JPH07261393A - Negative resist composition - Google Patents

Abstract

PURPOSE:To obtain a chemical amplification type resist having high resolution and high sensitivity by adding a material that generates a basic substance with the exposure for forming a pattern in the resist pattern forming process and another material that generates an acid in the post-exposure heating process to a resist composition. CONSTITUTION:This resist consisting of a base resin and a dissolution inhibitor also contains a compound that is decomposed with acid or heat to form an acid (heat-acid generating agent) and another compound that generates a basic substance with radiation-exposure (photo-base generating agent). At the time of selectively subjecting the resist film 2 to the exposure 1, the basic substance 4 is generated in the exposed part 3 of the resist in this process. In the subsequent heating process, since only the acid 6 is present in the unexposed part 2 of the resist, the decomposition of the dissolution inhibitor occurs there. On the other hand, since both the acid 6 and the basic substance 4 are present in the exposed part 3, the neutralization reaction of them with each other occurs and accordingly, no decomposition of the dissolution inhibitor occurs there. Thereafter, the resist is developed to obtain the negative resist pattern 7.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a negative resist composition.

[0002]

2. Description of the Related Art The degree of integration of a semiconductor integrated circuit is 4 in 2 to 3 years.
Highly integrated at twice the speed, but with this,
The dimension of the pattern of the circuit element is becoming finer year by year, and thus strict control of the dimensional accuracy is required.

In the manufacture of semiconductor integrated circuits, a method is used in which a fine pattern is formed on a film to be processed such as a semiconductor thin film, and the film to be processed is etched using this pattern as a mask. This pattern forming process is usually constituted by the following operations.

First, a solution containing a resin and a photosensitizer is applied on a film to be processed such as a semiconductor thin film and dried to form a resist film. Next, an exposure process of selectively irradiating an energy ray such as light is performed on the resist film, and then a mask pattern (resist pattern) is formed on the substrate by a development process.

Conventionally, in forming such a pattern, a resist material using a phenolic resin excellent in sensitivity to exposure light and dry etching resistance is often used.

However, at present, expectations for a chemically amplified resist utilizing an acid-catalyzed reaction having high resolution and high sensitivity are increasing. This chemically amplified resist material is composed of a resin containing a dissolution inhibitor and an acid generator (PA) for a positive resist.
G: Photoassid generator).
When this resist is exposed, an acid is generated from PAG, this acid diffuses into the resist by post exposure bake (PEB), and acts as a catalyst for the dissolution inhibitor,
It is dissociated from the resin. As a result, the exposed portion becomes soluble in the developing solution, so that a positive pattern is formed.

The negative resist is composed of a resin, a cross-linking agent and PAG, and the acid generated from PAG acts on the cross-linking agent as a catalyst to create active sites therein. The cross-linking of the resin progresses through the active points, and as a result, the cross-linked region becomes hardly soluble in the developing solution and thus forms a negative pattern. Currently commercially available chemically amplified negative resists include XP89131 from Shipley Co., Ltd. However, such cross-linked negative resists have low resolution because the dissolution rate contrast between unexposed areas and exposed areas is low. Is low, and the resist pattern is significantly deteriorated when it is out of focus.

However, on the other hand, in lithography of less than quarter micron, phase shift mask technology,
Modified lighting technology is essential. Among them, in the exposure method using the Levenson type phase shift mask, a negative type resist is required due to mask design restrictions.

[0009]

The problem to be solved by the present invention is, as described above, the low resolution and narrow depth of focus of the resist in the conventional chemically amplified negative resist.

[0010]

The present invention provides a photosensitive composition for solving the above-mentioned problems, in which a resist containing a base resin and a dissolution inhibitor is decomposed by an acid or heat to generate an acid. A compound that is generated (hereinafter, referred to as a thermal acid generator) and a compound that is generated by exposure to radiation to generate a basic substance (hereinafter, referred to as a photobase generator) are included. Win as these acid generators and base generators
le et al. J. Photopolym. Sci. Technol., Vol.3, No.3, 1
As announced in 990 419, 2-
Nitrobenzyl tosylate, benzylcyclohexylcarbamate (BC), nitrobenzylcyclohexylcarbamate (NBCC), 3,5-as photobase generator
Dimethoxybenzylcyclohexylcarbamate (DM
CC), N-cyclohexyl 1-4-methylphenylsulfonamide (CTSA), N-cyclohexyl 1-
4-naphthylsulfonamide (CNSA), 3-nitrophenylcyclohexylcarbamate (NPCC) and the like. Here, the above-mentioned acid generator and base generator are not particularly limited.

[0011]

EXAMPLE A resist patterning method using the present invention will be described below with reference to FIG. First, a resist film is formed on the substrate 5 by spin coating.
Next, the above resist film is heated to remove the solvent remaining in the resist. The temperature at this time is due to the acid in the resist,
It is desirable to set within a temperature range where the dissolution inhibitor does not decompose. After that, the resist film 2 is selectively exposed 1 as shown in FIG. In this step, the basic substance 4 is generated in the exposed portion 3 in the resist. Then, heating is performed as shown in FIG. In this heating step, only the acid 6 is present in the unexposed portion 2 in the resist, so that the dissolution inhibitor is decomposed. On the other hand, in the exposed portion 3, since the acid 6 and the base 4 are present, a neutralization reaction between them occurs. Therefore, decomposition of the dissolution inhibitor does not occur. Thereafter, as shown in FIG. 1C, the negative pattern 7 can be obtained by performing development.

As described above, when the present invention is used, the exposed portion has the same solubility as the unexposed portion of a normal positive resist, and the unexposed portion is not formed by the conventional resist insolubilizing method. Can have the same solubility as the exposed portion of the positive resist. Therefore, since the solubility contrast of the exposed portion and the unexposed portion similar to that of the positive type resist can be obtained, a resist pattern excellent in resolution and DOF characteristics can be obtained.

The resist pattern forming method according to the present invention will be described in detail below with reference to the drawings. These examples are described for the purpose of facilitating the understanding of the present invention, and do not limit the present invention. (Example 1) 10 g of a resin obtained by introducing the dissolution inhibiting group shown in A-1 of Table 1 into poly-p-vinylphenol as an alkali-soluble polymer, and 1 g of 2-nitrobenzyl tosylate,
And 1 g of B-1 (BC) in Table 2 was dissolved in 50 g of ethyl lactate, and this solution was filtered using a 0.2 μm fluororesin membrane filter to prepare a solution containing the photosensitive cleansing organism of the present invention. did.

Next, the solution was applied onto a silicon substrate and dried by heating on a hot plate at 80 ° C. for 60 seconds to form a resist film having a thickness of 1.0 μm. Then, the resist film through a mask having a predetermined pattern,
Exposure (70 mJ / cm ² ) was performed by a reduction projection exposure apparatus using a KrF excimer laser (wavelength 248 nm).

Further, the exposed resist film was heated on a hot plate at 120 ° C. for 90 seconds. Then, the resist was immersed in a 0.27N TMAH developer for 60 seconds.

When the shape of this pattern was observed with a scanning electron microscope, a line-and-space pattern having a good cross-sectional shape with a line width of 0.35 μm was formed. (Examples 2 to 7) Patterns obtained by adjusting the dissolution inhibiting groups A-2 to A-7 in Table 1 in the same manner as in Example 1 and performing patterning under the same conditions as in Example 1 The cross section was observed. As a result, a line and space having a line width of 0.35 μm and a good cross-sectional shape was formed.

[0017]

[Table 1] (Examples 8 to 13) The photobase generators B-2 to B-6 shown in Table 2 were prepared in the same manner as in Example 1, and patterning was performed under the same conditions as in Example 1. The cross section of the pattern was observed. As a result, a line and space having a line width of 0.35 μm and a good cross-sectional shape was formed.

[0018]

[Table 2]

[0019]

As described above, by using the present invention, it is possible to provide a photosensitive composition having a fine and fine shape and capable of forming a resist pattern having high resolution.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a pattern forming method using a photosensitive composition according to the present invention.

[Explanation of symbols] 1: exposure light 2: unexposed portion resist 3: exposed portion resist 4: base generated by light 5: substrate 6: acid generated by heat 7: pattern

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Claims (1)

[Claims] 1. A negative resist composition comprising a substance that generates a basic substance upon exposure to light for pattern formation in a chemically amplified resist pattern forming process and a substance that generates an acid in a post-exposure heating process. object.