Substrate Recess Silicide Formation Without Sidewall Deposition
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Solution Overview
Problem
Existing substrate processing methods struggle to selectively form a metal silicide film at the bottom of a recess in a substrate while preventing its formation on the side walls, especially in high aspect ratio structures.
Innovation Solution
A substrate processing method involving the preparation of a substrate with an epitaxial layer and an insulating film having a penetration portion, followed by forming a silicon film on the exposed epitaxial layer and a metal film on the silicon film, allowing the silicon film to react with the metal film to form a metal silicide film, while selectively etching the amorphous silicon film from the side walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal film is formed on the entire substrate surface, then metal silicide film can be formed, but it forms on both the bottom and side walls of the recess instead of selectively at the bottom
Solution Approach 1:
An amorphous silicon film is formed on the side walls of the recess before forming the metal film. This preliminary action creates a protective layer that prevents metal silicide formation on the side walls, allowing selective metal silicide film formation only at the bottom of the recess where the epitaxial layer is exposed
Solution Approach 2:
The amorphous silicon film acts as an intermediary layer between the metal film and the side wall surface. It selectively reacts with or protects the side walls, preventing direct reaction between the metal film and the crystalline silicon on side walls, thus enabling selective metal silicide formation at the recess bottom
2Manufacturing precision
If the recess has a high aspect ratio, then the device structure is more advanced, but it becomes difficult to control film thickness and prevent metal silicide formation on side walls
Solution Approach 1:
The amorphous silicon film is formed with different thickness characteristics on different surfaces - it conformally coats the side walls at a thickness that provides sufficient protection, while at the bottom of the recess where the epitaxial layer is exposed, the metal film can directly react to form metal silicide. This local differentiation enables precise control despite high aspect ratio
3Manufacturing precision
If conventional methods are used to form metal silicide film, then the process is simple, but the film thickness cannot be increased and selectivity cannot be improved
Solution Approach 1:
The process is segmented into distinct steps: first forming an amorphous silicon film on the side walls, then forming a metal film, and finally performing a reaction treatment. This segmentation allows independent optimization of each step - the amorphous silicon film thickness can be controlled separately from the metal silicide film thickness, enabling precise control of final film properties
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 enables the selective formation of a metal silicide film at the bottom of a recess with increased thickness, while preventing its formation on the top surface of the insulating film and the side walls, thus improving the aspect ratio and film thickness control.
Implementation Method 1
causing the silicon film to react with the metal film to form a metal silicide film
Implementation Method 2
a base having an epitaxial layer formed by epitaxial growth
Data Source
AI summary
A substrate processing method includes: preparing a substrate which includes a base having an epitaxial layer formed by epitaxial growth, and an insulating film formed on the base and having a penetration portion that exposes the epitaxial layer; forming a silicon film on a surface of the epitaxial layer exposed from the penetration portion rather than a side wall of the penetration portion; and forming a metal film on the silicon film formed on the surface of the epitaxial layer rather than the side wall of the penetration portion, and causing the silicon film to react with the metal film to form a metal silicide film.