JPH05127369A - Resist material - Google Patents

Abstract

PURPOSE:To provide a resist material capable of preventing the lowering of dimensional controllability of a chemical amplification system resist near the resolution limits and the generation of resist scums. CONSTITUTION:An organic material which acts as a base on acid formed by an acid generating agent, such as aniline, pyridine, imidazole or ammonium derivatives is added to the conventional chemical amplification system resist by a trace quantity or on the order of mu mole/gr. to constitute a resist material. That is to say, when the conventional resist is given photoirradiation through a mask pattern, the concentration distribution like that as shown in the figure (a) is obtained. When a trace quantity of basic organic substances is added to the conventional resist as shown in the figure (b), the distribution of the difference between the acid concentration and the base concentration is obtained as shown in the figure (c). Even if light contrast of the mask pattern near the resolution limits is lowered, since the acid concentration distribution in a mask edge part is made steep, dimensional controllability is improved. Further, since acid formed in the mask light shielding part by light interference is completely neutralized by a basic material, a problem of resist scums is dissolved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist material used in a lithography process at the time of manufacturing a semiconductor device, and more particularly to a chemically amplified resist material excellent in pattern resolution.

[0002]

2. Description of the Related Art In recent years, the demand for fine pattern formation has increased with the high integration of LSIs. Conventionally, the main focus of this fine pattern formation technology (lithography technology) is an exposure apparatus that uses g or i lines of a mercury lamp, and an ultraviolet exposure technology that combines a stepper and a novolac-based resist. In addition to improving the overlay accuracy), the resolution of novolac-based resist has been improved. However, when the exposure wavelength is shortened in order to further improve the resolution (eg, KrF excimer laser light, deep ultraviolet light such as mercury arc lamp light around 250 nm), the novolac-based resist absorbs the resin and the naphthoquinodiazide photosensitizer. However, a rectangular resist shape cannot be obtained. Furthermore, at present, the light intensity of the light source is weak (about 1/10) and the exposure time is long.

Chemically amplified resists have been proposed to overcome this situation. [Reference H. Ito
and C. W. Wilson, ACS Symposs
ium Series, 242, pp. 11 (198
4). Since this resist utilizes the catalytic reaction of the acid generated from the photosensitive acid generator, the required acid concentration is small (on the order of μmole / gram), and therefore a highly sensitive resist design is possible. Also, the resist shape can be greatly improved by selecting a low-concentration acid generator and a highly transparent resin.

FIG. 4 shows an example of an acid-catalyzed reaction in a negative resist, and FIG. 5 shows an example of an acid-catalyzed reaction in a positive resist.
[Reference J. W. Thackeray et a
l. , Proc. SPIE, 1086, pp. 34 (1
989), C.I. G. Wilson et al. J. E
retrochem. Soc. , 133, pp. 18
1 (1986). The negative resist is composed of three components of polyvinylphenol resin, melamine crosslinking agent, and acid generator, and the acid promotes the crosslinking reaction to insolubilize the exposed area. On the other hand, in the case of the positive type, it consists of two components, a resin in which polyvinylphenol soluble in a developing solution is protected with a tert-butoxycarbonyl group and an acid generator. It will melt.

[0005]

Although the above-mentioned conventional chemically amplified resists have greatly improved sensitivity and resolution, when the optical contrast decreases near the resolution limit, the dimensional uniformity decreases and the resist scum further increases. It had the drawback of being prone to occur. That is, in the case of the negative type, even a trace amount of acid is rapidly insolubilized due to the progress of the crosslinking reaction in the post exposure baking. Therefore, if the optical contrast at the time of exposure is lowered, the resist scum tends to remain. On the other hand, in the case of the positive type, it tends to be difficult to dissolve unless the removal of the protective group added to the resin occurs almost completely. Therefore, similar to the negative type, the resist scum is likely to occur along with the decrease in optical contrast.

An object of the present invention is to provide a resist material capable of forming a resist pattern without scum when a chemically amplified resist is used for forming a fine pattern and further suppressing a resist dimension variation.

[0007]

The chemically amplified resist material of the present invention is a material to which a trace amount of an organic material such as aniline, pyridine, imidazole or an ammonia derivative which acts as a base for an acid generated in the resist is added. is there. Next, the principle will be described.

FIG. 1 shows the acid concentration generated when the resist is irradiated with light through a mask pattern. FIG. 1A is a resist containing no basic organic substance, and FIG. 1B is a graph showing the acid and base concentrations in a resist containing a basic organic substance.
(C) represents the difference between the acid concentration and the base concentration. The following can be said from the figure. The acid concentration in the unexposed area is completely neutralized by the basic substance, and crosslinking or elimination of the protective group does not occur. Therefore, the problem of registration scum is solved. Furthermore, the concentration gradient of the acid that contributes to the catalytic reaction becomes steep at the pattern edge, which facilitates dimensional control.

[0009]

The present invention will be described below with reference to the drawings. The resist used will be described in the case where a basic organic substance of μmole / gram order is added to the three components of acid generator-crosslinking agent-resin. The added base concentration is very small, and the resist absorbance does not change significantly. FIG. 2 shows the results of applying the resist material of the present invention to the formation of a fine polycrystalline silicon gate pattern of a MOS transistor, but the basic process is the same as that of a normal acid catalyst resist. In FIG. 2A, a gate oxide film 202 is formed on a silicon substrate 201 by thermal oxidation, a polycrystalline silicon film 203 is further grown thereon by chemical vapor deposition, and then an acid catalyst type negative resist 204 of the present invention is applied. It shows the appearance. After that, a resist 20 is formed to form a gate polycrystalline silicon electrode.
4 is irradiated with excimer laser light 205 (FIG. 2
(B)). At that time, the exposure amount is optimized so that the acid concentration gradient at the mask edge portion becomes steep (10 to 50 mJ / cm 2).
^{About 2} ). Next, heat bake treatment is performed at 130 to 160 ° C. for 30 minutes.
It is carried out for about 2 to 3 minutes to cause a crosslinking reaction by an acid catalyst only in the mask opening (FIG. 2 (c)). Next, by developing with an alkaline aqueous solution such as tetramethylammonium hydride, a resist pattern 208 having excellent dimensional controllability and no resist scum as shown in FIG. 2D is obtained.

Finally, the polycrystalline silicon film 203 is made of CF ₃ , CCl ₂ F by using the resist pattern 208 as a mask.
_The gate electrode is formed by anisotropic etching with a reactive gas plasma such as _{2 and} removing the resist.

Next, the result of applying the present invention to a positive type resist will be described (FIG. 3). FIG. 3A is the same as FIG. 2A. Next, an excimer laser beam is irradiated (Fig. 3
(B)). Also in this case, similar to the negative type, even if some acid is generated in the mask light-shielding portion due to light interference, it is neutralized by the basic organic substance. On the other hand, in the mask opening, an acid exceeding the added base concentration is generated. Therefore, a post-exposure bake process
It is possible to completely eliminate the protecting group by sufficiently performing the treatment at 0 to 160 ° C. for about 1 to 3 minutes (FIG. 3).
(C)). Next, when resist development is performed with an alkaline developer, a scum-free resist pattern 3 is obtained as shown in FIG.
08 is obtained. At the end, the polycrystalline silicon film is etched using the resist as a mask to form a gate electrode.

Although only the formation of the fine gate electrode has been described above, the present invention can be applied to the formation of other fine resist patterns such as wiring patterns and contact hole patterns.

[0013]

As described above, when the chemically amplified resist to which the basic organic substance of the present invention is added is applied to the formation of a fine pattern, a scum-free resist pattern can be formed, and further, the resist dimension variation can be suppressed to be small. is there.

[Brief description of drawings]

FIG. 1 is a diagram showing acid and base concentration distributions for explaining the principle of the present invention, in which (a) is an acid concentration, (b) is a base (aniline, pyridine, imidazole, ammonia type) concentration, and (c). ) Indicates the difference between (a) and (b).

FIG. 2 uses the resist material of another embodiment of the present invention,
FIG. 9 is a cross-sectional view showing a step of forming a fine polycrystalline silicon gate pattern of a MOS transistor.

FIG. 3 uses the resist material of another embodiment of the present invention,
FIG. 9 is a cross-sectional view showing a step of forming a fine polycrystalline silicon gate pattern of a MOS transistor.

FIG. 4 is a diagram showing an example of an acid-catalyzed reaction of a conventional amplification type negative resist.

FIG. 5 is a diagram showing an example of an acid-catalyzed reaction of a conventional amplification positive resist.

[Explanation of symbols]

201,301 Silicon substrate 202,302 Gate oxide film 203,303 Polycrystalline silicon film 204 Chemically amplified negative resist with basic organic compound 304 Chemically amplified positive resist with basic organic compound 205,305 Excimer laser light 206,306 exposure area 207 cross-linking area of negative resist 307 removal of protective group of positive resist 208,308 resist pattern after development

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03F 7/039 501 H01L 21/027

Claims (2)

[Claims] 1. A chemically amplified resist that changes the solubility of a resist by utilizing a catalytic reaction of an acid generated from a photosensitive acid generator, and an organic material acting as a base for the acid generated in the resist is added. A resist material characterized by: 2. The resist material according to claim 1, wherein an aniline-based, imidazole-based, pyridine-based, or ammonia-based dielectric material is used as the basic material.