Browse Prior Art Database

Diffusion Boat

IP.com Disclosure Number: IPCOM000086259D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Wu, LL: AUTHOR

Abstract

A diffusion boat is shown that has been successfully used up to a temperature 1350 degrees C without damaging either silicon wafers or the boat itself.

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Diffusion Boat

A diffusion boat is shown that has been successfully used up to a temperature 1350 degrees C without damaging either silicon wafers or the boat itself.

A schematic diagram of this boat is shown in Figs. 1 and 2 which are the top view and side view, respectively. The boat consists of quartz rod holder 10, wafer holder 12, heat isolator 14, heat shield 16 and spacers 18. The wafers are item 20.

The quartz rod holder 10 is fabricated with thin quartz rods. The thermal conductivity of quartz will reduce heat flow from the furnace wall to the wafer 20. The wafer holder 12 is made of a silicon wafer (or sapphire with 1 mu finish for temperature higher than 1150 degrees C), and a silicon ring with spacers 18. The silicon ring is laid up on the silicon wafer. Then the wafer 20 to be processed is laid on the silicon wafer inside the silicon ring. Since the wafer 20 is laid horizontally, the mechanical stress arising either from its own weight or thermal mismatch is minimized.

The spacer 18 (20-30 mils) on the silicon ring is used to separate the holder from holder. Each holder is kept from sliding by four long quartz rods of the quartz rod holder 10. All surfaces of silicon pieces are lapped with alumina (320 grite) powder to obtain a dull surface. The main purpose of this lapping is to prevent sticking between two silicon pieces.

To trap heat which might still flow between the wafer holder 12 and the quartz, a heat isolator 14 is used. Three to four empty...