JP2985305B2 - Resist composition and method of forming resist pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist for an upper layer having a two-layer structure and a method for forming a resist pattern thereof.

[0002] Since it is necessary to process a large amount of information promptly, integration of a semiconductor device constituting a main body of an information processing device is progressing, and LSI and VLSI have been put into practical use. Here, integration is performed by downsizing unit elements, and the minimum line width of the wiring pattern has reached submicron.

[0003] Also, since multilayer wiring is performed,
Many fine steps exist on a semiconductor wafer forming an integrated circuit. Now, in the manufacture of semiconductor integrated circuits, selective exposure is performed after coating a resist on a semiconductor substrate,
A photolithography technique (photolithography or electron beam lithography) for dissolving an exposed or unexposed portion by development and opening a resist to form a window and then performing dry etching to etch a conductive film or an insulating film is indispensable.

For this reason, a multi-layer resist method having a three-layer structure or a two-layer structure is used as a method for forming a fine pattern with high accuracy without the influence of a step. It is used regularly.

[0005]

2. Description of the Related Art When a two-layer resist method is used, the thickness of a resist layer for directly forming a pattern by exposure can be made much smaller than that of a single-layer resist method, so that high resolution can be realized.

Here, the resist applicable to the upper layer resist must have sufficient resistance to oxygen plasma, and the following organosilicon polymer-based resin (hereinafter abbreviated as silicone-based resin) or An organic silicon-containing resin (hereinafter abbreviated as silicone-containing resin) is used.

[0007] Poly-P-chloromethylphenylsiloxane, polyallylsilsesquioxane, polyvinylsilsesquioxane and the like. However, since an organic solvent must be used for development after exposure of a silicone resist made of such a material, the resist swells violently, and the advantages of the two-layer structure resist method cannot be fully utilized. However, the resolution is not so improved.

For this reason, there has been a problem that a resist pattern required for manufacturing an VLSI requiring a submicron pattern cannot be stably formed.

[0009]

Various silicone resists have been proposed as upper-layer resists having a two-layer structure.
As noted above, the resolution has not improved much.

The above resist materials are all negative type resists. Therefore, there has been a need for a bodi-type pattern forming material which does not cause a decrease in resolution due to swelling during development.

[0011]

The above object is achieved by the following general formula:
A three-dimensional structure obtained by hydrolyzing an organosilicon compound represented by the formula (1), and subsequently replacing hydroxyl groups remaining in a polymer obtained by dehydration-condensation polymerization with a substituent containing an organosilicon represented by the following general formula (2) An organosilicon polymer having a network structure of, an inhibitor for dissolution of the organosilicon polymer in an alkaline aqueous solution, and an acid generator for generating an acid upon irradiation with ionizing radiation,
This problem can be solved by using a resist composition comprising an organic solvent and forming an upper layer resist of a two-layer structure resist.

[0012]

Embedded image

Here, R ₁ represents any of hydrogen, trialkoxysilyl group and trichlorosilyl group, which may be the same or different, and at least two or more of R ₁ are trialkoxysilyl groups or trichlorosilyl groups. Being a silyl group,

[0014]

Embedded image

Here, R ₂ is (CH ₂ ) _m COOH, (CH ₂ ) _n Ph
COOH, (where m is an integer of 1 to 10, n is an integer of 0 to 10),
Represents a lower alkyl group, an aryl group or a lower alkenyl group and may be the same or different, and at least 20% or more of R ₂ is (CH ₂ ) _m COOH or (CH ₂ ) _n Ph COOH
That.

[0016]

The silicone polymer represented by the above general formulas (1) and (2) alone is soluble in an aqueous alkali solution such as tetramethylammonium hydroxide (abbreviated as TMAH). Is difficult to dissolve in an alkaline aqueous solution.

The present invention utilizes the phenomenon that the dissolution inhibitor is weak to acids and loses the dissolution inhibiting effect due to the presence of the acid.
That is, an acid generator is added to the dissolution inhibitor, and the acid generator generates an acid upon irradiation with ionizing radiation. The acid causes the dissolution inhibitor to lose its dissolution inhibiting effect, and the silicone polymer is converted again into an alkaline aqueous solution. Utilizing the fact that it becomes soluble, examples of such a dissolution inhibitor include low molecular weight organic compounds represented by the general formulas (3) to (16) disclosed in JP-A-63-27829. Can be

Further, Japanese Patent Application Laid-Open Nos. 63-250642 and 63-24154
The polymer compounds represented by the general formulas (17) to (24) disclosed in No. 2 are also effective. In addition, Ph ₂ I ^{+
_{SbF 6 -, Ph 3 S +}} SbF 6 - onium salts such ^{_{as, (Ph 2 I +) 2}} CO 3
Salts containing carbonate ions such as ^2- , (Ph ₂ S ⁺ ) ₂ CO ₃ ^2- ,
Salts containing bicarbonate ions such as Ph ₂ I ⁺ HCO ₃ ⁻ _and Ph ₃ S ⁺ HCO ₃ ^−; triazine compounds having a chloromethyl group; and tosylate compounds such as orthonitrobenzyl alcohol sulfonate can be given. .

In the resist composition according to the present invention, the dissolution inhibitor is decomposed by irradiating ionizing radiation such as ultraviolet rays, electron beams, X-rays and ion beams in the presence of these acid generators, and the organic silicone resin is decomposed. Since the union becomes soluble in the alkaline aqueous solution, a positive resist is obtained.

When the resist composition according to the present invention is exposed to ionizing radiation, an acetophenone-based photosensitizer such as 2,2-dimethoxy-2, phenylacetophenone may be added as a sensitizer, if necessary.

The mixing ratio of the organic silicone polymer, dissolution inhibitor, acid generator and organic solvent constituting the resist composition according to the present invention varies depending on the required film thickness. And the organic silicone polymer is 4 ~
20 parts by weight, 0.2 to 20 parts by weight of dissolution inhibitor, 0.
It is preferably about 1 to 10 parts by weight.

In the case of forming a two-layer resist, a commercially available photoresist comprising a phenol novolak resin or a cresol novolak resin may be used as the lower resist.
For example, OFPR (manufactured by Tokyo Ohka) can be used.

The resist composition according to the present invention is excellent in oxygen plasma resistance because it uses a silicone polymer having a high Si content. In addition, it is a positive type, and an alkaline aqueous solution is used as a developer. Since the heat resistance of the silicone polymer is high, the resolution is excellent.

Therefore, it has all of the oxygen plasma resistance, sensitivity, and resolution essential for an upper layer resist for a two-layer structure.

[0025]

EXAMPLES Synthesis Example 1 (Production example of polymer) Forty methyl isobutyl ketone (MIBK) was added to a 500-cc four-necked flask.
cc, 25 cc of methanol, 25 cc of acetone, 50 cc of water, 5 cc of concentrated hydrochloric acid and 4.05 g of 1,3-diphenyl-1,1,3,3-tetramethyldisiloxane. did.

Next, 1,4-bis (trimethoxysilyl)
Dissolve 15.9 g of benzene in 35 cc of MIBK, and add 20 to the flask.
The mixture was added dropwise over a minute and stirred for 30 minutes. After cooling, MIBK and water (50 cc each) were added, and the upper MIBK layer was washed several times with water using a separatory funnel.

Next, after removing residual water by azeotropic distillation, the reaction solution was poured into a large amount of water to precipitate and recover a resin. After performing a molecular weight fractionation operation, the mixture was freeze-dried to obtain 12 g of a white powder.

[0028] This weight average molecular weight measured by gel Pamie Activation chromatography (abbreviated GPC) is 3.5 × 10 ⁴ The degree of dispersion in terms of standard polystyrene was 2.1.
Next, 10 cc each of methyldichlorophenylchlorosilane and pyridine were added to 100 g of a 4% MIBK solution of the obtained resin, followed by stirring at 80 ° C. for 2 hours.

After cooling, MIBK and water (50 cc each) were added thereto, and the upper MIBK layer was washed several times with water using a separatory funnel, and the remaining water was removed by azeotropic distillation. Thereafter, the reaction solution was poured into a large amount of water to precipitate and recover the resin, followed by freeze-drying to obtain 4.17 g of a white powder.

Thereafter, low molecular weight oligomers and impurities were removed by washing with ethanol and acetonitrile, and finally 2.16 g of a white powder was obtained. Next, the weight average molecular weight measured by GPC was 3.6 × 10 ^{4 in} terms of standard polystyrene, and the degree of dispersion was 2.2.

The polymer was dissolved in dry ethyl ether and poured into 2.4 g pieces of magnesium metal (Mg). Next, the solution is poured onto 20 g of finely ground dry ice, and then carboxylic acid is added to the synthetic polymer by adding 10 ml of 5N hydrochloric acid, whereby a polymer soluble in an aqueous alkaline solution can be obtained. Was.

Example 1 (Example of electron beam exposure) 1 g of the polymer obtained in the synthesis example, 0.1 g of poly p-trimethylsilyloxystyrene as a dissolution inhibitor, and 0.02 g of diphenyliodonium hexafluoroantimonate as an acid generator
Was dissolved in 15 ml of methyl isobutyl ketone, and the pore size was adjusted to 0.
The solution was filtered through a 1 μm membrane filter to obtain a resist solution.

Next, a novolak-based resist (M
P-1300, Shipley Co.) was applied to a thickness of 2.0 μm and hard-baked to form a flattened layer. The above resist solution was applied thereon to a thickness of 0.2 μm and baked at 80 ° C. for 20 minutes.

The thus-obtained two-layer resist film was exposed to an electron beam under the conditions of an acceleration voltage of 20 KV and an exposure of 40 μC / cm ^2.
After post-baking at 0 ° C. for 2 minutes, development was carried out using a 2.5% aqueous solution of tetramethylammonium hydroxide.

Next, the sample was put into a parallel plate type dry etching apparatus, and oxygen plasma (vacuum degree 2 Pa, power 0.22 W) was used.
/ Cm ² ) for 15 minutes to transfer the upper layer pattern to the lower layer.

As a result, a 0.7 μm punch pattern could be resolved. Example 2: (Excimer laser exposure example) 1 g of the polymer obtained by the synthesis example, 0.1 g of poly p-trimethylsilyloxystyrene as a dissolution inhibitor, and 0.02 g of diphenyliodonium hexafluoroantimonate as an acid generator are methyl isobutyl ketone. Dissolve in 15 ml, pore size 0.1
The solution was filtered through a μm membrane filter to obtain a resist solution.

Next, a novolak-based resist (M
P-1300, Shipley Co.) was applied to a thickness of 2.0 μm and hard-baked to form a flattened layer. The above resist solution was applied thereon to a thickness of 0.2 μm and baked at 80 ° C. for 20 minutes.

The thus-obtained two-layer resist film was exposed to light at a dose of 200 mJ / cm ² using a KrF excimer laser device (wavelength: 248 nm), post-baked at 110 ° C. for 2 minutes, and then 2.5% Development was performed using an aqueous solution of methyl ammonium hydroxide. Next, the sample was placed in a parallel plate type dry etching apparatus, and oxygen plasma (vacuum degree 2
Dry etching was performed for 15 minutes at Pa, power of 0.22 W / cm ² ) to transfer the upper layer pattern to the lower layer.

As a result, a space pattern of 1.0 μm could be resolved. Example 3: (Example in which dissolution inhibitor was changed by electron beam exposure) 1 g of the polymer obtained in Synthesis Example 2, ditertiary butyl terephthalate 0.02 g as dissolution inhibitor, and diphenyliodonium hexafluoroantimonate 0.02 as acid generator g in 15 ml of methyl isobutyl ketone,
The solution was filtered through a membrane filter having a pore size of 0.1 μm to obtain a resist solution.

Next, a novolak-based resist (M
P-1300, Shipley Co.) was applied to a thickness of 2.0 μm and hard-baked to form a flattened layer. The above resist solution was applied thereon to a thickness of 0.2 μm and baked at 80 ° C. for 20 minutes.

The two-layer resist film thus obtained was exposed to an electron beam under the conditions of an acceleration voltage of 20 KV and an exposure of 52 μC / cm ² ,
After post-baking at 0 ° C. for 2 minutes, development was performed using a 2.5% aqueous solution of tetramethylammonium hydroxide.

Next, the sample was placed in a parallel plate type dry etching apparatus, and oxygen plasma (vacuum degree 2 Pa, power 0.22 W) was used.
/ Cm ² ) for 15 minutes to transfer the upper layer pattern to the lower layer.

As a result, a punch pattern of 0.8 μm could be resolved.

[0044]

The resist according to the present invention is a positive resist mainly composed of a silphenylene siloxane resin having excellent plasma etching resistance and a three-dimensional network structure, and can be developed using an alkaline aqueous solution. Therefore, a resist pattern having excellent resolution can be obtained.

[Brief description of the drawings]

FIG. 1 is a general formula (1) of a dissolution inhibitor.

FIG. 2 is a general formula (2) of a dissolution inhibitor.

FIG. 3 is a general formula (3) of a dissolution inhibitor.

FIG. 4 is a general formula (No. 4) of a dissolution inhibitor.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Manami Fukuda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-2-29652 (JP, A) JP-A-63-241542 (JP, A) JP-A-3-139650 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03F 7/075 G03F 7/039

Claims (2)

(57) [Claims] The method according to claim 1 the organic silicon compound represented by the following general formula (1) was hydrolyzed, the organic silicon indicated hydroxyl groups remaining in the obtained dehydration condensation polymerization subsequent polymer by the following general formula (2) An organosilicon polymer having a three-dimensional network structure substituted with a substituent containing the same , an inhibitor for dissolving the organosilicon polymer in an alkaline aqueous solution, an acid generator for generating an acid upon irradiation with ionizing radiation, and an organic solvent A resist composition comprising: Embedded image Here, R ₁ represents any of hydrogen, trialkoxysilyl group and trichlorosilyl group, and may be the same or different, and at least two or more of R ₁ are trialkoxysilyl groups or trichlorosilyl groups. There is, Here, R ₂ is (CH ₂ ) _m COOH, (CH ₂ ) _n Ph COOH, (where m is an integer of 1 to 10, n is an integer of 0 to 10, Ph is a phenylene group), and a lower alkyl group. , An aryl group or a lower alkenyl group, which may be the same or different, wherein at least 20% or more of R ₂ is (CH ₂ ) _m COOH, (CH ₂ ) _n Ph CO
Be OH. 2. An organic polymer compound is applied as a lower resist on a substrate to be processed, and the step on the surface of the substrate is planarized, and then the resist composition according to claim 1 is applied as an upper resist. Characterized by selectively exposing to ionizing radiation, developing with an alkaline developer, etching using the formed upper resist pattern as a mask, and transferring it to a lower resist.