The photoresist film according to claim 1, wherein the photoresist film is formed using a chemically amplified resist film material containing a photoacid generator that generates an acid upon exposure. The pattern forming method according to 1.   In the formation of the photoresist film, at least one acid selected from sulfonic acid, imide acid, and methide acid is generated from the acid generator by exposure, and the solubility in the developer is changed by the deprotection reaction of the protecting group. The pattern forming method according to claim 1, wherein the pattern forming method is performed using a chemically amplified resist film material.   Formation of the photoresist film is a chemically amplified resist film material in which sulfonic acid is generated by exposure from an acid generator bonded to the main chain of the base polymer, and the solubility in a developing solution is changed by deprotection of the protecting group. The pattern forming method according to claim 1, wherein the pattern forming method is performed by using the method. The formation of the photoresist film has at least one repeating unit of the following repeating units (a1) and (a2) having an acid labile group, and has a weight average molecular weight in the range of 1,000 to 500,000. Based on a polymer compound in which the copolymerization ratio of the repeating units (a1) and (a2) is 0 ≦ a1 <1.0, 0 ≦ a2 <1.0, and 0.1 ≦ a1 + a2 <1.0 The pattern forming method according to claim 1, wherein the pattern forming method is performed using a resist film material that is a resin.

(In the formula, R ¹ and R ³ represent a hydrogen atom or a methyl group, R ² and R ⁶ represent an acid labile group. R ⁴ represents a single bond, or a linear or branched alkylene having 1 to 6 carbon atoms. R ⁵ may be a carbonyl group, an ester group or an ether group, and R ⁵ is a hydrogen atom, a fluorine atom, a trifluoromethyl group, a cyano group, or a straight chain, branched or A cyclic alkyl group, p is 1 or 2, and q is an integer of 0 to 4. X ₁ is a single bond, an ester group, an ether group, or a linking group having 1 to 12 carbon atoms having a lactone ring, A phenylene group or a naphthylene group, X ₂ is a single bond, —C (═O) —O—, or —C (═O) —NH—, wherein Ar is a hydrogen atom represented by R ⁴ , R ⁵ and OR; ⁶ is a phenyl group or a naphthyl group substituted by ⁶ . The formation of the photoresist film is a resist film material using the polymer compound as a base resin, the polymer compound having at least one repeating unit of the following sulfonium salt repeating units (b1) and (b2) The pattern forming method according to claim 9, wherein

(Wherein R ⁷ and R ¹¹ are a hydrogen atom or a methyl group, R ⁸ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , and R ¹⁴ are the same or different, linear or branched, having 1 to 12 carbon atoms. Or a cyclic alkyl group, which may contain a carbonyl group, an ester group or an ether group, or an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or a thiophenyl group, and R ⁸ R ⁹ , R ⁹ and R ¹⁰ , R ⁸ and R ¹⁰ may be bonded to form a ring, R ¹² and R ¹³ , R ¹² and R ¹⁴ , R ¹³ and R ¹⁴ are bonded Y may form a ring, Y is a single bond, methylene group, ethylene group, phenylene group, fluorinated phenylene group, —O—R ¹⁵ —, or —C (═O) —Z—R ¹⁵ —. in it. the Z is oxygen atom or NH, wherein ^{R 15} is Prime 1-6 linear, branched or cyclic alkylene group, an alkenylene group or a phenylene group, a carbonyl group, an ester group, an ether group, may contain a halogen atom or a hydroxy group.)   11. The pattern forming method according to claim 1, wherein the exposure of the photoresist film is performed using an electron beam or soft X-rays having a wavelength in a range of 3 to 15 nm.   The pattern forming method according to claim 11, wherein the exposure of the photoresist film is performed using an electron beam, and a mask blank is used as the substrate to be processed.

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