Other

Speedfam-Ipec Co Ltd

Takeshi Sadohara

Michihiko Yanagisawa

Yasuhiro Horiike

Shinya Iida

Chikai Tanaka

A wafer flattening system is provided to consecutively and automatically remove the natural oxide film from a wafer and flatten and smooth the wafer so as to improve the surface roughness of the wafer and improve the work efficiency. A step of immersing the wafer in an aqueous solution of hydrofluoric acid of a natural oxide film removing device is performed so as to remove the natural oxide film, then followed by a step of locally etching the surface of the wafer at a local etching apparatus by an activated species gas produced from SF gas to flatten the surface. Then, a step of giving a mirror finish to the wafer surface by a CMP apparatus is performed to smooth it. It is also possible to perform the step of removal of the natural oxide film by spraying the entire surface of the wafer by an activated species gas produced from a mixed gas of CF gas and H gas and possible to perform the step of smoothing by spraying the entire surface of the wafer by an activated species gas produced from a mixed gas of CF gas and O gas.

Wafer flattening system

A wafer flattening process for improving the micro-roughness of a wafer by local etching while maintaining a distance between a plasma discharge location and the wafer surface at a predetermined value. By executing a plasma generating step, SF,gas in a gas cylinder,is fed to the inside of an alumina discharge tube,then plasma discharge of the SF,gas is caused by a plasma generator,to produce an activated species gas G and which is locally sprayed from a nozzle portion,of the alumina discharge tube,to the surface of the silicon wafer W. In this state, by performing a local etching step, the surface of the silicon wafer W is flattened. At this time, the distance from the approximate center of the plasma discharge location to the surface of the silicon wafer W is set to a distance larger than 3000 times the mean free path of the ions in the activated species gas G and smaller than 6000 times. Due to this, the ions in the activated species gas G are extinguished before being sprayed from the nozzle portion,and therefore the surface of the silicon wafer W is etched by only the neutral radicals without being damaged.

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Ayase, Japan

Takeshi Sadohara