Precitec Optronik Gmbh

Martin Schoenleber

Christoph Dietz

Markus Kogel-Hollacher

Berthold Michelt

Thibault Bautze

Claus Dusemund

According to a method for measuring the distance between a workpiece and a machining head of a laser machining apparatus, a machining head is provided, which has a housing that has an interior and an opening for emergence of the laser radiation from the machining head. The laser radiation is directed on to the workpiece, after it has passed through the interior and the opening. An object beam is directed on to the workpiece by a light source of an optical coherence tomograph in such a manner that the object beam passes through the interior and the opening before being incident upon the workpiece. In addition to the object beam, a measuring beam passes through the interior. The measuring beam is used to compensate falsifications of the measured distance that have been caused by pressure fluctuations in the interior. The measuring beam in this case may be reflected at a reflective face that is formed on an inner face of an outlet nozzle that comprises the opening, which inner face delimits the interior.

Method for measuring the distance between a workpiece and a machining head of a laser machining apparatus

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 w.

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

According to the invention, a monitoring device () is created for monitoring a thinning of at least one semiconductor wafer () in a wet etching unit (), wherein the monitoring device () comprises a light source (), which is designed to emit coherent light of a light wave band for which the semiconductor wafer () is optically transparent. The monitoring device () further comprises a measuring head (), which is arranged contact-free with respect to a surface of the semiconductor wafer () to be etched, wherein the measuring head () is designed to irradiate the semiconductor wafer () with the coherent light of the light wave band and to receive radiation () reflected by the semiconductor wafer (). Moreover, the monitoring device () comprises a spectrometer () and a beam splitter, via which the coherent light of the light wave band is directed to the measuring head () and the reflected radiation is directed to the spectrometer (). The monitoring device () further comprises an evaluation unit (), wherein the evaluation unit () is designed to determine a thickness d(t) of the semiconductor wafer () from the radiation () reflected by the semiconductor wafer () during thinning of the semiconductor wafer () by means of a method that is selected from the group consisting of a 1D-se FDOCT method, a 1D-te FDOCT method and a 1D-se TDOCT method.

Monitoring apparatus and method for in-situ measurement of wafer thicknesses for monitoring the thinning of semiconductor wafers and thinning apparatus comprising a wet etching apparatus and a monitoring apparatus

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 w.

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Aschaffenburg, Germany

Martin Schoenleber