tailieunhanh - Advances in Solid State Part 12

Tham khảo tài liệu 'advances in solid state part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Dimension Increase in Metal-Oxide-Semiconductor Memories and Transistors 321 n-channel p-channel b Strained silicon FET with tensile-or compressive-CVD SiN cap films Fig. 18. Typical strained silicon MOSFET s SiGe buried layer a and CVD SiN cap films b . decomposited CVD whereas the compressive strain may be given by plasma-enhanced CVD. Almost 50 increase in carrier mobilities of both n- and p-channel transistors were obtained. Proposals of quasi 3-D transistors To cope with short-channel effects which will be more and more serious in response to the scaling of conventional 2-D transistors transistors of which channel was formed on both side walls of a silicon beam named trench-isolated transistor using side-wall gates TIS Hieda et al. 1987 and fully depleted lean-channel transistor DELTA Hisamoto et al. 1989 were proposed as shown in Fig. 19 a and b respectively. Because of horizontal current flow of the transistor this kind of transistors is called quasi 3-D in this article. In TIS full side walls were not used while main channel was formed on side walls of the thin silicon beam in DELTA. The bottom of the silicon beam is fully oxidized with localoxidation of silicon process LOCOS the beam is isolated from silicon substrate like SOI substrate. Advantages of the thin silicon channel were estimated. Fig. 19. Proposed quasi 3-D transistors of trench-isolated transistor using side-wall gates TIS a and fully depleted lean-channel transistor DELTA b 322 Advances in Solid State Circuits Technologies The author s group has proposed several devices with respect to quasi-3-D structures. One of them is corrugated channel transistor CCT Furukawa et al 2003 Sunami et al 2004 as shown in Fig. 20. Plural beam channels with 111 surface are formed by a crystallographically preferential etching with tetramethylammonium hydroxide TMAH atomically flat channel surface can be formed expecting less mobility degradation by avoiding rough surface of the channel. The current .