We investigated the effects of fluorine on boron diffusion in thin silicon oxides used for metal-oxide-semiconductor structures, including silicon dioxide and oxynitride. We used secondary ion mass spectroscopy to measure the boron penetration depth from p+-polycrystalline silicon to the silicon substrate through the silicon oxides for various fluorine doses. We compared experimental and simulated results and determined the boron diffusion coefficients in the silicon oxides. The diffusion coefficients have an Arrhenius relationship for each fluorine dose. The diffusion coefficients at a fluorine dose of 1×1016 cm−2 were 30 times larger than with no fluorine dose, and at a fluorine dose of 1×1015 cm−2, diffusion coefficients were 5 times larger. With oxynitride, fluorine has the same enhancing effect. With no fluorine, the diffusion coefficients were independent of oxide thickness. When fluorine is implanted into polycrystalline silicon, especially with a high dose, the diffusion coefficient is larger for thinner oxides because of the higher fluorine concentration.

The Ag-In-Sb-Te system is widely used for phase-change discs such as compact disc rewritable (CD-RW) and rewritable digital versatile disc (DVD+RW). To clarify the effect of Ag and In in the Ag-In-Sb-Te system, we studied the local structure of Ag-In-Sb-Te phase-change material by extended X-ray absorption fine structure (EXAFS). The results suggest that the existence of Ag contributes to the thermal stability of amorphous marks and existence of In contributes to high-speed phase-change.

We studied boron diffusion in thin silicon oxides including pure SiO2 and oxynitride that are used for metal‐oxide‐semiconductor transistors. We measured the boron penetration using secondary ion mass spectroscopy. By comparing simulated and experimental results, we found that the boron diffusivity in pure SiO2 , DPO , is 3.96×10−2expfalse(−3.65 normaleV/normalkTfalse)cm2/normals , and that in oxynitride containing 4% nitrogen, DNO , is 3.42×10−2expfalse(−3.75 normaleV/normalkTfalse)cm2/normals . We also obtained an analytical critical time model for the onset of boron penetration. Our model predicts that the critical time is proportional to reciprocal of diffusivity, and hence the time in oxynitride is about 2.5 times that in pure SiO2 .

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.

No abstract