Polymers and positive resist compositions

Details Polymers and positive resist compositions Polymers and positive resist compositions

1999-05-13

2001-04-24

Pezzuto, Helen L. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S258000, C526S286000, C526S287000, C526S288000, C526S313000, C526S318000

Reexamination Certificate

active

06221989

ABSTRACT:

This invention relates to a novel polymer in the form of a novolac resin in which some of the hydrogen atoms of hydroxyl groups are replaced by specific groups, and a positive resist composition comprising the polymer.
BACKGROUND OF THE INVENTION
Positive working resist compositions based on novolac resins are conventionally employed as interlayer insulating films in various electronic parts. Typically, these positive working novolac resin-base resist compositions for interlayer insulating films undergo thermal condensation at temperatures above 200° C. to form insulating films. Volume shrinkage occurs as the treating temperature rises. As a result, hardness increases, but insulation resistance declines. It is thus generally believed that a temperature of about 250° C. and a time of about 10 hours are appropriate for this treatment.
Further improvements in the performance of electronic parts are desired. If the insulating film-forming step involved in the manufacture of such electronic parts requires a treating temperature above 200° C., there is a possibility that metal layers in electronic parts be oxidized or deteriorated. To avoid any influence on metal layers, there is a desire to have an insulating material which can be briefly cured at lower temperature.
SUMMARY OF THE INVENTION
An object of the invention is to provide a polymer which is formulated into a positive resist composition having an improved sensitivity, resolution and developability in microfabrication and an improved heat resistance and low-temperature heat curability in the formation of interlayer insulating film. Another object is to provide a positive resist composition comprising the polymer.
Regarding a novolac resin having 1,2-naphthoquinonediazidosulfonyl ester groups substituted thereon, we have found that a novolac resin in which some of the hydrogen atoms of hydroxyl groups are replaced by 1,2-naphthoquinonediazidosulfonyl ester groups and some of the hydrogen atoms of the remaining hydroxyl groups are replaced by triazinyl groups, having a weight average molecular weight based on polystyrene of 1,000 to 30,000, has all the functions of an alkali-soluble resin, a photosensitive agent, and a heat-curing agent. This novolac resin affords a resist composition having an improved sensitivity, resolution and developability in microfabrication as well as an improved heat resistance and low-temperature heat curability in the formation of interlayer insulating film. The resist composition comprising the novolac resin is a photosensitive positive working resist composition which is effective in forming insulating layers in various electronic parts.
We have also found that in the above novolac resin having 1,2-naphthoquinonediazidosulfonyl ester groups and triazinyl groups substituted thereon, when some of the hydrogen atoms of the remaining hydroxyl groups in the novolac resin are further replaced by substituted carbonyl or sulfonyl groups, the resist scum left after development is minimized, which ensures to provide a resist composition with a further improved resolution.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, there is provided a novel polymer in the form of a novolac resin comprising recurring units of the following formula (1), wherein some of the hydrogen atoms of hydroxyl groups are replaced by 1,2-naphthoquinonediazidosulfonyl ester groups and some of the hydrogen atoms of the remaining hydroxyl groups are replaced by triazinyl groups of the following formula (2). The polymer has a weight average molecular weight based on polystyrene of 1,000 to 30,000. This polymer is referred to as a first polymer.
Herein m is an integer of 0 to 3, preferably an integer of 1 or 2.
Herein R
1
, R
2
, R
3
, and R
4
are independently hydroxymethyl or —CH
2
OR
5
groups, at least one of R
1
, R
2
, R
3
, and R
4
is a —CH
2
OR
5
group, and R
5
is a straight or branched alkyl group of 1 to 4 carbon atoms. Examples of the alkyl group represented by R
5
include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, and tert-butyl.
In one preferred embodiment, there is provided a novel polymer in the form of a novolac resin comprising recurring units of formula (1), wherein some of the hydrogen atoms of hydroxyl groups are replaced by 1,2-naphthoquinonediazidosulfonyl ester groups, some of the hydrogen atoms of the remaining hydroxyl groups are replaced by triazinyl groups of formula (2), and some of the hydrogen atoms of the remaining hydroxyl groups are further replaced by functional groups of at least one type selected from groups of the following general formulae (3), (4), and (5). The polymer has a weight average molecular weight based on polystyrene of 1,000 to 30,000. This polymer is referred to as a second polymer.
Herein R
6
is a straight, branched or alicyclic alkyl group of 1 to 30 carbon atoms, an aryl group of 6 to 20 carbon atoms, or an aralkyl group of 7 to 20 carbon atoms. Examples of the straight, branched or cyclic alkyl group of 1 to 30 carbon atoms represented by R
6
include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, tert-butylmethyl, n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, n-hexyl, palmityl, n-stearyl, cyclopropyl, cyclopentyl, cyclohexyl, and cholesteryl. Examples of the aryl group of 6 to 20 carbon atoms include phenyl, tolyl, ethylphenyl, propylphenyl, dimethylphenyl, methylethylphenyl, naphthyl, furyl, and biphenyl. Examples of the aralkyl group of 7 to 20 carbon atoms include benzyl, methylbenzyl, propylbenzyl, and dimethylbenzyl.
In the first polymer, the degree of substitution by 1,2-naphthoquinonediazidosulfonyl ester groups is preferably 0.03 to 0.3 mol, more preferably 0.05 to 0.2 mol, per hydrogen atom of hydroxyl group in the novolac resin. If the degree of substitution by 1,2-naphthoquinonediazidosulfonyl ester groups is less than 0.03 mol, the polymer would become poor in film retention, vague in pattern definition, and thus unsuitable for use as resist compositions. If the degree of substitution by 1,2-naphthoquinonediazidosulfonyl ester groups is more than 0.3 mol, the polymer would become less soluble in solvents and thus difficult to formulate as resist compositions.
Also, the degree of substitution by triazinyl groups of formula (2) is preferably 0.01 to 0.1 mol, more preferably 0.03 to 0.1 mol, per hydrogen atom of hydroxyl group in the novolac resin. If the degree of substitution by triazinyl groups is less than 0.01 mol, the polymer would become less heat-curable, failing to achieve the function of a low-temperature curable insulating film. If the degree of substitution by triazinyl groups is more than 0.1 mol, exposed areas of the polymer would become less soluble in solvents and thus the polymer become difficult to formulate as resist compositions.
In the second polymer, the degree of substitution by functional groups of formula (3), (4) or (5) is preferably 0.01 to 0.8 mol, more preferably 0.02 to 0.6 mol, per hydrogen atom of hydroxyl group in the novolac resin. At a degree of substitution of less than 0.01 mol, such less functional groups would fail to achieve the effect of minimizing resist scum after pattern formation. At a degree of substitution of more than 0.8 mol, exposed areas of the polymer would become less soluble in developer, giving rise to a problem in pattern formation.
The total degree of substitution by 1,2-naphthoquinonediazidosulfonyl ester groups, triazinyl groups, and functional groups of formula (3), (4) or (5) is preferably 0.03 to 0.85 mol, more preferably 0.05 to 0.7 mol, per hydrogen atom of hydroxyl group in the novolac resin. At a total degree of substitution of less than 0.03 mol, unexposed areas would become so soluble in developer that a pattern may not be formed or the pattern, even if formed, may be less heat resistant. At a total degree of substitution of more than 0.85 mol, unexposed areas would become less soluble in developer so that a pattern may not be formed.
The first and second polymers should have a weight average molecular weight based on polystyrene of 1,000 to

Affiliated with

Also associated with

Rating

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

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

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2528858