Leak-tight sealing for wafer handling module
08 February 2010
Trelleborg has helped semiconductor process equipment supplier, AP&S to develop a leak-tight sealing system for a novel thin wafer carrying system. The new ‘Cyclop Sealing’ capsule can be added, with only minor modification, to any semiconductor fabrication line
AP&S is a company that develops wet process equipment for the semiconductor industry. One of its more recent developments is the Cyclop Sealing capsule, a one-size-fits-all media tight carrying system that solves a number of problems associated with the processing of thin wafers.
The trend for semiconductor wafers to become thinner is being driven by a demand for chip cards and Radio Frequency Identification tags with a low package height. Case in point are the new device packaging schemes such as ‘chip-sized packages’ used in miniaturised products, and ‘Systems-in-a-Pack’ using chip stack methods, both of which are significantly smaller than conventional packages and require thinner semiconductor devices.
Conventional techniques for handling semiconductor wafers during processing and, in particular, for transferring wafers between processing tools, typically involve standard-sized cassettes, which hold a number of wafers at a time. This handling technique was developed for wafers that are rigid and typically 250μm or more in thickness. The latest, thinner wafers (of between 100μm and 50μm thickness) are extremely delicate and need to be fitted to a rigid carrier for handling.
AP&S’ new Cyclop Sealing capsule can be added to any semiconductor processing line with only minor modifications to existing processing tools, thus avoiding the expense of new equipment for processing thinner wafers. Its sealing system, jointly developed with Trelleborg Sealing Solutions, has a leakage rate below 0.1% even after lifetime testing of opening and closing cycles (at temperatures between +20°C and +90°C and at pressures from 0.5 to 2bar).
Vital to the capsule’s function is its sealing system (a patent for which is pending). Jointly engineered with Trelleborg Sealing Solutions, this protects the substrate from unwanted process influences and also any damage caused by forceful closing of the capsule. Each capsule consists of six components, the front ring, rear plate, locking ring and, making up the sealing system, three gaskets manufactured of specially developed sealing materials that are compatible with media commonly used in semiconductor processing.
Substantial research was undertaken to ensure that the capsule and its sealing system met industry requirements.
This included tests to evaluate surface tension optimisation; temperature change stability; mechanical stress due to media flow and relative movement; the influence on impermeability of structures on the substrate, and the reliability over lifetime opening and closing cycles. In all tests Cyclop Sealing performed well and met all the test criteria.
During opening and closing test the capsule underwent 2,600 automated opening and closing cycles without breach of the seal.
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