Film-thickness resistance monitor for dynamic control of vacuum-deposited films

Abstract

A simple, inexpensive film-thickness monitor has been developed which accurately and independently determines the thickness of a film at any time during a deposition process. The principle of operation is the change in resistance of a vacuum-deposited film on a polished sapphire substrate maintained at a constant deposition temperature. The device, which is easily calibrated and automated, was found to have routine application to many types of metal film depositions in production and the development laboratory. The relationship between film deposition thickness and measured conductance was found to be linear for metal films over a wide range of thickness at constant substrate temperatures, from room temperature to 600 °C. Data is presented which compares film thickness, as measured by interferometric and differential weighing techniques, with that predicted from resistance measurements. The monitor has been used for following changes in resistance during in situ, reactive, and air-exposed hydriding and for resistivity determinations of occluder film hydrides of erbium, scandium, and titanium.

Preparation and characterization of radioactive samples for various areas of research

“…Change in resistance of thin films has been used satisfactorily to determine film thicknesses of titanium up to 1.0 mg/cm 2 . 12 In addition, it is hoped that the electrical resistance can be used during tritium sorption into the titanium layer to monitor this process as well.…”

“…It has been shown that I the conductance of the titanium-hydrogen layer passes through a minimum value and then steadily increases until saturation is achieved. 12 The uniformity of the tritium content over the active area will be measured using a small ion chamber detector.…”