Minimizing overetch during a chemical etching process

US5501766A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Steven G. Barbee · Beekman, US
• Tony F. Heinz · Chappaqua, US
• Yiping Hsiao · San Jose, US
• Leping Li · Poughkeepsie, US
• Eugene H. Ratzlaff · Hopewell Junction, US
• Justin W. Wong · South Burlington, US

Key dates

• Filing date: Jun 30, 1994
• Grant date: Mar 26, 1996
• Expiry date: Jun 30, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/02
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A contactless method and apparatus for real-time in-situ monitoring of a chemical etching process to minimize overetch of at least one wafer in a wet chemical etchant bath are disclosed. The method comprises the steps of providing two conductive electrodes in the wet chemical bath, wherein the two electrodes are proximate to but not in contact with a wafer; monitoring an electrical characteristic between the two electrodes as a function of time in the etchant bath of the at least one wafer, wherein a prescribed change in the electrical characteristic is indicative of a prescribed condition of the etching process; detecting a minimum and maximum value of the electrical characteristic during etching; determining the times of the minimum and maximum values; and comparing the times of the minimum and maximum values to determine an overetch value. The overetch value may be compared to a desired value to control the etching process. Such a method and the apparatus therefor are particularly useful in a wet chemical etch station.