Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
1997-03-05
2004-03-02
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S322000, C430S331000
Reexamination Certificate
active
06699645
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for forming resist patterns. More particularly, the present invention relates to a method for forming fine resist patterns by using a chemical amplification resist having high resolution, high sensitivity and an excellent dry etching resistance. A pattern formation method of the present invention can be advantageously used in the production of, for example, semiconductor devices such as semiconductor integrated circuits (ICs) and others, because the method of the present invention can effectively prevent crack formation in the resist pattern and peeling of the resist pattern during the developing process of the resist patterns, and it does not require a specific waste treatment for the used developer.
2. Description of Related Art
Recently, due to increase in the integration degree of semiconductor ICs, highly integrated devices such as LSIs and VLSIs have been practically utilized. Further, in addition to this tendency, the minimum pattern size of the ICs generally has a size in the submicron order, and now even finer patterns are required. In the formation of a fine pattern, it is essential to use a lithographic process comprising coating a base or substrate having a film to be fabricated with a resist, selectively exposing the resist to form a latent image of a desired pattern, developing the latent image to form a resist pattern, and conducting dry etching through the resist pattern as a mask, followed by removing the resist, whereby a desired pattern of the film is obtained. As an exposure source used in this process, ultraviolet (UV) light such as g-line (wavelength of 436 nm) and i-line (wavelength of 365 nm) have been used. However, as a pattern becomes finer, far ultraviolet light, vacuum ultraviolet light, electron beams, X-rays and other radiation, which have shorter wavelengths, have been utilized. Particularly, recently, an excimer lasers such as KrF lasers having a wavelength of 248 nm and ArF lasers having a wavelength of 193 nm have become available as light sources. These light sources are expected to be effective in the formation of a finer resist patterns. Note that, in the specification of the present application, the term “radiation” includes light from these various light sources, i.e., ultraviolet light, far ultraviolet light, vacuum ultraviolet light, electron beams (EB), X rays, various kinds of laser beams and others.
In order to obtain a submicron pattern using an exposure light having a shorter wavelength such as far ultraviolet light or vacuum ultraviolet light, a resist is required to have an excellent transparency at the wavelength of the exposure light. Further, the resist is required to have a dry etching resistance sufficient to act as a mask. Such a resist is, for example, a radiation-sensitive material characterized by comprising a polymer or copolymer of an acrylate or &agr;-substituted acrylate having an adamantane skeleton in the ester portion thereof, which has been invented by the present inventors (see, Japanese Unexamined Patent Publication (Kokai) No. 4-39665). Further, similar resists include, for example, a chemically amplified radiation-sensitive material characterized by comprising a polymer or copolymer of an acrylate or &agr;-substituted acrylate having a norbornene skeleton in the ester portion thereof (see, Japanese Unexamined Patent Publication (Kokai) No. 5-257281) as well as a chemically amplified radiation-sensitive material comprising a polymer or copolymer of cyclohexylmaleimide (see, Japanese Unexamined Patent Publication (Kokai) No. 5-257285).
The chemically amplified radiation-sensitive materials or resist materials invented by the present inventors can simultaneously exhibit an excellent etching resistance which is equivalent to that of the conventional novolak resists, and a high transparency in the far ultraviolet region, because they contain one or more alicyclic hydrocarbon groups which can resist etching conditions. In addition to these advantages, if these resist materials are developed with a mixed solution consisting of an aqueous organic alkaline solution and isopropyl alcohol as a developer as is taught in Japanese Unexamined Patent Publication (Kokai) No. 7-234511 by the present inventors, after the patterning exposure thereof, it becomes possible to obtain a higher sensitivity and thus a higher resolution.
However, the prior art chemical amplification resists particularly containing an alicyclic hydrocarbon group in a molecule thereof, including the above-described chemical amplification resists found by the present inventors, can frequently cause a problem of difficulty in the pattern formation, because a hydrophobic property of the resist polymers or copolymers can be increased as a result of introduction of said alicyclic group. Namely, due to a high hydrophobic property thereof, the polymers or copolymers cannot exhibit a good compatibility with the developer, and thus the aqueous alkaline solution as the developer can only slightly permeate into the resist film. As a result, a notably increased stress is generated in the resist film during development thereof, because sudden permeation of the developer into the resist film is caused due to difficulty in a smooth development process. Consequently, during the development of the exposed resist film, the film is liable to form cracks and cause peeling of the resulting patterns. The proposed addition of isopropyl alcohol to an alkaline developer is effective to avoid the formation of cracks and peeling of the patterns, however, it needs an additional and specific waste treatment step, because the waste developer contains isopropyl alcohol, i.e., an organic solvent.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an improved method for forming a resist pattern, in which a chemical amplification resist having a high transparency to various radiation, including excimer light, and an excellent dry etching resistance is used, and according to which method it becomes possible to increase a permeability of the developer into the resist film, thereby improving a profile of the resulting resist patterns, and it also becomes possible to reduce the formation of cracks and peeling of the patterns, i.e., provide stable patterning characteristics, during the development step.
The present inventors have now found that the above object can be accomplished by a method for the formation of resist patterns from a chemically amplified resist, which comprises the steps of:
coating a resist on a substrate to be fabricated, said resist comprising an alkali-insoluble polymer or copolymer having a repeating unit containing a protected alkali-soluble group in which a protecting group to the alkali-soluble group can be cleaved upon action of an acid, thereby making the polymer or copolymer alkali-soluble, and an acid generator capable of generating an acid upon exposure of the resist to a radiation;
selectively exposing the resulting resist film on the substrate to a radiation capable of inducing the generation of an acid from said acid generator; and
developing a latent image formed upon said selective exposure in the resist film with an organic alkaline developer in the presence of a surface active agent containing a higher alkyl group in a molecule thereof.
As will be appreciated from the subsequent detailed description of the present invention, the pattern formation method of the present invention is particularly characterized by conducting the development of the patternwise exposed resist film by using an organic alkaline developer in combination with a surface active agent or surfactant containing a higher alkyl group, preferably, containing at least three carbon atoms in a molecule thereof, in addition to use of a chemical amplification resist, i.e., for example, a resist consisting of an acrylate or methacrylate polymer or copolymer containing an alicyclic moiety in an ester portion thereof and an acid generator. Surprisingly, the present method can i
Takahashi Makoto
Takechi Satoshi
Armstrong Kratz Quintos Hanson & Brooks, LLP
Ashton Rosemary
Fujitsu Limited
LandOfFree
Method for the formation of resist patterns does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for the formation of resist patterns, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for the formation of resist patterns will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3223666