In situ SiOx interfacial layer formation for scaled ALD high-k/metal gate stacks

This work addresses the issue of interfacial layer formation in scaled high-k/metal gate stacks: the possibility of growing a thin SiO_x interfacial layer in situ in a commercial ALD reactor has been evaluated, employing ozone-based Si oxidation. Three techniques (O₃, O₃/H₂O and Pulsed) have been developed to grow scaled sub-nm interfacial layers and have been integrated in MOS capacitors and MOSFETs. A comparison based on electrical characterization shows that the performance of the proposed in situ methods is comparable or superior to that of existing ex situ techniques; specifically, the O₃ method can grow aggressively scaled interfacial layers (4-5 Å) while preserving the electrical quality of the stack.