PHYSICAL AND ELECTRICAL CHARACTERISTICS OF THIN SILICON-NITRIDE DIELECTRIC FILMS DEPOSITED ON SMOOTH AND RUGGED POLYCRYSTALLINE SILICON AFTER RAPID THERMAL NITRIDATION

Rapid thermal nitridation (RTN) of the polycrystalline silicon (polysilicon) storage node prior to the deposition of the silicon nitride dielectric film has been investigated for capacitors with smooth and rugged electrodes. The nitridation process modifies the bonding arrangement on the polysilicon surface and leads to an enhancement of the nucleation and growth characteristics of the subsequent silicon nitride deposition process. This results in the growth of a thicker film on the RTN-treated surface for a given deposition time. For the same capacitance, the addition of the nitridation treatment reduces the leakage current through silicon nitride films deposited on smooth polysilicon while no such change in the leakage characteristics is seen for the rugged polysilicon film. However, for both smooth and rugged polysilicon electrodes, there is an improvement in the breakdown distribution as well as the time-dependent dielectric breakdown of the films with the nitridation process.