Aluminium sputter deposition onto polyimide-coated substrates

An aluminium deposition process onto PIQ (polyimide isoindroqui hazoline-dione: Hitachi Chemical)-coated substrates was developed for a continuous cassette-to-cassette sputtering machine. The baking process of the substrates in vacuum was studied for various film thicknesses and heating rates. PIQ releases water vapor upon heating in a vacuum and gives a maximum release rate at around 120 degrees C with a heating rate of 56 degrees C/min. PIQ was found to contain 0.5 wt% water vapor in a clean-room environment. PIQ-coated substrates were found to have a sufficiently stable and high emissivity, and the infrared thermometer was successfully applied. The double electromagnet sputtering cathode has been employed to ensure uniformity and long target life. Aluminium film characterization was done for the specularity, microstructure, and thermal stress.<>