Impact of Dislocations on Minority Carrier Lifetime in 300-mm Si Wafers During a High Thermal Budget Process

Abstract

A quantitatively analysis of the impact of process-induced dislocations on minority carrier lifetime in 300-mm Si wafer was presented. High thermal budget processes, such as oxidation and impurity diffusion, are essential in Insulated Gate Bipolar Transistor (IGBT) fabrication but can induce dislocations in large-diameter Si wafers. These dislocations may degrade the minority carrier lifetime, directly impairing device performance. Therefore, establishing a quantitative relationship between dislocation density and lifetime is crucial for process control and yield improvement. In this paper, we first demonstrate that dislocation propagation during thermal processes can be effectively suppressed by controlling the magnitude of a parameter “f”, which represents the dislocation propagation rate. Subsequently, wafers with varying dislocation density were fabricated through a series of consecutive thermal cycles. The dislocation density was determined by numerical calculation, while the corresponding minority carrier lifetime was measured using the micro-photoconductivity decay ( $\mu $ -PCD) method. A quantitative correlation between dislocation density and lifetime was established. These findings contribute to preventing dislocation-induced lifetime degradation during high thermal budget process in power device manufacturing.