![]() To minimize lattice distortion and other defects, the germanium content of the SiGe layers should be as low as possible. ALD deposits the gate dielectric and metal into the spaces between the silicon nanosheets. Then, once the inner spacers are in place, a channel release etch removes the SiGe. An indentation in the SiGe layers makes room for an inner spacer between the source/drain, which will eventually be deposited next to the pillar and the space where the gate will be. The next several steps are unique to nanosheet transistors, though. These devices start with alternating layers of silicon and silicon germanium (SiGe), patterned into pillars.Ĭreating the initial Si/SiGe heterostructure is straightforward, and pillar patterning is similar to fin fabrication. Horizontally stacked nanosheets are emerging as an industry consensus for 5nm, according to IBM. gate-all-around Source: Lam Research Nanosheet GAA In some cases, the gate-all-around FET could have InGaAs or other III-V materials in the channels.įig. It’s basically a silicon nanowire with a gate going around it. Considered the ultimate CMOS device in terms of electrostatics, gate-all-around is a device in which a gate is placed on all four sides of the channel. One promising and futuristic transistor candidate - gate-all-around FET - could circumvent the problem. ![]() As the fin width in a finFET approaches 5nm, channel width variations could cause undesirable variability and mobility loss.
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