JPH05127371A - Pattern formation - Google Patents

Abstract

PURPOSE:To form negative resist patterns of a high resolution by using an i-ray reduction stepper and to decrease the effect of standing waves. CONSTITUTION:A resist coating film consisting of an m,p-cresol novolak resin, 3,3'-dimethoxy-4,4'-diazide biphenyl, and naphthoquinone diazide sulfonate is exposed with patterns by light, such as i-ray (365nm) shorter in wavelength than 366nm and is then subjected to full-surface exposing by light, such as g-ray (436nm) of the wavelength longer than 400nm then to a baking treatment. The difference in the dissolution rate between the part exposed with the i-ray and the unexposed part increases to the difference larger than a resist which does not contain the naphthoquinone diazide sulfonate. The patterns of a high resolution are thus formed by using the reduction stepper of the short wavelength light, such as the i-ray.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the formation of negative patterns of high resolution photoresist suitable for semiconductor device fabrication.

[0002]

2. Description of the Related Art In order to improve the performance of semiconductor devices such as LSI and VLSI, it is necessary to improve the fineness of processing. Therefore, the photoresist used for the processing is required to have a particularly high resolution.

Recently, there has been a lithography using a phase shift mask as a microfabrication technique which has been particularly attracting attention.
For this purpose, a high-resolution negative resist is required. As a conventional high-resolution negative resist, a mixed system of polyvinylphenol and an azide compound (JP-A-59-222833).
Issue).

[0004]

In the conventional resist, since the maximum absorption wavelength of the photosensitizer is matched with the exposure wavelength, the absorbance is large, and a large difference in the exposure amount occurs between the resist surface and the vicinity of the substrate. Therefore, the pattern after development becomes an inverted trapezoid. In order to solve this problem, the search for an azide compound having high transmittance was promoted. The standing wave is a problem when the transmittance is high. When an exposure apparatus that assumes a single wavelength, for example, an i-line (365 nm) reduction projection exposure apparatus is used, a sawtooth pattern is formed in the film thickness direction due to the interference action of incident light and reflected light in the resist. ..

Further, in the mixed resist of the azide compound and the phenol resin, the dissolution rate of the unexposed area in the developing solution is lower than the dissolution rate of the phenol resin. In order to act as a negative resist, the dissolution rate of the exposed area must be lower than that, and it is difficult to increase the difference in dissolution rate between the exposed area and the unexposed area. This means that it is difficult to increase the contrast of the resist.

An object of the present invention is to provide a pattern forming method for a high resolution negative photoresist.

[0007]

In order to achieve the above-mentioned object, the present invention provides a coating film of a photoresist obtained by adding an azide compound and a naphthoquinonediazide compound to a phenol resin which can be dissolved in an alkaline aqueous solution. Pattern exposure is performed, the entire surface is exposed with light having a wavelength longer than 400 nm, and after baking, development is performed with an alkaline aqueous solution. For example, after pattern exposure with i-line (365 nm), the entire surface is exposed with g-line (436 nm) and baking processing is performed.

Phenol resins which can be dissolved in an alkaline aqueous solution used for the photoresist of the present invention include novolac resins, halogenated novolac resins, polyvinylphenol, polyvinylphenol halides, and styrene.
It is at least one polymer selected from the group consisting of maleic anhydride copolymers. As the azide compound, an azide compound that is sensitive to light having a wavelength shorter than 366 nm can be used. For example, 3,3'-dimethoxy-4,4'-diazidobiphenyl, 3,3'-dimethyl-4,4'-diazidobiphenyl, 3,3'-diethyl-4,4'-diazidobiphenyl, It is at least one kind of azido compound selected from 2,7-diazidofluorene, 4-azidochalcone, 4-azido-4′-methoxychalcone, and 4-azido-4′-morpholinochalcone. The naphthoquinonediazide compound can be used as long as it is a naphthoquinonediazide compound that is sensitive to light having a wavelength longer than 400 nm. For example,
1,2-naphthoquinonediazide-4-sulfonic acid ester and 1,2-naphthoquinonediazide-5-sulfonic acid ester are used. Phenolic compounds as sulfonic acid partners include 2,3,4-trihydroxybenzophenone and 2,2 ', 4,4'tetrahydroxybenzophenone, which are sulfonic acid esters having different esterification rates.

In the pattern forming method of the present invention, 40
Since the solubility-enhancing component in the alkaline aqueous solution is formed in the unexposed portion of the short-wavelength light by the overall exposure with light having a wavelength longer than 0 nm, the difference in the dissolution rate between the exposed portion of the short-wavelength light and the unexposed portion (large dissolution contrast) is negative. It becomes a pattern forming method.

[0010]

[Function] Naphthoquinone diazide compound, azide compound,
A resist made of a phenol resin undergoes a photochemical reaction in which a naphthoquinonediazide compound is converted to an indenecarboxylic acid by pattern exposure with light having a wavelength shorter than 366 nm and an insolubilization reaction due to a photochemical reaction of an azide compound. Since the amount of the naphthoquinonediazide compound is smaller than the amount of the azide compound, the solubility of the portion exposed to short-wavelength light (for example, i-line) in the aqueous alkaline solution is lowered. Long wavelength light (eg g
Since the indenecarboxylic acid is formed by the entire surface exposure of the light rays), the solubility of the unexposed portion of the short wavelength light (for example, i rays) in the alkaline aqueous solution is increased. As a result, the difference in dissolution rate between the exposed portion of the short wavelength light (for example, i-line) and the unexposed portion becomes larger than that of the resist containing no naphthoquinonediazide compound, and a high-resolution negative pattern can be obtained. Such an action does not cause a photochemical reaction with long-wavelength light (for example, g-line) and reduces the solubility in an alkaline aqueous solution with short-wavelength light (for example, i-line). This can be achieved if there is a photosensitizer that increases the solubility in an aqueous solution. Further, in the pattern exposure unit, short-wavelength light (for example, i-line) and long-wavelength light (for example, g-line) are exposed at different wavelengths, so that the effect of standing waves can be reduced.

[0011]

【Example】

Example 1 1 g of m, p-cresol novolac resin, 0.3 g of 3,3'-dimethoxy-4,4'-diazidobiphenyl, 0.1 g of trinaphthoquinonediazide sulfonate of benzophenone and 5 g of ethoxyethyl acetate.
And a Teflon membrane filter having a pore size of 0.2 μm to obtain a resist solution. After dropping the resist solution of the above composition on the silicon substrate and spin coating, 8
The resist film was baked at 0 ° C. for 10 minutes to form a 1 μm resist film. Light from a 600 WHg-Xe lamp was irradiated on the photoresist film on the wafer for pattern formation using a bandpass filter of 365 nm (i-line). 36
After irradiation of monochromatic light of 5 nm, a 436 nm (g line) bandpass filter was used to expose the entire surface of the photoresist to monochromatic light of 436 nm. After irradiation, the photoresist is heated at 80 ° C for 10
Bake for minutes tetramethylammonium hydroxide 2.38
% Aqueous solution, and the dissolution rate of the i-line exposed area and the unexposed area was measured. The result is shown in FIG.

Further, a resist solution containing no naphthoquinone diazide sulfonate, that is, 1 g of m, p-cresol novolac resin and 3,3'-dimethoxy-
0.3 g of 4,4'-diazidobiphenyl was dissolved in 5 g of ethoxyethyl acetate, and the dissolution rate after only exposure to i-line was also measured.

As a result, the dissolution rate of the i-line unexposed portion of the resist containing no naphthoquinone diazide sulfonate is higher than that of the resist containing naphthoquinone diazide sulfonate. In addition, the dissolution rate of the exposed portion is not significantly different between the resist containing the naphthoquinone diazide sulfonate and the resist not containing it. This indicates that the difference in dissolution rate between the exposed area and the unexposed area (dissolution contrast) is large in the resist containing naphthoquinonediazide sulfonate. Actually, this resist was exposed to 1050 mJ /
After the pattern exposure in dose of cm ^2, the entire surface exposure with irradiation dose of 200 mJ / cm ² using a g reduction projection exposure apparatus, 8
When baked at 0 ° C. for 10 minutes and developed with a 2.38% aqueous solution of tetramethylammonium hydroxide, a line / spacing pattern of 0.4 μm could be formed. In addition, the effect of standing waves could be reduced as compared with a resist containing no naphthoquinone diazide sulfonate.

<Embodiment 2> A resist film having the same composition as that of Embodiment 1 is applied onto a silicon wafer, and pattern exposure is performed using an i-line reduction projection exposure apparatus through a phase shift mask, and then g reduction projection exposure. The whole surface is exposed by using an apparatus,
Bake for 10 minutes tetramethylammonium hydroxide 2.
When developed with a 38% aqueous solution, a 0.4 μm line / spacing pattern could be formed. In addition, the effect of standing waves could be reduced by comparing the pattern formation using a resist containing no naphthoquinone diazide sulfonate under the same conditions.

Example 3 Example 1 was repeated except that the weight of the naphthoquinone diazide sulfonic acid ester was changed to 0.15 g.
A resist film was coated on a silicon wafer using the same composition as described above. When a pattern was formed by the same process as in Example 2, it was possible to form a line / spacing pattern of 0.3 μm.

<Embodiment 4> After coating Raycast RG-3900B manufactured by Hitachi Chemical on a silicon wafer, 200
Hard baking was performed at 20 ° C. for 20 minutes to form an organic film. A resist solution having the same composition as in Example 1 was applied on this organic film to obtain a resist film having a thickness of 0.5 μm. When a pattern was formed on this resist film by the same method as in Example,
A 275 μm line / spacing pattern could be formed.

[0017]

According to the pattern forming method of the present invention, a high resolution pattern can be formed by the exposure method using the i-line reduction projection exposure apparatus. Therefore, by applying to fine processing of semiconductor manufacturing such as a highly integrated circuit, pattern formation can be realized with high efficiency, and semiconductors can be obtained with high yield.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between a resist dissolution rate and an exposure amount according to the present invention.

[Explanation of symbols]

1 ... m, p-cresol novolak resin and 3,3′-dimethoxy-4,4′-diazidobiphenyl, a resist comprising trinaphthoquinone diazide sulfonic acid ester of benzophenone, 2 ... m, p-cresol novolak resin and 3, A resist composed of 3'-dimethoxy-4,4'-diazidobiphenyl.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03F 7/26 7124-2H H01L 21/027 7352-4M H01L 21/30 361 L (72) Inventor Noboru Moriuchi 2326 Imai, Ome, Tokyo Metropolitan Government Device Development Center, Hitachi, Ltd. (72) Inventor Seiichiro Shirai Ome, Tokyo Metropolitan Area 2326 Imai Device Development Center, Hitachi, Ltd. (72) Inventor Toshihiko Onozuka Ome, Tokyo 2326 Imai, Device Development Center, Hitachi, Ltd. (72) Inventor, Koji Hattori 1-280, Higashi Koikekubo, Kokubunji, Tokyo Metropolitan Institute, Hitachi, Ltd. (72) 1-280, Higashi Koikeku, Kokubunji, Tokyo Address: Central Research Laboratory, Hitachi, Ltd.

Claims (3)

[Claims] 1. A resist comprising an alkali-soluble phenol resin, an azide compound, and a naphthoquinonediazide compound is used to perform pattern exposure with light having a wavelength shorter than 366 nm, whole surface exposure with light having a wavelength longer than 400 nm, baking, and then an aqueous alkali solution. A pattern forming method characterized by performing development. 2. The azide compound according to claim 1 is 366n.
A photoreaction occurs when irradiated with light having a wavelength shorter than m.
A pattern forming method using a resist containing an azide compound that does not cause a photoreaction when irradiated with light having a wavelength longer than m. 3. The composition of the alkali-soluble phenolic resin, the azide compound and the naphthoquinonediazide compound in the resist according to claim 1 is in the range of 100 parts by weight, 20 to 40 parts by weight and 10 to 30 parts by weight, and the naphthoquinonediazide is contained. A pattern forming method using a resist in which the weight of the compound does not exceed the weight of the azide compound.