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 (polysi licon) storage node prior to the deposition of the silicon nitride die lectric film has been investigated for capacitors with smooth and rugg ed electrodes. The nitridation process modifies the bonding arrangemen t on the polysilicon surface and leads to an enhancement of the nuclea tion and growth characteristics of the subsequent silicon nitride depo sition process. This results in the growth of a thicker film on the RT N-treated surface for a given deposition time. For the same capacitanc e, the addition of the nitridation treatment reduces the leakage curre nt 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 elec trodes, there is an improvement in the breakdown distribution as well as the time-dependent dielectric breakdown of the films with the nitri dation process.