Catalyst-Assisted ALD of Silicon Films with In-Situ Cleaning
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Solution Overview
Problem
Existing low-temperature catalyst-assisted atomic layer deposition (ALD) methods for silicon-containing films like SiO2 and SiN suffer from high-temperature post-deposition processing requirements to remove impurities and defects, which can negate the benefits of low-temperature processing, especially for temperature-sensitive materials.
Innovation Solution
The method involves catalyst-assisted ALD with integrated in-situ reactive treatments that reduce or eliminate the need for high-temperature post-deposition processing by hydrogenating unreacted functional groups and removing carbon and chlorine impurities, using catalysts like furan and ethers for SiO2 and pyridine and tertiary amines for SiN, to form impurity-free silicon-containing films at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If low-temperature catalyst-assisted ALD is used to deposit silicon-containing films, then deposition temperature is reduced and thermal budget is conserved, but impurities (carbon and chlorine) are incorporated into the film requiring high-temperature post-deposition processing
Solution Approach 1:
The patent applies preliminary action by incorporating reactive treatment steps during the deposition process itself to remove impurities before they can be incorporated into the film. Chlorine-containing reactants are introduced during the deposition to react with and remove carbon impurities, and hydroxyl-containing reactants are introduced to remove chlorine impurities, thereby preventing impurity incorporation rather than requiring post-deposition correction
Solution Approach 2:
The patent converts the potentially harmful effect of residual surface functional groups and impurities into a benefit by using them as reactive sites for in-situ cleaning. The same surface groups that catalyze deposition also serve as sites for impurity removal through reactive treatments, transforming what would be a defect into a functional feature for self-cleaning during deposition
2Object-generated harmful factors
If high-temperature post-deposition processing is applied to remove impurities, then film purity is improved, but thermal budget is exceeded and temperature-sensitive materials are damaged
Solution Approach 1:
The patent merges the deposition process with the impurity removal process by integrating reactive treatment steps into the same deposition cycle. The cleaning reactions occur during the deposition sequence rather than as a separate post-deposition step, combining film formation and purification into a single integrated process that avoids high-temperature exposure
Solution Approach 2:
The patent changes the temporal and chemical parameters of impurity removal by performing cleaning reactions during deposition rather than after. Different reactants (chlorine-containing and hydroxyl-containing) are introduced at specific times during the deposition cycle to target different impurities, changing the process parameters to enable low-temperature in-situ cleaning
3Ease of manufacture
If conventional ALD is used without catalysts, then film deposition is achieved, but high substrate temperatures (>300°C) and large reactant exposures are required
Solution Approach 1:
The patent uses organic base catalysts (pyridine, tertiary amines, furan, ethers) as intermediaries that mediate between the reactants and the substrate surface. These catalysts lower the activation energy barrier for surface reactions, enabling deposition to proceed at room temperature or near room temperature instead of requiring high substrate temperatures
Solution Approach 2:
The patent changes the temperature parameter from high (>300°C) to low (room temperature or near room temperature) by introducing catalytic activity. The catalysts modify the reaction kinetics to proceed rapidly at low temperatures, fundamentally changing the thermal conditions required for deposition while maintaining ease of manufacture
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 deposition of high-quality silicon-containing films with reduced impurity levels, minimizing the need for high-temperature post-processing and maintaining the benefits of low-temperature ALD, thereby enhancing film properties and process efficiency.
Implementation Method 1
catalyst-assisted atomic layer deposition of silicon-containing films
Implementation Method 2
hydrogenating unreacted X-H functional groups and removing carbon and chlorine impurities from the substrate surface
Data Source
AI summary
A method is provided for low temperature catalyst-assisted atomic layer deposition of silicon-containing films such as SiO2 and SiN. The method includes exposing a substrate surface containing X—H functional groups to a first R1—X—R2 catalyst and a gas containing silicon and chlorine to form an X/silicon/chlorine complex on the surface, and forming a silicon-X layer terminated with the X—H functional groups by exposing the X/silicon/chlorine complex on the substrate surface to a second R1—X—R2 catalyst and a X—H functional group precursor. The method further includes one or more integrated in-situ reactive treatments that reduce or eliminate the need for undesired high-temperature post-deposition processing. One reactive treatment includes hydrogenating unreacted X—H functional groups and removing carbon and chlorine impurities from the substrate surface. Another reactive treatment saturates the silicon-X layer with additional X—H functional groups.