| Autor: |
S. Cherekdjian, W. Weisenberger |
| Rok vydání: |
1991 |
| Předmět: |
|
| Zdroj: |
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 55:30-34 |
| ISSN: |
0168-583X |
| DOI: |
10.1016/0168-583x(91)96130-d |
| Popis: |
The presence of energetic neutrals in a high-current, high-energy implant can result in nonuniformities on a silicon wafer. A larger concern is when the energetic neutrals are not of the desired energy. This is a major consideration when designing ion implanters with pre- and post-acceleration stages. This paper investigates the levels of pre-accelerated boron neutrals present in a 180 kV boron implant. The machines investigated were a Nova 20A and an Applied Materials PI9000. A comparison of their vacuum systems and their ability to cope with photoresist batches and argon backfill are presented. Silicon wafers were mapped by four-point probe resistivity measurements and the levels of pre-accelerated neutrals were quantified by spreading resistance profiles (SRPs). It is clearly demonstrated that good uniformity on a bare silicon wafer is not an indicator of a clean ion beam. Even though it is well understood that this problem is vacuum-related, modern high-current implanters are still being built and marketed with improper vacuum isolation and insufficient pumping capability. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
