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In Situ Measurement of Layer Thickness and Deposition Rate in Electroless Processes

IP.com Disclosure Number: IPCOM000044495D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Druschke, F: AUTHOR [+3]

Abstract

The changing optical transparency of electrolytes, employed for the electroless deposition of metallic layers, is monitored at selected wavelengths for continuously measuring the deposition rate of the layers and their thickness. In the figure, sample 1, e.g., the substrate of a printed circuit board, is immersed in tank 2 with a suitable electrolyte. An optical probing beam 3, generated by a monochromatic or white light source 4, traverses the electrolyte through optical windows 5a, 5b (and optical filters, if necessary) to impinge on photodetector 6 connected to an amplifier/recorder 7. The optical transmission of wavelength bands, specifically to the metal ions present in the electrolyte, varies with the concentration of the metal ions during the electroless process.

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In Situ Measurement of Layer Thickness and Deposition Rate in Electroless Processes

The changing optical transparency of electrolytes, employed for the electroless deposition of metallic layers, is monitored at selected wavelengths for continuously measuring the deposition rate of the layers and their thickness. In the figure, sample 1, e.g., the substrate of a printed circuit board, is immersed in tank 2 with a suitable electrolyte. An optical probing beam 3, generated by a monochromatic or white light source 4, traverses the electrolyte through optical windows 5a, 5b (and optical filters, if necessary) to impinge on photodetector 6 connected to an amplifier/recorder 7. The optical transmission of wavelength bands, specifically to the metal ions present in the electrolyte, varies with the concentration of the metal ions during the electroless process. For a Cu-EDTA complex, for instance, the corresponding wavelength is 650 nm, and for Fe ions, 632.8 nm. The proposed method affords a simple, yet accurate and continuous, determination of process parameters that were previously accessible only by discontinuous measurements (with a weighing step before and after deposition).

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