Method and apparatus for real-time correction of resist heating in lithography
US6420717B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 2000 |
| Grant date | Jul 16, 2002 |
| Priority date | — |
| Expiry date | Apr 11, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/30455
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The present invention relates to methods and procedures for determining resist temperature during energy beam lithography and adjusting process parameters, including reducing the beam current, to compensate for increased resist sensitivity due to heating. The present invention relates to methods of predicting resist heating in real-time as the writing proceeds thereby enabling beam compensation to be performed in real-time. A linear superposition approximation is described that provides a procedure for estimating the resist temperature at the point presently being written from previously written points. The present invention makes use of the thermal history of the pattern previously written as that history is recorded in the line of pixels immediately preceding the line whose temperature is to be determined prior to e-beam exposure, and a single number representing the thermal history of lines written before the immediately preceding line. The iterative methods for calculating resist heating in the present invention may be implemented digitally on a variety of devices. In addition, specific analogue circuitry to reproduce this iterative method is described, leading to rapid calcula…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.