SEMI F70.1 is a standardized semiconductor industry method for quantifying the number of particles a gas delivery system component sheds into the process gas stream. In contrast to steady-state methods such as SEMI F70, SEMI F70.1 deals with transient, pulse-induced particle generation. This makes the results more representative of real-life conditions, as mass flow controllers (MFCs) and valves are known to shed significantly more particles during actuation than during steady flow.
Sample selection and test preparation
Gas delivery components that can be tested using the SEMI F70.1 method include:
Mass flow controllers and mass flow meters
Diaphragm valves and air-operated shut-off valves
Pressure regulators
In-line filters and purifiers
Fittings and short subassemblies of gas panels and gas boxes
The component under inspection is plumbed into a low-background gas delivery test stand using electropolished, high-purity stainless steel tubing and fittings, so that the fixture itself does not contribute significantly to the measured particle count. The system is purged with UHP nitrogen or argon until the downstream background particle count stabilizes at or near zero. This establishes a clean baseline and leaves the component as the only variable in the measurement.
SEMI F70.1 experimental setup
A condensation nucleus counter (CNC) or a laser particle counter (LPC) is connected downstream of the gas delivery component to continuously sample the outlet gas stream and count particles. The minimum detectable particle size depends on the instrument and is typically ≥0.1 µm for LPCs, while CNCs are capable of resolving particles in the low nanometer range (down to ~4.5 nm with some instruments).
Active components such as MFCs are driven through repeated pulsed cycles or step changes at a defined frequency and duty cycle (e.g., rapid open/close, 0 to full scale and back to 0). For passive components such as filters and fittings, the pulses are created by switching the gas flow upstream of the component. This cyclic approach simulates the repeated flow transitions that gas delivery components experience in an actual process tool.
Particle counts are logged pulse-by-pulse over a statistically significant number of cycles, so that transient spikes coinciding with actuation events can be distinguished from the steady-state background.
Presentation of the results
The results of the SEMI F70.1 test are presented as a particle count histogram or a time-series trace synchronized to the actuation events. The trace shows sharp count spikes coinciding with each actuation, superimposed on a low, steady-state baseline. Numerical parameters are also reported, and these can include:
Background particle count
Particles added per liter of gas passed and per actuation cycle
Counts resolved into specified particle size bins (with an LPC)
The report will also include a comprehensive method description and instrument details.
Advantages of pulsed testing
SEMI F70.1 can identify failure modes that steady-state SEMI standards may miss because it isolates particle generation tied specifically to mechanical actuation, such as valve seating, diaphragm flexing, and flow transients through orifices. This matters because modern lithography and etch processes cycle gas delivery components on and off more often than they hold a steady flow.
The results give equipment makers and fabs a repeatable basis to compare MFC and valve designs for particle-shedding behavior under realistic dynamic duty cycles, which is critical as node sizes shrink and even nanometer-scale particle contamination on a wafer becomes yield-limiting.
Ordering the test
Measurlabs offers pulsed particle testing conducted in accordance with SEMI F70.1 and other semiconductor industry standards. The test setup can be customized to match your specific requirements, including minimum detectable particle sizes down to 4.5 nm.
You can contact us using the form below for more information or a quote. One of our experts will get back to you in one business day.