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In-situ etch depth control with precision around 1 nm via reflectance anisotropy spectroscopy during reactive ion etching of monocrystalline III/V semiconductors

在单晶 III/V 半导体的反应离子蚀刻过程中，通过反射各向异性光谱进行原位蚀刻深度控制，精度约为 1 nm

基本信息

批准号：
333645568
负责人：
Professor Dr. Henning Fouckhardt
金额：
--
依托单位：
Arbeitsgruppe Integrierte Optoelektronik und Mikrooptik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/333645568?language=en
关键词：
situ etch depth control precision

项目摘要

The aim of this project is the improvement of the precision of in-situ etch depth control during reactive ion plasma dry-etching. Three approaches shall be employed.The first concept (for the case of common RIE etch rates of a couple of 100 nm/min) uses Fabry-Perot oscillations, i. e. periodic changes of the reflectivity of a layer for etch-related shrinking layer thickness. The oscillations are to be observed simultaneously at two different photon energies, which differ by 1/10. This relates to the use of a vernier scale of a sliding caliper. Precision of 1-2 nm in etch depth determination should be possible this way. One problem might occur, if the RAS data could not be collected and used fast enough during the etch process. Then the etch rate would have to be reduced, e. g. by reduction of the ion energy. The second approach is going to use periodic changes of the RAS signal with changes monolayer by monolayer. This effect is known from epitaxy. But the proposer-s team has already seen such oscillations in the average reflectivity for not too large etch rates during GaAs dry-etching. They are to be called monolayer oscillations here, in order to distinguish them from the Fabry-Perot oscillations of the first approach. If the second concept was going to work, the best possible precision in etch depth determination would be reached, i. e. a single monolayer. But optimal results for the second approach are only to be expected for etch rates lower than usual (like 50-100 nm/min). A third concept is offered by praxis. Discrepancies in the RAS signal or variations due to differences in doping of different layers can be used. Dopings are common in optoelectronic layer sequences. And oftentimes etching is to be stopped exactly at an interface between two layers. First results of the team are going to be extended during the project. Questions are: Under which circumstances (layer and etch parameters) can p- and n-dopings be distinguished? Can even the doping level be extracted from the signal? If so, with which precision? Can these results be used on-line (during etching)? Are data collection and calculation times small enough?

本计画的目的在于改善反应离子电浆乾蚀刻制程中原位蚀刻深度控制的精确度。第一种概念（对于普通RIE蚀刻速率为100 nm/min的情况）使用法布里-珀罗振荡，即，e.层的反射率对于与蚀刻相关的收缩层厚度的周期性变化。振荡将在两个不同的光子能量下同时观察到，它们相差1/10。这涉及使用游标卡尺的游标刻度。在蚀刻深度测定中的1- 2nm的精度应该是可能的这种方式。如果RAS数据不能在蚀刻工艺期间足够快地收集和使用，则可能发生一个问题。那么蚀刻速率将不得不降低，例如。G.通过降低离子能量。第二种方法将使用RAS信号的周期性变化，其中逐层变化。这种效应是从外延中已知的。但是，在GaAs干蚀刻过程中，在不太大的蚀刻速率下，提案者的团队已经看到了平均反射率的这种振荡。为了与第一种方法中的法布里-珀罗振荡区别开来，这里将它们称为单层振荡。如果第二个概念起作用，则将达到蚀刻深度确定的最佳精确度，即。e.一个单层但是第二种方法的最佳结果仅在蚀刻速率低于通常（如50-100 nm/min）时才能预期。第三个概念是由实践提供的。可以使用RAS信号中的离散性或由于不同层的掺杂的差异而引起的变化。掺杂在光电子层序列中很常见。通常，蚀刻会精确地停止在两层之间的界面处。团队的第一个成果将在项目期间得到推广。问题是：在什么情况下（层和蚀刻参数）可以区分p型和n型掺杂？甚至可以从信号中提取掺杂水平？如果是，精确度如何？这些结果是否可以在线使用（在蚀刻过程中）？数据收集和计算时间是否足够短？