Thermal Oxide Film Thickness Control Through OH-Guided Drying
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Solution Overview
Problem
Forming a uniformly thin thermal oxide film on semiconductor substrates with good reproducibility is challenging due to variations in natural or chemical oxide films, and adjusting cleaning solutions affects detergency, making it difficult to control thermal oxide film thickness accurately.
Innovation Solution
A method involving correlation acquisition steps to determine optimal drying and thermal oxidation conditions based on OH group amounts and drying conditions, allowing for the formation of thermal oxide films with intended thin thickness without changing the cleaning chemical solution composition, ensuring high reproducibility and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the composition of the cleaning chemical solution is changed to adjust the amount of OH groups, then the thickness of the thermal oxide film can be controlled, but the detergency varies and cannot be maintained at a constant level
Solution Approach 1:
The invention changes the drying conditions (temperature, time, atmosphere) as parameters instead of changing the cleaning chemical solution composition. This allows control of OH group amounts in the chemical oxide film while maintaining constant cleaning solution composition and thus constant detergency. The drying step transforms the cleaning process from chemical composition adjustment to physical condition adjustment.
Solution Approach 2:
The invention performs a drying step immediately after cleaning and before thermal oxidation. This preliminary drying action controls the OH group content in the chemical oxide film formed during cleaning, which in turn controls the subsequent thermal oxide film thickness. By acting preliminarily on the substrate surface, the method avoids the need to change cleaning solution composition.
2Manufacturing precision
If different cleaning methods are used, then the thickness of the thermal oxide film changes, but the reproducibility and uniformity of the thermal oxide film cannot be ensured
Solution Approach 1:
The invention establishes a correlation between drying conditions and thermal oxide film thickness through systematic experimentation. This correlation serves as a feedback mechanism that allows prediction and control of thermal oxide film thickness based on drying conditions, enabling reproducible results without trial-and-error evaluation of each substrate.
Solution Approach 2:
The invention replaces the chemical control mechanism (changing cleaning solution composition) with a physical control mechanism (controlling drying conditions). This substitution makes the process more controllable and reproducible because drying conditions can be precisely controlled and measured, unlike chemical composition changes that affect multiple parameters simultaneously.
3Manufacturing precision
If the amount of OH groups in the chemical oxide film is increased to increase thermal oxide film thickness, then the film thickness can be controlled, but the cleaning solution composition must be changed which affects detergency
Solution Approach 1:
The invention segments the cleaning process into two independent steps: cleaning (with fixed solution composition) and drying (with controllable conditions). This segmentation allows the OH group content to be controlled in the drying step without affecting the cleaning step's detergency, simplifying the overall manufacturing process.
Solution Approach 2:
The drying step acts as an intermediary between cleaning and thermal oxidation. It controls the OH group content in the chemical oxide film without requiring changes to the cleaning solution, thus mediating the relationship between cleaning and oxidation while maintaining constant cleaning 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 method enables the easy and stable formation of thermal oxide films with constant thickness, improving reproducibility and accuracy, and maintaining detergency, suitable for producing high-quality semiconductor devices with uniformity and improved yield.
Implementation Method 1
a chemical oxide film (an oxide film formed by cleaning the semiconductor substrate with a cleaning solution)
Implementation Method 2
forming a thermal oxide film by thermal oxidation treatment
Implementation Method 3
thermal oxidation treatment under the same condition to a plurality of semiconductor substrates
Implementation Method 4
acquiring a correlation between an amount of OH groups in a chemical oxide film and drying conditions by forming chemical oxide film under the same cleaning condition followed by changed drying conditions
Data Source
AI summary
The present invention provides a method for forming a thermal oxide film, comprising the steps of: a step of acquiring a first correlation between an amount of OH groups and thickness of the thermal oxide film by forming a thermal oxide film by thermal oxidation treatment under the same condition after preparing a plurality of semiconductor substrates having chemical oxide films formed by cleaning and having different amounts of OH groups; a step of acquiring a second correlation between an amount of OH groups and drying conditions by cleaning under the same cleaning condition followed by changed drying conditions to substrates and measuring amounts of OH groups; a step of acquiring a third correlation between drying condition and thickness of thermal oxide film by using the first correlation and the second correlation; a step of determining drying condition and thermal oxidation condition by using the third correlation; a step of cleaning the substrates; and a step of drying and a thermal oxide film formation after the cleaning step using the drying conditions and thermal oxidation treatment conditions determined in the drying and thermal oxidation treatment condition determination step. This provides a method for forming thermal oxide film in which a thermal oxide film can be formed with intended thickness with good reproducibility while without changing the composition of the cleaning chemical solution.