Temperature Dependence of the Threshold Voltage Shift Induced by Carrier Injection in Integrated STI-Based LDMOS Transistors

Abstract

Large threshold voltage shifts (Δ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Vt</i> ) are experimentally observed in n-channel lateral DMOS transistors under high current-voltage regime. The effect is enhanced by the gate voltage as well as by the ambient temperature ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TA</i> ) . By approximating the curves with the usually adopted power-law dependence (Δ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Vt</i> = <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Atn</i> ), two different contributions are observed, and a clear increase of the exponent <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> is found. A numerical investigation is carried out, revealing that the electric field normal to the oxide interface ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">En</i> ) as well as the internal temperature ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> ) close to the source side of the MOS channel is mainly responsible for such enhanced degradation.