We have used chemical depth profiling, with a depth resolution of 10 A, in conjunction with x‐ray photoelectron spectroscopy to study the composition and chemical bonding in thin silicon oxides grown in N2O with both a conventional furnace and a rapid thermal annealer (RTA) process. The nitrogen profiles of RTA and furnace oxides differ, with the RTA oxides showing an increase in nitrogen concentration at the interface and the furnace oxides showing a more uniform nitrogen distribution. The percentage of nitrogen at the interface also differs, and correlates with a reduction in interface state generation under current injection for increased nitrogen concentration. The chemical environment for the nitrogen changes with distance from the interface, and this is attributed to an increasing number of nitrogen—silicon bonds near the interface.

Role of interfacial nitrogen in improving thin silicon oxides grown in N2O

Oxynitrides can suppress the diffusion of boron from the polycrystalline silicon gate electrode to the channel region of an ultralarge scale integrated device, and are therefore important potential substrates for thin SiO2 gates. Direct oxynitridation of Si in N2O is a simple and manufacturable N incorporation scheme. We have used rapid thermal oxidation to grow O2‐ and N2O‐oxides of technological importance (∼10 nm thick) in the temperature range 800–1200 °C. Accurate measurements of the N content of the N2O‐oxides were made using nuclear reaction analysis. N content increases linearly with oxidation temperature, but is in general small. A 1000 °C N2O‐oxide contains about 7×1014 N/cm2, or the equivalent of about one monolayer of N on Si (100). Nonetheless, this small amount of N can retard boron penetration through the dielectric by two orders of magnitude as compared to O2‐oxides. The N is contained in a Si‐O‐N phase within about 1.5 nm of the Si/SiO2 interface, and can be pushed away from the interface...

Rapid thermal oxidation of silicon in N2O between 800 and 1200°C: Incorporated nitrogen and interfacial roughness

This letter reports, for the first time, N/sub 2/O-grown oxides on both n-type and p-type 6H-SiC wafers. It is demonstrated that the N/sub 2/O-grown technique leads to not only greatly improved SiC/SiO/sub 2/ interface and oxide qualities, but also considerably enhanced device reliabilities as compared to N/sub 2/O-nitrided and conventional thermally oxidized devices. These improvements are especially obvious for p-type SiC MOS devices, indicating that N/sub 2/O oxidation could be a promising technique for fabricating enhancement-type n-channel SiC MOSFETs.

/pdf/improved-performance-and-reliability-of-n-2-o-grown-2d9reb5fwq.pdf

Improved performance and reliability of N 2 O-grown oxynitride on 6H-SiC

In this letter, we report our study on an oxide‐nitride‐oxide (ONO) heterostructure as a dielectric material in a metal‐insulator‐semiconductor field‐effect transistor with Si as a semiconductor. The electrical properties of the ONO dielectrics have been correlated with: (i) the process related effects; (ii) the accumulation of N atoms and its bonding with Si at the SiO2/Si interface; and (iii) the chemical bonding within the nitride layers. By combining the remote plasma enhanced chemical vapor deposition and the rapid thermal annealing process, the device quality ONO structure with an oxide equivalent thickness of 4.7 nm has been successfully manufactured.

Ultrathin device quality oxide‐nitride‐oxide heterostructure formed by remote plasma enhanced chemical vapor deposition

Role of Surface Chemistry in Semiconductor Thin Film Processing.

The composition of ultrathin oxides grown on both [100] and [111]Si substrates in pure N2O in a conventional furnace has been studied using Auger electron spectroscopy (AES) analysis, chemical etching, and electrical measurements. Results show a peak nitrogen concentration at the Si‐SiO2 interface which decreases from the Si‐SiO2 interface to the oxide surface. This nitrogen distribution is responsible for superior electrical properties of metal‐oxide‐semiconductor (MOS) devices with these films as gate dielectrics.

Study of the composition of thin dielectrics grown on Si in a pure N2O ambient

In this letter, the electrical properties of thin low‐pressure chemical vapor deposited (LPCVD) SiO2 annealed in N2O ambient have been studied and compared with thermal oxide of identical thickness. It is shown that N2O‐annealed CVD oxide exhibits less interface state generation and less flatband voltage shift under constant current stress than thermal oxide. It also has excellent uniformity and comparable breakdown characteristics. An oxynitride film formation at the Si/SiO2 interface by annealing in N2O is speculated to be the cause of these improvements.

Jinho Ahn

Papers

Study of the composition of thin dielectrics grown on Si in a pure N2O ambient

High quality thin gate oxide prepared by annealing low‐pressure chemical vapor deposited SiO2 in N2O