1. New technology for enhancing depth of focus using birefringent material
- Author
-
Dohoon Kim, Kyoung Ik Cho, Dae Yong Kim, and Hai Bin Chung
- Subjects
Materials science ,Birefringence ,business.industry ,Image quality ,Polarization (waves) ,Ray ,Waveplate ,law.invention ,Crystal ,Optics ,Cardinal point ,law ,Optoelectronics ,Photolithography ,business - Abstract
We propose a new technology for enhancing the depth of focus in sub-quarter-micron optical lithography. For this work, we introduce a new projection optical system that includes a birefringent optical component. The quartz crystal as a birefringent materials makes the incident light be resolved into the predetermined polarized direction of the component. By this concept, the focus latitude is increased by the birefringent optical component, which can create two or more focal planes at slightly different positions along the light axis. In addition, the exposure can be done at each focal plane simultaneously by the polarization condition of exposure light. In this paper, we report the basic ideas, and the simulation results that the focus latitude for patterns with a feature size of a sub-quarter-micron can be increased more than tow times using new technology comparing with the conventional method.
- Published
- 1999