Sub-100 nm Gate Technologies for Si/SiGe-Buried-Channel RF Devices

概要

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A novel fabrication process of sub-100 nm self-aligned T-gates for heterostructure field-effect transistors (HFETs) using optical contact lithography is presented. A 500-nm-wide polyimide fin is used as an implantation mask, shrunk by dry etching and subsequently replaced by a gate metal. A low-resistive gate head to form a T-shape is independently defined by wet chemical etching. Using this method, Si/SiGe modulation-doped field-effect transistors (MODFETs) have been prepared, having a gate length of 90 nm. The self-alignment enables the realization of very small source/gate and gate/drain spacings of 200 nm. This yields, together with an optimized salicide (self-aligned silicide) ohmic contact, a much lower access resistance compared to conventional gates defined by e-beam lithography. A record transit frequency $f_{\text{T}}$ of 90 GHz and a very high transconductance of 570 mS/mm have been achieved for MODFETs.
公益社団法人応用物理学会の論文
2003-04-15