Patent EP-1126320-A2 (EP)
Inventor: KIM JAE YOUNG
IPC: H01L21/027
Filed: 2001-01-05
Abstract: Disclosed is a chemically amplified positive photoresist composition
including: a multi-component copolymer represented by the formula 1 and having a
polystyrene-reduced weight average molecular weight (Mw) of 3,000 to 50,000 and
a molecular weight distribution (Mw/Mn) of 1.0 to 3.0; a low molecular weight
additive represented by the formula 2; an acid generator; and a solvent,
 
   wherein X and Y independently comprise a repeating unit selected from the
group consisting of monomers represented by the formulas (II), (III) and (IV):
 
   wherein R 1  is a hydrogen atom, a normal, branched, monocyclic or
polycyclic alkyl group having 1 to 20 carbon atoms, or a normal, branched,
monocyclic or polycyclic alkyl carbonyl group having 1 to 20 carbon atoms,
including acetyl group,  t -butyl oxycarbonyl group, cyclohexane carbonyl group,
adamanthane carbonyl group and bicyclo[2,2,1]heptane methyl carbonyl group; R 2 
is a hydrogen atom, a hydroxyl group, a carboxyl group, an alkyl or alkoxy group 
having 1 to 20 carbon atoms, an alkyl or alkoxy group containing a hydroxyl or
carboxyl group, a normal or branched alkyloxycarbonyl or alkoxyalkylcarbonyl
group, or a monocyclic or polycyclic alkyloxycarbonyl group; R 3  is a hydrogen
atom, or a normal, branched, monocyclic or polycyclic alkyl group having 1 to 20
carbon atoms, including methyl group, ethyl group, t-butyl group, isopropyl group,
adamanthyl group, and bicyclo[2,2,1]heptane methyl group; and  l ,  m, n  and  o  are
independently a number representing the repeating unit of the polymer and
satisfying 0 ≤  l /( l + m + n + o )  ≤  0.5, 0 ≤  m /( l + m + n + o )  ≤  0.5, 0 ≤  n /( l + m + n + o ) ≤ 0.35,
0.4 ≤  o /( l + m + n + o )  ≤  0.6, and 0.15 ≤ ( l + m )/( l + m + n + o ) ≤ 0.5,
 
   wherein R 4  and R 5  are the same as or different from each other and each
represents a normal, branched, monocyclic or polycyclic alkyl group having 1 to 20
carbon atoms; and R 6  is a hydrogen atom, or a normal, branched, monocyclic or
polycyclic alkyl or alkoxy group having 1 to 20 carbon atoms. 
     The low molecular weight additive for chemically amplified resist provided
by the present invention has a good compatibility with other normal resins and high
transparency to radiations as well as thermal stability in the range of temperature
used in processing the resist. The low molecular weight additive is readily
decomposed by the action of the acids generated under exposure, generating 2
equivalent weights of carboxyl acids per one equivalent weight of the low molecular
weight additives to enhance sensitivity and dissolution rate. Particularly, the additive 
has a structure containing a monocyclic or polycyclic alkyl group that increases dry
etching resistance. A resist composition comprising the additive may provide a
resist pattern excellent in sensitivity as well as adhesion to substrate and dry etching
resistance. Such a resist composition is a promising material greatly suitable for use
in the fabrication of semiconductor devices that are expected to have further
fineness. Especially, the resist composition is suitable for KrF or ArF excimer laser
lithography and thus useful in the fine engineering of less than 0.20 micron patterns.