Atomic-layer-deposited ultrathin Si-nitride gate dielectrics - a better choice for sub-tunneling gate dielectrics

The suitability of atomic-layer-deposited (ALD) Si nitride to meet the crying need for gate dielectrics with an EOT in the territory of 1 nm, has been investigated through an extensive and comparative study with conventional SiO/sub 2/ gate dielectrics. ALD Si nitride showed excellent reliability characteristics in all standard evaluations of MOS capacitors. Though the inversion layer mobility was slightly smaller for n-MOSFETs with an ALD Si nitride than for a SiO/sub 2/ gate dielectric, post-stress mobility degradation was much less for the ALD samples than for SiO/sub 2/ samples. The lower interface and bulk trap generation rates consistently explain the soft breakdown (SBD) free phenomena and the reduced mobility degradation for the ALD Si-nitride dielectrics. Therefore, the ALD Si-nitride dielectrics would be a better choice for sub-tunneling gate dielectrics.