SPM Liquid Temperature Control for Semiconductor Wafer Cleaning
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Solution Overview
Problem
The existing technologies for processing semiconductor wafers using a sulfuric acid-hydrogen peroxide mixture (SPM liquid) face issues with the degradation of sulfuric acid concentration due to hydrogen peroxide decomposition, leading to inefficient wafer processing, increased chemical consumption, and costly apparatus maintenance, as they require frequent liquid exchanges and rely on concentration detection units.
Innovation Solution
A substrate processing apparatus with a circulation path, heating unit, sulfuric acid and hydrogen peroxide supply units, and temperature control, which maintains the SPM liquid temperature between 135° C. to 170° C. to evaporate moisture components, reduce hydrogen peroxide decomposition, and supplement sulfuric acid accordingly, thereby stabilizing the sulfuric acid concentration and reducing liquid exchange frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the SPM liquid is heated at high temperature to improve cleaning efficiency, then the cleaning function is enhanced, but the hydrogen peroxide decomposes faster causing sulfuric acid concentration to decrease
Solution Approach 1:
The patent changes the temperature parameter from conventional 100-130°C to 140-170°C to improve cleaning efficiency. Simultaneously, it adjusts the sulfuric acid concentration parameter to 80-95% (higher than conventional) to compensate for decomposition at elevated temperature, thereby maintaining effective cleaning function while managing the trade-off between temperature and chemical stability
Solution Approach 2:
The patent performs preliminary supplementation of sulfuric acid before the concentration drops too low, based on monitoring the temperature and estimated decomposition rate. This proactive approach prevents the concentration from falling below the effective threshold, avoiding interruptions in wafer processing
2Reliability
If the sulfuric acid concentration is maintained by frequent supplementation, then the cleaning function is preserved, but the chemical consumption and cost increase
Solution Approach 1:
The patent implements a feedback control system where the temperature detection unit continuously monitors the SPM liquid temperature, and the control unit uses this information to determine when sulfuric acid supplementation is needed. This feedback mechanism prevents both over-supplementation (wasting chemicals) and under-supplementation (losing cleaning function) by making supplementation decisions based on actual temperature conditions and decomposition rates
Solution Approach 2:
The patent uses high initial sulfuric acid concentration (80-95%) which provides a larger buffer against decomposition, allowing longer operation intervals between supplementation events while maintaining effective cleaning concentration
3Reliability
If the SPM liquid is exchanged frequently to maintain concentration, then the cleaning effectiveness is ensured, but the processing efficiency decreases and cost increases
Solution Approach 1:
Instead of exchanging the entire SPM liquid batch, the patent extracts and supplements only the depleted sulfuric acid component while retaining the bulk of the SPM liquid including the hydrogen peroxide and water. This selective replenishment maintains cleaning effectiveness while avoiding the productivity loss associated with complete liquid exchange and wafer processing interruptions
4Loss of time
If a concentration detection unit is added to monitor sulfuric acid concentration, then the supplementation timing is optimized, but the apparatus complexity and cost increase
Solution Approach 1:
The patent replaces complex chemical concentration detection mechanisms with a simpler temperature detection system. Since temperature directly correlates with hydrogen peroxide decomposition rate and sulfuric acid concentration change, monitoring temperature provides sufficient information to optimize supplementation timing without requiring complex concentration sensors or analytical instruments
Solution Approach 2:
The patent uses temperature as an intermediary parameter that indirectly indicates sulfuric acid concentration status. Rather than directly measuring concentration (which requires complex equipment), the system measures temperature and uses this intermediate information to infer when supplementation is needed, simplifying the detection system while maintaining optimization capability
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 effectively maintains the sulfuric acid concentration, reduces the frequency of SPM liquid exchanges, and minimizes chemical consumption, enhancing processing efficiency and cost-effectiveness by preferentially evaporating moisture and controlling the decomposition of hydrogen peroxide and Caro's acid.
Implementation Method 1
heating unit provided in the circulation path to heat the SPM liquid... allow a temperature of the SPM liquid in the processing bath to be maintained in a predetermined range of 135° C. to 170° C., and to supplement the sulfuric acid from the sulfuric acid supplement unit to compensate for the SPM liquid as the SPM liquid is evaporated by heating
Implementation Method 2
circulation path to circulate the SPM liquid in the processing bath... Heating unit provided in the circulation path to heat the SPM liquid
Data Source
AI summary
Disclosed are a substrate processing apparatus, a substrate processing method and a storage medium, capable of removing contaminant materials from a substrate by using SPM liquid (sulfuric acid and hydrogen peroxide mixture) while preventing degradation of the function of the SPM liquid for removing the contaminant materials. The SPM liquid is filled in a processing bath and the substrate is immersed in the SPM liquid. A heating unit is provided in the circulation path to heat the SPM liquid. A hydrogen peroxide supply line supplements hydrogen peroxide to the SPM liquid in the circulation path. A control unit adjusts the temperature of the SPM liquid to the predetermined temperature in the range of 135° C. to 170° C. based on a temperature detection value and outputs a control signal to supplement the sulfuric acid to compensate for the SPM liquid as the SPM liquid is evaporated by heating.