Substrate Processing Apparatus Concentration Sensing with Lens Cooling
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Solution Overview
Problem
Existing substrate processing apparatuses face challenges in independently controlling the concentration of high-temperature phosphoric acid solutions used for etching silicon nitride films, as temperature changes affect measurement accuracy and require simultaneous control of temperature and concentration, leading to measurement errors and instability in etching processes.
Innovation Solution
A substrate processing apparatus with a concentration sensing system that measures absorbance characteristics using a light-transmitting section, light-emitting section, and light-receiving section, equipped with cooling mechanisms for lenses to minimize temperature-induced measurement errors, allowing independent concentration control and precise etching of silicon nitride films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If temperature control is used to maintain constant phosphoric acid bath temperature, then temperature stability is improved, but measurement precision of concentration deteriorates due to temperature-induced measurement errors
Solution Approach 1:
A temperature compensation mechanism is introduced as an intermediary element that measures the actual temperature of the phosphoric acid bath and uses this information to compensate for temperature-induced measurement errors in the concentration sensing system, thereby maintaining measurement precision despite temperature variations
Solution Approach 2:
The system dynamically adjusts measurement parameters based on temperature conditions by implementing temperature compensation algorithms that modify the concentration measurement calculations according to the actual bath temperature, allowing accurate concentration measurement across varying temperature ranges
2Temperature
If simultaneous control of temperature and concentration is implemented, then temperature stability is improved, but device complexity increases due to coupled control requirements
Solution Approach 1:
The control system is segmented into independent temperature control and concentration control modules, each managing its own parameter separately. This segmentation allows both parameters to be controlled simultaneously without requiring complex coupled control logic, reducing overall system complexity while maintaining stability
3Quantity of substance
If replenishment with diluent is increased to maintain concentration, then concentration control is improved, but temperature stability deteriorates due to temperature decrease from excessive replenishment
Solution Approach 1:
A dual feedback control system is implemented where both concentration and temperature sensors provide real-time feedback to their respective control modules. The temperature feedback allows the system to monitor temperature changes caused by diluent replenishment and adjust the replenishment rate accordingly, while the concentration feedback ensures the desired concentration is maintained, creating a balanced control mechanism
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 apparatus achieves precise concentration control of the processing liquid, reducing measurement errors and stabilizing the etching process, enabling independent adjustment of silicon nitride and silicon oxide film etching rates, and maintaining etching stability even during substrate immersion.
Implementation Method 1
concentration sensing means for sensing a concentration of the processing liquid by measuring absorbance characteristics of the processing liquid
Implementation Method 2
equipped with cooling mechanisms for lenses to minimize temperature-induced measurement errors
Data Source
AI summary
A substrate processing apparatus that performs processing by immersing a substrate into a processing liquid obtained by mixing phosphoric acid with a diluent includes a concentration sensing means for sensing the concentration of the processing liquid by measuring the absorbance characteristics of the processing liquid. The concentration sensing means includes a light-transmitting section that introduces the processing liquid into the inside to let the processing liquid pass therethrough, a light-emitting section that radiates light having a predetermined wavelength to the light-transmitting section, a light-receiving section that receives the light therefrom via the light-transmitting section, a first lens that condenses the light emitted from the light-emitting section to the light-transmitting section, a second lens that condenses the light that has passed through the light-transmitting section to the light-receiving section, and a cooling mechanism that cools at least one of these.