Method of measuring crystal defects in thin SI/SIGE bilayers

Abstract

Described herein is a method for delineating crystalline defects in a thin Si layer over a SiGe alloy layer. The method uses a defect etchant with a high-defect selectivity in Si. The Si is etched downed to a thickness that allows the defect pits to reach the underlying SiGe layer. A second etchant, which can be the same or different from the defect etchant, is then used which attacks the SiGe layer under the pits while leaving Si intact.

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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