Variations of hole mass in p-MOSFETs under process-induced mechanical stress

The influence of stress on transport properties in p-MOSFETs is rather well known for the case of biaxially strained channels obtained using heteroepitaxy. However, results concerning biaxial stress do not apply for other stress configurations. For the stress-engineering of sub-45 nm devices, simplified models of the valence-band structure are required which can predict the variation of electrical performances for any stress configuration and channel orientation. In this work, we use the analytical formulation of a 6 × 6 k.p strained Hamiltonian to derive transport parameters for holes in the cases of both tensile and compressive, [110] uniaxial and [001] biaxial stresses. Our calculations are found to be in strong agreement with previous results obtained using more intensive computations, and we show that the hole mobility variations experimentally observed in strained p-MOSFETs can be explained by the stress-induced changes of the highly anisotropic conductivity masses of holes.