SEDL / STP / STP1382-EB / STP13491S

Qualification of Epi Layers and Interface Properties by an Improved μ-PCD Technique

Pavelka, T
Managing director, Budapest,

Pages: 10    Published: Jan 2000

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Abstract

The microwave photoconductive decay (μ-PCD) and the surface photo voltage (SPV) techniques are proved to be powerful methods in the qualification of semiconductor bulk materials. They are applied best for standard wafers with homogeneous material quality. However, both methods have their limitations when measuring epitaxial layer (epi) wafers or silicon on insulator (SOI) structures. In its conventional realization the SPV measurement is limited by the active layer thickness. On the other hand an epi layer grown on highly doped substrate typically does not generate high enough signal in a μ-PCD measurement.

The aim of the present work is the introduction of a new, improved microwave photoconductive decay technique with sensitivity exceeding that of the conventional techniques by orders of magnitude. It is shown that such a method is not only able to provide material quality in case of epi and SOI structures but can help also in the qualification of interface properties.

Data are presented to show the above statement including maps of contamination distributions in epi structures.