Preparation of Thin Dielectric Film for Nonvolatile Memory by Thermal Oxidation of Si-Rich LPCVD Nitride

Abstract

In this work, we develop methods for fabricating high quality dielectric films for nonvolatile memory applications. Oxide/Si-rich nitride/oxide structures are fabricated where the Si-rich nitride layer was deposited by the low pressure chemical vapor deposition ͑LPCVD͒ technique. With a Si-rich nitride layer, the Fowler-Nordheim tunneling voltage can be cut down to 3 V for oxide thickness of about 100 Å. By reoxidizing the Si-rich nitride layer, secondary ion mass spectroscopy study reveals that the hydrogen content of nitride film and its interface can be reduced by more than 40%. With this method, high nitrogen content oxynitride and smoother oxynitride/oxide interfaces result and the interface charge trapping can be improved remarkably.

Nitride engineering and the effect of interfaces on Charge Trap Flash performance and reliability

“…The Refractive Indices of N + and Si + blanket films were measured using a spectroscopic ellipsometer and was found to be 1.983 and 2.125 respectively, consistent with their compositional difference [9]. In bi-layer stacks, Si + nitride of different thicknesses (see Table-2, devices D6 through D8) was deposited first, and then partially oxidized to produce ~2nm of SiON interface before N + nitride deposition [10]. The position of the SiON interfacial layer depends on the initial Si + nitride thickness as evident in Table-2.…”

Silicon oxynitride prepared by chemical vapor deposition as optical waveguide materials

“…High hydrogen content was found with oxynitride films prepared by chemical deposition method [4]. Hydrogen bonds in oxynitride films do not only affect the refractive index but also are the major sources for absorption loss of optical transmission in the oxynitride waveguide.…”

“…Several methods for solving this drawback have been proposed. The hydrogen content of oxynitride film was found to decrease by more than 40% by thermal oxidation of LPCVD silicon-rich silicon nitride film [4,5]. The hydrogen content can also be reduced significantly by increasing the nitric oxide flow rate during the PECVD growth of silicon oxynitride and conducting a high-temperature annealing after the deposition [6].…”

Effect of low temperature oxidation on dielectric properties of mercury sensitized photo-deposited silicon nitride films

“…However, the incorporation of hydrogen still takes place and therefore, the basic objective to obtain hydrogen free oxynitride films with a considerable amount of nitrogen to increase the dielectric constant of the film is not attained. Though efforts have been made to obtain hydrogen free oxynitride films by thermal nitridation of silicon oxide films with N 2 O, the nitrogen content of these films is very low [10]. So, in the present study, we opted for the thermal oxidation of photo-deposited silicon nitride films.…”