JP2765765B2 - Method for manufacturing phase shifter material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shifter material having a specific silicon oxide film and capable of forming a phase shifter having an excellent pattern shape, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the degree of integration of semiconductor devices has been remarkably increased, and accordingly, fine processing in a manufacturing process has been advanced. A dramatic improvement in resolution in microfabrication is often due to advances in photolithography, that is, higher performance of an exposure apparatus, higher performance of a resist, improvement of a resist process, and the like. However, in the field of semiconductor device manufacturing, further improvement in resolution is desired, and in order to obtain a resolution of 0.5 μm or less, it is a fact that conventional techniques cannot sufficiently cope with the situation.

Recently, a phase shift method using a phase shift mask has attracted attention as a new photolithography method for improving resolution. The phase shift method is a method of improving the resolution by giving a phase difference to the light transmitted through the photomask and utilizing the interference between the transmitted lights.

The phase shift method is an effective method for improving the resolution only by changing the photomask without changing the function of the optical system in photolithography. More specifically, the phase shift method has a photomask structure on the photomask. A transparent film that inverts the phase on one adjacent side of the opening, that is, a structure in which a phase shifter is provided. Since the phase of the adjacent transmitted light is inverted, an interaction that cancels each other works, and the pattern boundary portion The light intensity becomes zero, and the pattern is optically separated, so that a pattern that could not be resolved with a normal photomask can be formed.

Heretofore, as a material for forming the phase shifter, a coating solution prepared by hydrolyzing a silicon compound such as alkoxysilane or halogenosilane is applied onto a substrate such as a glass substrate, Was used to form a silicon oxide film by firing.

However, in the phase shifter material thus obtained, since the silicon oxide film has a hygroscopic property and absorbs moisture in the atmosphere, when a resist pattern is formed on this film, the phase shifter material is absorbed. There is a disadvantage that the shape of the resist pattern formed due to the influence of moisture is degraded, and sufficient accuracy cannot be obtained when etching the silicon oxide film.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a material capable of forming a phase shifter having a highly precise pattern shape by overcoming the drawbacks of the conventional phase shifter material. It is a thing.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to improve the physical properties of a silicon oxide film and obtain a phase shifter material that gives a phase shifter having a highly accurate pattern shape. Using an organic solvent solution containing a silazane compound as a coating solution, applying it to the substrate surface, drying it, and firing it in an oxidizing atmosphere, the above-mentioned object was achieved. Invented the invention.

That is, the present invention provides a phase shifter material characterized in that an organic solvent solution containing a silazane compound is applied to a substrate surface, dried, and then fired in an oxidizing atmosphere to form a silicon oxide film. Is provided.

The silicon oxide film in the conventionally used phase shifter material is formed in the presence or presence of water, and its infrared absorption spectrum is considered to be due to the presence of water. 3200-3600
Although a peak exists in the range of cm ⁻¹ , whereas the silicon oxide film formed by the method of the present invention has substantially no peak in this range, there is a clear difference in composition between the two. Is recognized.

In the method of the present invention, a silicon oxide film is formed on a substrate by applying an organic solvent solution containing a silazane compound to the surface of the substrate, drying the solution, and then firing the solution in an oxidizing atmosphere. This silazane compound is a general term for compounds having a Si—N bond in the molecule, but in the method of the present invention, it is preferable to use a silazane compound containing no oxidized atom in the molecule.

Such a silazane compound can be obtained by reacting a halogenosilane or an organohalogenosilane with ammonia or an amine in an organic solvent. The halogenosilane used at this time is, for example, SiCl ₄ , HSiCl ₃ , H ₂ SiCl ₂ , H ₃ SiCl
Examples of the organohalogenosilane include CH ₃ SiHCl ₂ and CH ₃ SiH ₂
Cl, CH ₃ SiCl ₃ , (CH ₃ ) ₂ SiCl ₂ , (C
_{H 3) 3 SiCl, C 2} H 5 SiCl 3, (C 2 H 5) 3 SiC
1, (C ₂ H ₅ ) (C ₆ H ₅ ) SiCl ₂ , (C ₂ H ₅ ) (C _{6
H 5) 2 SiCl, (CH} 3) 3 CSiHCl 2, (CH 3)
₂ CHSiHCl ₂ , (C ₆ H ₅ ) SiHCl ₂ , (C
_{6 H 5) SiCl 3, (} C 6 H 5) 2 SiCl 2, (C 6 H 5) 3
SiCl, C ₆ H ₅ CH ₂ SiCl ₃ , (C ₆ H ₅ CH ₂ ) ₂ S
iCl ₂ , (C ₆ H ₅ CH ₂ ) ₃ SiCl and the like can be mentioned.

On the other hand, the amines to be reacted with these halogenosilanes or organohalogenosilanes include lower alkylamines such as monomethylamine, ethylamine, propylamine and butylamine, polyamines such as ethylenediamine, benzylamine and phenethylamine. Aralkylamine and the like.

Examples of the organic solvent used in these reactions include toluene, xylene, diethyl ether and dichloromethane. Particularly preferred silazane compounds are HSiCl ₃ , H ₂ SiCl ₂ , H ₃ S in an organic solvent.
It is obtained by dissolving a halogenosilane such as iCl and blowing ammonia gas into it.

In the present invention, the reaction mixture of the halogenosilane or organohalogenosilane thus obtained and ammonia or amines can be used as a coating solution as it is, and the reaction mixture is subjected to distillation under reduced pressure or the like. After removing the solvent and recovering the desired silazane compound as an oily substance or a solid substance, this can be dissolved in a suitable organic solvent to prepare a coating solution.

In this case, the organic solvent includes methanol, ethanol, propanol, butanol, cyclohexanol, benzyl alcohol, dimethylolbenzene, furfuryl alcohol, tetrahydrofurfuryl alcohol, diacetone alcohol, ethylene glycol monoalkyl ether, diethylene glycol monoalkyl ether. Alkyl ethers, alcohols such as triethylene glycol monoalkyl ether and propylene glycol monoalkyl ether, alkyl acetates, diethylene glycol monoalkyl ether acetate, triethylene glycol monoalkyl ether acetate, propylene glycol monoalkyl ether acetate, acetoacetate ethyl ester, Alkyl lactate, Alkyl benzoate , Benzyl acetate, esters such as glycerol diacetate, acetone, methyl ethyl ketone, cyclohexanone, acetylacetone, isophorone, diethyl ketone, methyl isobutyl ketone,
Ketones such as methyl n-butyl ketone and acetonylacetone, n-pentane, n-hexane, isohexane,
Hydrocarbons such as n-heptane, n-octane, isooctane, benzene, toene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, and tetralin are used. The organic solvent may be used alone or in combination of two or more.

The coating solution used in the present invention has a silazane compound concentration of 1 to 60% by weight, preferably 10 to 30% by weight, and a viscosity of 0.5 to 50 cP, preferably 1 to 20 cP.
Those in the range of P are practically suitable. Such a viscosity can be adjusted by appropriately selecting the amount of the organic solvent or the type of the organic solvent depending on a desired film thickness or the like.

The method of the present invention is advantageous in that the above-mentioned coating solution is applied to the surface of a mask original on which a light-shielding film pattern made of a metal film such as chromium is formed by a conventional coating means such as a spinner method, a spray method, or a dipping method. 50-20
A polysilazane-based film is formed by drying at a temperature of 0 ° C., and then the polysilazane-based film is converted into a silicon oxide film by firing in an oxidizing atmosphere, for example, in the air or an oxygen atmosphere. As firing conditions in this case,
The temperature is selected within the range of 200 to 800 ° C. for a time of 15 to 60 minutes. By such baking, a uniform silicon oxide continuous film having a thickness of 0.2 to 3.0 μm is formed. As described above, the phase shifter material obtained in this manner is obtained by converting a polysilazane-based coating into a silicon oxide film, and the silicon oxide film may contain nitrogen or carbon as long as the object of the present invention is not impaired. And those containing

In order to manufacture a phase shift mask using a phase shifter material obtained by the method of the present invention, for example, a material in which a silicon oxide film is formed on a light-shielding film pattern forming surface of a mask master as described above, Lithography, that is, forming a resist film on the silicon oxide film, irradiating it with actinic radiation through a mask having a predetermined pattern, and then performing development processing to form a resist pattern on the silicon oxide film. Next, the silicon oxide film is removed by etching using the formed resist pattern as a mask to obtain a phase shifter having a predetermined pattern on a substrate surface, for example, a light shielding film pattern forming surface of a mask master.

In this case, in order to improve the adhesiveness between the silicon oxide film and the resist film, the silicon oxide film is applied immediately before the coating liquid for forming the resist film is applied on the silicon oxide film.
It is desirable to heat in the range of -600 ° C. Further, if necessary, a known hexamethyldisilazane treatment may be performed on the silicon oxide film as an agent for improving the adhesion to the resist film.

In the manufacture of the phase shift mask, it is necessary to pattern the phase shifter with high precision and high resolution. Therefore, the resist to be used is preferably a chemically amplified negative type resist. Examples of such a resist include a cresol novolak resin and a resist composition containing a hydroxystyrene-based polymer, a triazine compound, and an alkoxymethylated amino resin. However, the resist that can be used is not limited to this, and any resist that can pattern the phase shifter with high precision and high resolution can be used. Either a negative type or a positive type can be used.

[0022]

The phase shifter material obtained by the method of the present invention has a uniform and dense silicon oxide film having low hygroscopicity, does not cause cracking or peeling unlike the conventional one, It can form a pattern with high accuracy and high resolution because of its good adhesion to, and is suitable for high fine processing in the field of semiconductor device production.

[0023]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 TEFP (manufactured by Tonen Co., Ltd.), which is a 20% by weight xylene solution of a reaction product of halogenosilane and ammonia, was applied to the entire surface of a mask original having a chromium pattern formed on a glass substrate. Is spin-coated at 700 rpm in a xylene atmosphere, and dried at 150 ° C. for 30 minutes to form a film having a thickness of 0.4.
After forming a 6 μm polysilazane-based film, the film was baked in the air at 500 ° C. for 60 minutes to obtain a silicon oxide film. This silicon oxide film had a thickness of 0.4 μm, no crack was observed on the surface, and was a film having extremely high uniformity. The presence of water could not be confirmed from the infrared absorption spectrum of the obtained coating.

Next, on the obtained silicon oxide film, THMR-iN100 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a chemically amplified negative resist, was applied for 4000 r by a spinner.
pm for 20 seconds and 9 ° C on a hot plate at 90 ° C.
After drying for 0 second to form a resist film having a thickness of 1.0 μm, the i-line reduced projection exposure apparatus LD-501 was used.
After selectively exposing i-line with 1iA (manufactured by Hitachi, Ltd.) and performing heat treatment at 110 ° C. for 90 seconds,
By immersing in a 35% by weight aqueous solution of tetramethylammonium hydroxide for 1 minute, the non-irradiated portion of the i-ray was dissolved and removed to form a resist pattern on the silicon oxide film.

Next, an oxide film etching apparatus TUE-1 was used by using a mixed gas using CF ₄ + CHF ₃ + He gas at a flow rate of 25 + 25 + 100 (SCCM).
0.7 (by Tokyo Ohka Kogyo Co., Ltd.)
After removing the silicon oxide film by etching using the resist pattern as a mask under the conditions of r and 150 W, the resist pattern was patterned by ashing removal using an ashing device TCA-2400 (manufactured by Tokyo Ohka Kogyo Co., Ltd.). A phase shift mask on which a silicon oxide film was formed was prepared.

Example 2 TH which is the chemically amplified negative resist used in Example 1
A phase shift mask was prepared by the same operation as in Example 1 except that TSMR-V50 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is an i-line sensitive positive type photoresist, was used instead of MR-iN100.

Example 3 After a silicon oxide film was formed by the same operation as in Example 1, a hexamethyldisilazane treatment was performed, and then a chemically amplified negative resist, THMR-, similar to that in Example 1 was used.
Using iN100 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), a phase shift mask was prepared by the same operation.

Example 4 After a silicon oxide film was formed by the same operation as in Example 1, THMR-iN100 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a chemically amplified negative resist similar to that in Example 1, was applied. A phase shift mask was prepared in the same manner as in Example 1 except that a heat treatment was performed at 200 ° C. for 30 minutes before the heat treatment.

COMPARATIVE EXAMPLE The concentration in terms of SiO ₂ obtained by partially hydrolyzing tetraethoxysilane in the presence of ethyl alcohol was 12% by weight.
Is applied on the same mask master as in Example 1, and
After drying at 50 ° C. for 30 minutes to form a film having a thickness of 0.46 μm, the film was baked in air at 500 ° C. for 60 minutes to obtain a silicon oxide film.

The silicon oxide film was a film having high uniformity without occurrence of cracks on the surface. When a resist pattern was formed on the silicon oxide film in the same manner as in Example 1, the resist pattern was Was confirmed, and the silicon oxide film was etched by the same operation as in Example 1. However, a silicon oxide film pattern with excellent precision was not obtained, and was not practical as a phase shifter material. When the infrared absorption spectrum of the silicon oxide film used here was measured, an absorption peak was clearly confirmed in the range of 3200 to 3600 cm ⁻¹ due to water.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-292643 (JP, A) JP-A-2-211451 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) G03F 1/08

Claims (1)

(57) [Claims] 1. A method for producing a phase shifter material, comprising applying an organic solvent solution containing a silazane compound to a surface of a substrate, drying the applied solution, and then baking it in an oxidizing atmosphere to form a silicon oxide film.