Impact of hot carrier on RF N-LDMOS reliability for radar application after pulsed life test

Abstract

This Study presents a bench is dedicated to high RF power device lifetime tests under RF pulses for radar application. This bench combined the stress tests (RF, electrical and thermal,) applied to devices and have a direct impact on their lifetime. A complete device electric characterization (I-V, C-V and RF) has been conducted before/after different temperatures (3000 hours at 150° C and 10° C), and material clarifications for the phenomenon of failure, the reliability of different tests was compared. The prevailing physical acoustics concerned were studied and validated using the Silvaco-Atlas simulator. The main objective is to find a relationship between the electrical parameters degradation to failed physical phenomena caused by impact ionization. The degradation of N-LDMOS performance is tied to the hot carriers (traps) and trapped electrons, which leads to the accumulation of negative charge in the Si/SiO2 interface. More interface states (i.e. important buildup of negative charge) are created at low temperature due to impact ionization phenomenon. This is the reason why the electrical degradations are so high at 10°C.