Abstract: Conventional methods of etching TiSix use Cl2 or HBr as the plasma etchant. However, these methods can lead to undesirable residues, due to the presence of silicon nodules in the TiSix The present invention overcomes the residue problem by adding a fluorine containing gas to the plasma etchant, which is then able to effectively etch the Si nodules at an etch rate which is approximately the same as the etch rate of the TiSix, so that the undesirable residue is not formed. A method of etching TiSix is provided, wherein the surface of the TiSix is exposed, typically through a patterned mask, to a plasma etchant. The plasma etchant comprises (i) at least one fluorine containing gas, such as SF6, NF3, CxFy, and compatible mixtures of such gases; and (ii) a gas selected from the group consisting of HBr, Cl2, and combinations thereof.

Abstract: A method for dry-etching a silicon substrate by the use of a mask selectively formed on the silicon substrate, in which method a reaction product of dry etching is deposited, during dry etching, in a uniform thickness on the side wall of each groove formed in the silicon substrate by dry etching. In the inventive method, etching is conducted by using, as an etching gas, a mixed gas containing Cl.sub.2, HBr, O.sub.2 and He or a mixed gas contained Cl.sub.2, HBr and CO, under the conditions of an etching pressure of 0.02-0.05 Torr, a RF power density of 1.01-1.64 W/cm.sup.2 and a substrate temperature of 40-50.degree. C. With this method, the tapered sectional shape of each groove formed in the silicon substrate can be controlled easily and etching can be conducted at high reproducibility.