Nitrogen Profile Study for SiON Gate Dielectrics of Advanced Dynamic Random Access Memory

Abstract

A new class of organic conductors, mixed valence DIPS@. polyiodides. have been used as conductive addRives in reticulate doping c# polymers. Conductive films have been prepared using three modaications of the reticulate doping technique: a Standard one-step method (direct casting), a two-step method consisting d swelling the film containing molecularly dispersed DIPS@, polyiodldes, and a recently developed method in which oxidation d molecularly dispersed DIPS@. and simuitaneous crystallization of as polyiodides in situ I s induced by treatment d the pristine film containing the donor with 12/CH2C12 vapours. The first and the third methods have been found to be the most advantageous. Conductive films with additive concentrations as low as 0.5 wt% and conductivities d Me order of lo-' S an-' were obtained. In all three methcds, the best results have been obtained when lhe conductive network consisted o f the mast conducting DIPSb, 2.281 salt. Europ. Patent 0 134 026 Jeszka J K and Wacz A 1992 h!yn A&. EchnoL 3 139 Strzelecka H and Rivory J 1980 Matec Res. BUN. 15 897 and reierences therein. Albouy P A, Pouget J P and Strzelecka H 1987 Phys. Rev. B 35 173 and references therein. h e t L C, Reynolds G A, Schneider E M and Perlstein J H 1979 Solid Stare Commun 30 1 Gionis y Fugnitto R, Meyer G, Strzelecka H and Dubis J C 1982 Mol. Cyst. Liq. Cyst. 90 153 and references therein. Strzelecka 6 Vincente R, Ribas J, Legros J P, Cassow P, Petit P and Andre J J 1991 Polyhedmn 10 687 Wan A, Kryszewski M 1989 MakmmoL Chem. Suppl.

Electrical and structural properties of ultrathin SiON films on Si prepared by plasma nitridation

“…[4][5][6] Finally, nitrogen forms a barrier against the diffusion of dopants, especially boron atoms, from the highly doped polysilicon gate to the dielectric. 2,[4][5][6][7] This diffusion has detrimental effects to the reliability of the dielectric material. 2 Therefore, nitrogen incorporation increases the thermal stability of the gate dielectric.…”

“…The temperatures involved are typically lower than those of the thermal processes. They can be tuned to allow for higher N concentrations near the oxynitride/poly-Si interface and a low N concentration near the Si/oxynitride interface while maintaining an overall large N incorporation ͑N concentrations from 2% to ϳ50% are possible 3,[5][6][7]9,11,13 ͒. This control over the N depth profile makes plasma nitridation the best choice for ultrathin ͑Ͻ3 nm͒ oxides.…”

“…17,18 With the present widespread use of ultrathin oxynitrides as gate dielectrics by the industry, it is important that a batch wafer process is used for SiO 2 nitridation. Plasma techniques described above as the most suitable for high level N incorporation have been demonstrated in most cases 6,7 in laboratory equipment not necessarily suited for mass production. In the following, we examine the nitridation of thin SiO 2 films produced in a minibatch reactor, capable of processing simultaneously various wafer size samples, which is therefore closer to industrial needs.…”

On the Interface Flattening Effect and Gate Insulator Breakdown Characteristic of Radical Reaction Based Insulator Formation Technology

“…So far, this process equipment has been adopted in industry mostly for the nitridation of top surface of oxides and oxidation for corner rounding processes. 8,9) However up to now, this technology has not been applied as the gate insulator formation process in the actual LSI manufacturing. The main stumbling block is the higher early breakdown probability of the radical oxides compared to the thermal oxides when applied to current manufacturing lines.…”

Depth Profile of Nitrogen Atoms in Silicon Oxynitride Films Formed by Low-Electron-Temperature Microwave Plasma Nitridation

“…Silicon oxynitride (SiON) formed by plasma nitridation is widely used as a gate insulator in metal-oxide-semiconductor field-effect transistors (MOSFETs) for reducing the gate leakage current and for suppressing the boron penetration from the polycrystalline silicon (poly-Si) gate into both the gate dielectrics and Si substrate in p-channel MOSFET. [1][2][3][4][5][6][7][8] The nitrogen concentration in SiON films should be high to improve boron immunity and to increase the dielectric constant when MOSFET devices are scaled down and the effective oxide thickness (EOT) becomes smaller. However, it is known that nitrogen atoms in SiON films induce the degradation of the negative bias temperature instability (NBTI) in p-channel MOSFET by two means of hole-trap generation.…”