Hydrogen promoted copper migration in the high pressure anneal process

To meet the requirement of lower processing temperature in the high pressure anneal process (EPA), Cu films deposited by physical vapor deposition (PVD) with addition of hydrogen were investigated. Experimental results on the hole filling performance under high pressure, the grain growth, the micro-hardness measurement and the film stress measurement revealed that the hydrogen addition markedly changes the properties of the Cu film. It is especially effective in softening the PVD-Cu film and/or in promoting the Cu atom diffusion which also promotes grain growth. As a result the processing temperature may be lowered down to around 400 degreesC, which is the highest temperature allowable for the interconnection structures with organic low-k dielectric layers.