Method for detecting the transition between different materials in semiconductor structures

US6200822A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Volker Becker · Marxzell, DE
• Franz Laermer · Stuttgart, DE
• Andrea Schilp · Schwäbisch Gmünd, DE

Key dates

• Filing date: Jun 17, 1999
• Grant date: Mar 13, 2001
• Expiry date: Jun 17, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L22/26
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A method for detecting the transition between different materials in semiconductor structures during alternating etching and covering steps for anisotropic depthwise etching of defined patterns performed using a plasma. Provision is made for ascertaining, by way of an intensity measurement of at least one specific substance contained in the plasma, the beginning of each etching step by the fact that a characteristic threshold is reached, this also being achievable by way of an external synchronization signal which indicates the beginning and end of each etching step; for then, when the threshold value is reached, starting a delay time which is longer than the course of a first concentration maximum; for a second concentration maximum then to be ascertained after the delay time has elapsed; and for the second concentration maxima of the etching steps to be monitored as to whether they exceed or fall below the predefined value, in order to detect a material transition.