III-V semiconductors get excited by a laser at a wavelength above their band gap. The photon energy applied to the material will force carriers into the conductance band. Once the excitation ends, the carriers will recombine in the valence band and emit photon energy. The characteristics of these emitted photons is a signature of the material characteristics and gives information about the composition and structure of the material.
The PL signature of a material can tell you about the material properties and - if a full wafer is mapped – give critical information about reactor health, final device performance and give an early indication about the final device performance.
Parameters to be controlled using photoluminescence are:
Peak Wavelength — Eg / Composition
FWHM — Composition Variation
Peak & Integrated Intensity — Defects / Crystal Quality / Impurities (O2)
Maps — Uniformity & Electrically Active Material / Surface Defects
Nanometrics PL metrology lineup provides very flexible metrology solutions for different use cases:
RPMBlue: LED reactor monitoring
RPMBlue-FS: Multi-purpose PL mapper for UV, VIS and IR applications
Imperia: PL/thickness and defect inspection system for production control
Vertex: Multi-purpose R&D and production monitoring.