Front End | Electronic Components Supply Network ‘Chips: thrice ‘cooked’ and then some’


The ongoing shortages of some semiconductors key to many manufacturing operations has dominated headlines in the trade media for some time and is now getting much needed exposure in mainstream publications and greatly improving public understanding of technology manufacturing’s role in economic success. In this article, Adam Fletcher, chairman of the Electronic Components Supply Network (ecsn), provides an overview of the current problems besetting chip manufacturers but notes “the semiconductor market is highly competitive and I’m confident that the economic necessities of commercial organisations will result in a market correction in the near future”.


Increasing public awareness The current shortage of semiconductors limiting the availability of electronic goods and new cars has provided the public with some idea of the importance of the electronics industry and particularly of advanced semiconductor manufacturing. In conversations with civil servants and industrialists about the investment needed to support advanced semiconductor manufacturing the general response is invariably one of disbelief and the assertion that “there must be easier ways to generate growth and profit than by making huge and risky investments in semiconductor manufacturing”. They may well be right: The short history of the semiconductor industry is littered with organisations that have struggled to become financially successful and have survived primarily by merger and acquisition to bolster both the market opportunity and the economics of size, scale, learning and knowledge. But it requires deep pockets and a healthy appetite for risk.


The most advanced manufacturing operations


Manufacturing advanced semiconductor products is today the most technically complex and challenging manufacturing process, period! It starts with only a handful of highly specialised organisations able to manufacture a silicon ‘boule’ (an object the size of a large log), achieved


10 April 2022


by melting polysilicon with boron and phosphorous at 1420˚C, ‘seeding’ it and then ‘rotating and pulling’ it to produce pure polycrystalline silicon. The ‘boule’ is then sliced into 1mm thick ‘wafers’ which are lapped, chemically etched and polished to exacting tolerances before being either annealed, vaporised, ion implanted or bonded according to the requirements of the semiconductor manufacturer, before being consigned to an inert-gas filled ‘carrier’ for onward ‘travel’ through the multiple stages of the ‘batch’ manufacturing process. The batch of wafers are oxidised and coated with insulating and conducting materials along with a photoresist and ‘cooked’ in a furnace, which is why semiconductor plants are often referred to as ‘foundries’. Patterns are then ‘printed’ on to the wafers using UV light or electron beam lithography. When the photoresist is chemically removed the unprotected layers are exposed and the wafer is returned to the furnace and heated to remove the solvent chemicals. Unprotected areas of the wafers are cleaned by gases and chemicals in an ‘etching’ process. Finally, the wafer is ‘doped’ by the addition of a conductive layer and metal is added by a chemical vapor deposition process and the wafer is ‘etched’ once again. This ‘oxidisation and coating, lithography, bake, doping, metal deposition and etching’ cycle is repeated hundreds of times until all the transistor layers have


Components in Electronics


been completely produced on the batch of wafers. Each ‘cycle’ generally taking 24 hours due to heating / cooling required and equipment availability / capacity, so it’s no surprise that the lead-time to manufacture a wafer is directly related to the time it takes to complete each process cycle and the number of cycles required. The entire process is subject to exacting statistical process control standards to ensure the manufacturing process is reliably repeated and any process flaws identified and corrected quickly. The value of the wafer increases with each process ‘cycle’ and an error can effectively scrap the entire ‘batch’ of partially process wafers which will then take ‘n’ cycles (time) to recover. At this point the initial ‘front end’ semiconductor wafer manufacturing process is complete and the ‘batch’ of wafers in their ‘carrier’ is ready to undergo ‘back-end’ assembly into a physical package, undergo multiple test cycles and device sort (based on performance characteristics i.e. fastest, lowest power etc.,) and finally inserted into tape & reel, tray or tube packaging. This is also a very complex process where there is inevitably a degree of ‘yield loss’, which only significant on-going investment in specialist production capacity is able to mitigate. No surprise then that this concluding stage is often outsourced to specialist third-party organisations.


Nuts economics Building a new state-of-the-art


semiconductor foundry with the capacity to process 50,000 wafers a month is projected to cost circa $15billion. This investment must be depreciated in three to five years, which suggests that output sales revenues - internal and/or external - need to be in the range $3-to-$5 billion per year, demanding 24/7/365 operation. To return a profit a semiconductor foundry needs to continually operate in excess of 70 per cent of its planned capacity but ideally would deliver capacity utilisation in the 95 per cent+ range with a ‘process yield’ (known good product) of 99 per cent+. In addition, the operating costs and capital equipment upgrades need to be funded over the depreciation period, as do the carefully choreographed maintenance operations. Only large and successful organisations (or governments) have the where-with-all to make this investment and the funding costs (the interest rates charged) reflect the very high-risks involved.


Boom bust and third-party foundries In the 00s the cost of building a semiconductor foundry increased significantly resulting in a rapid migration toward outsourcing to dedicated third party ‘foundry partners’ producing wafers for multiple customers and able to operate profitably by achieving both high-capacity utilisation rates and process yields. Since the financial crisis in 2008 and despite


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