The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl 4 following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photoninduced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states/doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl 4 lead to a remarkably enhanced production of anionic, Si − and Cl − , fragments and excited neutral atomic, Si * , fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl 4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.

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Recent studies of electron cyclotron resonance (ECR) plasma etching for fabricating fine patterns of less than a half-micron indicate a serious problem in the etched profiles caused by a charge build-up of the patterns. The relationships between the local pattern distortion and the plasma properties measured by the electrostatic probe are investigated. Lowering the electron temperature perpendicular to the surface normal is one of the most effective techniques for eliminating the local side etch. It is enhanced by setting the wafer at the lower magnetic field. As the large space charge bends the ion trajectories, the higher ion current density also enhances the local side etch. The distribution of plasma potential which accelerates the ions can reduce the local side etch in spite of the higher current density.

The dependence of TiN/TiSi2 bilayer formation on Si by lamp annealing of Ti upon annealing temperature, ambients, and impurity in Si was investigated. In NH3 ambient, nitridation ratio on undoped Si at 680 and 800 °C is 40% and 25%, respectively. When annealing is performed in N2, the nitridation ratio of Ti is only about 25% at both 680 and 800 °C. The above dependence of nitridation ratio on annealing ambient is due to the difference in decomposition energy of gas molecules. The nitridation ratio increases on arsenic-implanted Si because of a retardation effect of the arsenic on the silicidation reaction. The bilayer formation process was applied to the AlSi contact metallization on the n+ diffused layer. From measurements on electrical characteristics of the AlSi/TiN/TiSi2/n+ Si contact system, the following results were obtained: (1) Contact resisitivity is 3.5–5.3×10−7 Ω cm2. (2) The TiN/TiSi2 contact electrode is thermally stable against Al. In particular, when the bilayer is formed in NH3 at comparatively lower temperature, its thermal stability is still further improved. This is due to the formation of the thicker surface TiN layer.

Silicidation of titanium (Ti) thin films sputter-deposited onto silicon (Si) was performed by the halogen lamp annealing method. This method was found to be quite effective in forming oxide-free and homogeneous titanium disilicide (TiSi2). Temperature dependence of silicidation was investigated by using Rutherford backscattering spectroscopy, x-ray diffraction, and sheet resistance measurements. It was found that the dominant crystal phase of silicide formed during annealing at 600 and 625 °C for 90 sec was titanium monosilicide (TiSi), and that a homogeneous TiSi2 with resistivity of ∼15 μΩ cm was formed at 700 °C. Self-aligned TiSi2 with low resistivity can be obtained with two-step annealing: the first-step annealing was carried out below 600 °C and followed by removal of unreacted Ti on silicon dioxide (SiO2), and the second-step annealing was carried out above 650 °C.