VAPOR PHASE ETCHING AND POLISHING OF SEMICONDUCTORS

1,180,187. Etching. MOTOROLA Inc. 9 April, 1968 [8 May, 1967], No. 17008/68. Heading B6J. [Also in Divisions C7 and H1] Semi-conductor material, e.g. silicon or germanium, is etched or cleaned by contacting with a gaseous mixture of hydrogen and an interhalogen compound of fluorine while the temperature of the semi-conductor material is maintained above 100‹ C. The interhalogen may be C1F, C1F 3 , BrF, BrF 3 , BrF 5 , IF 5 or IF 7 and the concentration of the interhalogen in a gas stream passing over the Si or Ge should be between 0À01% and 2% by weight, the nitrogen content being below 50 p.p.m. by weight. The apparatus used (Fig. 1, not shown) is similar to that disclosed in Specification 1,047,942. This etch-cleaning process may be an intermediate step in the formation of various semi-conductor devices, the methods of formation being analogous to those which are also disclosed in the above-mentioned Specification. The semi-conductor material is etched non-preferentially, that is, all the crystal structures present are attached to give a smooth surface.