Browse Prior Art Database

Exhaust Flowmeter/mass Spectrometer Plasma Process Monitor

IP.com Disclosure Number: IPCOM000060683D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hoffarth, JG: AUTHOR [+3]

Abstract

The development of plasma etch processes for a variety of applications has been limited by the lack of an effective real- process monitor. Laser interferometry is effective in monitoring etch rates for a small area but fails to work in an environment where highly non-uniform treatment of large surfaces is used. A measurement that is representative of a total process is accomplished by using an exhaust flowmeter in conjunction with mass spectrometry to determine the total mass of products removed from a plasma system at any time.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 84% of the total text.

Page 1 of 1

Exhaust Flowmeter/mass Spectrometer Plasma Process Monitor

The development of plasma etch processes for a variety of applications has been limited by the lack of an effective real- process monitor. Laser interferometry is effective in monitoring etch rates for a small area but fails to work in an environment where highly non-uniform treatment of large surfaces is used. A measurement that is representative of a total process is accomplished by using an exhaust flowmeter in conjunction with mass spectrometry to determine the total mass of products removed from a plasma system at any time.

The feasibility of this measurement is seen in the following example. For the process in which an organic polymer is etched with a CF4/02 gas, the total carbon in can be calculated from the gas composition and the gas feed rate. The etching process produces carbon effluent species; the total amount can be calculated from the composition of the polymer and the measured etch rate as determined by a suitable vehicle such as weight loss coupons.

The total etch rate produces a measurable amount of product carbon relative to the carbon present from the CF4 feed gas. The concentration of carbon in the exhaust stream can be determined by mass spectrometry, and the total carbon can be determined with the recommended flow rate measurement. The difference between this mass and that input from the CF4 feed is the total amount of carbon from etching. Using the known chemical formula for the et...