Application
Use of peristaltic pumps to deliver slurry and cleaning chemistries to CMP tools is imprecise due to the pulsation caused by these pumps. Replacing these pump delivery components with pressurized supply and integrated flow controllers allows for precision slurry dispense in semiconductor wafer polishing. Malema’s LFC-7000 ultrasonic flow controller retrofit kits provide the precise flow control required for process optimization.
Solution
Malema Sensors® LFC-7000 series slurry flow controllers use an advanced ultrasonic flow sensor with digital signal processing (DSP) and a state-of-the-art flow regulating valve, ensuring accurate flow measurement and control. Improved flow control performance and time to achieve flow control has saved our semiconductor manufacturer customers around 20% to 30% of CMP slurry compared to peristaltic pump slurry delivery.
Features
- High Accuracy – Controls flow rate to within ±1% of set point
- Fast Response – < 3 seconds (typically < 2 seconds for most applications)
- All PTFE/PFA wetted part construction – insures compatibility with UHP liquid chemicals, DI water and CMP slurries (slurry module with Pt cured Silicone tubing)
- Low maintenance - modules featuring ultrasonic flow meters with no moving parts provide the ultimate in tool uptime (slurry module with pinch tube replacement cycle of 3 years or longer)
Benefits
- Tight flow control ensures consistent within-waferand wafer-to-wafer polishing performance resulting in high yield
- Tight flow control helps reduce slurry consumption
- Improves throughput
- Less maintenance- ensures longer tool uptime and lower operating cost
Comparison of LFC-7000 Performance to the Industry-Standard
Figures 1 and 2 show the comparison in time to achieve flow set point in an industry standard pump-based delivery system versus a Malema LFC-7000 delivery module. The industry standard system achieved marginal flow control in ~15 seconds, vs. < 2 seconds for the LFC-7000 to achieve much tighter flow control accuracy and repeatability, meaning less downtime at the beginning of a polishing step before wafers can be processed. Figures 3 and 4 show
the standard flow control range of an industry standard system at ~±40 ml/min, meaning to achieve a required 200 ml/min flow rate minimum, the set point is set to 250 ml/min. The Malema LFC-7000 series is able to control the flow rate between 200 ml/min and 202 ml/min, saving 50 ml/min of slurry per dispense point.
Malema’s LFC-7000 with its improved flow control accuracy and time to achieve flow set point has saved our customers approximately 20% — 30% of CMP slurry use in a typical application.