At-Speed Defect Localization by Combining Laser Scanning Microscopy and Power Spectrum Analysis

The defect detection capabilities of Power Spectrum Analysis (PSA) [1] have been successfully combined with local laser heating to isolate defective circuitry in a high-speed Si Phase Locked Loop (PLL). The defective operation resulted in missed counts when operating at multi-GHz speeds and elevated temperatures. By monitoring PSA signals at a specific frequency through zero-spanning and scanning the suspect device with a heating laser (1340 nm wavelength), the area(s) causing failure were localized. PSA circumvents the need for a rapid pass/fail detector like that used for Soft Defect Localization (SDL) [2] or Laser-Assisted Defect Analysis (LADA) [3] and converts the at-speed failure to a DC signature. The experimental setup for image acquisition and examples demonstrating utility are described.