GB1115055A - Film deposition in an evacuated chamber - Google Patents

Abstract

<PICT:1115055/C6-C7/1> An adherent film is deposited on a substrate 20 connected as cathode from material supported by a filament 26 connected as anode by evacuating the apparatus at 28, introducing gas at 30 to give a pressure between 10 and 100 microns of mercury, applying a voltage between the anode and cathode to form a glow discharge 32 with a dark space 31 around the cathode thereby bombarding the substrate with positive ions of the gas, maintaining the glow discharge for a period of time to clean the substrate, and evaporating from the filament material to be deposited into a positive glow region of the glow discharge where atoms of the material are positively ionized and accelerated toward the substrate together with un-ionized thermal atoms of the material. A direct current voltage in excess of 1000 is employed. The material to be evaporated may be in the form of a winding, be in a boat or be in the form of stranded wire. Fig. 4 (not shown) illustrates apparatus where a substrate (52) is kept cold during deposition. The substrate may be metallic, a semi-conductor or an insulator. Where it is non-conductive a cathodic mesh grid (48) Fig. 3 (not shown) may be placed in front of it. The gas may be inert and may have some reactive gas mixed with it. Reactive gas combines with ions of evaporated material at the surface of the substrate to give a compound film on the surface. The gas may be A, He or A and O. Examples are of depositing Au, Al, Mo, Ta and W. Metals may be deposited on metals with which they are non-soluble, thus the following couples may be produced Ag-Fe, Cu-Mo, Ag-Ni, Ag-Mo, Au-Mo, Ni-Pb and Ag-W. Details are given for depositing (1) Al on Fe with prior cleaning in dilute nitric acid, (2) Au on Si, (3) Ti on high alumina ceramics, and (4) Al2O3 on Cu using a 10% O2-90% A gas mixture.