Continuous scale optical proximity correction by mask maker dose modulation
US5657235A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 3, 1995 |
| Grant date | Aug 12, 1997 |
| Priority date | — |
| Expiry date | May 3, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70441
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Energy levels (dose) are manipulated to modify the resultant photomask representation in a controlled manner such that the final image in the semiconductor device fabrication is close to an ideal image. Feature sizes and shapes are modified by assigning relative mask writer doses rather than physically manipulating feature sizes in layout designs. This approach, based on coding of relative dose information onto the design data, allows continuous scale line width variation for all features without impact to data volume. Two embodiments are described. In the first embodiment, distortion knowledge in the form of a lookup table or convolution function is applied to CAD data which is fractured into numerous designs having specific dose assignments. In the alternative embodiment, distortion knowledge in the form of a lookup table or convolution function is applied to CAD data which generates an attribute file containing hierarchical dose information that is mapped onto the mask data. Both embodiments compensate specific mask feature sizes through dose offsets during the mask exposure process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.