Method of characterizing group III-V epitaxial semiconductor wafers incorporating an etch stop layer
US5639343A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 13, 1995 |
| Grant date | Jun 17, 1997 |
| Priority date | — |
| Expiry date | Dec 13, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/14
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
The present invention comprises a method of characterizing a group III-V epitaxial semiconductor wafer in a characterization profiling apparatus having an electrolytic cell. The wafer contains at least a Group III-V compound first-layer and a thin etch stop layer atop of the first layer and at least one second layer atop of the etch stop layer having a differing composition from the etch stop layer. The wafer is placed in the electrolytic cell and the surface of the at-least second layer is etched with a citrate buffer solution of citric acid and a salt of citric acid under anodic bias conditions. The etchant is highly selective and etching terminates upon reaching the etch stop layer. A Schottky diode is formed between the wafer and the solution, and the wafer is characterized in situ by performing capacitance-voltage measurements which are evaluated to determine the threshold voltage of the semiconductor wafer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.