Method of measuring crystal defects in thin SI/SIGE bilayers

Abstract

Disclosed herein are methods for characterizing crystal defects in thin Si layers on SiGe alloy layers. This method uses a defect etchant that is highly defect selective to Si. The Si is etched to the thickness of the underlying SiGe layer. The SiGe layer under the pit is then etched to keep the Si intact using a second etchant that is the same as or different from the defect etchant.

Description

technical field [0001] The present invention relates to semiconductor device fabrication, and more particularly, to determining crystal defects in a Si layer formed on a SiGe alloy layer. The methods described here can be used to form Si / SiGe bilayers atop bulk Si substrates, or silicon-on-insulator (SOI) based substrates. The method of the present invention can be used to measure defect density in strained Si layers grown on relaxed SiGe layers as well as in any other Si / SiGe film system. Background technique [0002] An important tool for developing and evaluating high-quality Si / SiGe bilayers is a reliable method for determining the defect density in the layer. The term "Si / SiGe bilayer" is used throughout this application to describe a structure having a Si layer on top of a SiGe layer. In particular, the precise determination of the crystallographic defect density in thin strained Si layers on relaxed SiGe layers is important in both the development of strained Si mat...

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Problems solved by technology

[0007] Considering the problems with existing techniques using electron microscopy or the lack of reliable chemical etching techniques to determine the defect density in Si / SiGe bilayers, there is a need for a new and improved method to characterize the defects in Si / SiGe bilayers. crystal defects

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