In ArF lithography for < 90nm L/S, amorphous carbon layer (ACL) deposition becomes inevitable process because thin
ArF resist itself can not provide suitable etch selectivity to sub-layers. One of the problems of ACL hardmask is surface
particles which are more problematic in mass production. Limited capacity, high cost-of-ownership, and low process
efficiency also make ACL hardmask a dilemma which can not be ignored by device makers. One of the answers to these
problems is using a spin-on organic hardmask material instead of ACL hardmask. Therefore, several processes including
bi-layer resist process (BLR), tri-layer resist process (TLR), and multi-layer resist process (MLR) have been investigated.
In this paper, we have described spin-on organic hardmask materials applicable to 70nm memory devices. Applications
to tri-layer resist process (TLR) were investigated in terms of photo property, etch property and process compatibility.
Based on the test results described in this paper, our spin-on hardmask materials are expected to be used in mass
production.
As the feature sizes of integrated circuits shrink, thinner photoresist coating should be used in order to avoid
high aspect ratio which can cause pattern collapse. Especially for 193 nm lithography, photoresist coating is too thin to
subsequent etching step. One of the solutions to this problem is using hardmasks which have good etch selectivity to
adjacent layers. In this paper, silicon-based anti-reflective spin-on hardmasks (Si-SOH) are described. One of the
major problems of silicon based polymers in the hardmask compositions is poor storage stability because silanol group is
reactive enough to condense each other, which can instigate molecular weight increase to yield gel-type particles. The
storage stability of our hardmask materials have been improved by thermodynamically controlled synthesis and reactive
mask strategy. Especially the reactive masked silanol groups can take part in crosslinking reaction under the process
conditions without additional deprotection step. Although this strategy could encounter intermixing problems with
other layers, we can produce silicon-based hardmasks without any deleterious effects. These hardmasks show antireflective
properties and great etch selectivity to both photoresists and organic hardmasks (C-SOH).
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