Negative bias temperature instability modeling for high-voltage oxides at different stress temperatures

Negative bias temperature instability (NBTI) of pMOS structures is a critical reliability concern for modern semiconductor devices. We propose and evaluate an enhanced NBTI model with the following additions to the standard reaction-diffusion (RD) model [1] (a) coupling to the semiconductor device equations to self-consistently include the oxide field, surface hole concentration, charged carriers, fast interface states (Fermi-level dependent charges), and slow oxide charges, (b) fully dynamic dispersive multiple trapping transport equations [2], in contrast to the commonly used non-equilibrium approximation [3, 4] or standard diffusion equations [1, 5], (c) generalized equations suitable to describe transport and trapping of either H or H2, (d) distributed oxide charges with different dynamics, in contrast to a fixed relation between interface and oxide traps. The oxide charges are generated by the diffusing species at oxide defects (E ′ centers [6]) forming slow positive charges (H2 is cracked first [7] while H 0 is trapped right away) turning them into hydrogen complexed E centers [8]. Although for ultra-thin oxides the importance of oxide charges is controversial [9, 10], for thicker oxides, as used in power and high-voltage devices, they are fundamental [11].