Transistors with high concentration of boron doped germanium

摘要

Techniques are disclosed for forming transistor devices having source and drain regions with high concentrations of boron doped germanium. In some embodiments, an in situ boron doped germanium, or alternatively, boron doped silicon germanium capped with a heavily boron doped germanium layer, are provided using selective epitaxial deposition in the source and drain regions and their corresponding tip regions. In some such cases, germanium concentration can be, for example, in excess of 50 atomic % and up to 100 atomic %, and the boron concentration can be, for instance, in excess of 1E20 cm−3. A buffer providing graded germanium and/or boron concentrations can be used to better interface disparate layers. The concentration of boron doped in the germanium at the epi-metal interface effectively lowers parasitic resistance without degrading tip abruptness. The techniques can be embodied, for instance, in planar or non-planar transistor devices.

主权项

1. A transistor device comprising:
a substrate having a channel region; a gate electrode above the channel region, wherein a gate dielectric layer is provided between the gate electrode and the channel region and spacers are provided on sides of the gate electrode; and source and drain regions disposed in respective cavities defined in the substrate and adjacent to the channel region, each of the source and drain regions including a tip region that extends under at least one of a corresponding one of the spacers and the gate dielectric layer, wherein the source and drain regions and corresponding tip regions comprise a boron-doped germanium layer having
a germanium concentration in excess of 50 atomic %, anda boron concentration in excess of 1E20 cm−3.