Effects of halo implant on hot carrier reliability of sub-quarter micron MOSFETs

Abstract

Halo implants with various tilt angles and energies were compared from the point of hot carrier reliability. Our study shows that a larger tilt or a deeper, more energetic halo implant leads to stronger reverse short channel effects and higher electric field in the extension/channel junction. However, the net impact of a sharper extension/channel junction on hot carrier degradation was found to be minimal, because the weaker halo devices have higher substrate current resulting from higher drain currents which counterbalances increased electric field in the extension-channel junction for the stronger halo devices. However, when devices from two lots with similar performance parametrics, such as similar threshold voltage (V/sub t/) roll-off, were compared, larger tilt/lower energy halo devices were found to have less degradation than lower tilt/higher energy halos.