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Semiconductor Leading Edge Technologies, Inc.

Satoshi Kume

Yukihisa Wada

A cleaning apparatus is provided with a processing bath to be filled with a cleaning chemical, an ultrasonic oscillator, and a retainer for holding a substrate to be immersed into a cleaning chemical. The front surface of the substrate is cleaned while ultrasonic waves are radiated from the ultrasonic oscillator onto the back surface of the substrate.

Apparatus and method of cleaning a substrate

On the sides of a gate electrode, layered-film sidewalls are formed which includes a first oxide film such as an NSG film or a TEOS film and a second oxide film such as a BPSG film or a PSG film. After the layered-film sidewalls are used as a mask for forming source and drain regions of a MIS transistor, the second oxide film of the sidewalls is selectively removed. At the removal, wet etching is performed with an aqueous solution containing hydrofluoric acid, and acetic acid or isopropyl alcohol. This makes etching selectivity between oxide films higher and removes only the upper second oxide film. As a result, in the formation of two types of oxide films which differ in their etching properties, the etching selectivity can be prevented from deteriorating.

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Kanagawa, Japan

Satoshi Kume