Numerical aperture (NA) has been significantly improved to 1.35 by the introduction of water-based immersion
193-nm exposure tools, but the realistic minimum feature size is still limited to 40 nm even with the help of robust
resolution enhancement techniques (RETs). Double patterning processes are techniques that can be used for
fabricating etching mask patterns for 32-nm nodes and possibly for 22-nm nodes as well, but the aspect ratio of
such etching mask patterns have been reduced with scaling. At the same time, dramatic improvements in the
etching durability of photo resist have not been made. This paper introduces a robust pattern-slimming process that
maintains pattern height.
Double patterning processes are techniques that can be used to form etching mask patterns for 32nm node and possibly
for 22nm node as well. The self-aligned spacer process has drawn much attention as an effective means of enabling the
formation of repetitive patterns. The self-aligned spacer process is now being used in actual device manufacturing, but it
has many process steps driving up process cost while also assuming a 1D pattern. This paper demonstrates extensions of the self-aligned spacer process by an enhanced 2D positive spacer process and a newly developed spacer DP process using a 1D negative spacer.
In the field of photolithography, a variety of resolution enhancement techniques (RETs) are being applied under the mainstream technology of 193-mm water-based immersion lithography. The resolution performance of photoresist, however, is limited at 40 nm. Double patterning (DP) is considered to be an effective technology for overcoming this limiting resolution. Many double-patterning techniques have come to be researched such as litho-etch-litho-etch (LELE), litho-litho-etch (LLE), and self-aligned spacer DP, but as the pattern-splitting type of double patterning requires high overlay accuracy in exposure equipment, the self-aligned type of double patterning has become the main approach. This paper introduces the research results of various double-patterning techniques toward 22nm nodes and touches upon newly developed elemental technologies for double patterning.