Method of estimating mechanical stress on Si body of MOSFET using drain–body junction current

Abstract

A simple and accurate method of estimating the mechanical stress σ on the Si body of a MOSFET is proposed. This method measures the doping concentration of the body, N d, and the onset voltage V hl for the high-level injection of the drain–body junction, uses N d, the ideality factor η, and the Fermi potential ϕf ≈ V hl/2η to calculate the intrinsic carrier concentration n i of the Si body, and then uses the calculated n i to obtain the bandgap energy E g of the Si body. σ is estimated from E g using the deformation potential theory. The estimates of σ agree well with those obtained using previous methods. The proposed method requires one MOSFET, whereas the others require at least two MOSFETs, so the proposed method can give an absolute measurement of σ on the Si body of a MOSFET.