Phosphoric Acid Storage Tank Heating for Etchant Concentration Control
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Solution Overview
Problem
The concentration of silicon in etching liquids used for substrate processing systems can become excessive, leading to silicon oxide deposition on silicon oxide films, inhibiting the etching process, and the concentration of phosphoric acid can decrease due to moisture absorption, affecting the etching process's effectiveness.
Innovation Solution
A storage device with a heating mechanism and controller is used to maintain the concentration of phosphoric acid by adjusting the temperature to balance evaporation and absorption, and a deposition preventing/reducing agent is added to the etching liquid to prevent silicon oxide deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the processing liquid is stored at room temperature, then the operation is simple, but the phosphoric acid concentration decreases due to moisture absorption
Solution Approach 1:
The patent applies parameter changes by controlling the temperature of the processing liquid to maintain a specific range (5°C to 40°C, preferably 10°C to 30°C). This temperature control parameter change balances moisture absorption and evaporation rates, preventing concentration deviation without requiring complex operational procedures. The heating mechanism enables this parameter control while keeping the system relatively simple.
2Stability of the object's composition
If the temperature is increased to reduce moisture absorption, then the concentration stability improves, but the energy consumption increases
Solution Approach 1:
The patent applies partial action by heating the processing liquid only to a moderate temperature range (5°C to 40°C, preferably 10°C to 30°C) rather than to high temperatures. This partial heating is sufficient to reduce moisture absorption while avoiding excessive energy consumption. The system does not require continuous high-temperature maintenance, making the energy input moderate and efficient.
Solution Approach 2:
The patent optimizes the temperature parameter to balance concentration stability and energy consumption. By maintaining temperature within a specific range rather than using extreme values, the system achieves adequate concentration control with moderate energy input. The heating mechanism provides flexible parameter adjustment to match actual operational needs.
3Device complexity
If no temperature control is applied, then the device complexity is low, but the etching process becomes ineffective due to concentration decrease
Solution Approach 1:
The patent implements a relatively simple temperature control mechanism that maintains the processing liquid within a specific temperature range (5°C to 40°C). This parameter control is sufficient to prevent concentration deviation and ensure etching effectiveness without requiring complex multi-component systems. The heating mechanism provides the necessary control with minimal added complexity.
Solution Approach 2:
The patent employs a feedback control system where the controller monitors the temperature of the processing liquid and adjusts the heating mechanism accordingly. This feedback loop ensures the temperature remains within the optimal range, maintaining concentration stability and etching effectiveness. The feedback mechanism is implemented in a straightforward manner, adding minimal complexity while significantly improving reliability.
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
The solution ensures stable etching performance by maintaining the concentration of phosphoric acid and preventing silicon oxide deposition, thereby ensuring proper etching processes.
Implementation Method 1
The heating mechanism heats the processing liquid that is stored in the storage tank
Implementation Method 2
a temperature of the processing liquid is adjusted in such a manner that an amount of evaporation of water for the processing liquid
Implementation Method 3
an amount of absorption of moisture for the processing liquid in the storage tank
Data Source
AI summary
A storage device according to an aspect of the present disclosure includes a storage tank, a heating mechanism, and a controller. The storage tank stores a processing liquid that contains an aqueous solution of phosphoric acid and an additive. The heating mechanism heats the processing liquid that is stored in the storage tank. The controller controls the heating mechanism to execute a concentration maintaining process where a temperature of the processing liquid is adjusted in such a manner that an amount of evaporation of water for the processing liquid in the storage tank approaches an amount of absorption of moisture for the processing liquid in the storage tank.