Development of High Sensitivity X-Ray and Electron-Beam Resist Processes.
Abstract
Plasma-initiated polymerization was used to form ultrahigh molecular weight (greater than ten million grams per mole) poly (methylmethacrylate) (UHMW PMMA) from liquid methyl methacrylate (MMA). The PMMA thus obtained was exposed to beams of 10 KV electrons ranging in dose from 0.1-10 micro-coulombs per square centimeter. For comparison, identical exposures were carried out using commercial PMMA resist (KTI) with a molecular weight of about 0.7 million grams/mole. Using 1:1 methyl ethyl ketone and isopropanol to develop the exposed resist, 0.5 micron pattern sizes were formed in both resist materials. Pattern fidelity in the UHMW PMMA was virtually identical to that obtained with KTI PMMA, but a factor of three lower dose could be used with the UHMW material. This lowered dose arose because the dissolution rate of the unexposed resist was a factor of 30 lower for UHMA than for KTI PMMA. A new spinner was designed and built to allow improved control of spin-cast films. Modeling studies based upon non-Newtonian behavior were initiated to enable prediction of film thickness as a function of position on a wafer, solution viscosity, and spin speed. In an attempt to further improve the sensitivity of UHMW materials, synthetic studies were undertaken to introduce halogen atoms into the MMA molecule. Chlorinated MMA was synthesized and is currently being investigated for its plasma-initiation susceptability. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 20, 1981
- Accession Number
- ADA107833
Entities
People
- D. W. Hess
Organizations
- University of California, Berkeley