High temperature specimen stage and detector for an environmental

Abstract

An environmental scanning electron microscope is provided which is capable of maintaining a specimen at a temperature up to approximately 1500.degree. C. In this environmental scanning electron microscope, a specimen chamber maintains the specimen enveloped in gas in registration with a final pressure limiting aperture of the objective lens assembly. The specimen chamber includes a specimen stage having a sample platform for supporting the specimen under examination at a first vertical height and a specimen heating assembly which includes a non-inductively wound heater coil which is positioned closely adjacent to the sample platform and extends to a second vertical height which is significantly above the first vertical height so that the top of the specimen is maintained at a high temperature. In this environmental scanning electron microscope, a heat shield assembly is positioned above the specimen heating assembly in the specimen chamber to avoid radiant heat loss and which has an adjustable bias voltage applied thereto to accelerate secondary electrons through its central opening to be collected by an electron detector. Moreover, in order to enhance image quality, the final pressure limiting aperture and the electron detector are biased at different voltages with the bias applied to the final pressure limiting aperture floated to provide for automatic compensation. A specimen stage moving assembly is also provided to move the specimen stage with respect to the heat shield assembly to enhance the field-of-view of the specimen.