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Tom's Hardware Visits STMicroelectronics In Rennes, France
By , Matthieu Lamelot,
1. Tom's Hardware Visits STMicroelectronics

Chris Angelini: As many of you know, Tom's Hardware is an international organization. We have teams of writers in the U.S., Germany, Italy, Russia, and France. Last year, our friends based in Paris had the opportunity to visit STMicroelectronics' factory in Rennes. The following story recounts their experience learning about the company's history, its current projects, and future aspirations. Their nationalism shines through, but they think they have something to be proud of in STMicro's achievements. We welcome you to read on.

"French factory," they say, is almost an oxymoron. When was the last time you saw a news story about the success of a manufacturing plant in the land of Beaujolais and Brie? I won’t even ask for the last time you heard about a semiconductor fab operating in France that’s actually hiring because it continues to meet a growing demand and manages to stay competitive. The poor overall economic picture and pessimistic approach newspapers like to take in speaking of the electronics industry in France would lead you to think that that scenario is utopian at best.

So, imagine our surprise when a source told us the STMicroelectronics plant in Rennes was recruiting. Don’t get us wrong. We believe firmly in French and European expertise, of which innovators like Crocus Technology, SOITEC, and STMicroelectronics are proof. But a French semiconductor plant that’s not moving offshore and is actually hiring in the middle of an economic crisis? We decided we had to investigate. Lo and behold, not only is the story true, but the site in question recently made news because its circuits were built into Curiosity, the robot rover that landed on Mars.

So we sat down with Patrick Galloy, CEO of STMicroelectronics Tours SAS. He heads the Rennes site as well as the plant in Tours, which employs 1500 people. He was joined by Jean-François Vadrot, manager of the High-Reliability Aerospace Products Business Unit. STMicroelectronics is a French-Italian semiconductor company with a broad catalog of products, including everything from SoC (System-on-Chip) solutions to Digital Signal processors (DSPs) and components for the consumer electronics, automotive, and many other markets. But it's known on Tom's Hardware largely for its MEMS (MicroElectroMechanical Systems).

Between them, the two men have 30 years of experience in the French semiconductor world. They direct one of the sites that’s less well-known to the general public and yet shows significant growth in a niche market for components used in aerospace applications. They agreed to answer our questions about the business line that is responsible for the Rennes plant’s current success, and they also opened their doors to our cameras. What follows is mainly drawn from that conversation. We decided not to print the entire interview, but instead to give you a history of the site, the development of its aerospace-high reliability components business, the challenges such an operation faces, and the plant’s future outlook. It’s no fairy tale, but it is a story that deserves to be told.

2. History Of The Rennes Site

Once upon a time, life was painful indeed. In 2003, the Rennes plant’s front-end activity (wafer etching) was moved to Singapore. In the collective memory (and also according to Wikipedia), that meant the closure of the Rennes site. But as our photos show, the information propagated by the media at the time, announcing a complete shutdown of the plant, was false. The plant is still open, and its back end (hermetic die assembly, now its core business), is not new, nor is it the result of a repurposing after the move to Singapore. So it’s important to go back over the site’s history.

The Rennes site dates back to 1960s. Initially built by Fairchild, it was bought by SGS (Società Generale Semiconduttori) Microelettronica, an Italian semiconductor group that merged with France’s Thomson Semiconducteurs in 1987 to become SGS-Thomson. In 1998, Thomson SA withdrew from the company, which then became STMicroelectronics.

From the start, the Rennes site had a front-end activity that included the entire process of fabricating die on a wafer (implantation, diffusion, epitaxy, photolithography, metallization, and testing). In the 2000s, the fab was producing 150 mm (six-inch) wafers. The front end accounted for 90 to 95 percent of activity at the site. It was moved to Singapore in 2003-2004 under the impetus of an “economic rationalization.”

But the Rennes plant had also had back-end activity since its inception, and the assembly of chips for the aerospace market is not a recent operation at all; SGS began doing this in 1977. So, the activity has always existed. It wasn't a matter of “transforming” or repurposing it. But there was significant growth due to the increasing success of the back-end operation.

The 2003 Facelift

When the front end was moved offshore, the back end employed 44 people and accounted for five to 10 percent of the site’s business. In 10 years, STMicroelectronics multiplied that volume by a factor of eight, and now employs around 100 people.

The company owes its growth to heavy marketing and technological investments that increased its products’ presence on the aerospace market. Another key strategic move was its acquisition of European and American qualifications, making Rennes the only STMicroelectronics site able to product chips that can be sold on any aerospace market in the world.

To optimize management of this growing business line, in 2006, Rennes was attached to the company’s site in Tours. It employs mostly production operators, but the company has also strengthened the technical teams. Today, there are two teams on the site, with a small additional weekend group needed for running the reliability tests, which last approximately 1000 hours (and up to 2000 and even 4000 hours for certain components). A night shift is being put in place to handle the increase in business.

The explosion of activity at the site is also related to some notable achievements. The French fab’s most recent exploit is the inclusion of chips from Rennes in the Mars rover Curiosity (and we were assured that the memory chips that were corrupted by cosmic radiation weren’t from their facility). The Rennes site is now indissociable with space.

3. The Beginnings And Development Of The Rennes Back End

The European Space Agency (ESA) was created in 1975 to coordinate the European space programs and certify suppliers authorized to sell their products on that market. Two years later, SGS was the first European supplier to be granted certification. This was first intended for a plant in Italy, but in 1979, that business was moved to Rennes along with the certification.

In 1985, India recognized the European certification, which gave SGS access to the Indian space agency. Japan followed in 1990. So the aerospace activity was already profitable at the time, but growth perspectives were limited by the impossibility of breaking into the American market, which obviously did not recognize the European certification.

STMicro’s El Dorado

So, around 1995, the company decided to work on obtaining American certifications. There are two—one for integrated circuits and the other for dedicated components (diodes, transistors, etc.). STMicroelectronics was granted the former in 2000 after meeting the criteria set by the Defense Logistics Agency of the U.S. Defense Department. Still, it was five or six years before the company was accepted by U.S. manufacturers. The aerospace market is very wary of new arrivals, and certification doesn’t automatically mean you’ll win contracts. You need to build a name and a reputation.

In 2011, STMicroelectronics received the second certification, which entitled the company to sell its entire catalog of products in the U.S. The American market, which then accounted for one to two percent of the aerospace activity’s business volume, now accounts for 25 percent. In short, the development of business at Rennes is the result of greater geographical penetration. And the trend continues. In addition to the U.S., the company is making progress on the Russian and Chinese markets, which have strong growth potential.

Growth Despite Constraints

There are no major differences between American and European certifications, and the components sold in Europe are identical to the ones sold to the U.S. There are slight divergences in the test protocols, but nothing of fundamental importance. Putting up with these bureaucratic disadvantages is the price to pay for being able to sell your products on the world’s markets. And, in fact, it’s one of the strong points of the Rennes site. Few fabs in the world today have all of these certifications.

During our conversation, we clearly felt that having to manage three quality systems for the same component was a heavy constraint, and Vadrot admitted that if he had a magic wand, his first wish would be to unify the certifications more effectively and make them more consistent. Still, despite these disadvantages, Rennes has not only adapted, but developed itself in order to offer know-how and technologies that make the French plant a leader on the aerospace market. But what, exactly, does the Rennes fab do?

4. A Demanding Selection Process

In the jargon of semiconductor manufacturers, the back end is all the stages of fabrication that come after the etching of the transistors onto the wafer of silicon (the front end). A naked die serves no purpose. It has to be protected and connected to the outside world. To do this, the die is soldered into a case or package, and its microscopic interfaces are connected to pins of a size that can be more easily handled.

Rennes receives its wafers from other STMicroelectronics fabs around the world (mainly Singapore, Tours, and Catania). But they’re not ordinary wafers. They’re already suited to aerospace requirements. The Rennes site has no R&D center, but it does have a radiation expert who works with the laboratories at the front-end plants to design chips that are capable of withstanding the ionizing radiation present in space (the same radiation that was responsible for the failure of Curiosity’s memory chip). They’ve been through their own special development and testing track before leaving the front end.

Preliminary Wafer Selection Tests

Once in Rennes, the wafers are cut into individual dies. STMicroelectronics then takes a sampling of chips that will undergo all stages of manufacturing, and then be irradiated by cobalt-60 sources in special laboratories (not on-site, since the use of a radioactive source requires specific expertise). The goal is to verify that the wafer the chip was taken from meets nominal performance standards. Theoretically, there’s no problem, since it was designed and developed to meet those standards. But if the results are not up to standard, the entire wafer has to be rejected.

The chip maker makes a point of adopting highly demanding selection criteria. They can’t afford to run any risk with a component that must be functional for 15 to 20 years (the life expectancy of a satellite in space). So, it's better to junk an entire wafer than risk a malfunction in a satellite in orbit or a robot on Mars.

Once the wafer is accepted, it’s cut up (diced) into individual chips. After dicing, each chip is examined under a microscope. The operation requires many different handlings, which limits the production cadence. An operator can sort a maximum of 140 chips per hour, or approximately 1000 chips per day. The selection is rigorous. At this stage, the question is not just whether the chip is functional. A visual defect alone is enough to cause the die to be rejected, even if it’s operational. Here again, the approach is to take zero risk with the final component that will ship.

Rigorous Selection

If there are any rejects, they mostly occur before packaging of the die. The initial selection criteria are so demanding that the chips that enter the production chain rarely encounter problems. However, the various certifications require that items be taken out of the circuit for testing at each stage of production.

After dicing, the chip is soldered into a case or package. The quality of the assembly is tested—a percentage of the chips are separated out and subjected to a die pull-off test. The packaging used is different from that found in consumer components. Instead of plastic, ceramic is often used—generally alumina (Al2O3) or aluminum nitride (AlN)—or else metal (steel or kovar, which is an alloy of iron, nickel, and cobalt). The choice of the case depends mainly on the type of chip it will house. Chips that need no power will use a ceramic case. Signal processing components, for example, use ceramic. Dies with a Thermal Design Power (TDP) of a few watts, such as power components that require a current of 3 to 5 A and a tension of a few volts, use metal packaging.

Contrary to popular belief, the choice of packaging doesn’t depend on the environment in which the chip will operate. Whether it is used in space or in a drill head 20 km underground, the component will be identical. The high-reliability standards these chips must meet are intended to satisfy operation under any conditions. So the choice of the case depends only on the characteristics of the circuit it houses.

5. Highly Rigorous Tests

Once the die is mounted in its case, the wires must be soldered to connect the chip and the pins. This operation can seem archaic compared with the processors used in PCs or smartphones, whose dies are connected via direct contact with bumps on their epoxy carriers. But due to the reliability constraints of the aerospace sector, older, tried, and proven methods are used.

The certifications require that the wires be tested for mechanical strength. Here again, a percentage of the components will be culled from the production lines to undergo destructive tests to determine the force needed to break the wires and the failure mode (at the chip, at the case, in the middle of the wire, etc.).

The next stage is closure of the case, which must be totally hermetic. To avoid corrosion, the dies are kept in a dry nitrogen atmosphere. The case is sealed in various ways depending on its shape, size, and type. Ceramic cases are sealed in a furnace. Metal ones can be sealed using electrical welding. STMicroelectronics has 34 different cases in its catalog and needs to have that many devices available for sealing them.

Once the case is sealed, all that remains is to mark it. STMicro Rennes recently moved from ink marking to laser marking, which is more durable. Fabrication as such is now complete. But ahead is a long period of tests to verify the quality of the fabrication and the chip’s resistance to aging.

Real Little Jewels

The chips will be X-rayed to check the welds at the interface between the chip and the carrier and the weld joint between the upper and lower half of the package to ensure that there are no voids in the welds.

The testing also checks for the presence of particles inside the packages, since the tiniest grain of dust would have disastrous consequences. Each package is also tested with a leak detector.

The chips are also subjected to a certain number of thermal cycles (between -55 degrees Celsius and 125 degrees Celsius, or -67 degrees Fahrenheit to 257 degrees Fahrenheit) and thermal shocks. At each stage, STMicroelectronics checks the electrical performance of the dies and a test report is kept for each chip produced. At the end of the process, the result is a component that Patrick Galloy calls a “one-of-a-kind little jewel.” Each die is marked with a unique serial number that makes it possible to track its life since the start of fabrication, part by part, chip by chip, and test by test. All results are sent to the customer, and also archived for at least 10 years.

STMicroelectronics preferred not to disclose the number of functional chips that leave the Rennes fabrication facility (that data is currently kept secret). But it’s easy to see that the yields have to be significantly lower than in a more traditional fab that isn’t subject to the same constraints and destructive tests for guaranteeing the quality and reliability of the chips.

6. Operations At The Site

Two major factors account for the growth of STMicroelectronics’ Rennes site over past 10 years.

Marketing Advantages

The aerospace market is growing by approximately five percent per year, and the company has taken advantage of the trend. Its chips equip the Curiosity Mars rover, but also Galileo, the European GPS system, Meteosat, the Ariane launcher, the Astra television broadcasting satellites, the SPOT Earth observation satellite, and almost all satellites launched today.

Its customers include equipment manufacturers who sell parts of satellites, but also satellite manufacturers themselves. Its biggest client is the European Space Agency and its alter ego in France, the CNES (Centre National d’Études Spatiales), since STMicroelectronics gives it independence from the U.S. That takes concrete form in financing for development projects. The company also works with private players around the world and has privileged relationships with the European satellite systems integrators Thales-Alenia and EADS-Astrium.

Technological Advantages

The other factor that explains STMicroelectronics’ growth in this market and the explosion of activity at Rennes lies in the technologies the site can produce. Satellite manufacturers are not looking for the latest SoCs or the highest frequencies. They want mature technologies that have been proven over several years. For a satellite that will spend 20 years in orbit, reliability is much more important than using the latest fabrication process.

Concretely, the chips sold by STMicroelectronics use processes that date back three to five years (the company is currently working on qualification of 65 nm chips), but it also markets wafers that use a 7.5 µm (7,500 nm) process. That’s an advantage, because it has the only fab in the world that can still use that process, which dates from the 1970s, yet is still quite appropriate for high-reliability applications. One of the best-selling transistors for aerospace use is the 2N2222, introduced by Motorola in 1962.

Obviously, its production has been adapted to the new standards that govern fabrication, and the maturity of the technologies has resulted in optimized fabrication methods. Still, STMicroelectronics’ strength lies in the fact that it’s one of the rare companies in the world that can produce older-generation chips and make a profit.

Finally, there’s also a technological advantage in being able to take the time necessary to develop chips for aerospace use. Unlike certain components for consumer devices that take six months between development and marketing, four and five years can go by between the time a chip is developed and the time it’s marketed. Being able to maintain the necessary investments during that period requires resources that aren’t available to all chip makers on the market.

7. Challenges For The Rennes Site

The increase in business at STM’s Rennes site since 2003 has resulted in new hirings, better management of the facilities, the installation of new equipment, and improvements in processes. Aerospace work requires highly “manual” processes, given the relatively small quantities of chips sold and the many fabrication stages they undergo. The Rennes site produces approximately 200,000 units per year. A normal back end at STMicroelectronics produces between 12 million and 15 million per day.

Faced with the burgeoning growth in demand, Patrick Galloy says if he had that magic wand, he’d use it to produce more and faster, right away. But the constraints of aerospace production require careful management of any increase in production, taking costs into account and maintaining the reliability of the products that leave the plants.

STMicroelectronics invests between $500,000 and $800,000 a year in the Rennes fab. It plans to hire a night shift and install semiautomatic machines to optimize production. A project called Sirius has also been launched with the goal of improving employee working conditions and performance.

Another challenge is training the teams in the different quality standards. The aerospace industry is too small for schools to offer courses aimed at that specific market. So the site hires engineers and trains them in certification requirements itself, in partnership with the ESA.

8. Perspectives For The Future

Rennes has a promising future. Thanks to its innovations, the site hopes to double its current business volume in five years. STMicroelectronics plans to integrate its technologies for reducing power consumption and increasing chip performance into its high-reliability circuits. The other major future trend is MEMS. The company made a name for itself by building its systems into numerous consumer products, and development is underway to convert the chips for aerospace use. That will take a few more years.

The company’s growth will also require extending its geographic presence and its marketing activities. Rennes is driven largely by the aerospace market, but the chips used in satellites are also popular in the health and petroleum industries. Labs-on-a-Chip (LOCs) for implantation in the human body require reliable components, and drill heads working 20 km underground cost a fortune if they break down. The submarine-cable telecommunications market, which uses repeaters to transmit signals, also requires high-reliability chips in order to limit repairs on difficult-to-access cables.

STMicroelectronics has some presence on these markets, but the challenge in the coming years will be promoting its chips and its expertise to growth industries. The company is also struggling to improve its geographical penetration. The certifications it has are a major advantage, but they’re not always enough to convince certain companies who are wary of “foreigners.” So it needs to work on brand image and international relations.

Finally, the future of the Rennes site might also be tied to diversification of its business activities. STMicroelectronics is looking into the possibility of becoming a service provider, making its expertise and its certifications available to customers that will send their dies to be assembled at the French site. The advantage for the customer is not having to spend five years getting the necessary licenses. We know negotiations with certain partners are in progress, but the names of the players are still unknown.

Rennes Is Immune To Offshoring

We’ll end with an answer to the first question that came to mind as we prepared to write this piece: if the fab’s front end was sent offshore, isn’t there a risk that the back end will be too? The answer is no, and here’s why:

The Rennes site can’t be moved because of the knowledge and skills of its people, who are able to meet the requirements of three rigorous international certifications. Moving the plant without moving its teams couldn’t be done without major investments and without generating delays that remain incompatible with the customers’ needs, Vadrot and Galloy told us. Rennes is special enough that it’s hard to imagine relocating it.

Also, the cost imperatives that lead to offshoring are less pressing, since the Rennes plant’s products have high added value and so are less subject to the pressures of productivity and yield that affect fabs that make consumer-oriented chips. The customers pay for the expertise, the international qualifications, and the assurance that a chip will operate for two decades without the slightest problem. As a further added value, customers also get the data collected during the tests that make each chip fully traceable.

9. A Little French National Pride

It was hard for us to maintain our objectivity while doing this article. Seeing a French semiconductor plant that not only has phenomenal future potential, but also expertise that makes it almost impossible to relocate offshore ignited our enthusiasm. We often write about GlobalFoundries, Intel, Foxconn, or TSMC; but for once, we can talk about our own STMicroelectronics Rennes—a site that excels in a rapidly expanding niche market.

We might be criticized for showing such national pride, but maybe we can be forgiven since the French site’s success stems from its having adapted to the constraints of globalization. Obviously, the site no longer resembles what it was before the 2000s, but the fact is that no semiconductor fab looks like what it did 10 years ago. The realities of the market are cruel and impartial. Its axioms are profitability and productivity, and they hold sway without discrimination or considerations of a moral and social nature. The idea that a small European front end can and must rival the Asian fabs that have been built in the past 10 years is ridiculous and dangerous.

Instead of doing what it did in the past or closing its doors completely, the Rennes site invested in what made it unique. We can’t talk about this issue without citing the paper on modern economic theory by Karla Hoff and Joseph Stiglitz, published by the World Bank, which shows that the developed countries will remain competitive by accumulating highly skilled labor. They can no longer compete with the developing countries, where the low cost of living makes very low average wages possible. The only solution for the developed countries is to have ultraspecialized labor and expertise that can’t be found anywhere else. That’s exactly what accounts for the success of the Rennes site, and there’s good reason to be proud of it.