JPH11143078A - Chemically amplified resist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a chemically amplified resist superior in resolution and capable of high integration of semiconductor devices by forming the chemically amplified positive resist comprising a polyhydroxystyrene resin changeable in polarity by an acid catalyst and a photo-acid-generator having a protective group decomposable by acid catalytic reaction. SOLUTION: This chemically amplified positive resist comprises the polyhydroxystyrene resin changeable in polarity by the acid catalyst and the photo-acid-generator having a protective group decomposable by the acid catalytic reaction. This photo-acid-generator is derived from disulfonyldiazomethane having the protective group (-R) decomposable by acid catalytic reaction. The protective group (-R) may be the one used as the protective group for the common chemically amplified resist resins, such as a tertiary butoxycarbonyl ethoxyethyl group called acetal type protective groups and tetrahydropyranyl groups and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art The mainstay of the conventional exposure technique is an exposure technique in which an exposure apparatus using g-ray (436 nm) and i-ray (365 nm) as the exposure light is combined with a novolak resist. However, with the high integration of LSI devices, lithography using excimer laser light (248 nm, 193 nm), which is far ultraviolet light advantageous for further miniaturization, becomes necessary. There is a problem that absorption is large, a good resist shape cannot be obtained, and sensitivity is greatly reduced.

Therefore, a chemically amplified resist utilizing an acid catalyzed reaction of an acid generated from a photoacid generator has been devised, and has become the mainstream as a resist for short-wavelength photolithography or a resist for electron beam lithography.

A chemically amplified resist is disclosed in, for example,
As disclosed in JP-A-44045 and JP-A-5-80516, it is composed of at least a polyhydroxystyrene resin and a photoacid generator, and a part of the -OH group of the polyhydroxystyrene resin is protected by a hydrophobic alkyl group. Substituted as a group to form -OR. Upon exposure, an acid is generated from the photoacid generator, and the protecting group is removed from the polyhydroxystyrene resin by an acid catalyzed reaction, so that the resin becomes hydrophilic and becomes soluble in the developer.

In order to improve the resolution of a chemically amplified resist, it is necessary to increase the dissolution contrast (the ratio of dissolution rates between exposed and unexposed portions). For this purpose, a method of increasing the dissolution rate of an exposed portion or decreasing the dissolution rate of an unexposed portion can be considered. For this purpose, studies have been made on the types of protecting groups of the resin and the introduction ratio thereof, but no studies have been made on photoacid generators.

Conventional photoacid generators include, for example, those based on disulfonyldiazomethane (FIG. 6 (a)) and those based on onium salts (FIG. 6 (b)). FIG. 7 shows the exposure dose dependence of the speed of a chemically amplified resist using a disulfonyldiazomethane-based photoacid generator. Thus, the dissolution contrast of the conventional chemically amplified resist is 1
It was about 2,000 to 2,000.

[0007]

In order to improve the resolution of a chemically amplified resist, a higher dissolution contrast is required. However, a conventional chemically amplified resist using a photoacid generator has an improved dissolution contrast. Had limitations.

An object of the present invention is to provide a chemically amplified resist capable of improving the resolution of the resist due to the high dissolution contrast of the chemically amplified resist and thus enabling high integration of semiconductor devices.

[0009]

In order to improve the resolution, the chemically amplified resist of the present invention has a protecting group (a dissolution inhibiting ability for a developing solution) in which a photoacid generator is decomposed by an acid catalyzed reaction. Alkyl group having the formula:

That is, the present invention relates to a chemically amplified positive resist comprising at least a polyhydroxystyrene resin whose polarity is changed by an acid catalyst and a photoacid generator, wherein the photoacid generator is protected by an acid catalyzed reaction. A chemically amplified resist comprising:

When a photoacid generator having a protective group which is decomposed by an acid catalyzed reaction in the molecular structure is used, the dissolution rate of the unexposed portion is reduced because the photoacid generator has a dissolution inhibiting effect due to the protective group. . On the other hand, in the exposed area, the dissolution rate increases because the protecting group is decomposed by the acid-catalyzed reaction. As a result, the dissolution contrast of the resist increases, and a high resolution can be obtained.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of a photoacid generator used in the chemically amplified resist of the present invention.

The photoacid generator used in the present invention is of the disulfonyldiazomethane type and has a protecting group (-R) on the benzene ring which is decomposed by an acid-catalyzed reaction. The protecting group (-R) may be one which is used as a protecting group of a general chemically amplified resist resin, and is, for example, a t-butoxycarbonyl group (t-BOC group) or an ethoxyethyl group called an acetal-type protecting group. And a tetrahydropyranyl group (THP group). FIG. 2 shows a chemical reaction formula of the photoacid generator used in the present invention in exposure and acid catalysis. Exposure generates benzenesulfonic acid (acid 1) having a protecting group from the photoacid generator. The acid 1 is further converted into benzenesulfonic acid (acid 2) having no dissolution inhibiting ability by the protective group being decomposed by an acid-catalyzed reaction.

FIG. 3 shows the exposure dose dependency of the dissolution rate of the chemically amplified resist using the photoacid generator of the present invention. When the photoacid generator is used, the dissolution rate of the unexposed portion is lower than when the conventional photoacid generator is used (FIG. 7). On the other hand, the dissolution rate is high in the exposed part. This is because the protective group is decomposed by the acid-catalyzed reaction, and the portion having the protective group becomes a hydroxyl group and is easily dissolved by the developer. As a result, the dissolution contrast is increased (about 10,000 to 20,000), and high resolution is obtained.

FIG. 4 shows a second embodiment of the photoacid generator used in the chemically amplified resist of the present invention. The photoacid generator shown in this embodiment is of a disulfone type and does not have an azo group unlike the first embodiment. Therefore, the first
Higher transmittance than the chemically amplified resist of the example of
Although the sensitivity is reduced, a rectangular resist shape can be obtained.

FIG. 5 shows a third embodiment of the photoacid generator used in the chemically amplified resist of the present invention. The photoacid generator shown in this example has not benzenesulfonic acid but cyclohexanesulfonic acid in the molecule. For this reason,
As in the second embodiment, the transmittance is higher than that of the chemically amplified resist of the first embodiment, and a more rectangular resist shape can be obtained although the sensitivity is reduced.

[0017]

As described above, the chemically amplified resist of the present invention contains a photo-acid generator having a protective group which is decomposed by an acid-catalyzed reaction in the molecular structure. Since the group has a dissolution inhibiting effect, the dissolution rate of the unexposed portion decreases. On the other hand, in the exposed area, the dissolution rate increases because the protecting group is decomposed by the acid-catalyzed reaction. As a result, the dissolution contrast of the resist increases, and a high resolution can be obtained.

Further, the rectangularity of the resist pattern is improved by optimizing the basic skeleton of the photoacid generator, the type of the protecting group, and the amount of the photoacid generator added, thereby improving the dimensional accuracy. In the case of the above embodiment, both resolution and dimensional accuracy are 10
% Or more.

[Brief description of the drawings]

FIG. 1 is a molecular diagram of a photoacid generator according to a first embodiment of the present invention.

FIG. 2 is a chemical reaction formula in light exposure and acid catalysis of the photoacid generator used in the present invention.

FIG. 3 shows the exposure dose dependency of the resist dissolution rate of the present invention.

FIG. 4 is a molecular diagram of a photoacid generator according to a second embodiment of the present invention.

FIG. 5 is a molecular diagram of a photoacid generator according to a third embodiment of the present invention.

FIG. 6 is a molecular diagram of a conventional photoacid generator.

FIG. 7 shows the dependence of the conventional resist dissolution rate on the exposure dose.

Claims (7)

[Claims] 1. A chemically amplified positive resist comprising at least a polyhydroxystyrene resin whose polarity is changed by an acid catalyst and a photoacid generator, wherein the photoacid generator has a protective group which is decomposed by an acid catalyst reaction. Characterized chemically amplified resist. 2. The chemically amplified resist according to claim 1, wherein the protecting group of the photoacid generator is a t-butoxycarbonyl type protecting group. 3. The chemically amplified resist according to claim 1, wherein the protective group of the photoacid generator is an acetal-type protective group. 4. The chemically amplified resist according to claim 1, wherein the photoacid generator is a disulfonyldiazomethane compound. 5. The chemically amplified resist according to claim 1, wherein the photoacid generator is a disulfonyl compound. 6. The chemically amplified resist according to claim 1, wherein the acid generated by exposure from the photoacid generator is a benzenesulfonic acid compound. 7. The chemically amplified resist according to claim 1, wherein the acid generated by exposure from the photoacid generator is a cyclohexanesulfonic acid compound.