High Temperature Reverse Bias (HTRB) & Temperature Humidity Bias (THB) Reliability Failure Mechanisms and Improvements in Trench Power MOSFET and IGBT

High Temperature Reverse Bias (HTRB) reliability failure is found to be caused by huge amount of undesirable hydrogen proton (H+) ions from packaging resin or external environment, while Temperature Humidity Bias (THB) reliability failure is known to be caused by moisture accumulation. A commonly known method of improving HTRB is by increasing phosphorus concentration in the PMD layer to enhance device gettering capability against H+. However, this is usually achieved at the expense of THB reliability as excessive phosphorus on the PMD surface gives rise to moisture accumulation and caused THB failure. In this paper, we performed a series of experiments to uncover two elements in PMD that are responsible to getter H+, which are Phosphorus-Oxygen-Hole-Center (POHC) and dangling bonds. We also discussed 2 possible ways to boost these H+ gettering elements to improve HTRB reliability without the adverse impact on THB reliability: Utilization of Plasma Enhanced Chemical Vapor Deposition (PECVD) Phospho-Tetraethyl-Orthosilicate (PTEOS) in PMD layer to replace the commonly used Atmospheric Pressure Chemical Vapor Deposition (APCVD) or Sub Atmospheric Chemical Vapor Deposition (SACVD) Boro-Phospho-Tetraethyl-Orthosilicate (BPTEOS) and the introduction of Tetraethyl-Orthosilicate (TEOS) capping layer on PMD layer. Both methods have proven to greatly alleviate HTRB and THB reliability marginality problems.