Title :
Corrosion of tungsten due to plasma charging in a metal plasma etcher
Author :
Bothra, S. ; Sur, H. ; Liang, V. ; Annapragada, R. ; Patel, J.
Author_Institution :
VLSI Technol. Inc., San Jose, CA, USA
Abstract :
Accelerated corrosion of tungsten in tungsten-plug vias was observed due to charging of certain test structures during metal etch in a plasma etcher. This charge is shown to be a positive charge and is responsible for the accelerated dissolution of tungsten during subsequent wet solvent strip processes. It is shown that this phenomenon can be avoided by passivating the tungsten in a low pH solution, such as dilute nitric acid, and by using an electron beam to discharge the metal structures, prior to immersing the wafers in a polymer strip solvent
Keywords :
corrosion; dissolving; electron beam applications; failure analysis; integrated circuit interconnections; integrated circuit metallisation; integrated circuit testing; integrated circuit yield; passivation; plasma materials processing; sputter etching; surface charging; tungsten; HNO3; W; accelerated W dissolution; accelerated corrosion; dilute nitric acid passivation; electron beam metal structure discharge; low pH passivation solution; metal etch; metal plasma etcher; passivation; plasma charging; plasma etcher; polymer strip solvent; positive charge; test structure charging; tungsten corrosion; tungsten-plug vias; wafer polymer strip solvent immersion; wet solvent strip processes; Acceleration; Corrosion; Etching; Life estimation; Plasma accelerators; Plasma applications; Solvents; Strips; Testing; Tungsten;
Conference_Titel :
Plasma Process-Induced Damage, 1998 3rd International Symposium on
Conference_Location :
Honolulu, HI
Print_ISBN :
0-9651577-2-5
DOI :
10.1109/PPID.1998.725615
