Investigation on Distinct Two-Stage <i>R</i> ON Degradation Mechanisms in STI- and LOCOS-Based Triple RESURF LDMOS Devices

In this article, the distinct two-stage on-state resistance (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><small>on</small></sub>) degradation mechanisms in shallow trench isolation (STI)-and local oxidation of silicon (LOCOS)-based triple reduced surface field (RESURF) lateral diffused MOS (LDMOS) are thoroughly investigated. Threshold voltage (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>th</roman></sub>) degradation and charge pump (CP) experiments confirm that hot carrier injection (HCI) damage primarily locates in the field oxide (FOX) regions. In STI device, the initial rapid <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><small>on</small></sub> increase is attributed to hot electrons injection at the source-side bottom corner, driven by the parallel electric field. In LOCOS device, the initial slight <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><small>on</small></sub> decrease is dominated by hot holes injection under the poly edge, driven by the perpendicular electric field. Subsequently, in the second stage, the generation of interface traps (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>it</roman></sub>) under poly edge causes a gradual <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><small>on</small></sub> increase in both devices. These findings reveal the distinct two-stage <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><small>on</small></sub> degradation mechanisms in STI-and LOCOS-based triple RESURF LDMOS and provide valuable insights for improving HCI immunity in the STI architecture, with recommendations as refining edge geometries, sidewall angles, and corner radius to alleviate impact ionization and electric fields crowding.