Investigation of Kirk-Effect Induced Hot-Carrier-Injection in High-Voltage Power Devices

Hot-carrier-injection (HCI) effect is expected to well correlate with substrate current $(\mathrm{I}_{\mathrm{SUB}})$. However, in high-voltage (HV) device which features extended lightly-doped drain region (Ndrift), two $\mathrm{I}_{\mathrm{S}\mathrm{U}\mathrm{B}}$ peaks are frequently observed and found to have different HCI degradation. Our data showed that the worst-case HCI after long term stress doesn't necessarily occur at largest $\mathrm{I}_{\mathrm{S}\mathrm{U}\mathrm{B}}$ which is usually found at full VG operation due to Kirk-effect. The HCI dependence on $\mathrm{I}_{\mathrm{S}\mathrm{U}\mathrm{B}}$ peak location in HV device is further investigated through TCAD simulation. Our study proved the changes in impact ionization location under 2nd$\mathrm{I}_{\mathrm{S}\mathrm{U}\mathrm{B}}$ peak by Kirk-effect, thus leads to less $\mathrm{Id}_{\mathrm{lin}}$ degradation in long term stress. Nit generation at pinch-off point is found to alter IIG (impact-ionization generation) location at HV high resistance drift region and could be explained through IIG simulation by TCAD.