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Proceedings Paper

Advanced process control system for vertical furnaces
Author(s): Rudolf Berger; Claus Schneider; Wolfgang Lehnert; Lothar Pfitzner; Heiner Ryssel
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Paper Abstract

For the first time, a layer thickness sensor has been integrated into a vertical furnace for in situ sensing of the layer growth as well as for post process control of the batch. Because of its high accuracy and versatility, an in situ spectroscopic ellipsometer (SE) was selected. The adaption of the SE to the vertical furnace was performed with only minor modifications to the furnace geometry. The ellipsometer light beam is guided through the base plate into the furnace tube and directed onto the wafer by quartz glass prisms operated in total internal reflection (TIR) mode. This arrangement introduces an additional phase shift in the polarization state of the light which can be determined and subtracted from the measured phase shift. The ellipsometer setup is mechanically fixed to the boat loader. SE measurements therefore can be performed with the wafer boat out of the furnace tube as well as during the process run with the wafer boat inserted. The SE thus can be used for in situ end-point detection during layer growth and also for post process measurements on selected wafers of the batch during the unloading sequence. A realtime controller and a run-by-run controller integrated into the furnace controller utilize the layer thickness data measured in the in situ and in the post process mode, respectively, for immediate and automated correction of the parameter settings during the actual process run and for the following process run. The advantages of this novel furnace control system such as a reduction in time needed for process optimization, the avoidance of monitor wafers and a better control in integrated multilayer processing can be beneficial for future thermal batch/minibatch processing.

Paper Details

Date Published: 13 September 1996
PDF: 11 pages
Proc. SPIE 2876, Process, Equipment, and Materials Control in Integrated Circuit Manufacturing II, (13 September 1996); doi: 10.1117/12.250893
Show Author Affiliations
Rudolf Berger, Univ. Erlangen-Nuernberg (Germany)
Claus Schneider, Fraunhofer-Institut fuer Integrierte Schaltungen (Germany)
Wolfgang Lehnert, Fraunhofer-Institut fuer Integrierte Schaltungen (Germany)
Lothar Pfitzner, Fraunhofer-Institut fuer Integrierte Schaltungen (Germany)
Heiner Ryssel, Univ. Erlangen-Nuernberg and Fraunhofer-Institut fuer Integriete Schaltungen (Germany)

Published in SPIE Proceedings Vol. 2876:
Process, Equipment, and Materials Control in Integrated Circuit Manufacturing II
Armando Iturralde; Te-Hua Lin, Editor(s)

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