Adaptive Membrane Masks for Next Generation Lithographies
Final Progress rept. 1 Jul 2000-31 Mar 2003
LOUISIANA STATE UNIV BATON ROUGE
Pagination or Media Count:
The overlay accuracy, and hence the minimum useable feature size, in any integrated circuit lithography is often limited by distortions that are present in the mask and wafer. In this work selective heat loads are applied to membrane masks, thereby generating therrnal strains to compensate these distortions. Computer models have been developed that describe these effects, obtaining excellent agreement between a finite element model used at LSU and an analytical model developed at MIT. The special case of a scanned exposure, e.g., in SR X-ray lithography, is particularly well understood. Two experimental programs have been implemented, which demonstrate agreement between measured thermally generated displacements and the predictions of the computer models. At LSU the displacements were measured over an 11 x 11 array of alignment sites. Because of lithographic problems not all the sites were functional however the average displacements showed fair agreement with the computer predictions. At MIT the thermal input was generated by a modified 35 mm slide projector, and a holographic-phase-shift interferometer measured the resulting displacements to sub-wavelength accuracy. Detailed MARKET plots of the MIT data show good agreement with the computer predictions.
- Electrical and Electronic Equipment
- Numerical Mathematics
- Operations Research