Cathodic sputtering method - with intermittent reverse polarity of electrodes to suppress overloading of plasma with reactive products

摘要

In the appts. to prevent excess production of reactive products in the plasma during a cathodic sputtering process, the anode and cathode are intermittently switched round using a switch (35, 56). The switch may be a thyristor (56) and the frequency of changing the polarity is determined by the amt. of reactive product in the plasma. The main DC power supply (40) is connected via an inductor (54) to the cathode. A capacitor (55) is connected in parallel with the conductor (54) and an inductor (51) is connected in parallel to the lead from the source to the anode. The vacuum chamber is earthed and made of electrical conductive material. A reactive and a neutral gas are fed into the chamber from supplies (16,17). USE/ADVANTAGE - Appts. is used in spatter etching and coating processes. By avoiding overloading the plasma with reactive products and thereby preventing excess coating with these products, abnormal and dangerous electric discharge (arcing) is avoided. Also quality problems such as pinholes in the coating are avoided.