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Browse Prior Art Database

Variably Spaced Wafer Boat

IP.com Disclosure Number: IPCOM000061145D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Dellacorte, RT: AUTHOR [+4]

Abstract

A modification to the conventional boat used to hold semicon- ductor wafers in open tube deposition processes results in improved deposition uniformity. The boat is lengthened and additional guard wafers are inserted in the gas inlet end, thereby improving the flow of reactant gases over the wafers being processed.

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Variably Spaced Wafer Boat

A modification to the conventional boat used to hold semicon- ductor wafers in open tube deposition processes results in improved deposition uniformity. The boat is lengthened and additional guard wafers are inserted in the gas inlet end, thereby improving the flow of reactant gases over the wafers being processed.

The reactant concentration decreases as the reaction-deposi- tion proceeds along the length of the boat and there are trans- ient laminar flow conditions or end effects in areas where obstructions to the flow are present, such as around the ends of the boat. Variably spaced boats used in conventional processing have product waferst at both the gas inlet and outlet ends flanked by three equally speced guard wafers, so product wafers will not be affected by the end effects. Additionally, the wafer spacing is increased from the gas inlet end to the gas outlet end of the boat. This enhances gas diffusion between the wafers and thereby counters the effect of decreased reactant concentrations on the resistivity level.

It has been determined that gas flow in the furnace tubes is laminar and that laminar flow inlet lengths for the gases flowing around the deposition boat front are significant. This is believed to contribute to deposition nonuniformity on product wafers located in this area of the boat. The variably spaced boat was modified to include addtional wafers at the front of the boat ahead of any product wafers. This modifica...