Wafer Level Stress: Enabling Zero Defect Quality for Automotive Microcontrollers without Package Burn-In
Chen He, Yanyao Yu
Abstract
Automotive microcontrollers demand extremely high reliability requirements. Burn-In (BI) stress to screen out early life failures caused by latent defects has become a quality requirement for automotive semiconductors. However, as feature size continues to scale down, performing BI stress on packaged parts has started to run into challenges including increased risks of thermal runaway and overstress, together with continuously increased cost and cycle time. In this paper, we present a new wafer level stress methodology consisting of enhanced High Voltage Stress Test (eHVST), Wafer Level Burn-In (WLBI), and enhanced Advanced Outlier Limit (eAOL) screens, which can achieve Zero Defect quality for automotive microcontrollers without package BI. It has been successfully implemented in production for NXP S32K1 automotive microcontrollers with benchmark DPPB (Defective Parts Per Billion) level of quality from over 20 million parts shipped in last several years.