Dielectric Breakdown Properties of SiO₂ Films Grown in Halogen and Hydrogen‐Containing Environments

Abstract

Thermal oxidation of silicon, in the presence of chlorine or bromine compounds, effectively improved the dielectric breakdown characteristics (as measured with a voltage ramp) of the resulting <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML1" overflow="scroll"> <mml:msub> <mml:mi mathvariant="normal">SiO</mml:mi> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> films. At high halogen concentrations the oxidation rate was erratic; the optimal initial breakdown properties were attained by oxidizing with about one‐half of the halogen‐containing additive that would cause etching of the Si. Oxidation in the presence of halides increased the resistance of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML2" overflow="scroll"> <mml:msub> <mml:mi mathvariant="normal">SiO</mml:mi> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> films to dielectric breakdown under accelerated bias‐temperature stressing. The maximum time to failure varied semilogarithmically with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML3" overflow="scroll"> <mml:mi mathvariant="normal">HCl</mml:mi> </mml:math> concentration and increased by 0.3 to 0.65 decade per per cent of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML4" overflow="scroll"> <mml:mi mathvariant="normal">HCl</mml:mi> </mml:math> (0–3% <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML5" overflow="scroll"> <mml:mi mathvariant="normal">HCl</mml:mi> </mml:math> range) for applied fields from 2 to 7 MV/cm, respectively. Higher oxidation temperatures further improved the resistance of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML6" overflow="scroll"> <mml:mi mathvariant="normal">HCl</mml:mi> </mml:math> oxides to dielectric wear‐out. The longer wear‐out times were attributed to hydrogen rather than the halogen and could be achieved by oxidation in small concentrations of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML7" overflow="scroll"> <mml:msub> <mml:mo>H</mml:mo> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mo>O</mml:mo> </mml:math> , annealing in H2, or.implantation of H2 or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML8" overflow="scroll"> <mml:msub> <mml:mo>H</mml:mo> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mo>O</mml:mo> </mml:math> .