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Continuous Monitoring of the Etching of Reflecting Opaque Layers

IP.com Disclosure Number: IPCOM000087115D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Moritz, H: AUTHOR

Abstract

The etching of opaque layers is monitored by bringing into interference monochromatic light emanating from a light source and reflected by the areas being etched and the masked areas, respectively. The intensity of the resulting light is recorded against time. The progress in the etching process can be monitored as a function of the intensity fluctuations. After the layer has been etched from the substrate, the intensity becomes constant.

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Continuous Monitoring of the Etching of Reflecting Opaque Layers

The etching of opaque layers is monitored by bringing into interference monochromatic light emanating from a light source and reflected by the areas being etched and the masked areas, respectively. The intensity of the resulting light is recorded against time. The progress in the etching process can be monitored as a function of the intensity fluctuations. After the layer has been etched from the substrate, the intensity becomes constant.

The arrangement for monitoring the etching process comprises a photoresist pattern and an apparatus. The photoresist pattern (Figs. 2A and 2B), for example, consists of a sequence of parallel lines 10 or takes the form of a chessboard pattern 11. The apparatus (Fig. 1) comprises a light source 1 from which a monochromatic light beam emanates, a semitransparent mirror 2 upon which the beam impinges at an angle of about 45 Degrees, an etch tank 3 filled with an appropriate etchant and provided with a window 4 through which the light beam passes, a sample holder 5 to hold area 9 on sample 8 with the photoresist pattern perpendicular to the light beam, and a lens 6 focusing the light reflected by the masked and unmasked areas of said pattern and by semi-transparent mirror 2 on photocell 7, the output of which is plotted by a recorder. A typical output of the photocell, indicating the progress and the end of the etching process, is shown in Fig. 3.

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