Stress-Induced Effects in Electronic Characteristics of n-Type MOSFETs in Resin-Molded Packages

The shift of the DC characteristics of nMOSFETs during a resin-molding process was investigated experimentally. A silicon chip including the nMOSFETs was encapsulated in a quad flat package, and the drain current and transconductance shifts were measured. The drain current decreased during the resin-molding process, while no significant shift in threshold voltage was observed. The experimental results were estimated adequately from the residual stress predicted by numerical and experimental analysis, and from the stress sensitivity of the nMOSFETs measured by the four-point bending method. Also, we verified the validity of an electron mobility model that includes the effect of stress, used for drift-diffusion device simulation, by comparison with experimental results, and several improvements to the electron mobility model were found out.