JP3055512B2 - Chemically amplified positive resist - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically amplified positive resist, and more particularly, to a method of exposing a photoresist film formed on a semiconductor substrate through a mask or a reticle on which a desired semiconductor integrated circuit pattern is drawn, and performing a PEB process. And a chemically amplified positive resist suitable for forming a photoresist pattern by developing using a developing solution.

[0002]

2. Description of the Related Art In conventional photolithography, g-line (436 nm) and i-line (365 nm) are used as exposure light. As a resist, a novolak resin is used as a base resin, and naphthoquinonediazide is used as a photosensitive agent. The mainstream was a dissolution-suppressing positive-type resist that used a resist.

However, lithography using excimer laser light (248 nm , 193 nm , etc.) , which is far ultraviolet light that is advantageous for further miniaturization, is required, and a conventional g-line or i-line resist has a light absorption. Too big,
A good resist pattern could not be obtained, and the sensitivity was greatly increased.

Therefore, in recent years, a chemically amplified resist utilizing a sensitization reaction of an acid catalyst generated from a photoacid generator has been devised, and has been devised as a resist for short wavelength lithography or a resist for electron beam lithography requiring high sensitivity. It is becoming mainstream.

However, a chemically amplified resist, particularly a two-component positive resist comprising a protective polyvinylphenol resin and a photoacid generator (see, for example, JP-A-4-44045) .
The three-component positive resist, thus generated acid exposure is neutralized with a base disappearance or air in the resist film surface region lost added distribution), or to a dissolution inhibitor protection type bisphenol A Since the solubilization reaction does not proceed in the subsequent PEB treatment, a surface hardly soluble layer is generated.

Therefore, as shown in FIG. 5, there is a problem that the resist pattern 502 on the wafer 501 obtained after development has a T-shape, and the resolution, the depth of focus, and the dimensional accuracy are impaired.

As shown in FIG. 4, this is a phenomenon often seen in a high-resolution resist in which the dissolution rate ratio between an exposed portion and an unexposed portion, that is, the dissolution contrast is increased and the gradient of the dissolution characteristic is increased.

As a method of solving this problem, several methods have been proposed so far, for example, a method of replacing the atmosphere of PEB treatment with an inert gas to prevent acid deactivation (Japanese Patent Application Laid-Open No. 4-369221). JP), also formed surface insoluble layer thin removing method (JP-a 4-22195
No. 1). Among them, a method of applying a protective film on the resist surface to prevent acid deactivation (Japanese Patent Laid-Open No. 4-20 / 1990)
No. 4848) was often used.

[0009]

[SUMMARY OF THE INVENTION However, in the method of preventing and applying a protective film to a conventional resist surface Sanshitsukatsu, the effect is insufficient for the prevention of the acid deactivation of the resist surface and In the case where the acid disappears from the resist surface before the PEB treatment after the exposure, this method cannot prevent the formation of a surface insoluble layer, and the resist pattern after development tends to have a T-shaped shape. is there.

In particular, when a fine pattern is formed, deterioration in the shape, resolution, depth of focus, and dimensional accuracy of a photoresist pattern caused by such a surface insoluble layer is fatal. Therefore, it is necessary to improve the resist material itself.

[0011]

According to the present invention, there is provided a chemically amplified positive resist composition comprising at least a resin having a protective group which is hardly soluble in alkali and a photoacid generator. Characterized by adding hexamethoxymethylmelamine. In that case, the addition amount of hexamethoxymethyl melamine as a cross-linking agent can be 1 to 10% relative to the base resin. Further, the addition amount of hexamethoxymethylmelamine as a cross-linking agent may be 2% of the base resin. As the base resin, a t-BOC protected polyhydroxystyrene resin and a photoacid generator ( triphenylsulfonium) were used.
A two-component chemically amplified positive resist composed of mhexafluoroantimonene ) can also be used. It is also very suitable to use the photoacid generator in an increased ratio with respect to the base resin for the purpose of preventing a decrease in sensitivity. Further, it is very preferable that the amount of the photoacid generator is 5% with respect to the base resin.

The chemically amplified positive resist of the present invention is obtained by crosslinking hexamethoxymethyl melamine used in a negative resist in order to eliminate the surface insoluble layer which causes the T-shaped shape of the chemically amplified positive resist. agents (for example, JP-a-3-75652 JP) containing as. The crosslinking agent crosslinks the base resin by the acid generated in the exposed area, and as a result, the dissolution rate of the exposed area can be reduced, the dissolution contrast is optimized, and the gradient of the dissolution characteristic, which most affects the resist performance, is reduced. Provided is a chemically amplified positive resist which is enlarged to ensure high resolution and suppress formation of a surface insoluble layer.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a chemical formula of a compound added to a chemically amplified positive resist according to an embodiment of the present invention and acting as a crosslinking agent.

This compound is combined with a conventional t-BOC protected polyhydroxystyrene resin and a photoacid generator ( triphenyls
Ruphonium hexafluoroantimonene ) was added to a two-component chemically amplified positive resist of 2% relative to the base resin.

At this time, in order to prevent a decrease in sensitivity, the amount of the photoacid generator is increased from 3% to 5% relative to the base resin.

Using this chemically amplified resist, as shown in FIG. 3, a resist film is formed on a wafer 301, and is exposed by a KrF excimer laser stepper through a mask or a reticle on which a desired semiconductor integrated circuit pattern is drawn, and PEB is exposed. Processing and development with a 2.38% aqueous solution of TMAH.

As a result, the dissolution characteristics shown in FIG. 3 were obtained, and a rectangular resist pattern 302 having no surface insolubilized layer as shown in FIG. 5 was obtained.

[0018]

As described above, the chemically amplified positive resist of the present invention can almost completely eliminate the T-shaped resist pattern, and can obtain a rectangular resist pattern. .

Further, by adjusting the amount of hexamethoxymethyl melamine, which is the dissolution promoter of the present invention, to the resist material, the dissolution rate of the resist film in the developer can be controlled, and the resist performance has the greatest effect. The gradient of the dissolving characteristics which influences can be increased, and the resolution of the resist can be increased. As a result , the resolution, the depth of focus, and the dimensional accuracy can be significantly improved (10% or more).

The effect is particularly great for forming a fine pattern, and a rectangular photoresist pattern can be formed with good reproducibility.

[Brief description of the drawings]

FIG. 1 is a view showing a chemical formula of a compound added to a chemically amplified positive resist according to an embodiment of the present invention.

FIG. 2 is a dissolution characteristic diagram of a chemically amplified positive resist according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a pattern using a chemically amplified positive resist according to the embodiment of the present invention.

FIG. 4 is a dissolution characteristic diagram of a conventional chemically amplified positive resist.

FIG. 5 is a cross-sectional view of a pattern using a conventional chemically amplified positive resist.

[Explanation of symbols]

301 wafer 501 wafer 302 Chemically amplified positive resist pattern 502 Chemically amplified positive resist pattern

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03F 7/039 G03F 7/004 H01L 21/027

Claims (6)

(57) [Claims] 1. A chemically amplified positive resist composition comprising at least a resin having a protective group which is hardly soluble in alkali and a photoacid generator, wherein hexamethoxymethylmelamine which functions as a crosslinking agent is added. Positive resist. 2. The chemically amplified positive resist according to claim 1, wherein the amount of hexamethoxymethylmelamine added as the crosslinking agent is 1 to 10% relative to the base resin. 3. The chemically amplified positive resist according to claim 1, wherein the addition amount of hexamethoxymethylmelamine as the crosslinking agent is 2% relative to the base resin. 4. The base resin comprises a t-BOC protected polyhydroxystyrene resin and a photo-acid generator ( triphenyls).
4. The chemically amplified positive resist according to claim 2, wherein the positive resist is a two-component chemically amplified positive resist composed of ruphonium hexafluoroantimonene ). 5. The chemically amplified positive resist according to claim 4, wherein the amount of the photoacid generator is increased by a ratio of the resin to the base resin. 6. The chemically amplified positive resist according to claim 5, wherein the amount of the photoacid generator is 5% relative to the base resin.