Browse Prior Art Database

Lufran Hot Phosphoric Baffle System

IP.com Disclosure Number: IPCOM000105730D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Chandler, WF: AUTHOR [+2]

Abstract

Disclosed is a corrective measure to eliminate condensate and acid fumes from attacking equipment in a clean bench, and use baffle system to re-direct fumes and condensate away from sensitive areas.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 88% of the total text.

Lufran Hot Phosphoric Baffle System

      Disclosed is a corrective measure to eliminate condensate and
acid fumes from attacking equipment in a clean bench, and use baffle
system to re-direct fumes and condensate away from sensitive areas.

      An acid bath system needed to etch/strip Silicon Nitride is
operated at a very high temperature, usually between 160 and
185ºC.  This creates vapors which must be contained under a lid.
Installation of a baffle system re-directs the condensation runoff
caused by the vaporization of the hot acid.  This action directs the
condensed vapor away from exhaust ports, sensitive areas of the
etch/strip system, and also reduces permeation into the bench exhaust
plenum.

      In semiconductor processing, the use of chemical baths to etch
various films is required.  A hot phosphoric tank called a Lufran
system is used to etch silicon nitride Si sub 3 N sub 4 The problem
was with the design of the bath which allowed the condensed
phosphoric acid to run down the side of the tank (bath).  The problem
that resulted from this was that the acid was drawn through the
exhaust ports contaminating and attacking the equipment installed in
the bench.  As the condensed phosphoric acid continues to return to
the tank, the lower annular seal is attacked which causes the tank to
leak.

      To solve the aforementioned problem, a 2-inch-wide baffle
system of a quarter-inch white polypropylene was fabricated and
installed.  The baffle...