As computer chips get smaller and the number of devices on them increases, the requirements for lithography reduction becomes more significant. One way to improve resolution and contrast of sub-micron features is to use an Image Reversal (IR) resist system. Further improvement can be obtained using a Contrast Enhancement Layer (CEL). The CEL provides a contact mask for the underlying resist system. The CEL allowed for the IR resist to produce better defined lines and spaces. Resolving 1 um lines was possible. However, the 1 um spaces were not. Overall, the contrast enhance material did improve resolution and contrast of the larger features (>2um), however, when the experiment was replicated, the same results were not seen. There was some adhesion problems with the IR resist, and there was still some difficulty in removing all of the CEL.
Nutter, Richard W. IV
"The Effects of Contrast Enhancement Material over an Image Reversal Resist System,"
Journal of the Microelectronic Engineering Conference: Vol. 6
, Article 16.
Available at: https://scholarworks.rit.edu/ritamec/vol6/iss1/16