A novel SIMS based approach to the characterization of the channel doping profile of a trench MOSFET

We present here a new technique which for allows the accurate characterization of the channel doping profile using secondary ion mass spectrometry (SIMS) analysis within the active area cells of a trench MOSFET. The technique involves the chemical removal of the entire structure apart from the silicon mesas and trenches, followed by the deposition of undoped silicon (polycrystalline or epitaxial) to refill the trenches. The SIMS profiles obtained are then corrected for the trench geometry to reveal the underlying doping profile within the MOSFET cells.