Issued Patents 1989
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4885472 | Silicon grid as a reference and calibration standard in a particle beam lithography system | — | 1989-12-05 |
| 4837443 | Guard ring for a differentially pumped seal apparatus | Glen E. Howard | 1989-06-06 |
| 4818838 | Apparatus for preselecting and maintaining a fixed gap between a workpiece and a vacuum seal apparatus in particle beam lithography systems | Lee H. Veneklasen | 1989-04-04 |