Apparatus and method for synchronizing sample stage motion with a time delay integration charge-couple device in a semiconductor inspection tool

An apparatus for controlling charge transfer for a time delay integration (TDI) charge-coupled device (CCD) for a semiconductor inspection system, comprising:

• a phase and frequency controller arranged to generate a reference signal based on measured vertical and lateral positions of a stage holding a sample being inspected;
• and,
• a control system:
• including a phase lock loop arranged to generate a control signal based on the reference signal;
• and,
• arranged to generate, using the control signal, a pixel clock to control charge transfer of the CCD and to correct a difference between an apparent lateral position of an imaged pixel of the sample and an actual lateral position of the imaged pixel, wherein:
• light used to charge the CCD is reflected from a surface of the sample at an acute angle;
• and,
• the reference signal generator is arranged to generate the reference signal based on the acute angle.