Sputter deposition of aluminum and other alloys at cryogenic temperatures

Structures of thin films deposited at ambient temperatures are similar to those of the bulk material whereas at lower temperatures films have significantly reduced grain size and may become amorphouslike. A two‐stage cryorefrigerator was installed in a sputtering system to allow thin films of aluminum and aluminum–copper alloy to be deposited onto substrates cooled to cryogenic temperatures less than 30 K. Gases used for sputtering were argon, neon, and helium at pressures ranging from 0.40 to 2.0 Pa. A standard planar magnetron cathode was used. Vapor pressure–temperature data for gases show that argon will not cryocondense on substrate surfaces at temperatures greater than 40 K and neon will not cryocondense at temperatures above 11 K. Helium is considered for sputtering at substrate temperatures below 11 K. The purpose of this work is to determine the deposition rates using argon, neon, and helium and microstructure changes occurring when thin films are deposited onto cryogenically cooled substrates. D...