Browse Prior Art Database

Automatic Inline Analysis of Recirculated Etch Media

IP.com Disclosure Number: IPCOM000121656D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Related People

Reischmann, RW: AUTHOR

Abstract

By using a combination of a photospectrometer and a special optical system, it is possible to control, for example, recirculated etch media by photometric analysis in an online mode.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Automatic Inline Analysis of Recirculated Etch Media

      By using a combination of a photospectrometer and a
special optical system, it is possible to control, for example,
recirculated etch media by photometric analysis in an online mode.

      The key unit is a multichannel photospectrometer 1 comprising a
PC 2 and the appertaining operating software. To simultaneously
analyze several media by one spectrometer, the primary light of lamp
3 is split into the required number of individual beams.  These
different illumination paths are switched in a wrap-around fashion by
a chopper 4 and a chopper controller 5.  Light is transferred to and
from the terminal immersion cells by means of glass fibers, with the
length of each path being preferably adjustable in a range of 0.1 to
1.0 mm to compensate for the optical density of the analyzed medium.

      The housings of the immersion cells are made of materials
withstanding aggressive solutions, using, for example, TEFLON* and
Al2O3 ceramics for alkaline and acidic media, respectively.

      The photometric signals generated by the immersion cells are
transferred to the photometer.  The resultant spectra are converted
by the computer into concentration values which are used as process
control data.
*  Trademark of E. I. du Pont de Nemours & Co.