ALD Mixed Film Composition Control via Adsorption Suppression
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Solution Overview
Problem
Existing film-forming methods using atomic layer deposition (ALD) struggle to regulate film composition without affecting film thickness and composition uniformity when forming mixed films of two or more compounds, leading to issues with concentration uniformity and increased film thickness due to uncontrollable adsorption of raw material gases.
Innovation Solution
A film-forming method where a first film is formed by alternately supplying a first raw material gas and an oxidizing gas, followed by a second film formed by adsorbing the first raw material gas to suppress the adsorption of the second raw material gas, allowing for precise control of film composition without increasing film thickness or compromising uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conventional ALD method of alternately forming each compound film is used, then a mixed film can be formed, but the film composition cannot be precisely regulated without affecting film thickness and composition uniformity
Solution Approach 1:
The film formation process is segmented into distinct cycles where each cycle forms a unit film with controlled composition. By dividing the mixed film formation into multiple unit film formations with different raw material gas supply ratios, precise composition regulation is achieved while maintaining overall uniformity through the systematic repetition of these segmented cycles.
Solution Approach 2:
The raw material gas supply ratios and process parameters are changed between different unit film formation cycles to achieve desired composition gradients. By systematically varying parameters such as gas flow rates, temperature, and pressure across different cycles, precise composition control is realized without compromising film thickness uniformity.
2Length of stationary object
If the number of ALD cycles is increased to regulate film thickness, then the desired thickness can be achieved, but the concentration uniformity of elements in the mixed film deteriorates
Solution Approach 1:
Preliminary actions are taken within each ALD cycle to ensure complete adsorption and reaction before proceeding to the next cycle. By充分 supplying raw material gases and reaction gases within each cycle and ensuring complete surface coverage before advancing, the method maintains concentration uniformity even when multiple cycles are performed to achieve the desired film thickness.
Solution Approach 2:
The ALD process maintains continuous useful action through optimized cycle design where each cycle completes the full adsorption-reaction sequence without interruption. This continuity ensures that element concentration remains uniform throughout the film thickness as each cycle contributes equally to the overall film structure.
3Quantity of substance
If raw material gas supply is increased to achieve desired composition, then the composition ratio can be adjusted, but the film thickness increases uncontrollably
Solution Approach 1:
The raw material gas supply is applied periodically in controlled cycles rather than continuously. By supplying raw material gases for specific durations within each cycle and then pausing for reaction and purge phases, the method achieves precise composition ratios while controlling the total film thickness through the number and duration of cycles.
Solution Approach 2:
The gas supply system operates dynamically with adjustable flow rates, pulse durations, and cycle frequencies. This dynamic control allows real-time adjustment of composition ratios independent of film thickness, as the system can vary gas supply parameters within each cycle without directly proportionally increasing the deposited film thickness.
4Area of stationary object
If the adsorption of raw material gas is enhanced to improve film coverage, then the film coverage is improved, but the concentration uniformity of elements deteriorates
Solution Approach 1:
Preliminary anti-action is applied by controlling the adsorption phase to achieve complete surface coverage while preventing excessive adsorption that would lead to non-uniform concentration. By carefully limiting the adsorption time and gas flow rate to achieve monolayer coverage without over-adsorption, the method maintains both complete film coverage and uniform element concentration.
Solution Approach 2:
The mechanical adsorption process is replaced and controlled through chemical reaction mechanisms where raw material gases react specifically with surface sites. This chemical substitution ensures uniform distribution of elements as the reaction proceeds uniformly across the substrate surface, maintaining both complete coverage and concentration uniformity.
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 formation of mixed films with a desired composition and thickness, reducing the concentration of specific elements to extremely low levels without non-uniformity, using ALD to regulate the adsorption of raw materials effectively.
Implementation Method 1
supplying the first raw material gas to the substrate and causing the first raw material gas to be adsorbed on the substrate to suppress the adsorption of the second raw material gas
Implementation Method 2
forming a first film containing a first element on a substrate by performing an operation of forming a unit film on the substrate a plurality of times, the operation including a sub-step of supplying a first raw material gas containing the first element to the substrate and causing the first raw material gas to be adsorbed on the substrate and a sub-step of supplying a first reaction gas to the substrate and causing the first reaction gas to react with the first raw material gas
Data Source
AI summary
A film-forming method includes: forming a first film by performing an operation of forming a unit film a plurality of times, the operation including sub-step of supplying a first raw material gas containing a first element to a substrate and causing the first raw material gas to be adsorbed thereon, and sub-step of supplying a first reaction gas to the substrate; and forming a second film on the substrate by performing an operation of forming a unit film at least once, the operation including sub-step of supplying a second raw material gas containing a second element to the substrate and causing the second raw material gas to be adsorbed thereon, and sub-step of supplying a second reaction gas to the substrate, wherein a mixed film is formed by performing the forming the first film and the forming the second film, respectively once, or a plurality of times.