Gate electrode and froming method thereof

Abstract

A gate electrode which has a structure in which a tungsten silicide layer is formed on an amorphous silicon layer is disclosed. A gate insulation film is formed on a semiconductor substrate, an amorphous silicon layer is formed on the gate insulation film by using disilane gas, and a tungsten silicide layer is formed on the amorphous silicon layer containing trace amounts of foreign matter. The grain size of the amorphous silicon layer is such that the foreign matter cannot enter the gate insulation film.

Description

technical field [0001] The invention relates to a gate electrode of a transistor used in a semiconductor device, in particular to a gate electrode with a tungsten silicide structure laminated on amorphous silicon. Background technique [0002] Generally, a gate electrode of a MOS transistor is formed on a semiconductor substrate on which a gate insulating film is formed first, prior to a source electrode and a drain electrode. The gate electrode is formed of polysilicon, and in order to improve its performance, either it is replaced by amorphous polysilicon, or a tungsten silicide layer is stacked on the polysilicon. [0003] figure 2 This is a conventional example, and is a partial cross-sectional view of a semiconductor element having a structure in which tungsten silicide is laminated on a polysilicon layer. [0004] see figure 2 , the existing gate structure is to form a gate oxide film (SiO 2 ) 12, stacking a polysilicon layer 14 and a tungsten silicide layer 16 seq...

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Problems solved by technology

As a result, the thickness of the gate oxide film 12 increases, and the electrical characteristics of the gate oxide film 12 deteriorate significantly.

[0009] On the other hand, when tungsten silicide is formed on amorphous silicon, the grain size of the formed amorphous silicon is larger than that of polycrystalline silicon, but since the size of these grains is as small as 0.5 μm, fluorine atom penetration still occurs when forming tungsten silicide question

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