Monitoring
Assessing semiconductor process gas purity via ultra-high sensitivity analysers
By Keith Cornell, strategic marketing manager, analytical instruments group environmental & process monitoring, at Thermo Fisher Scientific
T
he electronics sector is booming, and society’s growing hunger for increasingly powerful and compact devices is leaving semiconductor fabs struggling to keep up with demand. The microscopic scale of modern wafer assemblies means that they are extremely sensitive to contamination during manufacture, and even trace levels of impurities in ultra- high purity (UHP) process gases can lead to the scrappage of entire batches. Semiconductor fabs therefore need high sensitivity analysers to identify low level contamination of UHP gases before production is affected. This article highlights the pressures that manufacturers are facing, and takes a look at the cutting- edge solutions that are being employed to ensure a robust process and a quality end product.
A rapidly evolving market We are living through an era of increasingly short electronic device life cycles, driven by consumer desire for the latest and greatest mobile phones, computers and games consoles. At the same time, an increasing number of companies are embracing concepts such as the internet of things, artificial intelligence, machine learning and cloud computing, all of which require large amounts of processing power. Semiconductors are at the heart of all of these applications, so it is no surprise that the market has grown at a record pace in the past few years, and it is estimated to exceed £600 billion per annum by 2028 1
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The performance of semiconductors has increased at a remarkable rate since the first microchip was fabricated in 1958, almost perfectly matching Gordon Moore’s prediction of exponential growth. This is thanks to the rapid miniaturisation of transistors – which can now measure just a few nanometres in width – allowing
www.cieonline.co.uk.
assisting in the creation of wafer surface features. It is therefore no surprise that, as the demand for semiconductors continues to rise, so does the need for massive volumes of UHP gases, which make up the largest material expense behind silicon. Even extremely low levels of impurities in these gases – in the parts per trillion (ppt) range – can impact semiconductor production, penetrating wafer micropores to negatively affect material properties and leading to product failure. Furthermore, if these faults are not detected before the product reaches the market, it can lead to reputational damage and loss of future revenue. Identifying defective devices via comprehensive quality control procedures before they are shipped can protect manufacturers from these repercussions, but contaminated gas supplies can still ravage profitability through unnecessary waste, production line suspension and delays in supply. There has therefore been an industry-wide call for gas providers to implement increasingly strict testing protocols to guarantee the purity of the UHP gases that they deliver.
Proving purity
massive amounts of computational power to be packed into ever smaller envelopes. However, at this scale, even small manufacturing defects can significantly hamper device performance.
Demand for electronic specialty gases
UHP gases – including nitrogen, oxygen, argon, hydrogen and helium – are vital for semiconductor production. They are used for a range purposes, including inerting – to protect components from the harmful effects of moisture, oxygen and other contaminants in the atmosphere – etching and annealing applications, as well as
Regardless of supplier testing procedures, it is still common for semiconductor fabs to analyse these gases for trace impurities as part of their routine quality control programs, often using inline gas chromatography. However, the detection limits of this technique – between 100 and 500 ppt – are no longer sufficient in an industry where gas purity is a limiting factor. As a result, semiconductor fabs are turning to atmospheric pressure ionisation mass spectrometry (API-MS) to improve both analytical sensitivity and the range of contaminants that can be detected, including moisture, oxygen, carbon dioxide, carbon monoxide and methane. API-MS is fast becoming the industry
standard technique for the continuous monitoring of UHP gases, and combining this approach with advanced electronics and dedicated software solutions has further increased its sensitivity. However, the detection limits offered by a majority of instruments are still insufficient to meet the guidelines established by the semiconductor industry’s International Technology Roadmap of less than 100 ppt per impurity. Today, two of the only UHP electronic gas analysers that can provide sufficiently sensitive limits of contamination detection are the Thermo Scientific APIX δQ and APIX Quattro instruments, which boast impurity detection down to 10-50 ppt, far below the recommended limit.
Conclusion
The inverse correlation between a semiconductor’s size and its sensitivity to contamination means that low level impurity detection technologies are becoming more important than ever as electronic devices continue to shrink. Consequently, continuous monitoring techniques are now routinely employed in production to avoid the introduction of UHP gas impurities into the manufacturing process. Ultra-high sensitivity API-MS systems can offer manufacturers an accurate and reliable means of monitoring gas purity in real time, eliminating the potential for contamination and allowing semiconductor fabs to meet the needs of today’s fast-paced electronics market.
https://www.thermofisher.com/apixforsemicon
Global Semiconductor Market - Industry Trends & Forecast Report 2028. BlueWeave Consulting.
References 1
Components in Electronics March 2024 43
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