Plasma implanted ultra shallow junction boron depth profiles: Effect of plasma chemistry and sheath conditions

Plasma based implant systems produce multiple ion species as compared to a beamline implant using a single mass selected ion, such as BF2+. Similarly, plasma implant produces a distribution of ion energies relative to the nearly monoenergetic ions of a beamline implant. To evaluate the significance of these differences, the ultra shallow junction (USJ) dopant depth profiles of these two implant techniques are compared with an advanced secondary ion mass spectrometry (SIMS) profiling technique and a novel diagnostic to measure the “as-implanted” ion mass and energy distributions during the pulse of a plasma implant. The plasma and beamline implants match depth and dose extremely well, consistent with the measured plasma ion characteristics. Additionally, the depth profile effects of plasma pulse timing, relative to the application of the bias voltage pulse, a collisional sheath, and USJ dose loss during device mask removal are explored.