Thermally stimulated desorption and x-ray photoelectron spectroscopy were used to study the air oxidation at room temperature of HF-treated Si(100) surfaces. The desorption results indicated an appreciable density of hydrogen at the surface. Air oxidation experiments with predesorbing surface hydrogen were carried out and an obtained linear relationship between the amount of H2 desorption and oxidation indicated that the oxidation was allowed by H2 desorption. The surface hydrogen was also found to be stable in air at room temperature and to contribute to a retardation in air oxidation of the surface.

The relation between generation of neutral electron trap centers and hole trapping in thermally grown SiO2 under Fowler–Nordheim tunneling stress has been investigated. The experimental results show that the density of neutral electron trap centers is proportional to the density of trapped holes under Fowler–Nordheim tunneling stress with various electric fields and the total number of electrons injected into the oxide. The generation mechanism is explained by a model based on strained bonds.

We have applied cathodoluminescence (CL) and Raman spectroscopies to shallow trench isolation (STI) processes in large scale integration to investigate crystalline defects and stresses by extracting the wafer after each process. A sample with high standby leakage current clearly showed dislocation-related luminescence lines (D lines) in the regions surrounding the memory cell. These regions contain various sizes of active and field areas ranging from 0.5to5μm. However, a normal sample showed no D lines in any region through the STI processes. The D lines were observed after liner oxidation, which was performed after trench patterning. Raman microprobe measurements showed that the trench patterning process generated a large inhomogeneous stress distribution up to 200MPa in the regions surrounding the memory cell. The inhomogeneous stress distributions caused by the trench patterning and the subsequent thermal processes are likely the main causes of dislocations. A comparison between the D lines in the CL spectra and the stress measured by a Raman microprobe clarified the mechanism of generation of crystalline defects. We can thus optimize the process conditions in STI processes by these spectroscopic methods.

X-ray photoelectron spectroscopy (XPS) has been applied to characterize the damage introduced into SiO2 by ion implantation. By measuring the peak width of Si2p from SiO2 which corresponds to perturbation of the SiO2 network, good depth profiles of the damage have been obtained for implanted samples and subsequently annealed samples. The results show that the damage distributed more widely than that calculated from energy deposition and that the perturbation of the network is caused not only by radiation damage but also by the existence of impurities in the network. It has been found that the XPS method is effective to understand the atomic structure, and thus, electrical properties of SiO2.

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