SPV Diffusion Length
Printer-friendly version
Diffusion length is a property of a bulk semiconductor material, telling how long an excess carrier travels, on average, before recombining to achieve equilibrium carrier concentration. The diffusion length of a semiconductor with a perfect crystal lattice and no comtamination will be long, and any imperfections in the semiconductor material or contamination will reduce the diffusion length. Thus, monitoring diffusion length is an excellent method to detect contamination.
The most common way of measuring diffusion length is via SPV, a technique that uses the SPV response of multiple wavelengths to calculate diffusion length. This measurement technique works well in semiconductor grade silicon where the wafer thickness is greater than 3 times the diffusion length.
The WT-2000 offers maps of diffsion length measurements for semiconductor wafers, via a benchtop system. The WT-3000 offers similar capability via a dual FOUP system for 300mm wafers.
Laser-SPV TOOL
Surface Photovoltage (SPV) technique for mapping heavy metal contamination and crystal defects in bulk silicon wafer
FEATURES:
Detects
- Impurities due to heavy metal contamination and transition metal contamination
- Crystal defects
Unique Laser-SPV feature: surface stabilization after HF dip within 5 min
Operation frequency: from 100Hz to 1600Hz (low frequency is necessary for long LD measurements)
No surface passivation is necessary for bare wafers
