Browse Prior Art Database

Opening Diffusion Capsules

IP.com Disclosure Number: IPCOM000076068D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Pak, MS: AUTHOR

Abstract

Capsule diffusion is accompanied by long and tedious post cleaning operations to take off diffusion source powder from the wafer surfaces. The source powder comes onto the surfaces during wafer loading and capsule opening operations. The forces holding the particles to the surfaces are electrostatic and mechanical in nature, since ultrasonic agitation removes them.

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Opening Diffusion Capsules

Capsule diffusion is accompanied by long and tedious post cleaning operations to take off diffusion source powder from the wafer surfaces. The source powder comes onto the surfaces during wafer loading and capsule opening operations. The forces holding the particles to the surfaces are electrostatic and mechanical in nature, since ultrasonic agitation removes them.

The conventional method of opening evacuated capsules is to grind away a portion of the capsule to 25-35 mil thickness, puncture a small hole through this film with a pointed object and a mallet. Once the vacuum is released, the whole capsule is sawed or broken open. In this method, no provision is made to minimize or eliminate powder contamination during wafer loading and capsule opening.

The source powder 8 in this technique is not in the proximity of the wafers 12, but in its own closed container 10. A quartz fitted (porous) cover 6 covers the container 10. properly fitted, it will allow free passage to gases (air, diffusing atoms) and block the passage of source powder during wafer load, pump down and capsule opening operations. The source powder is, thereby, prevented from reaching the wafers 12 both during wafer loading and capsule opening operations. The container containing the source powder 8 is placed on or next to wafer boat 14 and wafers 12 are loaded thereon. The container 10 and loaded boat 14 are placed with plug 16 in capsule 15, pumped down to a low pressure ...