Peak Systems, Inc.

Other

Stephan E Lassig

Ahmad Kermani

John L Crowley

Noel H Johnson

Gary R Rickords

Thomas J DeBolski

The present invention is an apparatus for calibrating a temperature feedback value in a water processing chamber to automatically compensate for variations in infrared emissions from a heated semiconductor wafer due to variations in composition and coatings from wafer to wafer. A calibration wafer with an imbedded thermocouple is used to generate a table relating actual wafer temperatures to power supplied to the heating chamber and infrared emissions detected by a pyrometer. A sample wafer of a batch to be processed is subsequently placed in the chamber at a known power level, and any difference between the detected infrared emission value and the value in the table is used to adjust the entire table according to a first predetermined formula or table. Before each wafer is processed, a known source of infrared light is reflected off the wafer and detected. The reflected light value is compared to a reflection measurement for the sample wafer. The difference in reflection measurements is correlated to emissions from heating, and the calibration table is fine-tuned with the correlation value according to a second predetermined formula or table to account for variations in emissions between individual wafers due to variances in wafer surface conditions.

Apparatus and method for compensating for errors in temperature

The present invention is a method and apparatus for calibrating a temperature feedback value in a wafer processing chamber to automatically compensate for variations in infrared emissions from a heated semiconductor wafer due to variations in composition and coatings from wafer to wafer. A calibration wafer with an imbedded thermocouple is used to generate a table relating actual wafer temperatures to power supplied to the heating chamber and infrared emissions detected by a pyrometer. A sample wafer of a batch to be processed is subsequently placed in the chamber at a known power level, and any difference between the detected infrared emission value and the value in the table is used to adjust the entire table according to a first predetermined formula or table. Before each wafer is processed, a known source of infrared light is reflected off the wafer and detected. The reflected light value is compared to a reflection measurement for the sample wafer. The difference in reflection measurements is correlated to emissions from heating, and the calibration table is fine-tuned with the correlation value according to a second predetermined formula or table to account for variations in emissions between individual wafers due to variances in wafer surface conditions.

A semiconductor wafer heating chamber has an optical element between a light source and a wafer for redistributing the light from the light source. The optical element is constructed in such a manner as to produce the desired illumination (and thus heating) pattern on the semiconductor wafer from the light source. Preferably, the light source is a long-arc lamp mounted above a base plate of a heating chamber. A primary reflector is mounted above the long-arc lamp and is shaped to produce a substantially uniform light distribution on the base plate. A quartz window is mounted between the arc lamp and the base plate. The quartz window acts as a lens to redistribute the light from the lamp and the reflector on a wafer. The window can be constructed as a diffraction grating with a series of lines formed by etching into the window or depositing material on the window to produce a diffraction pattern which gives the desired illumination pattern on the wafer. Interchangeable quartz windows are used to produce different illumination patterns which are appropriate for different size wafers and different types of heating processes.

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Milpitas, CA, United States of America

Stephan E Lassig