GaAs表面及Al_xGa_（1－x）As／GaAsHBT外基区表面（NH_4）_2S／SiN_x钝化工艺研究

分析了ＡｌｘＧａ１－ｘＡｓ／ＧａＡｓＨＢＴ外基区表面复合电流及外基区表面复合速度对直流增益的影响，用光致发光（ＰＬ）谱和Ａｌ／ＳｉＮｘ－Ｓ／ＧａＡｓＭＩＳ结构Ｃ－Ｖ特性，研究了ＧａＡｓ表面（ＮＨ４）２Ｓ／ＳｉＮｘ钝化工艺的效果及其稳定性。结果表明，ＥＣＲ－ＣＶＤ淀积ＳｉＮｘ覆盖并在Ｎ２气氛中退火有助于改善ＧａＡｓ表面硫钝化效果的稳定性。在此基础上形成了一套包括（ＮＨ４）２Ｓ处理、ＳｉＮｘＥＣＲ－ＣＶＤ淀积及退火并与现有ＨＢＴ工艺兼容的外基区表面钝化工艺，使发射区面积为４×１０μｍ２的器件增益比钝化前提高了４倍，且６０天内不退化。

Passivation Technique with (NH_4)_2 S/SiN_x on the Surface of GaAs and Al_x Ga_(1-x)As/GaAs HBT Extrinsic Base

The effect of surface recombination current and passivation at theextrinsic base region on the current gain of a Np+n AlxGa1-xAs/GaAs HBT isdiscussed.The passivation of GaAs surface using sulfide solution and SiNxoverlayer of ECR-CVD was evaluated by photoluminescence (PL) technology and C-V characteristic measurement of an Al/SiNx-S/GaAs MIS structure.and the result shows that SiNx deposited by ECR-CVD and annealing in N2 ambient help to improve the stability of sulfur passivation effect,a passivation techniquecompatible to the present process of HBT including (NH4)2 S solution treat ment,SiNx ECR-CVD deposition and annealing technique was obtained,bywhich the current gain of a 4×10μm2-area-emitter AlxGa1-x As/GaAs HBT wasincreased by about four times compared with that before passivated; the passivation effect was stable for some 60 days.