Kenichi Hikazutani

Ashing of Ion-Implanted Resist Layer

The stripping method of high-dose ion-implanted resist layers was studied on the basis of the chemical structure of carbonized layers formed by ion implantation and that of residues remaining on the wafer surface after O2 plasma ashing. The chemical structure of the carbonized layer was observed with solid NMR and that of residues was analyzed with XPS. A decrease in the etching rate of the high-dose ion-implanted resist was caused by carbonization of polymers of the resist. Residues were mainly formed during O2 plasma ashing by chemical reaction between oxygen and implanted species, i.e., the main component of residues was oxide of the implanted species. On the basis of these results, to remove the high dose ion implanted resist without damage, we developed a two-step ashing process which was composed of H2 RIE and downstream ashing, and achieved the purpose.

Interface Roughness Produced by Nitrogen Atom Incorporation at a SiO2/Si(100) Interface

The critical amount of nitrogen atoms at the interface, above which the roughness of the oxynitride/Si(100) interface increases, was studied using noncontact-mode atomic force microscopy and X-ray photoelectron spectroscopy. The interface roughness was found to increase upon increasing the amount of nitrogen atoms at and near the interface if the amount of nitrogen atoms is greater than 0.37 monolayers. This increase in interface roughness was found to be reflected in an increase in surface roughness of almost the same amount.

The Analysis of Slip Extension and Induced Stress in 300 mm Diameter Wafers on Three-point Symmetrical Support

We performed slip tests using 300 mm diameter wafers on an inner three-point symmetrical boat in a batch-type vertical furnace. The maximum temperatures necessary to avoid a slip are shown for low-oxygen content and heavily boron-doped wafers. After studying the dependence of slip extension on wafer-annealing time at temperatures above 1100°C, we discuss the influence of bending stress on slip extension. It is emphasized that inner three-point symmetrical support has an advantage that the resolved shear component of thermal stress is considerably lower than that in the peripheral support as well as that of bending stress is.