TL;DR
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.
What you might see
- across-wafer uniformity outside spec
- center-thick or edge-thick film pattern
- gradual shift over multiple lots
- showerhead holes partially blocked
- process monitor wafer failing acceptance
Likely causes
Showerhead holes partially clogged with deposited film, altering gas distribution
Mass flow controller (MFC) calibration drift changing the actual gas ratio
Target erosion or target depletion in PVD modules changing sputter uniformity
Wafer chuck or susceptor temperature non-uniformity from heater element degradation
Required tools
- Ellipsometer or reflectometer for film measurement
- MFC calibration kit
- Thermocouple wafer or temperature mapping kit
- Showerhead wet-clean chemicals (as specified in maintenance log)
- Torque wrench for showerhead installation
Safety first
- Showerhead wet-clean chemicals may include hydrofluoric acid solutions. Use HF-rated PPE including face shield, butyl rubber gloves, and a chemical-resistant apron.
- Purge the chamber fully and confirm gas-safe status before opening the showerhead port.
Procedure
- 1
Run a dedicated process monitor wafer and measure film thickness at 49 or 121 points with an ellipsometer or reflectometer.[1]
- 2
Review the uniformity map to identify whether the non-uniformity pattern is radial, center-thick, edge-thick, or asymmetric.
- 3
Check all MFC set-point vs. actual readings on the process controller. An actual flow more than 2% from set-point on any gas line requires recalibration.
- 4
Recalibrate out-of-spec MFCs using the system calibration routine or replace the MFC if it cannot hold calibration.
- 5
Inspect the showerhead visually through the chamber port. Remove and clean the showerhead if buildup is visible, following the wet-clean procedure in the maintenance log.
- 6
Check the susceptor or wafer chuck temperature uniformity using a thermocouple wafer or the built-in heater diagnostics. A center-to-edge delta above 5 degrees C indicates heater degradation.
- 7
For PVD modules, review the target life counter. Replace the target if erosion depth approaches the end-of-life threshold.
- 8
Run a qualification wafer after any repair. Accept the chamber only when the uniformity map is within specification.
Sources
Applied Materials Applied Materials Endura / Centura CVD / Deposition System general technical documentation, Applied Materials
Applied Materials CVD system general process qualification and uniformity procedures (general)
More guides for Applied Materials Applied Materials Endura / Centura
How to troubleshoot deposition rate drop on an Applied Materials Endura / Centura
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.
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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