Selective Thin-Film Growth on Semiconductor Substrates Without Film Damage
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Solution Overview
Problem
The challenge of forming vertically oriented fins in semiconductor devices with high accuracy is hindered by the inability of silicon nitride films to act as ideal masks during etching, leading to non-ideal shapes and increased aspect ratios, which complicates the processing of LSI circuits.
Innovation Solution
A method involving the removal of natural oxide films, followed by selective growth of silicon nitride films using inorganic materials and deposition gases, while employing a substrate processing apparatus with controlled gas supply systems to ensure precise film formation on specific layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If SiN film is used as a hard mask for etching, then the etching process can be performed, but the SiN film is etched on both upper and side surfaces leading to non-ideal vertical fin shapes
Solution Approach 1:
The patent segments the mask function into two separate materials: SiN film for protecting the channel region and oxide film for defining the fin pattern. This segmentation allows each material to perform its specific function optimally without the interference that causes non-ideal etching shapes when using SiN alone as mask.
Solution Approach 2:
The oxide film acts as an intermediary layer between the SiN film and the etching process. It provides the necessary mask properties for vertical etching while the SiN film continues to protect the channel region, thus mediating between the conflicting requirements of etching capability and shape accuracy.
2Ease of manufacture
If SiN film is used as hard mask, then etching can proceed, but the aspect ratio of fin increases making it difficult to process to predetermined depth
Solution Approach 1:
By dividing the mask function between SiN film and oxide film, the patent enables better control over etching parameters. The oxide film provides superior mask properties that allow achieving lower aspect ratios while maintaining etching processability, thus reducing fin complexity.
3Object-affected harmful factors
If natural oxide film is present on substrate, then substrate is protected, but it prevents selective growth of thin films on specific regions
Solution Approach 1:
The patent extracts and removes the natural oxide film from the substrate surface before performing selective film growth. This extraction eliminates the barrier that would prevent precise selective growth, while the damage to other films is minimized through controlled processing conditions.
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 approach allows for the selective growth of thin films on substrates, minimizing damage to other films and achieving the desired vertical fin structures with improved processing accuracy.
Implementation Method 1
a first oxide film is removed from a surface of a substrate by supplying a first inorganic material to a substrate
Implementation Method 2
a second oxide film is formed on a surface of the first film by supplying an oxidizing agent to the substrate
Implementation Method 3
modifying the second oxide film formed on a surface of the first film by supplying a second inorganic material to the substrate
Implementation Method 4
selectively growing a film on a surface of the second film by supplying a deposition gas to the substrate
Data Source
AI summary
Described herein is a technique capable of selectively forming a thin film on a substrate while suppressing damage to other films of the substrate. According to the technique, there is provided a substrate processing method including: (a) providing a substrate where a first oxide film is removed from a surface thereof by supplying a first inorganic material thereto so as to expose at least a first film containing silicon and a second film different from the first film on the surface of the substrate and a second oxide film is formed on a surface of the first film by supplying an oxidizing agent to the substrate, and modifying the second oxide film formed on the surface of the first film by supplying a second inorganic material to the substrate; and (b) selectively growing a film on a surface of the second film by supplying a deposition gas to the substrate.