Depth measurement system for determining depth of blind bores in semiconductor workpieces has IR source with beam splitter and polarizer directing beam into workpiece at 45 degree angle

摘要

The blind bores depth measurement system uses interference effects. It has an IR source sending radiation (S) to a Michelson interferometer (10) with a beam splitter (13) at a 45 degree angle and two mirrors (11,12). The IR leaving the Michelson interferometer passes through a polarizer (21) and impinges on the workpiece (1) at a 45 degree angle. IR reflected from the workpiece passes through a second polarizer (22) to an IR detector (15).