Reduction of radiation thermometry deviation errors in a CVD reactor

摘要

Devices for reducing radiation thermometry error errors in housings such as CVD reactors. In one embodiment, a radiation thermometer uses a non-focused telecentric lens assembly. The unfocused telecentric array is focused at infinity, but is used to capture radiation from a relatively close target (for example, within a few meters) that is out of focus. The capture of collimated radiation from the target reduces the contribution of scattered radiation. In another embodiment, scattered radiation originating from a particular segment of a peripheral heating element may be localized by one of several mechanisms, including reducing the radiation (eg, operating temperature) of the particular segment, or capturing or deflecting a portion of the radiation from the one specific segment is reduced. Radiation thermometers mounted near an axis extending from the center of the wafer receptacle and over the particular segment are less susceptible to radiation and thus provide a more reliable temperature measurement.