Apparatus and method for monitoring a thickness of a silicon wafer with a highly doped layer

US9230817B2 · kind B2 · utility

Assignee

• PRECITEC OPTRONIK GMBH · DE

Inventors

• Martin Schoenleber · Aschaffenburg, DE
• Christoph Dietz · Obertshausen, DE

Key dates

• Filing date: Mar 5, 2014
• Grant date: Jan 5, 2016
• Expiry date: Mar 5, 2034

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L2924/0002
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

Apparatus for monitoring a thickness of a silicon wafer with a highly-doped layer at least at a backside of the silicon wafer is provided. The apparatus has a source configured to emit coherent light of multiple wavelengths. Moreover, the apparatus comprises a measuring head configured to be contactlessly positioned adjacent the silicon wafer and configured to illuminate at least a portion of the silicon wafer with the coherent light and to receive at least a portion of radiation reflected by the silicon wafer. Additionally, the apparatus comprises a spectrometer, a beam splitter and an evaluation device. The evaluation device is configured to determine a thickness of the silicon wafer by analyzing the radiation reflected by the silicon wafer by an optical coherence tomography process. The coherent light is emitted multiple wavelengths in a bandwidth b around a central wavelength wc.