Concentration measurement
in the
semiconductor industry
in the
semiconductor industry
Inline concentration measurement for semiconductor wet processes:
LiquiSonic® monitors chemical concentrations in SC1, SC2, BOE/BHF, cleaning and etching processes in real time.
Up to ±0.02 wt%
Real-time measurement
Maintenance-free
Cost-saving
Inline concentration measurement for SC1, SC2, BOE/BHF and wafer cleaning
In wafer manufacturing, chemical concentrations in cleaning and etching baths must be maintained precisely. LiquiSonic® enables continuous inline monitoring of wet processes such as SC1, SC2, SPM, DHF, BOE/BHF and TMAH-based development processes - without delayed laboratory analysis and without consumables.
Challenges
In semiconductor manufacturing, the exact ratio of chemical concentrations is crucial, but conventional laboratory analyses often deliver results too late. With LiquiSonic® SensoTech enables reliable real-time monitoring that can be integrated seamlessly into existing processes. The system provides precise measurement data without maintenance and thus increases process reliability and efficiency.
Challenges
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Chemical concentrations not within the target range
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Time-consuming laboratory analyses
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No immediate and reliable information on the chemical composition
Solution
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Clear monitoring with LiquiSonic®
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Immediate display of the chemical concentration
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Seamless integration into existing systems
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Maintenance-free and without consumables
Benefits
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Traceable and reliable measurement results
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Measurement results in real time
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Completely maintenance-free sensors and chemical-resistant materials
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Easy integration into systems of any size and configuration
Our solution: The LiquiSonic® measurement system
Monitor concentration in real time
LiquiSonic® combines modern ultrasonic technology with temperature-compensated measurement to deliver precise results for critical chemical mixtures in semiconductor manufacturing. Real-time monitoring ensures stable product quality, reduces deviations and provides data for process optimization. This lowers operating costs and chemical consumption while increasing process reliability and efficiency.
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Ensure quality: Real-time monitoring guarantees precise results without deviations.
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Reduce costs: Optimized processes for maximum reliability and lower consumption.
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Increase efficiency: Higher product quality with reduced operating costs.
Technical details and specifications
Ultrasonic measurement principle
The speed of sound in liquids is directly related to the concentration of dissolved substances. Highly precise time measurements enable exact determination of the concentration.
Conductivity integration
In three-component systems, conductivity is used as a second physical parameter to determine both concentrations unambiguously.
Temperature compensation
Two PT1000 sensors integrated into the measuring cell ensure automatic temperature compensation and thus precise measured values under all conditions. By directly recording the process temperature, the speed of sound is corrected in real time, which improves stability and accuracy even under fluctuating conditions.
Economic benefits
Real-time concentration measurement increases quality, efficiency and reliability, while at the same time costs and resource consumption decrease:
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Reduced operating costs through lower chemical consumption and fewer laboratory analyses
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Less scrap and rework, as deviations can be detected and corrected immediately
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Stable product quality ensures competitiveness and reduces complaints
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More efficient processes through real-time data instead of delayed laboratory measurements
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Higher plant availability through maintenance-free sensors without consumables
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Process optimization through precise data leads to continuous improvement and better resource utilization
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Fast ROI thanks to savings in energy and operating costs
Technical specifications
Measurement accuracy | Up to ±0.02 wt% |
Temperature range | 5 °C to 60 °C |
Pressure range | Up to 4 bar |
Material & coating | PFA |
Digital transmission | Up to 1,000 m (more on request) |
Interfaces | 4-20 mA, Profibus, Ethernet, Modbus, fieldbus, ... |
Protection class | IP65 |
Calibration | One-time factory calibration |
Maintenance | Completely maintenance-free |
Application examples
Typical chemical process steps and our used for this process solutions for cleaning and etching processes as well as special etching and development processes:
SC-1 (APM)
NH4OH/H2O2
SC-2 (HPM)
HCl/H2O2
SPM (Piranha)
H2SO4/H2O2
Oxide removal (DHF)
HF
Oxide removal (BOE/BHF)
HF/NH4F
Si₃N₄ etching
H3PO4
Isotropic silicon etching
HF/HNO3
Anisotropic silicon etching (MEMS)
KOH/Si
TMAH/Si
Photoresist development
TMAH
Nitric acid / acetic acid
HNO3/CH3COOH
HF / HCl
HF/HCl
Success stories and references:
Detailed case studies and customer references are available from our sales team. Contact us for specific application examples from your industry.
The key benefits at a glance
Consistent quality
Real-time monitoring prevents deviations and ensures consistent product quality.
Cost savings
Lower chemical consumption and reduced operating costs through optimized processes.
Maximum efficiency
Real-time data enables faster decisions and optimized processes.
Maintenance-free
Sensors are chemical-resistant and require no consumables.
Frequently asked questions
Unlike optical methods, which are affected by color or haze, conductivity-based methods, which are sensitive to electrical conductivity, or density-based methods, which can be disturbed by temperature or gas bubbles, ours ultrasonic method is independent of these influences.
The LiquiSonic® measurement technology also contains neither moving parts nor components that can wear out or be consumed. After installation, the measuring system is therefore completely maintenance-free and drift-free.
The sensors offer digital signal transmission up to 1000 m and enable continuous inline measurement without sampling.
Our system uses ultrasonic transit-time measurement to determine the speed of sound in liquids. This speed of sound correlates directly with the chemical concentration and enables measurement accuracies of up to ±0.02 wt% for the semiconductor industry. The integrated temperature compensation ensures stable results even under fluctuating process conditions.
The system delivers results in real time. It performs over 30 measurements per second. Based on these measurements, you receive a current measured value every secondThis fast response time enables effective process control and early detection of deviations.
LiquiSonic® can be used for inline concentration measurement in various wet-chemical semiconductor processes, for example in SC1/APM, SC2/HPM, SPM/Piranha, DHF, BOE/BHF, TMAH-based development processes as well as in selected etching processes with HF, H₃PO₄, KOH or HNO₃. The specific design depends on the medium, concentration range, temperature, pressure and process setup.
Yes, LiquiSonic® enables continuous monitoring of chemical concentrations in SC1 and SC2 processes directly in the ongoing process. This makes concentration deviations visible at an early stage, so recipes can be maintained more consistently and cleaning processes can be controlled better.
Yes, BOE and BHF processes based on HF and NH₄F can be monitored with LiquiSonic® inline. Especially in sensitive etching processes, continuous concentration measurement helps keep process windows stable and detect fluctuations at an early stage.
Yes, LiquiSonic® can be integrated into existing wet process systems, wet benches, or supply systems. Depending on the system design, connection is made via suitable process connections and industrial interfaces such as 4–20 mA, Profibus, Ethernet, Modbus, or fieldbus.
Our semiconductor sensors operate reliably in a temperature range from 5 °C to 60 °C and pressures up to 4 bar.
Yes, by combining sound velocity measurement with additional physical variables (e.g. conductivity), multiple components can be determined simultaneously. This also allows other additives in semiconductor manufacturing to be monitored.
The semiconductor measurement system is completely maintenance-free. There are no mechanical wear parts, seals, or optical windows that could be attacked. Regular calibration is not required - the LiquiSonic® sensors remain stable for years.
The system offers various digital interfaces (e.g. Profibus, Ethernet / IP, Foundation Fieldbus) as well as analog 4-20 mA outputs. Integration is carried out easily via standardized protocols.
The sound velocity of a liquid depends on temperature. LiquiSonic® therefore records the process temperature in addition to the sound velocity and automatically compensates for temperature influences. This keeps the concentration values stable and reliable even when temperatures fluctuate.
Related applications
Texturing and etching baths
In etching baths, material layers are selectively removed to create desired surface structures.
Circuit board cleaning
Cleaning removes organic residues, particles, and oxides so that the conductor tracks can be processed reliably.
Pickling bath monitoring
Pickling baths remove oxides or contaminants from metal surfaces and must therefore be kept constantly within the correct concentration range.
Green liquor monitoring
Green liquor is a highly alkaline by-product in paper production whose concentration must be monitored for stable downstream processes.
Acid concentration measurement
The precise determination of concentrations in aggressive chemicals is crucial to ensure reactions proceed in a controlled and safe manner.
Gas scrubbers
In gas scrubbers or neutralization systems, pollutants are removed from exhaust air or liquids, which requires precise control of the chemicals used.