The optical properties of thin films are known to be affected by microstructural inhomogeneities. In this paper we study, using ellipsometry, the influence of microstructural disorder on the refractive index at 632.8 nm and on its dependence on temperature in the range 300–700 K in the case of thin noncrystalline low-pressure chemical-vapor deposition silicon films. It is found that films with large amorphous component have a behavior distinct from that shown by polycrystalline films. In particular, both the refractive index n and the thermo-optic coefficient dn/dT at room temperature have larger values for amorphous films than for polysilicon films. Furthermore, the thermo-optic coefficient dn/dT is found to vanish at about 500 K in the case of highly noncrystalline films.

It is well known (1–4) that substantial amounts of chlorine can be incorporated in normalHCl grown thermal oxides on silicon to effectively passivate sodium ions. It has been of interest to find out if similar effects can be obtained for oxides chlorinated by implanting Cl ions at the surface of SiO2 films on Si. It appears (5, 6), however, that when these films are annealed at temperatures in excess of 700°C, no Na neutralization property is evident. In this paper, we show with the help of 4He ion Rutherford backscattering (RBS) experiments on chlorine implanted into a thermal oxide film on Si that the oxide loses about 10 (50) percent of the implanted Cl during annealing at 600°C (1100°C) in nitrogen for 30 min. We obtain the diffusion coefficient D of Cl in SiO2 at various temperatures with the help of a process simulation program (SUPREM II) and show that for D∼D0expfalse(−Enormala/normalkTfalse) , D0=10−12 cm2/normals and Enormala∼0.5 normaleV . Corrections for system resolution and energy straggling effects are made to obtain the actual Cl density profiles in the SiO2 film. It is seen that Cl at 50 keV has a range of 440Å in SiO2 with a standard deviation of 220Å for a gaussian form.

Structural damage created in thermal oxides on silicon as a result of exposure to energetic ion beams leads to a change of its dielectric and chemical properties. Adverse effects on the oxide–silicon interface in the form of creation of interface states are also to be expected. Ion implanted oxides in MOS structures are studied with the help of MOS capacitance– and conductance–voltage characteristics, reactions of these oxides in etchant solutions, and ellipsometry. Interesting pattern of recovery of these properties is seen when the ion implanted samples are annealed at increasing temperatures.

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