Kabushiki Kaisha Toshiba

Kunihiro Terasaka

Akihito Yamamoto

Kikuo Yamabe

Hideyuki Kobayashi

Naohiko Yasuhisa

Souichi Nadahara

Riichiro Shirota

Seiichi Aritome

Kazuhiro Shimizu

Tadashi Iguchi

Hiroaki Tsunoda

Kazuhito Narita

Hirohisa Iizuka

Naoki Koido

In a nonvolatile semiconductor memory device, a charge accumulation layer is formed between adjacent two device isolation regions, at least a portion of the charge accumulation layer sandwiched with the device isolation regions has side walls each having a taper angle of 80 degrees or more and less than 90 degrees so that the charge accumulation layer at a lower end has a width wider than that at an upper end, a size of an opening of each of the device isolation regions is 0.25 &mgr;m or less, and a gate length of a memory cell is 0.2 &mgr;m or less.

Nonvolatile semiconductor memory device having tapered portion on side wall of charge accumulation layer

A method of processing a semiconductor substrate includes the step of subjecting a semiconductor substrate to a heat treatment under a gaseous atmosphere. The method comprises the step of subjecting a semiconductor substrate to a heat treatment at temperatures not lower than 1100.degree. C. under a non-oxidizing atmosphere, wherein heat treatments before said heat treatment applied to the semiconductor substrate are applied under heat treating temperatures and heat treating time which fall within a region defined by a line connecting four points of (900.degree. C., 4 minutes), (800.degree. C., 40 minutes), (700.degree. C., 11 hours) and (600.degree.0 C., 320 hours) in a graph, in which the heat treating temperature is plotted on the abscissa and the heat treating time is plotted on the ordinate of the graph.

Semiconductor substrate and method of processing the same

A method of processing a semiconductor substrate includes the step of subjecting a semiconductor substrate to a heat treatment under a gaseous atmosphere. The method comprises the step of subjecting a semiconductor substrate to a high temperature heat treatment at temperatures not lower than 1100.degree. C. under a non-oxidizing atmosphere, wherein heat treatments before the high temperature heat treatment applied to the semiconductor substrate are applied under heat treating temperatures and heat treating time which fall within a region defined by a line connecting four points of (900.degree. C., 4 minutes), (800.degree. C., 40 minutes), (700.degree. C., 11 hours) and (600.degree. C., 320 hours) in a graph, in which the heat treating temperature is plotted on the abscissa and the heat treating time is plotted on the ordinate of the graph.

Method for heat treating a semiconductor substrate to reduce defects

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Tokyo, Japan

Kunihiro Terasaka