SensArray Introduces APTI Peak Temperature Monitor Wafers for Plasma Etch and Other Processess

June 20, 2000, Santa Clara, Calif.
SensArray“ Corporation, a provider of innovative temperature metrology instrumentation for semiconductor processes, today introduced APTI (Arrays of Peak Temperature Indicators) monitor wafers. These non-contaminating, non-invasive wafers provide a unique approach to permanent, accurate peak wafer temperature indication for plasma etch processes.

Temperature-indicating sensor arrays, located as close as 3 mm from the wafer edge, are embedded in the APTI wafer and sealed under sapphire windows. They autoload and process like product wafers without system downtime or risk of arcing or chamber contamination. Accuracy is not impaired by changes in etch power density or vacuum conditions.

Now processes can be routinely checked at the wafer to verify that actual wafer temperatures are within process limits—without the limitations in using stick-on decals or having to open the chamber to the environment. APTI wafers record the peak temperature and temperature uniformity in any process environment. They are especially useful for accurate characterization of temperature-sensitive plasma etch processes.

Temperature uniformity measurements from 40∞C to 121∞C with resolution to 4∞C correlate with SensArray’s APTOS® real-time, in situ plasma temperature measurement systems. Together, they provide a comprehensive solution for plasma etch process and equipment temperature analysis.

According to Dr. Mei Sun, Vice President of Research and Development for SensArray, “Our extensive studies have found that stick-on decals do not accurately measure wafer temperature and can be in error by as much as 20°C to 30°C. The thermal contact between wafer and decal is uncertain and not reproducible. In a process environment that is delivering thermal energy to the wafer by ion bombardment or surface exothermic chemical reactions, a thermally isolated decal will record a temperature that is related to the thermal energy at the top surface of the decal, which does not necessarily represent the actual wafer temperature. Since decal materials have poor conductivity and the energy heating the wafer must pass through the decal, a vertical thermal gradient is developed causing the indicator to float above the wafer temperature.

Temperature indication repeatability is difficult to achieve because of the variables in decal construction and installation. “Another major source of error in using decals is that many temperature-sensitive components used in decals shift their temperature indication point significantly when exposed to vacuum. The convenience and accuracy of APTI wafers should lead to their fast acceptance as an invaluable temperature verification tool for critical etch processes,” Dr. Sun continued.

For further information on APTI wafers, APTOS, or other SensArray metrology products, call SensArray at 408-330-5600 or visit the web site at www.sensarray.com.