Silicide Film Formation with a Diffusion Prevention Layer
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Solution Overview
Problem
Existing film forming methods for titanium silicide films on doped silicon wafers face challenges in preventing impurity diffusion, which can lead to increased contact resistance and impurity introduction.
Innovation Solution
A film forming method that includes forming a diffusion prevention layer containing an impurity on a doped silicon region, followed by the formation of a metal film and a metal silicide film through a reaction with the silicon, where the impurity-containing gas is supplied without being converted into a plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plasma process is used to form a titanium silicide film on a doped silicon region, then the film formation efficiency is improved, but impurity diffusion from the doped region to the film increases
Solution Approach 1:
A diffusion prevention layer is formed on the doped silicon region before forming the titanium silicide film. This preliminary action blocks impurity diffusion during subsequent plasma processing while allowing the titanium silicide film to be formed efficiently on top of the prevention layer.
Solution Approach 2:
The diffusion prevention layer acts as an intermediary between the doped silicon region and the titanium silicide film. It mediates the interaction by preventing direct contact between the plasma and the doped region, thereby stopping impurity diffusion while still enabling film formation through the intermediary layer.
2Device complexity
If conventional film formation methods are used, then the process is simple, but contact resistance increases due to impurity diffusion
Solution Approach 1:
The film formation process is segmented into distinct stages: first forming a diffusion prevention layer, then forming the titanium silicide film on top. This segmentation allows each layer to perform its specific function - the prevention layer blocks impurity diffusion while the titanium silicide film provides low contact resistance.
Solution Approach 2:
The structure uses composite materials with the diffusion prevention layer (containing silicon and impurity) combined with the titanium silicide film layer. This composite structure combines the impurity-blocking capability of the prevention layer with the low-resistance property of the titanium silicide film.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively prevents impurity diffusion from the doped region to the titanium silicide film, maintaining a high impurity concentration in the doped region and reducing contact resistance.
Implementation Method 1
supplying an impurity-containing gas that contains the impurity to the substrate without converting the impurity-containing gas into a plasma
Implementation Method 2
forming a metal silicide film by a reaction between the metal film and the silicon of the doped region
Data Source
AI summary
A film forming method includes: (a) preparing a substrate having a doped region, which contains silicon with an added impurity, formed on a surface; (b) forming a diffusion prevention layer, which contains the impurity, on the doped region; and (c) forming a metal film on the doped region where the diffusion prevention layer is formed, and forming a metal silicide film by a reaction between the metal film and the silicon of the doped region, wherein (b) includes supplying an impurity-containing gas that contains the impurity to the substrate without converting the impurity-containing gas into a plasma.