Boron Diffusion in Nitrided-Oxide Gate Dielectrics Leading to High Suppression of Boron Penetration in P-MOSFETs

Abstract

Nitrided-oxide gate dielectrics have been proposed to suppress boron penetration in deep submicron metal-oxide-semiconductor field effect transistors (MOSFETs). However, few quantitative reports have been released on how nitrided oxides enlarge the permissible thermal budget. We evaluated the diffusivities of a nitrided oxide formed by annealing SiO2 in NO gas and demonstrated that this film enables us to use BF2 + for scaled devices. We also proposed a model depicting boron penetration through the nitrided-oxide layer.

Anomalous B penetration through ultrathin gate oxides during rapid thermal annealing

“…It can be seen that there is no significant difference between RTA and furnace data for B diffusion in SiO from BF -doped polysilicon sources. The effective activation energy for the combined RTA and furnace BF data is 3.6 eV, which agrees with previous results [17]. However, there is a substantial difference (factor of 20 at 1000 C) between the RTA and furnace results for B diffusion in SiO from Bdoped polysilicon.…”

“…1(a), (b), and 2 are included in Fig. 3 along with other published data that describe B diffusion in SiO as a function of either RTA or furnace annealing temperatures for B or BF -doped polysilicon [3]- [5], [10]- [12], [17]. It can be seen that there is no significant difference between RTA and furnace data for B diffusion in SiO from BF -doped polysilicon sources.…”

High-density transition layer in oxynitride interfaces on Si(100)

“…3. An interfacial layer near substrate/oxide interface is anticipated to be a diffusion barrier for dopants due to its high density, which is consistent with an empirical model of Aoyama et al 19 to explain their measurements on boron penetration through oxynitride layers. This is also consistent with results of a reliability study of oxynitrides for boron diffusion by Wristers et al 20 Therefore, suppressed diffusivities of oxynitrides are mainly attributed to high-density interfacial layers near substrates.…”

Growth and characterization of SiON thin films by using thermal-CVD machine

“…These films are extensively used in VLSI circuits as an interlevel dielectric layer, passivation layer and also for the CMOS VLSI for adjusting the threshold voltage of the MOS devices [1][2][3]. Due to continuously variable refractive index, SiON films are of growing interest in integrated optoelectronic devices [4][5][6][7][8][9][10][11] also.…”