Browse Prior Art Database

Etch Develop Rate Cell

IP.com Disclosure Number: IPCOM000086030D
Original Publication Date: 1976-Jul-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Giuffre, GJ: AUTHOR [+4]

Abstract

Because the reflected light intensity is measured at discrete time increments and divided by a reference light intensity from the light source, he rate of change of reflectivity can be measured and corresponds to the etch/develop rate. The completion of the etch is calculated by knowing this rate and the thickness of the layer being etched.

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Etch Develop Rate Cell

Because the reflected light intensity is measured at discrete time increments and divided by a reference light intensity from the light source, he rate of change of reflectivity can be measured and corresponds to the etch/develop rate. The completion of the etch is calculated by knowing this rate and the thickness of the layer being etched.

An end-point detector determines the time required to etch or develop a layer on a substrate such as a semiconductor wafer 1. The detector includes a light source 2 which channels light through fiber optic probes 3 directed at a tank 4 of etchant/developer and at different portions of the substrate, when the substrate has been inserted into the tank 4 by the gripper means 5. The temperature of the tank is controlled by circulating water through an outer jacket 6 and a heat exchanger 7 operated by a temperature controller 8.

Each channel of light is received on the opposlte side of the tank 4 and split, passing the substrate reflected light through two filter wheels 9A and 9B. The specific filter 10 is identified by sensors 11A and 11B. The different filters 10 in the two filter wheels permit the reflected light signals to be observed at different wavelengths, so as to select the best signal response for the particular layer being etched/developed.

The light signal, received at the photodetectors 12A and 12B, is amplified, then converted to digital signals and sent via data collection circuitry 13 to a bu...