Chemical vapor deposition of titanium from titanium tetrachloride and hydrocarbon reactants

Abstract

A new process for depositing titanium metal layers via chemical vapor deposition is disclosed. The process provides deposited titanium layers having a high degree of conformality, even in trenches and contact openings having aspect ratios greater than 1:5. The reaction gases for the improved process are titanium tetrachloride and a hydrocarbon gas, which for a preferred embodiment of the process is methane. The reaction is carried out in a plasma environment created by a radio frequency source greater than 10 KHz. The key to obtaining titanium metal as a reaction product, rather than titanium carbide, is to set the plasma sustaining electrical power within a range that will remove just one hydrogen atom from each molecule of the hydrocarbon gas. In a preferred embodiment of the process, highly reactive methyl radicals (CH3—) are formed from methane gas. These radicals attack the titanium-chlorine bonds of the tetrachloride molecule and form chloromethane, which is evacuated from the chamber as it is formed. Titanium metal deposits an a wafer or other substrate that has been heated to a temperature within a preferred range of 200-500° C.

Dependencies are inferred from the claim text.