The Second Harmonic generated by laser irradiation occurs in places where symmetry in the material is broken, such as at hetero-interfaces and various types of crystalline defects. In non-centrosymmetric materials, such as GaAs, Second Harmonic will also be generated from the bulk material.
Surface + Buried Interface Characterization
- Trace metal contamination
- Sub-50nm particles
- Structural defects
- Film stack measurements
- Thin film quality
- Charge trapping dynamics
Benefits of Second Harmonic Generation
- Non-destructive surface + subsurface analysis
- High in-line throughput
- Enhanced defect + contaminant sensitivity
- No sample preparation
- No consumables or reagents
- Non-contact optical technique
Abstract — Time dependent second harmonic optical signals were measured across silicon-on- insulator (SOI) wafer coupons contaminated by Cu-63 ion implanted into the buried oxide (BOX) and near the SOI/BOX and BOX/Bulk interfaces. Average signals after 1 second of exposure for all spatial points were compared between wafers and used to differentiate contamination levels post ion-implantation.
Non-Destructive Contamination Detection in Thick and Extremely-Thin SOI (ISTFA 2015)
Non-destructive optical second harmonic generation (SHG) is shown to be an effective method for detecting surface and subsurface non-visual defects in commercial thick and extremely-thin(ET) SOI wafers. A method is demonstrated for removing contributions (noise) from layer thickness variations observed in thick SOI, increasing the sensitivity and enabling detection of trace surface metal contamination. Sub-surface contamination, otherwise missed by the standard flow of non-destructive characterization methods, is shown to be detected by SHG.