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
2000-11-02
2002-08-27
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
C526S319000, C526S320000, C526S328000
Reexamination Certificate
active
06440636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polymeric compound (polymer) which is useful as a photoresist resin for use in, for example, micromachining of semiconductors, and to a photoresist resin composition containing the polymeric compound.
2. Description of the Related Art
Positive photoresists for use in manufacturing processes of semiconductors must concurrently have different characteristics such as a characteristic that an exposed portion is made soluble in alkali by the application of light, adhesion to silicon wafers, plasma-etching resistance, and transparency to light used. The positive photoresists are generally used as a solution containing a base compound polymer, a lightact-ivatable acid generator, and several types of additives for controlling the above characteristics. It is very important for the main compound polymer to have the above individual characteristics in balance to prepare an appropriate resist according to its use.
The wavelength of a light source for exposure in lithography for use in semiconductor manufacturing becomes shorter and shorter in recent years, and ArF excimer laser with a wavelength of 193 nm is promising as a next-generation light source. The use of a unit containing an alicyclic hydrocarbon skeleton has been proposed as a monomeric unit for a resist polymer for use in the ArF excimer laser exposure system (e.g., Japanese Patent No. 2776273). Such an alicyclic hydrocarbon skeleton is highly transparent with respect to light with the aforementioned wavelength and is resistant against etching. The use of a polymer having an adamantane skeleton as a resist polymer is also known, which adamantane skeleton exhibits an especially high etching resistance among alicyclic hydrocarbon skeletons. However, such alicyclic hydrocarbon skeletons are highly hydrophobic and have therefore low adhesion with respect to substrates, although they have a high etching resistance as mentioned above. To improve this disadvantage, the aforementioned Japanese patent therefore proposes a copolymer containing a highly hydrophilic monomeric unit (adhesion-imparting monomeric unit) having, for example, a carboxyl group or a lactone ring. However, the monomeric unit is not resistant to etching, and the etching resistant of the overall polymer becomes insufficient when the polymer contains a sufficient amount of the monomeric unit to satisfy the required adhesion.
Separately, Japanese Unexamined Patent Application Publication No. 11-109632 has a try at imparting hydrophilicity to an adamantane skeleton by introducing a hydroxyl group to the adamantane skeleton. However, the polymer proposed in the publication uses t-butyl (meth)acrylate as a monomeric unit (alkali-soluble monomeric unit) which becomes soluble in alkali by action of an acid generated by light irradiation, and the etching resistance of the overall polymer is still insufficient.
Attempts have been made to use a monomeric unit having an adamantane skeleton itself as an alkali-soluble monomeric unit (e.g., Japanese Unexamined Patent Application Publications No. 9-73173, No. 9-90637, No. 10-274852, No. 10-319595, No. 11-12326, and No. 11-119434). However, monomers lacking etching resistance are used as the adhesion-imparting monomeric units in these polymers, and the overall resulting polymers are still insufficient in etching resistance.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a polymeric compound having not only satisfactory transparency, alkali-solubility, and adhesion but also a high etching resistance, as well as to provide a photoresist resin composition containing the polymeric compound.
After intensive investigations, the present inventors found that when a polymer containing a monomeric unit having an adamantane skeleton with a specific structure is used as a photoresist resin, the resulting photoresist resin has a satisfactory etching resistance, in addition to excellent transparency, alkali-solubility, and adhesion. The present invention has been accomplished based on these findings.
Specifically, the present invention provides, in an aspect, a polymeric compound which includes at least one monomeric unit represented by the following formula (I):
wherein R
1
is a hydrogen atom or a methyl group; and each of R
2
and R
3
is independently a hydrogen atom or a hydroxyl group.
The polymeric compound may further include at least one monomeric unit selected from monomeric units represented by the following formula (IIa) and (IIb):
wherein R
1
is a hydrogen atom or a methyl group; each of R
4
and R
3
is independently a hydrogen atom, a hydroxyl group, an oxo group, a carboxyl group, or a —COOR
6
group, wherein R
6
is a t-butyl group, a 2-tetrahydrofuranyl group, a 2-tetrahydropyranyl group or an 2-oxepanyl group, and wherein R
4
and R
5
are not concurrently hydrogen atoms; and each of R
7
and R
8
is independently a hydrogen atom, a hydroxyl group, or an oxo group.
Preferably, the polymeric compound may further comprise, in addition to the above monomeric units, at least one monomeric unit selected from a monomeric unit represented by the following formula (III):
wherein each of R
1
and R
9
is independently a hydrogen atom or a methyl group; a monomeric unit represented by the following formula (IV):
wherein R
10
is a tricyclo[5.2.1.0
2,6
]decylmethyl group, a tetracyclo[4.4.0.1
2,5
.1
7,10
]dodecylmethyl group, a norbornyl group, an isobornyl group, or a 2-norbornylmethyl group, R
11
is a substituent of R
10
selected from a hydrogen atom, a hydroxyl group, a hydroxymethyl group, a carboxyl group, and a —COOR
12
group, wherein R
2
is a t-butyl group, a 2-tetrahydrofuranyl group, a 2-tetrahydropyranyl group, or an 2-oxepanyl group; and R
1
has the same meaning as defined above; a monomeric unit represented by the following formula (Va) or (Vb):
wherein each of R
13
, R
14
, R
15
, R
16
, R
17
, R
18
, R
19
, and R
20
is independently a hydrogen atom or a methyl group, and R
1
has the same meaning as defined above; a monomeric unit represented by the following formula (VI):
wherein n denotes an integer of 1 to 3; and R
1
has the same meaning as defined above; and a monomeric unit represented by the following formula (VII):
wherein R
1
has the same meaning as defined above.
Monomeric units each having an adamantane skeleton may occupy, for example, 50% to 100% by weight, and preferably 70% to 100% by weight of overall monomeric units constituting the polymer.
The polymeric compound can be used as a photoresist resin.
In another aspect, the present invention provides a photoresist resin composition which includes the polymeric compound and a light-activatable acid generator.
The terms “acrylic(acryl)” and “methacrylic(methacryl)” may be generically referred to as “(meth)acrylic” or “(meth)acryl” herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invented polymeric compound comprises at least one monomeric unit represented by the formula (I) (hereinafter referred to as “monomeric unit 1”) as a structural unit constituting a polymer molecule.
In the monomeric unit of the formula (I), a moiety containing an adamantane skeleton is eliminated from a carboxylic acid moiety combined with a principal chain by action of an acid to thereby yield a free carboxyl group. The monomeric unit 1 therefore acts as an alkali-soluble unit which becomes soluble in development using an alkali. The monomeric unit has the adamantane skeleton and therefore has a satisfactory transparency and a very high etching resistance. Of the monomeric units of the formula (1), monomeric units in which at least one (preferably both) of R
2
and R
3
is a hydroxyl group are highly hydrophilic and exhibit adhesion activity. Accordingly, the polymeric compound can exhibit a satisfactory adhesion activity by appropriately incorporating these monomeric units or other hydrophilic monomeric units. The invented polymeric compound can therefore be advantageously used as a photoresist resin.
In a preferred
Asakawa Koji
Funaki Yoshinori
Inoue Keizo
Okino Takeshi
Shida Naomi
Ashton Rosemary
Birch & Stewart Kolasch & Birch, LLP
Kabushiki Kaisha Toshiba
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