Substrate Processing Selective Etching Water Removal
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Solution Overview
Problem
Existing substrate processing methods face challenges in achieving a high selectivity ratio during selective etching of silicon nitride films, particularly due to the inhibitory effect of adsorbed water on the formation of protective films, leading to reduced etching selectivity and excessive etching of oxide films.
Innovation Solution
A substrate processing method that involves a water removing step to eliminate adsorbed water, followed by a silylating step to form a protective film on the oxide surface, and then an etching step using a silylated substrate with an etching agent like hydrofluoric acid vapor, enhancing the selectivity ratio of nitride film removal over oxide film removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silylating agent is supplied to form a protective film on the oxide film, then the protective film formation is enhanced, but water on the substrate surface reacts with the silylating agent with priority, inhibiting protective film formation
Solution Approach 1:
The patent applies preliminary action by performing a water removing step before the silylating step. The water removing unit eliminates adsorbed water from the substrate surface prior to silylation, ensuring that the silylating agent can react with the oxide film without competition from water molecules. This preliminary removal of harmful water prevents the inhibition of protective film formation and enables reliable silylation even on hygroscopic oxide films.
2Productivity
If selective etching is performed on a substrate with adsorbed water, then the etching process can proceed, but the selectivity ratio (nitride film removal amount/oxide film removal amount) is reduced due to inhibited protective film formation
Solution Approach 1:
The patent applies preliminary action by removing water before etching to enable proper protective film formation. The water removing unit operates prior to the etching step, eliminating adsorbed water that would otherwise prevent effective silylation. This ensures that when the etching agent is supplied, the protective film is already in place on the oxide film, allowing high selectivity ratio etching to proceed efficiently.
3Device complexity
If the silylating step is performed before water removal, then the process sequence is simplified, but the silylating agent reacts with water instead of the oxide film, preventing protective film formation
Solution Approach 1:
The patent applies preliminary action by reordering the process sequence to perform water removal before silylation. The water removing unit eliminates adsorbed water from the substrate surface prior to introducing the silylating agent. This ensures that the silylating agent reacts with the oxide film to form the protective film, rather than being consumed by reaction with water. The patent explicitly states that performing silylation before water removal would cause the silylating agent to react with water with priority, inhibiting protective film formation.
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 significantly improves the selectivity ratio of nitride film etching by preventing the reaction of the silylating agent with water, allowing for efficient protective film formation and selective etching of nitride films, even with hygroscopic oxide films, thereby increasing the nitride film removal efficiency while minimizing oxide film loss.
Implementation Method 1
a silylating step of supplying a silylating agent to the substrate after the water removing step... The silyl group of the silylating agent is thereby made to react with the oxide film exposed on the substrate and form the protective film that covers the oxide film
Implementation Method 2
an etching step of supplying an etching agent to the substrate after the silylating step... By performing etching in this state, selective etching of the nitride film on the substrate can be performed with high selectivity
Implementation Method 3
a water removing step of removing water from a substrate... By the water removing step, a protective film that protects the oxide film is formed more readily in the silylating step
Data Source
AI summary
A substrate processing method includes a water removing step of removing water from a substrate, a silylating step of supplying a silylating agent to the substrate after the water removing step, and an etching step of supplying an etching agent to the substrate after the silylating step. The substrate may have a surface on which a nitride film and an oxide film are exposed and in this case, the etching step may be a selective etching step of selectively etching the nitride film by the etching agent. The etching agent may be supplied in a form of a vapor having an etching component.