TL;DR
A falling deposition rate usually means depleted precursor source, MFC drift, or reduced RF power delivery. Check source levels and run an RF match diagnostic first.
What you might see
- film thickness below target on monitor wafers
- process time increasing to meet target thickness
- RF reflected power higher than usual
- precursor source consumption higher than expected
Likely causes
Precursor canister or solid source depleted or near end-of-life
MFC calibration drift reducing the actual precursor flow
RF impedance match detuned, reducing plasma power coupling efficiency
Chamber wall coating buildup altering chamber conductance
Required tools
- Precursor source weight log or level gauge
- MFC calibration kit
- RF power meter
- Ellipsometer for rate-check wafer measurement
Safety first
- Precursor canisters for CVD may contain pyrophoric or toxic materials. Follow the site hazardous materials handling procedure for canister swap.
- Lock out the RF generator before accessing the match network or antenna components.
Procedure
- 1
Review the precursor source weight or level log. Replace the canister if weight is below the minimum refill threshold.[1]
- 2
Check all gas flow MFCs for set-point vs. actual deviation and recalibrate any line with more than 2% error.
- 3
Run the RF match auto-tune routine on the process controller and verify forward and reflected power are within specification.
- 4
Check the RF generator output power reading against the set-point. A drop in output power indicates a generator fault.
- 5
Review the chamber wall coating thickness. If the last full wet-clean was beyond the scheduled interval, schedule a chamber clean.
- 6
Run a rate-check wafer after any corrective action and compare results to the process baseline chart.
Sources
Applied Materials Applied Materials Endura / Centura CVD / Deposition System general technical documentation, Applied Materials
Applied Materials CVD system general precursor management and RF tuning procedures (general)
More guides for Applied Materials Applied Materials Endura / Centura
How to fix film thickness uniformity drift on an Applied Materials Endura / Centura
Uniformity drift is usually a dirty showerhead, a depleted target, or a gas flow calibration error. Run a process monitor wafer and check the MFC calibrations first.
How to diagnose process chamber vacuum loss on an Applied Materials Endura / Centura
Vacuum loss is most often a failed o-ring, a leaking gate valve, or a saturated cold trap. Perform a base-pressure rate-of-rise test to locate the leak.
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