High‐precision low‐cost quartz‐crystal thin‐film monitor with temperature control

摘要

An accurate thin‐film thickness monitor capable of a resolution of at least 0.01 nm is described. The errors arising from the temperature dependence of the crystal resonant frequency are minimized by heating a closely matched reference crystal until their temperatures are equalized; and by subtracting their frequencies of oscillations. These functions are performed by simple electronic devices.