Method for passivating the sidewalls of a tungsten word line

Details Method for passivating the sidewalls of a tungsten word line Method for passivating the sidewalls of a tungsten word line

1995-12-22

1998-04-07

Quach, T. N.

Pipes and tubular conduits

Repairing

438596, 438653, 438655, 438656, H01L 21283, H01L 21336

Patent

active

057364559

ABSTRACT:
This invention embodies a process for passivating the edges of a tungsten metal layer within a word line stack. After the word line stack is patterned (i.e., formed by masking and etching the stack of globally-deposited layers) as shown in FIG. 1, a conformal silicon film is blanket deposited. Deposition of the silicon film may be accomplished by any available technique, such as chemical vapor deposition or plasma-enhanced chemical vapor deposition. The wafer is then heated so that the tungsten in contact with the silicon film is converted to tungsten silicide. In a preferred embodiment of the invention, only a portion of the silicon film is allowed to react with the edge of the tungsten layer. The remainder of the silicon film is converted to silicon dioxide by subjecting the wafer O.sub.2 in a furnace or rapid thermal processing chamber. Alternatively, the remainder of the silicon film may be converted to silicon dioxide by subjecting the wafer to O.sub.2 or O.sub.3 in a plasma reactor. In an alternative but equivalent embodiment of the process, the tungsten metal is converted to tungsten silicide and the remainder of the silicon film is converted to silicon dioxide using a single piece of equipment. This is done by first heating the wafer in a nitrogen-containing ambiance, and then ramping the temperature upward and replacing the nitrogen-containing ambiance with an oxidizing ambiance.

REFERENCES:
patent: 4716131 (1987-12-01), Okazawa et al.
patent: 5003375 (1991-03-01), Ichikawa
patent: 5227320 (1993-07-01), Johnson et al.
patent: 5341016 (1994-08-01), Prall et al.
patent: 5364803 (1994-11-01), Lur et al.
patent: 5600153 (1997-02-01), Manning

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