Modification of a 100-mA-class high-current oxygen implanter and its application to ultrathin film MOSFET/SIMOX

Abstract

In order to put the SIMOX technology to actual use, Eaton Corporation and NTT jointly developed the 100-mA-class high-current oxygen implanter, NV-200, in 1986. Both NTT and Eaton Corporation kept working to improve the NV-200, to make it more sophisticated. As a result, by changing the Duopigatron ion source's filament material from conventional Re to LaB 6, it was possible to extend the lifetime of the filament from 20 to 90 h. Concerning the problem of metallic contamination of the SIMOX substrate, we have looked into the cause of the problem, and have succeeded in circumventing the contamination. Using the SIMOX substrate produced by the NV-200, we have test-fabricated ultrathin film MOSFET with an active layer of 0.1 μm thickness. In the MOSFET, the thickness of the gate oxide is 74 Å and the gate length is 0.5 μm, whereas the maximum values of the transconductance of p- and nMOSFET are 90 and 174 mS/mm. These figures are superior to the MOSFET/bulk. It has been proven that NV-200 can actually be used for ultrafine MOSFET/SIMOX.