Abstract
In Electron beam gun (EB-gun) assisted metal evaporator, monitoring of surface temperature is essential for characterisation. Pyrometers having the advantage of non-contact measurement are used for monitoring the temperature of EB heated surface. The opacity introduced by the deposition of metal vapour on the viewing port during evaporation process hinders the monitoring. Indirect viewing using methods like periscope viewing has been reported to have poor accuracy of measurement due to uncertain value of reflectivity of in-situ coated metal mirrors. Multiple collisions of approaching atomic vapour with purge gas molecules and scattering the atoms is an attractive technique for long duration monitoring of surface temperature. In this method a controlled leak of inert gas is introduced to locally increase the pressure, without significantly increasing the pressure of process chamber. This approach increases the collision probability of the approaching atoms with gas molecules due to higher molecular number density, and scatters the atoms away from optics window.In the current study this technique has been successfully tested for monitoring of temperature of electron beam heated surface, using direct viewing optics port, with high evaporation rate. Successful monitoring of the surface temperature had been demonstrated for more than an hour.
Published Version
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