Title :
High-reliability tungsten-stacked via process with fully converted TiAl3 formation annealing
Author :
Shohji, Reijiroh ; Uda, Mitsuru ; Nakamura, Takashi ; Yoda, Tetsuya ; Itoh, Yoshitake
Author_Institution :
Semicond. Oper. Yasu, IBM Japan Ltd., Tokyo, Japan
fDate :
8/1/1999 12:00:00 AM
Abstract :
The tungsten-stacked via structure will be widely used in future generations of semiconductors to increase the density of aluminum wiring. One problem with this structure is that film separation is sometimes observed at the interface between the aluminum wiring and the oxide layer. This separation occurs only in the specific stacked via structure, and it carries a risk of a potential reliability of via open problem. Some experiments aimed at solving this separation problem revealed that the stress induced by insufficient TiAl3 formation during the heat cycle of metal annealing is strongly related to the film separation. The occurrence of the insufficient TiAl3 formation is highly dependent on the condition of the interface between the titanium and aluminum, and it is also dependent on the ambient gas used for the ramp-up step in the metal annealing process. If these processes are optimized properly the stress value of TiAl3 formation indicates the position of the maximum stress point during metal annealing. It was demonstrated that monitoring of the maximum stress point is one method for determining whether the TiAl3 is fully formed
Keywords :
aluminium alloys; annealing; metallisation; titanium alloys; tungsten; TiAl3; TiAl3 alloy; W; aluminum wiring; film separation; intermetallic compound formation; maximum stress point; metal annealing; oxide layer; reliability; semiconductor manufacturing; tungsten stacked via; Aluminum alloys; Annealing; Electromigration; Intermetallic; Optical films; Semiconductor films; Stress; Titanium; Tungsten; Wiring;
Journal_Title :
Semiconductor Manufacturing, IEEE Transactions on