Selective SiN Film Growth on Semiconductor Substrates Without Film Damage
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Solution Overview
Problem
In the miniaturization of LSI circuits, it is challenging to achieve high processing accuracy for fins in field effect transistors (FETs) using silicon nitride (SiN) films as hard masks, due to etching issues that result in non-ideal vertical shapes and increased aspect ratios.
Innovation Solution
A method involving the sequential steps of removing natural oxide films, forming oxide films, modifying surfaces, and selectively growing thin films on substrates, utilizing inorganic materials and gases like DHF, SC1 liquid, ClF3, SiCl4, and NH3 to control film growth and prevent damage to unintended surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If SiN film is used as hard mask for fin processing, then the fin can be formed with controlled current path, but the SiN film is etched on side surfaces resulting in non-vertical fin shapes
Solution Approach 1:
The patent applies preliminary action by forming a protective oxide film on the SiN film surface before the etching process. This oxide film is formed through exposure to oxygen plasma or thermal oxidation, creating a protective layer that prevents side surface etching during subsequent processing steps, thereby maintaining fin verticality
Solution Approach 2:
The patent introduces an intermediary oxide film between the SiN hard mask and the etching environment. This oxide film acts as a mediator that protects the SiN film from direct etching attack on side surfaces, allowing vertical fin formation while maintaining the masking function of the SiN layer
2Manufacturing precision
If SiN film is used as hard mask, then fin formation is enabled, but the aspect ratio increases making it difficult to process fin to predetermined depth
Solution Approach 1:
The patent forms a protective oxide film on the SiN film before etching, which prevents material loss during processing. This preliminary protection allows for more aggressive etching conditions that can achieve greater depths while maintaining better aspect ratio control
Solution Approach 2:
The patent changes the physical and chemical parameters of the SiN film surface by oxidizing it, which modifies the etching characteristics. The oxidized surface has different etch resistance properties that enable better depth control and reduced aspect ratio
3Object-affected harmful factors
If natural oxide film is present on substrate, then other films are protected, but selective film growth is prevented
Solution Approach 1:
The patent removes the natural oxide film from the substrate surface using HF-based cleaning solutions before forming new films. This extraction of the natural oxide layer enables precise control over where films grow, allowing selective epitaxial growth only on intended regions
Solution Approach 2:
The patent performs preliminary oxide removal and surface preparation before film formation. By removing natural oxide and creating a clean, controlled surface state, the substrate is prepared to receive films only in specific locations, enabling selective growth while protecting other areas
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 growth of thin films, such as SiN films, on specific surfaces while preventing damage to other films, thereby improving the accuracy and aspect ratio of fin structures in semiconductor devices.
Implementation Method 1
removing a natural oxide film from a surface of a substrate by supplying a first inorganic material to the substrate
Implementation Method 2
forming an oxide film by oxidizing a surface of the first film by supplying an oxidizing agent to the substrate
Implementation Method 3
modifying the surface of the first film by supplying a second inorganic material to the substrate
Implementation Method 4
selectively growing a thin 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 method of manufacturing a semiconductor device, including: (a) removing a natural oxide film from a surface of a substrate by supplying a first inorganic material to the substrate wherein a first film and a second film different from the first film are exposed on the surface of the substrate; (b) forming an oxide film by oxidizing a surface of the first film by supplying an oxidizing agent to the substrate; (c) modifying the surface of the first film by supplying a second inorganic material to the substrate; and (d) selectively growing a thin film on a surface of the second film by supplying a deposition gas to the substrate, wherein (a) through (d) are sequentially performed.