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Means to Measure Flow over a Sidewall within a Plating Cell

IP.com Disclosure Number: IPCOM000238474D
Publication Date: 2014-Aug-27
Document File: 1 page(s) / 29K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed are various means to measure the flow of chemistry across a weir within a plating cell in order to confirm that the chemistry within the cell is covering the wafer and is correctly mixed and maintained.

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Means to Measure Flow over a Sidewall within a Plating Cell

In order to maintain a uniform current distribution, many plating cells pump chemistry up through a bottom opening within a plating cell. Then, the plating chemistry cascades over a weir and back into the reservoir. The flow rate coming out of the pump is measured. Several incidents have resulted in cracked fittings or secondary flow paths within the plating cell. This is a problem because the chemistry can move back into the reservoir through these cracks. This has led to non-fully immersed wafers during plating and/or incomplete mixing of the chemistry within the plating cell leading to defects on the wafer.

This solution establishes various means to measure the flow of chemistry across a weir within a plating cell in order to confirm that the chemistry within the cell is covering the wafer and is correctly mixed and maintained. The first part of the novel contribution is a method and apparatus for detection of desired flow over a sidewall of a chemical container. This is an improvement over the detection of flow into the container, because it can be used to verify that the liquid is flowing along its correct path through the container, without bulk flow loss through other paths. Sensors are installed in representative locations along the intended overflow path. The second part of the novel contribution is a method and apparatus for detecting various flow rates over a sidewall of a chemical container....