SEDL / STP / STP990-EB / STP26035S

Use of Polysilicon Deposition in a Cold-Wall LPCVD Reactor to Determine Wafer Temperature Uniformity

Starov, V
PresidentSenior Process Technician, Applied Photonics Research Inc.Varian Associates Inc., Redwood CityFremont, CACA

Lane, L
PresidentSenior Process Technician, Applied Photonics Research Inc.Varian Associates Inc., Redwood CityFremont, CACA

Pages: 9    Published: Jan 1989

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Abstract

In the Varian 5101 LPCVD reactor operating in a Rapid Thermal Processing (RTP) mode the wafer is heated directly by a radiant heater. The wafer temperature in this case is measured by a pyrometer pointing at its center. To obtain a temperature map of the entire wafer, we have developed and characterized a polysilicon deposition process. Using the polysilicon thickness as a “chemical thermometer” [1], we have been able to improve the radiant heater design to obtain a temperature uniformity of 0.2% across a 100 mm wafer and 0.5% on wafers up to 150 mm. As an example of application of our study, the optimized design was used to deposit selective tungsten with thickness uniformity of 4% across 140 mm scan on 150 mm wafer.