Method for preparing self-aligning silicide of metal oxide semiconductor

Abstract

The invention provides a method for preparing a self-aligned silicide of a metal-oxide-semiconductor (MOS) transistor. In the invention, an ion implantation step is performed before the metal-oxide-semiconductor transistor is subjected to self-aligned silicide treatment, and the implanted Ions (such as: fluorine, chlorine, bromine, iodine, boron and boron difluoride) will first react with the silicon substrate and the surface of the gate, and produce a barrier effect (barrier efreet) in the silicidation process, which can prevent cobalt metal or It is cobalt silicide that infiltrates into the gate or source / drain region to produce a spike phenomenon, which avoids causing junction leakage or reducing the breakdown voltage of the metal oxide semiconductor transistor.

Description

technical field [0001] The invention relates to a method for preparing a self-aligned silicide of a metal-oxide-semiconductor transistor, in particular to a cobalt silicide (CoSi 2 ) preparation method. Background technique [0002] With the increase of semiconductor element integration (integrity), in order to avoid the leakage junction (Leaky Junction) between the gate and the source / drain, a self-aligned silicide (self-aligned silicification, also known as salicification) is In the semiconductor process, a silicide layer is formed on the surface of the source / drain region and the gate region by silicide treatment to avoid leakage current. [0003] The most common material commonly used to prepare the silicide layer is titanium (Ti) metal, and its preparation process is as follows Figures 1(a) to 1(d) shown. First, a silicon substrate 101 with metal oxide semiconductor transistors is provided, as shown in FIG. 1( a ). The metal-oxide-semiconductor transistor includes a...

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Problems solved by technology

Third, because cobalt-silicon is closer to the mid-bandgap level than titanium-silicon, cobalt metal or cobalt silicide will penetrate into the interior of the silicon substrate during the silicidation reaction to generate a spike. Phenomenon, in the shallow junction (shallow junction) structure is easy to cause junction leakage current and breakdown voltage drop, therefore, the preparation method of cobalt silicide is also more complicated than the preparation method of titanium silicide

However, the above methods still cannot avoid the formation of cobalt titanide and cobalt silicide spike phenomenon

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