Inspection of semiconductor pattern images against their database definition is increasingly used for validation of stepper reticles. Systems like the Cambridge Instruments Chipcheck use transmitted visible light optics to generate a high contrast video signal from the etched chrome plate image. This type of system can quickly and effectively "catch" repeating type defects which would be missed by die to die type comparators. More recently, the incident illumination capabilities of Chipcheck have been utilised to inspect developed resist images for wafer stepper reticle validation prior to production flow. This technique has many operational benefits compared with manual inspection or "glass wafer" techniques both in speed and accuracy.