SELF-ALIGNED SUBCHANNEL IMPLANT COMPLEMENTARY METAL-OXIDE-SEMICONDUCTOR DEVICES FABRICATION

High-speed and low-power complementary metal-oxide semiconductor devic es with subchannel implants have been proposed and demonstrated recent ly. In subchannel implant devices, the alignment of the gate and the b uried implant region is a critical issue. In this article, a fully sel f-aligned gate and subchannel implant fabrication method is proposed u sing either focused-ion-beam or conventional ion implantation. This me thod defines the gate and produces the subchannel implant in the same step. By doing this, the buried implant region and gate are automatica lly aligned. By exposing the resist with a Bf ion beam, we verified th at the dose needed to produce the subchannel implant matches the dose needed to expose the resist (10(13) ion/cm(2)). We have simulated the implant profile and the expected device performance. The subthreshold current was found to be decreased by 1-2 orders of magnitude. Since th e process requires implantation through the gate oxide, capacitors wer e built over the gate oxide for C-V measurement and implanted over a r ange of doses. Proper postimplantation treatment has been developed to prevent increasing of the interface state density. (C) 1997 American Vacuum Society.