Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1993 · 11 citations · 0 references
EngineeringElectrical EngineeringManufacturing EngineeringHeat TransferMicroelectronicsSemiconductor DevicesTemperature MeasurementTemperature MetrologyThermal Expansion AnalysisThermal ManagementThermal ProcessingThermal Properties Of SemiconductorsCrystal Plane OrientationDopant EffectsSiliconSilicon WafersThermal ExpansionThermal Expansion MeasurementThermal Expansion ObservationThermal Management Of Semiconductor Devices
A new method of temperature control for rapid thermal processing of silicon wafers is presented whereby in-situ wafer temperature is determined by measurement of wafer thermal expansion via a laser autofocus mechanism. Various potential error sources are considered including wafer bow, effects of wafer doping and crystal orientation. Results are provided showing that variations in crystalline orientation and dopant levels have no measurable effect on expansion of the silicon substrate, allowing a direct correlation of wafer expansion to temperature. The expansion measurement technique and implementation into a rapid thermal processing system as a temperature control is described. Preliminary data show the wafer to wafer repeatability of temperature is 1% (3-(sigma) ) using wafer expansion as the control.