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Advanced Node Semiconductor Materials Reliance on SQC

The semiconductor manufacturing industry is driven by the continuous quest for economical production of smaller, more powerful, and more energy-efficient chips in a fiercely competitive environment. Fabrication facilities operate up to 24 hours a day, 7 days a week, 365 days a year producing hundreds of identical die (unpackaged chips) on single silicon wafers that each undergo over 600 processing steps, taking up to 60 days of processing time from start to finish.

Companies at the forefront of the industry are utilizing advanced node semiconductor manufacturing techniques to produce the current generation of chips used in mass market consumer electronic devices. A chip can contain billions of transistors and the structure of these units has evolved from planar to 3D architecture. The latest technology node in production uses devices where the smallest printed feature is just 14nm in width (by contrast, a single piece of paper is 100,000nm thick) and deposited films can be counted in numbers of atomic layers.

Implementing an additional dimension to transistor architecture increases both manufacturing complexity and cost. Enormous financial commitments are required to be competitive in this industry, with annual R&D and capital investments in the order of $10B USD. It is no wonder that quality expectations of materials used in advanced node semiconductor manufacturing are unrivalled in their stringency.

One tool Linde uses to ensure that their suppliers meet these meticulous quality requirements is Statistical Quality Control (SQC): the use of statistical methods to monitor and control a process. In SQC, process data is used to calculate upper and lower control limits, which are distinct from specification limits. There are a number of control chart trend rules (Western Electric Rules) used in SQC to identify unusual occurrences. The most basic of these is rule #1 – one point beyond either control limit – and this must be adopted in application of SQC.

Linde requests SQC control charts from their suppliers on a quarterly basis to ensure that incoming materials received are high-quality, consistent, and predictable in performance and that potential instabilities in product characteristics are identified early.

The figure below shows a simplified example of a SQC chart for Material Y produced by a supplier using moisture content as a key control parameter being monitored and assuming one batch produced per day. All values are hypothetical.

This level of focus on stability is crucial to semiconductor customers, who can already link deposited film thickness variations to minor cylinder-to-cylinder product differences. As semiconductor manufacturing technology continues to advance to smaller and more complex geometries, there will be even greater emphasis on impurity specifications and tighter control limits.

Linde’s semiconductor customers inhabit a global, fast-paced, high-precision manufacturing environment. Supporting customers in this environment requires Linde to engage in active collaboration with their suppliers in areas such as implementation of robust SQC processes. Through this approach, Linde contributes to establishing the high-quality supply chain required to enable success for their customers.

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This blog post was contributed by Ryan McGrath, Head of Global Quality Management, Linde Electronics. For more information, contact Francesca Brava at francesca.brava@linde.com.

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