JPS62240953A - Resist - Google Patents

Abstract

PURPOSE:To enhance sensitivity and resolution by using a resist composed of a polymer consisting of specified repeating units, a copolymer containing said units, or a mixture of the polymer or copolymer containing said units and another polymer or copolymer not containing them. CONSTITUTION:The resist to be used is composed of the polymer consisting of the repeating units each represented by formula I derived from a monomer represented by formula II, the copolymer containing said units, or a mixture of the polymer or copolymer containing said units and another polymer or copolymer not containing them. As a monomer to be copolymerized with the monomer of formula II, styrene, acrylonitrile, and the like are enumerated. A preferable molecular weight of the polymer or copolymer having said units is 10,000-1,000,000, thus permitting the obtained resist to be high in sensitivity and resolution to ionizing radiation beams and superior in dry etching resistance.

Description

[Detailed description of the invention] Rt! i (7■1), Shako The present invention relates to a negative resist.

- In recent years, the demand for high performance and high integration of semiconductor integrated circuits has been increasing.For this reason, as a lithography technology, conventional ultraviolet rays Instead of photolithography using
Efforts are being made to establish ultra-fine pattern processing techniques through lithography using ionizing radiation with shorter wavelengths and higher energy, such as electron beams, soft X-rays, and ion beams.

On the other hand, in order to enable ultra-fine lithography technology by changing the radiation source, the resist material used must also have properties corresponding to the changes. That is, it must be sensitive to ionizing radiation and have the characteristics of a resist.

Generally used as a resist for ultra-fine lithography using high-energy ionizing radiation.

It is essential that the material has the following characteristics.

(a) High sensitivity to ionizing radiation.

(b) High resolution.

(c) It is possible to form a homogeneous thin film.

(d) Excellent dry etching resistance since dry etching is applied, which is essential for high-density, fine patterning.

(e) Excellent developability.

Conventionally, many types of t4i radiation-sensitive resists used for the above purpose have been developed, and these are:
It is divided into positive type, in which a decay reaction occurs when irradiated with ionizing radiation and the irradiated part becomes solubilized, and negative type, in which crosslinking reaction occurs due to irradiation with ionizing radiation and the irradiated part becomes insolubilized.

Among these, the positive type generally has the disadvantage that the range of application of the developer is narrow and the dry etching resistance is weak.

On the other hand, many negative resists are superior to positive resists in these respects.

Typical negative resists that have been developed so far include polyglycidyl methacrylate systems, glycidyl methacrylate-ethyl acrylate copolymer systems, and unsaturated carboxylic acid-methacrylate copolymer systems. Although these resists are highly sensitive to electron beams, they have several drawbacks in practical use and are not necessarily satisfactory. For example, in a glycidyl methacrylate resist, a large amount of scum is generated at both ends of a drawn pattern, resulting in a decrease in resolution, and in practical terms, only a resolution of about 2 μm can be obtained. Furthermore, all of the above resists have a drawback that they have low dry etching resistance, making it difficult to apply the dry etching process that is essential for forming fine, high-density patterns.

In addition, the styrene copolymer containing the above-mentioned repeating unit (1) of the present invention, or a mixture of the copolymer and the following polymer, is described by Eli M, Pearee, at al, J.
, Macromol, Sci, Che+n, , A2
1,1] 81-1216 (1984).

a) Polyalkyl methacrylates b) Bisphenol A polycarbonate C) Polyphenylene sulfone d) Polystyrene acrylonitrile copolymer and others However, this document is concerned with the study of the compatibility of the styrene copolymer with these polymers, and what should be done with it? There is no mention of its use or anything that suggests it.

Steps to Solve the Problems The present inventor has aimed to provide an ionizing radiation-sensitive negative resist that has high sensitivity and high resolution to ionizing radiation and has good dry etching resistance. As a result of repeated research aimed at this purpose, it was discovered that a resist containing a polymer or copolymer having a specific repeating unit could achieve the above object, and the present invention was achieved.

That is, 1 the present invention is directed to a polymer consisting of a repeating unit [+] or a copolymer containing a repeating unit [■], or
A resist characterized by being composed of a mixture of a copolymer containing η (coalescence or a repeating unit [1]) consisting of a repeating unit [■] and a copolymer containing a repeating unit [1] (copolymerization or copolymerization) at the m-position [1]. This is a summary.

The monomer that produces the polymer consisting of the above-mentioned repeating unit (1) of the present invention is a monomer of the following general formula (1), and the monomer that is polymerized with the monomer to produce a copolymer includes styrene, Acrylonitrile, fumaric acid, maleic acid, vinyl ketone, nitrostyrene, cyanostyrene,
Examples include compounds such as acrylic esters such as methyl acrylate and butyl acrylate, halogenated styrenes such as chlorostyrene, dimethylaminostyrene, vinylpyridine, and butadiene.

The resist of the present invention also includes a mixture of a polymer consisting of repeating unit [1] or a copolymer containing repeating unit (1), and a polymer or copolymer containing no repeating unit (1). , the above polymers are preferably mutually soluble.

In the above mixture, other compatible polymers include the above formula (1) [(hexafluoro-2-hydroxyl-
Polymers that can hydrogen bond with polymers or copolymers having repeating units of [propyl) styrene] include polyvinyl acetal-based, polyacrylate-based, polycarbonate-based, polyester-based, polyamide-based, polyvinyl acetate-based polymers, etc. can give.

As a method for producing the monomer (ME Cn) above, 1, for example, using chlorostyrene as a starting material, magnesium and hexafluoroacetone are subjected to a Grignard reaction,
The manufacturing method can be mentioned.

Furthermore, the polymer consisting of the above-mentioned repeating unit (1) or the copolymer containing the above-mentioned repeating unit (1) of the present invention may be
62 (II) and various other monomers by a conventional radical polymerization method. In the case of a copolymer with styrene, it can also be produced by using polystyrene as a starting material and reacting it with hexafluoroacetone under an aluminum chloride catalyst.

The molecular weight of the polymer or copolymer having the repeating unit [1] of the present invention is 5,000 to 1,500,000, and from the viewpoint of film formability, resolution, and sensitivity, it is 10,000 to 1,0.
00,000 is preferred.

In the case of the copolymer of the present invention, 2N)[(hexafluoro-
The proportion of the [2-hydroxyl-propyl)styrene] component is 5 mol % or more, and if it is less than 5 mol %, the effect [1] (especially sensitivity) is not so great. In addition, in the mixture of the polymer or copolymer of the present invention and other polymers, the proportion of other polymers is preferably 3 to 95 mol%, and if it is less than 3 mol%, the effect of introducing other polymers (film forming properties, etc.) If the amount exceeds 95 mol %, the properties will only be that of other polymers.

Next, a method of performing lithography using the resist of the present invention will be described.

First, the resist of the present invention is prepared using an aromatic solvent such as benzene or xylene, a ketone solvent such as acetone or methyl ethyl ketone, a chlorinated hydrocarbon solvent such as chloroform or ethylene chloride, or ethyl acetate.

A 3-15% by weight solution is prepared by dissolving it in an ester solvent such as methyl cellosolve acetate or a mixed solvent to prepare a 3-15% by weight solution having a good viscosity when applied. Next, this resist solution is uniformly applied onto a semiconductor substrate to be processed or a mask substrate by a conventional method such as a spinner coating method, and prebaked to a thickness of 0.000 mm.
A resist film of about 1 to 2 μm is formed. The prebaking conditions generally include a temperature range of 70° C. to 180° C. and a time range of about 20 to 40 minutes, although it depends on the type of solvent used.

Next, a desired part of the resist film is irradiated with ionizing radiation such as an electron beam or soft X-ray according to a conventional method to draw a pattern, and then treated with a developer to select the unirradiated parts of the resist film. A resist pattern is formed by separately dissolving and removing the resist. As the developer, the same solvents as those used in preparing the resist solution described above are preferably used.

After development, the resist is applied to the substrate with the pattern.

If necessary, a boss bake treatment and a scum removal treatment are further performed, and then etching is performed to form an etching pattern on the exposed portion of the substrate. Bost baking treatment is performed at a temperature of 100° C. to 150° C. for a time of 20 to 40° C., for example. The scum removal treatment can be carried out, for example, by using oxygen plasma for 1 to 2 minutes at a pressure of 0°9 to 100 W of Torrt output.

Both wet etching and dry etching can be applied to etching, but it is suitable for semiconductor substrates with high silver density,
Dry etching, which is suitable for forming fine patterns, is more suitable for processing mask substrates and the like, and the resist of the present invention has sufficient dry etching resistance.

After etching, if the resist pattern is removed using a stripping solution or the like, one cycle of one lithography process is completed.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

After adding 7 g of magnesium to a 200 cm three-necked flask and placing it in a nitrogen atmosphere, add tetrahydrofuran (THF) in which 5 cm of P-chlorostyrene and 2 cm of ethyl bromide were dissolved.
) 20 cm3 was added, then 25 g of p-chlorostyrene was added to THFlo, keeping the reaction temperature at 35°C while stirring.
The solution dissolved in "ocm" was slowly dropped. After dropping 1
The mixture was refluxed for a period of time, and then 40 g of hexafluoroacetone gas was slowly passed into the reaction solution over a period of about 3 hours. After the reaction is complete, pour into a large amount of ice water, wash the resulting solid with 5% hydrochloric acid solution, 10% sodium hydroxide solution, and 5% hydrochloric acid solution in this order. After drying, p-(hexafluoro-2
-hydroxyl-propyl)styrene was obtained.

9:) 5 g of p-(hexafluoro-2-hydroxyl-propyl) styrene obtained was added to 10 am3 of benzene, and to this was added azobisisobutyronitri
) After adding 0.005 g, the mixture was reacted at 60'C for 40 hours. After the reaction, the reaction mixture was poured into methanol to recover the polymer, and the resulting polymer was purified by precipitation twice in a benzene-methanol system to obtain a yield of 82%. The molecular weight was determined to be 105,000 by gel permeation chromatography (GPC).

The above polymer was dissolved in xylene and filtered through a 0.2 μm filter to obtain a resist solution with a concentration of 8% by weight. This resist solution was applied onto a chrome mask substrate using a spinner coating method.

A uniform resist film having a thickness of 5,000 wafers was obtained by prebaking at 90° C. for 30 minutes. Next, apply a beam diameter of 0 to this resist film.
．． An electron beam was irradiated at 25 μm and an acceleration voltage of 10 kV. After irradiating with varying exposure doses, chlorobenzene was exposed to 6
After immersion for 0 seconds and rinsing with isopropyl alcohol, the residual film rate was plotted against the exposure amount to form a sensitivity curve, and the exposure amount at which the residual film rate after development was 50% was defined as the sensitivity. The sensitivity of this resist film is 7. OX 10-'coulomb/
It was 0m2.

Example 2 Polystyrene Log with a molecular weight of 500,000 and 150 g of carbon disulfide were added to a 200 r, m' Mitsuro flask, and after the outside was cooled with water, 4 g of aluminum chloride was added. Next, while stirring the solution, hexafluoroacetone Jog was slowly passed through the solution over a period of about 1 hour.

After the reaction, the polymer was recovered by pouring it into a large amount of water, and the obtained polymer was purified by precipitation twice using a methylene chloride-rl-hexane system. Elemental analysis revealed that the proportion of p-(hexalolo-2-hydroxylpropyl)styrene of general formula (1) was 31 mol%. The molecular weight of the produced polymer is 74
It was 10,000.

The above polymer was dissolved in xylene and filtered through a 0.2 μm filter to obtain a resist solution with a concentration of 4%.

After coating and prebaking this resist solution in the same manner as in Example 1, electron beam irradiation was performed and f! 1
J image shows 3XlO-'CuD', // cm
” sensitivity was obtained.

Further, using this resist, a resist film having a thickness of 5,000 layers was obtained on a chrome mask substrate in the same manner as above, and a pattern was drawn by irradiating this with an electron beam having a beam diameter of 0.5 μm and an acceleration voltage of 10 kV. After drawing, the image was developed using chlorobenzene for 60 seconds.

A resist pattern was obtained by rinsing with IT''A for 30 seconds.

Next, the substrate with the resist pattern set was heated to 120℃ for 3
After 0 min post-bake, pressure I T .

rr, scum removal treatment was performed for 1 minute using oxygen plasma with an output of 100 W. Pressure 3XL for this board
The exposed portion of the chromium film was etched for 5 minutes by reactive sputter etching using a mixed gas of 014 and 02 at an O-' Torr and an output of 300 W. The amount of film reduction of the resist pattern was 180 per minute, indicating sufficient dry etching resistance.

After etching, the substrate was immersed in a stripping solution consisting of a sulfuric acid-hydrogen peroxide mixture at 70 DEG C. for 5 minutes, and then the resist pattern was stripped off to obtain a photomask having a chromium pattern consisting of 1 .mu.m lines and spaces.

Example 3 7 g of p-(hexafluoro-2-hydroxyl-propyl)styrene synthesized in Example 1 and 3 g of styrene were added to 10 cm3 of benzene, and AIBN 0.002
After adding g and reacting at 55°C for 40 hours,
The polymer was poured into methanol in a large container to recover the polymer, and the resulting polymer was purified by precipitation twice in a benzene-methanol system to obtain a yield of 85%. The molecular weight of the obtained polymer is O
It was 350,000 from PC.

The above polymer was dissolved in xylene and filtered through a 0.2 μm filter to obtain a resist solution having a concentration of 6% by weight. After coating and prebaking this resist solution in the same manner as in Example 1.

After electron beam irradiation and development with chlorobenzene for 60 seconds, the result was 35. OXI O-'C/cm'' sensitivity was shown.

0'' 1.0 g of the polymer synthesized in Example 2 and polyvinyl dodecylal with a molecular weight of 300,000 and an acetalization rate of 84%.
Dissolve 0g in chlorobenzene.

The resist solution was filtered through a 0.2 μm filter to obtain a resist solution having a concentration of 5%. This resist solution was coated and prebaked in the same manner as in Example 1, and then irradiated with an electron beam and developed.
showed a sensitivity of

Furthermore, using this resist, a resist pattern was formed on a chrome mask in the same manner as in Example 1, and after scum treatment and post-baking in the same manner as in Example 2, reactive sputter etching was performed using a mixed gas of CQ and 0□. The frosted part of the chromium film was etched for 5 minutes. The amount of film loss for the resist pattern was 230 layers per minute, and for the polyvinyl dodecyl homopolymer it was 360 layers per minute, indicating sufficient dry etching resistance.

Further, using this resist, a thickness of 15
A pattern was formed on a silicon wafer having a silicon oxide film of 0.00%, followed by scum treatment and post-baking in the same manner as in Example 2, and then a 40% ammonium fluoride aqueous solution and a 48% hydrofluoric acid aqueous solution were mixed at 10= It was immersed in an etching solution mixed at a ratio of 1:1 and etched for 3 minutes.

After etching, the substrate was heated to 5 Torr using oxygen plasma.
, the resist was removed by processing under the conditions of 300W, and the result was 1.0
A silicon oxide film pattern consisting of μm lines and spaces was obtained.

[Examples 5 to 1] Copolymer of monomer of general formula [1]] and styrene (A
) and counterpolymer (B) in various ratios (A/R)
The results of coating and prebaking according to the method shown in Example 4 are shown in Table 1.

All of the resists of the present invention have good film formability.

(Hereinafter, blank space) The present invention relates to P-(hexafluoro-2-hydroxyl-propyl) styrene polymer, p-(hexafluoro-2-
Copolymers of hydroxyl-propyl) styrene and heptamers copolymerizable with them, or (compatible with)
It is possible to obtain a resist that is made of a mixture with other polymers, has good adhesion to the substrate and film formability, has high sensitivity to ionizing radiation, high resolution, and has excellent dry etching resistance. can.

Claims (2)

[Claims] (1) A polymer consisting of a repeating unit [I] or a copolymer containing a repeating unit [I], or a polymer consisting of a repeating unit [I] or a copolymer containing a repeating unit [I] and repeating A resist comprising a polymer or a mixture with a copolymer that does not contain the unit [1]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼〔I〕 (2) The molecular weight of the polymer consisting of repeating unit [I] or the copolymer containing repeating unit [I] is 10.0
00 to 1,000,000.