二次离子质谱技术在砷化镓工艺中的应用

砷化镓工艺过程中出现的问题往往与杂质的分布有关 ,二次离子质谱技术是研究各种成分的三维分布的主要测试方法之一 ,由于其自身的特点使其成为分析器件失效原因的最有效的检测手段。利用 SIMS技术对砷化镓材料、离子注入、外延生长、光刻、欧姆接触形成、肖特基势垒形成及钝化等工艺中出现的典型问题进行了研究分析 ,找出了失效原因 ,为改进工艺提供了依据。     

SIMS investigations into the effect of growth conditions on residual impurity and silicon incorporation in GaN and AlxGa1−xN

We have investigated the effect of metal-organic chemical vapour deposition growth conditions on impurity incorporation in GaN and AlGaN. Secondary ion mass spectrometry depth profile analyses were performed on GaN and AlGaN wafers with multiple layers in which temperature, V/III ratio, growth rate, carrier gas, Al content, and Si doping were varied. Trends in oxygen, carbon, and silicon concentrations were studied. Similar trends were observed for both GaN and AlGaN. Growth temperature, composition and V/III ratio had the largest effect on impurity incorporation. Silicon and oxygen incorporation were less susceptible to growth conditions than that of carbon.     

SIMS analysis of nitrided oxides grown on 4H-SiC

This paper shows for the first time, physical evidence of nitrogen incorporation at the oxide-SiC interface as a result of post-oxidation annealing in nitric oxide (NO). Using secondary ion mass spectroscopy (SIMS) analysis, the location and shape of the nitrogen profile is seen to be almost identical to that found in oxide-silicon interfaces. Close examination of oxygen and carbon SIMS profiles and atomic force microscope scans also indicate a sharper interface when annealing is done using NO compared to inert gases such as N₂ or argon, possibly due to the removal of carbon clusters which form at the interface during oxidation. As in the case of silicon, NO annealing shows great promise as a processing step in the production of device quality gate oxides on SiC.     

WC–Co substrate surface pretreatments with aluminum compounds prior to polycrystalline CVD diamond deposition

Without pretreatment, the adherence of polycrystalline chemical vapour deposition (CVD) diamond films on WC–Co substrates is rather poor due to Co presence in the binder phase. Therefore several attempts to immobilize the Co on the substrate surface have already been investigated. However, results are not fully satisfying. In this paper, solutions or suspensions of various Al compounds have been applied to the WC–Co surface to form stable Co/Al compounds before diamond deposition. By means of SIMS depth profile analysis it is shown that surface pretreatment with Al(OC₂H₅)₃/conc. CH₃COOH or Al(NO₃)₃ leads to the formation of Co/Al compounds which suppress the Co mobility resulting in improved adherence of the diamond layer. Evidence for Co/Al compounds has also been found after pretreatment with Al(OH)₂–OOCCH₃ in neutral solution, although the quality of the diamond crystals was changed to ballas. The use of Al(OH)₂–OOCCH₃ in a basic as well as an acid medium produced no Co/Al reaction.     

空气中分子沾污(AMC)的实时监测

简要地介绍了AiM监测器的原理及应用效果,该系统可以对沉积于SiO2表面的空气分子沾污AMC进行实时监测,所获得的数据对于了解洁净室内的工艺过程与产生AMC间的相互关系特别有用。通过监测吸附物总量的长期变化趋势,可以确定洁净室内环境沾污的基本值,以便有利于对新污染源的早期确认。     

As在HgCdTe外延层中的扩散系数

使用二次离子质谱分析(SIMS)方法研究了As在碲镉汞分子柬外延样品中的扩散系数．获得了在240℃．380℃和440℃温度下As在碲镉汞材料中的扩散系数,并发现它与退火过程中Hg的分压有关,且Hg空位对As的扩散有明显的辅助增强作用．研究表明在低温段的240℃／24—48小时的退火中As的扩散非常有限,对样品中As的浓度分布影响不大,而在高温段380℃／16小时和440℃／30分钟退火中,As扩散较为明显,能使原来的PN突变结变缓．综合比较As杂质的电学激活以及As扩散因素,高温段440℃／30分钟的退火条件较理想．