Phosphoric Acid Replenishment Control for Etching Selectivity
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Solution Overview
Problem
Existing substrate processing methods for semiconductor and liquid crystal display manufacturing struggle to maintain the silicon concentration of phosphoric acid aqueous solutions within a specified range, leading to inefficiencies in etching selectivity between silicon nitride and silicon oxide films, as they cannot intentionally control the replenishment timing and amount of phosphoric acid solutions.
Innovation Solution
A substrate processing method and apparatus that include a phosphoric acid tank, a recovery unit, and a replenishing unit, where the silicon concentration of the phosphoric acid aqueous solution is monitored and adjusted by recovering and replenishing the solution based on detected concentration levels, allowing for intentional control of the liquid amount and silicon concentration to maintain stability during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the phosphoric acid aqueous solution is continuously replenished to maintain constant total amount in the tanks, then the liquid amount is maintained, but the silicon concentration cannot be controlled within the specified range leading to unstable etching selectivity
Solution Approach 1:
The system implements feedback control by detecting the silicon concentration of the phosphoric acid aqueous solution and automatically adjusting the replenishment amount and timing. The detection unit measures the silicon concentration, and when it deviates from the specified range, the control unit adjusts the replenishment quantity to maintain the concentration within the required range, ensuring stable etching selectivity.
Solution Approach 2:
The invention changes the replenishment parameters (amount and timing) based on the detected silicon concentration. Instead of fixed replenishment, the system dynamically adjusts the replenishment quantity to maintain silicon concentration within the specified range, thereby controlling etching selectivity stability while managing the quantity of phosphoric acid solution.
2Stability of the object's composition
If fresh phosphoric acid aqueous solution is supplied to maintain constant total amount, then the liquid level is stabilized, but the replenishment timing and amount cannot be intentionally controlled
Solution Approach 1:
The control unit uses feedback from the detection unit to determine the optimal replenishment timing and amount. The system monitors the silicon concentration and liquid amount, then intentionally controls the replenishment parameters to maintain liquid level stability while providing operational flexibility for concentration management.
Solution Approach 2:
The replenishment system transitions from static fixed-amount replenishment to dynamic adjustable replenishment. The control unit can intentionally adjust the replenishment timing and quantity based on real-time detection data, enabling flexible control while maintaining liquid amount stability through adaptive parameter changes.
3Loss of substance
If the phosphoric acid aqueous solution is recovered and reused, then the liquid amount is conserved, but the silicon concentration increases beyond the specified range affecting etching performance
Solution Approach 1:
The system implements selective recovering and discarding based on silicon concentration. The phosphoric acid aqueous solution is recovered and reused when silicon concentration is within the specified range, conserving the liquid. When concentration exceeds the range, the system adjusts replenishment to dilute and restore the concentration, balancing resource conservation with performance requirements.
Solution Approach 2:
The invention changes the silicon concentration parameter of the phosphoric acid solution through controlled replenishment. By adjusting the amount of fresh solution added to the recovered solution, the system restores the silicon concentration to the specified range, enabling continued reuse of the phosphoric acid solution while maintaining etching performance.
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 stabilizes the silicon concentration of the phosphoric acid solution, enabling precise control over etching selectivity and reducing the frequency of solution replacement, thereby improving processing efficiency and reducing costs.
Implementation Method 1
silicon concentration of the phosphoric acid aqueous solution increases due to dissolving of silicon
Implementation Method 2
a spin chuck that rotates a substrate while holding it horizontally
Data Source
AI summary
When a silicon concentration of a phosphoric acid aqueous solution inside a tank reaches an upper limit value of a specified concentration range, the phosphoric acid aqueous solution is drawn off from the tank and/or an amount of the phosphoric acid aqueous solution returning to the tank is decreased to decrease a liquid amount inside the tank to a value not more than a lower limit value of a specified liquid amount range. When the liquid amount inside the tank decreases to the value not more than the lower limit value of the specified liquid amount range, the phosphoric acid aqueous solution is replenished to the tank to increase the liquid amount inside the tank to a value within the specified liquid amount range and decrease the silicon concentration of the phosphoric acid aqueous solution inside the tank to a value within the specified concentration range.