Substrate Etching Uniformity via Oxygen-Saturated Alkaline Solution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The in-plane uniformity of the etching amount from the center to the peripheral portion of a substrate, such as a semiconductor wafer, is not sufficient in existing substrate processing methods.
Innovation Solution
A substrate processing method and apparatus that includes low temperature dissolving processing to dissolve oxygen in an alkaline aqueous solution cooled below room temperature, followed by etching processing using the oxygen-saturated solution, with optional oxide film removing and temperature raising processes to enhance uniformity. The method uses alkaline solutions like TMAH, KOH, or ammonia, and is performed under an oxygen atmosphere with a heater in the supply line to maintain oxygen saturation and improve etching uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processing is performed without oxygen dissolution, then the process is simple, but the in-plane uniformity of etching amount is insufficient
Solution Approach 1:
Oxygen is dissolved in the alkaline aqueous solution before the etching processing begins. This preliminary action ensures that oxygen is already present in the solution at the start of etching, enabling uniform oxidation of the polysilicon layer across the entire substrate surface, including peripheral regions, thereby achieving uniform etching throughout the in-plane area.
Solution Approach 2:
The temperature of the alkaline aqueous solution is lowered to enhance oxygen dissolution. By changing the temperature parameter to a lower value before etching, the solubility of oxygen in the solution increases, ensuring sufficient oxygen concentration for uniform etching across the substrate, particularly at the peripheral portions where oxygen depletion would otherwise occur.
2Manufacturing precision
If oxygen is dissolved in the alkaline aqueous solution, then etching uniformity improves, but additional processing steps are required
Solution Approach 1:
Oxygen dissolution is performed as a preliminary step before etching, allowing the solution to become saturated with oxygen in advance. This ensures that when etching begins, sufficient oxygen is already available throughout the solution, enabling uniform etching across the entire substrate without requiring extended etching time to compensate for oxygen depletion.
Solution Approach 2:
Lowering the solution temperature increases oxygen solubility, allowing more oxygen to dissolve in a given time. This parameter change enables faster oxygen saturation of the solution, reducing the time required for the oxygen dissolution step while ensuring sufficient oxygen availability for uniform etching.
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 significantly improves the in-plane uniformity of the etching amount across the substrate, ensuring consistent etching from the center to the peripheral regions by maintaining oxygen saturation and optimizing the etching process conditions.
Implementation Method 1
a low temperature dissolving processing for dissolving oxygen in an alkaline aqueous solution cooled to a predetermined temperature lower than a room temperature
Implementation Method 2
an etching processing for etching a substrate by supplying the alkaline aqueous solution in which oxygen is dissolved to the substrate
Data Source
AI summary
The substrate processing method according to an exemplary embodiment includes a low temperature dissolving processing and an etching processing. The low temperature dissolving processing dissolves oxygen in an alkaline aqueous solution cooled to a predetermined temperature lower than the room temperature. The etching processing etches a substrate by supplying the alkaline aqueous solution in which oxygen is dissolved to the substrate.