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?

该项目的目的是提高反应离子等离子体干法刻蚀过程中原位刻蚀深度控制的精度。应采用三种方法。第一个概念（对于几个 100 nm/min 的常见 RIE 蚀刻速率的情况）使用 Fabry-Perot 振荡，即。 e.层反射率的周期性变化，导致与蚀刻相关的层厚度收缩。将在两个不同的光子能量下同时观察振荡，这两个光子能量相差 1/10。这涉及到游标卡尺的游标刻度的使用。通过这种方式，蚀刻深度测定的精度应该可以达到 1-2 nm。如果在蚀刻过程中无法足够快地收集和使用 RAS 数据，则可能会出现一个问题。那么蚀刻速率就必须降低，例如。 g。通过降低离子能量。第二种方法是利用 RAS 信号的周期性变化，逐层变化。这种效应从外延中已知。但提议者的团队已经发现，在砷化镓干法蚀刻过程中，蚀刻速率不太大时，平均反射率会出现这种振荡。这里将它们称为单层振荡，以便将它们与第一种方法的法布里-珀罗振荡区分开来。如果第二个概念可行，则可以达到蚀刻深度确定的最佳精度，即。 e.单个单层。但第二种方法的最佳结果仅在蚀刻速率低于平常（如 50-100 nm/min）时才可预期。第三个概念是由实践提供的。可以使用由于不同层的掺杂差异而导致的 RAS 信号的差异或变化。掺杂在光电层序列中很常见。通常，蚀刻恰好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扩展。问题是：在什么情况下（层和蚀刻参数）可以区分 p 掺杂和 n 掺杂？甚至可以从信号中提取掺杂水平吗？如果是的话，精度是多少？这些结果可以在线使用（蚀刻期间）吗？数据收集和计算时间是否足够短？