Mobility enhancement in local strain channel nMOSFETs by stacked a-Si/poly-Si gate and capping nitride

Performance Enhancement by Local Strain in <110> Channel n-Channel Metal–Oxide–Semiconductor Field-Effect Transistors on (111) Substrate

“…The improvement in drain current is proportional to the thickness of the SiN layers. Since the SiN capping layer can provide tensile strain in the channel region and thus increase the electron mobility of the devices fabricated on a conventional (100) orientation substrate, 13) this result implies that capping with SiN has also the same advantage of providing tensile strain in the channel region for nMOSFETs on the (111) substrate. For the devices on the (100) orientation substrate, this SiN-capping-layer-induced tensile strain can cause the sixfold degenerate valleys of the silicon con-duction band to split into two degeneracy states: electrons with a longitudinal effective mass axis perpendicular to the interface in two lowered valleys, and those with a longitudinal mass axis parallel to the interface in four raised valleys.…”

“…9,10) The mobility of pMOSFETs on a (111) substrate can be improved owing to the low hole effective mass of the substrate; however, the low-field mobility of a (111) nMOSFETs is still less than that of (100) substrate. Therefore, it is very important to determine how to increase electron mobility in the channel region [11][12][13] on a (111) substrate.…”

Measurement of Strain in Freestanding Si/SixNy Membrane by Convergent Beam Electron Diffraction and Finite Element Method

“…2) The conventional procedure for introducing strain in Si films is to deposit Si x N y on a Si substrate. 3) In this study, Si x N y is deposited to surround a bridge-shaped freestanding Si membrane (FSSM). Since the strain at the two ends of the bridge part significantly affects the carrier mobility of the device to be fabricated, the strain and microstructure at the ends of the bridge part are investigated in the present study.…”

Optimized Si-Cap Layer Thickness for Tensile-Strained-Si/ Compressively Strained SiGe Dual-Channel Transistors in 0.13 µm Complementary Metal Oxide Semiconductor Technology

“…A promising candidate to reach this demand is to exploit the strain-induced band-structure modification. A recent study has shown that n-type metal-oxide-semiconductor fieldeffect transistors (NMOSFETs) with biaxial or uniaxial tensile stress in a Si-cap layer, which separately provides by conventional strained Si on relaxed Si 1Àx Ge x structures 1,2) or by the use of heavy mechanical stress produced by a tensile Si nitride-capping layer 3,4) exhibit improved drive current due to the enhancement in electron mobility. However, tensile strain in the Si channel for electron mobility enhancement has less p-type metal-oxide-semiconductor field-effect transistors (PMOSFETs) benefit.…”