Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-06-12
2003-01-14
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C326S044000, C326S044000
Reexamination Certificate
active
06506537
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a positive-type radiation-sensitive resin composition suited for ultrafine processing using radiations of various types such as ultraviolet radiations, far-ultraviolet radiations, X-radiations and charged-particle radiations.
2. Description of the Prior Art
In the field of fine processing as typified by the fabrication of integrated-circuit devices, the size of processing in lithography is being made finer in order to achieve a higher degree of integration. In recent years, there is a demand for techniques that enable fine processing in a line width of 0.5 &mgr;m or smaller in a good reproducibility. Accordingly, resists used therein are also required to enable formation of patterns of 0.5 &mgr;m or finer in a good precision. However, in conventional processes making use of visible radiations (wavelength: 800 to 400 nm) or near ultraviolet radiations (400 to 300 nm), it is very difficult to form fine patterns of 0.5 &mgr;m or finer in a high precision. Accordingly, extensive studies are made on radiations having a shorter wavelength (wavelength: 300 nm or shorter).
Radiations having such a short wavelength may include, e.g., mercury lamp bright-line (wavelength: 254 nm), far-ultraviolet radiations as typified by those of KrF excimer laser (wavelength: 248 nm), ArF excimer laser (wavelength: 193 nm) or F
2
excimer laser (wavelength: 157 nm), X-radiations such as synchrotron radiations (e.g., EUV lithography), and charged-particle radiations such as electron radiations. Among these, lithography making use of, in particular, excimer lasers has come to especially attract notice because of their characteristics ensuring a high output and a high efficiency. Accordingly, resists used in lithography are demanded to enable formation of fine patterns of 0.25 &mgr;m or finer in a high sensitivity and in a high resolution and a good reproducibility.
Then, as a resist suited for the far-ultraviolet radiations such as those of KrF excimer laser, “chemically amplified resist” is proposed in which a radiation-sensitive acid generator capable of forming an acid by irradiation with radiations (hereinafter “exposure”) is used so that the sensitivity of a resist can be improved by the catalytic action of this acid.
Such chemically amplified resists include, e.g., as disclosed in Japanese Laid-open Publication (Kokai) No. 59-45439, a combination of a resin protected with a t-butyl group or a t-butoxycarbonyl group with a radiation-sensitive acid generator, and, as disclosed in Japanese Laid-open Publication (Kokai) No. 60-52845, a combination of a resin protected with a silyl group with a radiation-sensitive acid generator. Besides these, many reports are made on the chemically amplified resists such as a resist containing i) a resin having an acetal group and ii) a radiation-sensitive acid generator (Japanese Laid-open Publication (Kokai) No. 2-25850).
However, especially because of the design size having come to be 0.25 &mgr;m or finer, in the case of conventional single-layer chemically amplified resists, resist films formed may absorb radiations more greatly with an increase in layer thickness to maintain a high resolving performance with difficulty. On the other hand, films formed thin in order to improve resolving performance may have so insufficient a resistance to dry etching as to be not usable as masks for substrate processing. Thus, limitations of relying on trade-off of layer thickness have gradually come to be apparent. To solve this problem, in recent years, multilayer-type resist materials suited for lithographic techniques making use of KrF excimer laser or ArF excimer laser are being energetically brought to a more advance state (Proc. SPIE, Vol. 3333). As resist film materials for upper layers of such multilayer resist films, usually used are photosensitive films which contain silicon atoms, having a high resistance to dry etching. Resist films thus formed, containing silicon atoms, have a characteristic feature that they have so high a resistance to etching as to be usable in the form of thin films and hence any absorption of radiations by resist films can be kept small and good-shape patterns can be obtained in a high resolution. However, these resists have had a problem that they may greatly change with time in sensitivity when stored over a long period of time and are not suitable for the long-term storage of stocks that is necessary when devices are mass-produced.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a radiation-sensitive resin composition which is effectively responsive to radiations of various types, has superior sensitivity and resolution and also a superior long-term storage stability, and further which is also useful as an upper-layer resist in processing making use of positive-type chemically amplified multilayer resist films.
According to the present invention, the above object can be achieved by a positive-type radiation-sensitive resin composition comprising:
(A) a low-molecular compound having at least one amino group having one or two hydrogen atoms bonded to a nitrogen atom wherein at least one hydrogen atom of said hydrogen atoms has been substituted with a t-butoxycarbonyl group;
(B) a radiation-sensitive acid generator; and
(C) an alkali-insoluble or alkali-slightly-soluble silicon-atom-containing resin having been protected with an acid-cleavable group, the resin being capable of turning alkali-soluble upon cleavage of the acid-cleavable group.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described below in detail. Herein, “(meth)acrylic”, “(meth)acryloyl”, (meth)acrylate, or the like generically includes “acrylic and methacrylic”, “acryloyl and methacryloyl”, “acrylate and methacrylate” or the like, respectively.
The radiation-sensitive resin composition of the present invention consists basically of a component (A) a compound containing a substituted amino group (substituted-amino-group-containing compound), a component (B) a radiation-sensitive acid generator, and a component (C) a resin containing an acid-cleavable group (acid-cleavable-group-containing resin).
(A) Substituted-amino-group-containing Compound
The compound of the component (A) [hereinafter “component-(A) compound”] in the present invention is a low-molecular compound derived from a compound having at least one amino group having one or two hydrogen atom(s) bonded to a nitrogen atom [hereinafter “amino compound (a)]. That is, The component (A) low molecular compound is formed by substitution of at least one hydrogen atom of said hydrogen atom(s) of the amino group with a t-butoxycarbonyl group.
The amino compound (a) may, in other words, be any of those having a hydrogen atom bonded to nitrogen (i.e., N—H bond), without limitations to its form of existence. One hydrogen atom may be bonded to a nitrogen atom or two hydrogen atoms may be bonded to the same nitrogen atom. More specifically, the amino group of the amino compound (a) is meant to be what is called a primary amino group or a secondary amino group. This amino group has no limitations on its adjoining atom or group, and may be bonded adjoiningly to, e.g., a carbonyl group or a thiocarbonyl group.
Where the amino compound (a) has two or more amino groups and also has two or more t-butoxycarbonyl groups, each t-butoxycarbonyl group may be bonded to the same or different nitrogen atom.
In radiation-sensitive resin compositions used as chemically amplified resists, it is known that the incorporation of an acid diffusion control agent having the action to control a phenomenon where the acid generated from the radiation-sensitive acid generator upon exposure diffuses into resist films and to control any unwanted chemical reaction in unexposed areas brings about an improvement in storage stability of the resin compositions and an improvement in resolution as resists and also can keep resist pattern line width from changing because of variations of a post-exposure delay (PED) of
Kobayashi Eiichi
Numata Jun
Yamachika Mikio
Yamamoto Masafumi
Ashton Rosemary
JSR Corporation
Kelber Steven B.
Piper Rudnick LLP
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