Abstract: One more study for pushing resolution limit down below industry agreed optical limit was performed. It was pursued for practical application, not limited to experimental purpose only. The first work was concentrated on studying how much we could lower the resolution and improve the process latitude of dense lines, which was thought as the most critical one. OAI and BARC played a role for that purpose, were expected to improve DOF as much as 105% and 15%, compared to conventional illumination and non-BARC process, respectively. It was also known from simulation that mask biasing was important to maximize DOF for dense and isolated line. It could be used to reduce CD and resist profile difference of dense and isolated features as well. Ultimate resolution was only possible by very high contrast resist. All the efforts in this work achieved quarter micron i-line process which has 1.2 micrometer DOF for dense lines, 0.8 micrometer overlap DOF and 10% exposure latitude both for dense and isolated features. !8
展开▼
