Positive resist fluid and positive resist composition

Details Positive resist fluid and positive resist composition Positive resist fluid and positive resist composition

1999-11-12

2002-07-16

Chu, John S. (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

C430S906000, C430S910000

Reexamination Certificate

active

06420082

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a positive resist fluid for use in ultramicrolithographic processes such as the production of ULSIs and high-capacity microchips and in other photofabrication processes, more particularly, a positive resist fluid excellent in the storage stability of the fluid and in defocus latitude depended on line pitch.
The present invention further relates to a positive photoresist composition for use in ultramicrolithographic processes such as the production of ULSIs and high-capacity microchips and in other photofabrication processes, more particularly, a positive photoresist composition capable of forming an ultrafine pattern with a light in the far ultraviolet region, including an excimer laser light, and especially with a light having a wavelength of 250 nm.
BACKGROUND OF THE INVENTION
The degree of integration in integrated circuits is increasing more and more in recent years, and it has become necessary to form an ultrafine pattern having a line width of 0.5 &mgr;m or smaller in the production of semiconductor substrates for ULSIs and the like. With this trend, the exposure light wavelengths of illuminators for use in photolithography are increasingly becoming shorter so as to meet the above requirement, and the use of excimer laser lights having shorter wavelengths among far ultraviolet rays (e.g., XeCl, KrF, and ArF excimer laser lights) has now come to be investigated.
For use in lithographic pattern formation in the above wavelength region are chemical amplification type resists.
In general, the chemical amplification type resists are roughly divided into three groups, i.e., 2-component systems, 2.5-component systems, and 3-component systems. The 2-component systems comprise a combination of a compound which generates an acid upon photodecomposition (hereinafter referred to as a photo-acid generator) and a binder resin. This binder resin has, within its molecule, groups which decompose by the action of an acid to enhance the solubility of the resin in an alkaline developing solution (the groups being referred to also as acid-decomposable groups). The 2.5-component systems comprise such a 2-component system which further contains a low-molecular compound having an acid-decomposable group. The 3-component systems comprise a photo-acid generator, an alkali-soluble resin, and the above low-molecular compound.
Although the chemical amplification type resists are suitable for use as photoresists for irradiation with ultraviolet or far ultraviolet rays, they need to meet property requirements for use with a particular illuminator among ultraviolet and far ultraviolet illuminators. For example, a resist composition has been proposed which contains a polymer obtained by incorporating acetal or ketal groups as protective groups into a hydroxystyrene polymer and showing reduced light absorption especially in the case of using 248-nm KrF excimer laser light. Examples thereof are given in, e.g., JP-A-2-141636 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-2-19847, JP-A-4-219757, and JP-A-5-281745. Furthermore, a similar composition in which a t-butoxycarbonyloxy or p-tetrahydropyranyloxy group is used as an acid-decomposable group is proposed in, e.g., JP-A-2-209977, JP-A-3-206458, and JP-A-2-19847.
Although these prior art compositions are suitable for irradiation with 248-nm KrF excimer laser light, they show insufficient sensitivity when an ArF excimer laser is used as an illuminator because they essentially have still too high an absorbance. These compositions further have drawbacks accompanying the low sensitivity, such as, e.g., deteriorations in resolution, focus latitude, pattern profile, etc. Those prior art compositions hence still necessitate improvements in many points.
On the other hand, a photoresist composition for an ArF illuminator has been proposed which comprises a combination of a (meth)acrylic resin even more reduced in absorption than partially hydroxylated styrene resins and a compound generating an acid upon light irradiation. This type of composition is disclosed in, e.g., JP-A-7-199467 and JP-A-7-252324. In particular, JP-A-6-289615 discloses a resin containing acrylic acid units each having an organic group having a tertiary carbon atom and bonded to one of the oxygen atoms of the carboxyl group through an ester bond.
JP-A-7-234511 discloses an acid-decomposable resin containing repeating units derived from an acrylic or fumaric ester. However, the resist composition disclosed therein is insufficient in pattern profile, adhesion to substrates, etc. Thus, none of the prior art photoresist compositions proposed so far for use with an ArF illuminator has satisfactory performances.
Furthermore, resins in which an alicyclic hydrocarbon structure has been incorporated for the purpose of imparting dry-etching resistance have been proposed.
In JP-A-9-73173, JP-A-9-90637, and JP-A-10-161313 is described a resist material containing an acid-responsive compound which contains both alkali-soluble groups each protected by a structure containing an alicyclic group and structural units which are made alkali-soluble upon elimination of the alkali-soluble groups by the action of an acid.
JP-A-9-90638 discloses an energy-ray-sensitive material containing a polymer having sulfonamide structures in side chains and the main chain thereof. There is a description therein to the effect that a chemical amplification type resist which is capable of accurately giving a desired pattern and undergoes reduced pattern shrinkage upon elimination of protective groups is obtained due to the use of the polymer.
Although various resins having acid-decomposable groups have been investigated for use in chemical amplification type photoresists as described above, there has been room for improvement. Specifically, the conventional chemical amplification type photoresists still have problems, for example, that the photoresists when stored in a liquid state, deteriorate in resist performance (deterioration of resist-fluid storage stability).
Since recent devices tend to contain various patterns, resists are required to have various performances. One of these i s defocus latitude depended on line pitch (Dense Vias). Adevice has an area where lines are densely disposed and a pattern area where lines are separated by spaces wider than the lines, and further has isolated lines. It is, therefore, important to resolve various lines with high reproducibility. However, to reproduce such various lines is not always easy because of optical factors, and how to attain the desired reproduction based on an improvement in resist has remained unclear.
Moreover, although resins having an alicyclic hydrocarbon structure incorporated therein for imparting dry-etching resistance have been proposed, this type of system has exceedingly high hydrophobicity as an adverse influence of the incorporation of the alicyclic hydrocarbon structure. As a result, the resist containing this resin has drawbacks, for example, that the resist is difficult to develop with an aqueous tetramethylammonium hydroxide (hereinafter referred to as TMAH) solution, which has conventionally been used extensively as a resist developing solution, and the resist may peel off the substrate during development.
Measures have been investigated in coping with such a hydrophobized resist. Among these is to incorporate an organic solvent such as, e.g., isopropyl alcohol, into a developing solution. Although such measures give some degree of results, several problems still remain unsolved, e.g., the fear of resist film swelling and process troublesomeness.
With respect to an approach based on resist improvement, many attempts have been made to compensate for various hydrophobic alicyclic hydrocarbon structures by incorporating hydrophilic groups.
A technique which has been generally employed is to copolymerize acrylic or methacrylic acid as a monomer having a carboxyl structure with a monomer having an alicyclic hydrocarbon group. This measure is effective i

Affiliated with

Also associated with

Rating

Positive resist fluid and positive resist composition does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Positive resist fluid and positive resist composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Positive resist fluid and positive resist composition will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2915584