Method of forming tungsten pattern for a semiconductor device

Abstract

A capping film having a lower etch rate than a tungsten film is formed thereon and a photoresist layer is formed on the capping film. Preferably, the capping film is a titanium-based layer or an aluminum-based layer. After a photoresist pattern is formed by exposing and developing the photoresist film, the tungsten film is patterned by a dry etch method. During the etching of the tungsten film, the capping film reacts with the etching material to form a polymer which serves as a hard mask for the tungsten film. Preferably, the capping film also has a lower reflectivity at the exposing wavelength for the photoresist than the tungsten film, so the exposure of the photoresist may be controlled. Alternatively, or additionally, an anti-reflective film is provided between the capping film and the photoresist to further reduce the effect of the reflection of the tungsten film. Thus, patterning failures can be prevented. Such a method is particularly advantageous when the tungsten film pattern formed thereby is to be used as a bit line in a semiconductor device, particularly a pattern having a design rule of 0.34 .mu.m or less.

Dependencies are inferred from the claim text.