Description of Technique: HIBS is used to detect ultra-trace levels of heavy impurities on the surface of a Si wafer. HIBS has advantages over TXRF, including:
- Improved sensitivity for most elements
- Quantifying composition without standards
- Measurement on rough surfaces.
HIBS is accomplished by focusing a 120 keV beam of C+ions onto a small spot at the wafer's surface. The backscattered ions are collected by a time-of-flight (TOF) detector array with a large solid angle. The flight time of the backscattered C identifies the near-surface impurities and the total counts in each peak quantifies the composition.
Detection Limits: ~6 x109 Fe/cm2 to ~3x108 Au.cm2 on Si (100x better with VPD).
Elemental Range: Ar to Pu.
X-Y Scanning: Anywhere on a 200 mm wafer.
Spatial Resolution: 3 mm.
Sampling Depth: ~10 nm.
Quantitative: Composition without standards.
Destructive: Yes, for wafer reapplication. No, for further analysis.
Specimen Requirements: 10 mm x 10 mm minimum, 200 mm wafer maximum.
Cleanliness: Class 10 environment for sample loading.
Analysis time: ~30 minutes per point.
- Complement or replace TXRF and ICP-MS measurements.
- Calibration of standards.
- Research and development of processes and tools.
- Investigating process contamination (wet station, plasma, implant, etc.).
Point of Contact: Barney L. Doyle