DEPTH-DEPENDENT SPECTROSCOPIC DEFECT CHARACTERIZATION OF THE INTERFACE BETWEEN PLASMA-DEPOSITED SIO2 AND SILICON

We demonstrate the use of low-energy cathodoluminescence spectroscopy (CLS) to study optical transitions at defect bending arrangements at S i-SiO2 interfaces prepared by low-temperature plasma deposition. Varia ble-depth excitation achieved by different electron injection energies provides a clear distinction between luminescence derived from (i) th e near-interface region of the oxide film, (ii) the Si-SiO2 interface, and (iii) the underlying crystalline Si substrate. Cathodoluminescenc e bands at similar to 0.8 and 1 eV are assigned to interfacial Si atom dangling bonds with different numbers of back-bonded Si and O atoms. CLS also reveals higher photon energy features: two bands at similar t o 1.9 and 2.7 eV assigned to suboxide bonding defects in the as-grown oxide films, as well as a substrate-related feature at similar to 3.4 eV. The effects of hydrogenation at 400 degrees C and rapid thermal an nealing at 900 degrees C, and especially the combination of both proce ss steps is shown to dramatically reduce the intensities of the CLS fe atures assigned to interfacial and suboxide bonding defects. (C) 1998 American Institute of Physics. [S0003-6951 (98)03632-8].