Strained silicon MOSFET technology

Abstract

Mobility and current drive improvements associated with biaxial tensile stress in Si nand p-MOSFETs are briefly reviewed. Electron mobility enhancements at high channel doping (up to 6 x IO" cm-') are characterized in strained Si n-MOSFETs. For low inversion layer carrier concentrations, channel-dopant ionized impurity scattering does reduce the strain-induced mobility enhancement, but the enhancement is recovered at higher inversion charge concentrations, where screening is efficient. Mobility enhancement in strained Si p -MOSFETs is also discussed. There are process integration challenges and opportunities associated with this technology. Dopant diffusion, and its impact on profile engineering in strained Si CMOS structures, is one example. While the slower diffusion of B in Si,.,Ge, enables improved doping profile control, the diffusivity of the n-type dopants is dramatically enhanced in Sia.nGea.2.

High-performance nMOSFETs using a novel strained Si/SiGe CMOS architecture

“…C-V profiling of MOS capacitors on the Si/SiGe and Si control device wafers confirmed that of the Si/SiGe wafer was equivalent to that of the Si control wafers. Therefore, the lower values observed for the strained Si/SiGe device are mainly attributed to the differing electron affinities of the materials [16], [28]. The variation of transconductance with gate overdrive, -, for 0.2 m L 5 m W silicided strained Si and Si control devices is presented in Fig.…”

Selective epitaxy growth of Si1−xGex layers for MOSFETs and FinFETs

“…For many years, the majority of the research was focused on biaxial strained-Si on the relaxed SiGe virtual substrate due to its potential for mobility enhancement for both p-and nMOSFETs [4,5,21]. However, most of these works demonstrated the hole mobility improvement was degraded to a near zero at large vertical electric field [4,22,23] (where this is the operating range of commercial MOSFETs) as shown in Fig.…”

“…4 have to be minimized. The importance to establish an epi-model for SEG is highlighted when the growth faces pattern dependency in which the SiGe layer profile is affected by the pattern layout [15,17,21,38,[40][41][42][43][44]. During recent years, various methods have been proposed to decrease the pattern dependency in SEG of SiGe layers but an effective method which completely eliminates this problem has not yet been presented [15,17].…”

Strain coefficient measurement for the (100) uniaxial strain silicon by Raman spectroscopy

“…The strain silicon technology has a long history [11][12][13][14]. Four problems are involved in the microelectronics applications.…”