Electro-thermal modeling of trench-isolated SiGe HBTs using TCAD

The modern SiGe HBT structure with shallow and deep trench isolation (STI and DTI) is analyzed from electrothermal standpoint using TCAD system. The electrical parameters β, f_T, f_max, maximal temperature T_max, and thermal resistance R_TH are under consideration. TCAD simulation confirms the fact that the presence of STI and DTI in SiGe HBT structures gains the self-heating effect in comparison with traditional Si BJT structures, where DTI is not used. It is shown that for high power regimes (I_C = 0.5-3 mA; V_CE = 4-5 V) the set of electrical parameters β, f_T, f_max significantly degrade, temperature T_max can reach the critical values about 500 K, and the thermal resistance RTH increases thrice in HBT structure with STI and DTI. These results agree with published experimental data.