When we talk about semiconductor manufacturing, we might bring up images in our head of massive fabs,
yellow clean rooms, and people walking around in bunny suits.
That mental image might lead us to presume semiconductor
manufacturing to be this squeaky clean endeavor.
But when we say "clean", we really mean "clean" in the sense that we want to keep the product
free of particles. We really have no idea what is going on in those fabs
for the people working and living around there.
These companies use immense amounts of toxic and carcinogenic materials
to make the beautiful chips that power our machines. And,
if we were to simply look at the historical record, then there is reason for concern.
I have been thinking about this for a while now. In this video, I want to look at one of the big
reasons why semiconductor manufacturing left the Silicon Valley: It is a dangerous, toxic process
that can cause an immense amount of harm to both people and the environment.
It is difficult to study the health and environmental effects of modern
semiconductor manufacturing because its practitioners are extremely secretive. Thus
specifics vary. But all wafer fabrication facilities perform a few core processes.
They are deposition, resist coating, light exposure, etching, resist removal, and washing.
These processes are repeated over and over again until the chips are at the desired level of
sophistication. Feel free to stop and google them first if you don't know what they are.
Hundreds of chemical compounds are used in these processes. One study of two Korean
semiconductor memory facilities found over 400 chemical ingredients. Ingredients, meaning that
they can be combined with each other to make the actual compound to be used in the process.
However, the researchers could not review 40% of those 400 ingredients
because they had been classified as a trade secret.
This particular study found that only 10% of the non-trade secret chemicals are classified as a
human carcinogen by the International Agency for Research on Cancer. However, those carcinogenic
chemicals - mostly sulfuric acid - makes up 30% of total volume used in the facility.
Sulfuric acid is used for removing the photo-resist and cleaning the wafer.
It is harmful to the eyes and skin, damages the teeth and lungs,
and when inhaled raises lung cancer risks by up to 64%.
Right, so sulfuric acid can give you cancer, especially when you breathe it in. But the
reality is that these factories use so many tons of chemicals each year - the paper notes over
45,000 tons per factory - that even if a chemical is not technically classified as a carcinogen,
it can still do some serious damage at scale.
For instance, the second most used chemical ingredient at the two factories is Cyclohexanone.
It is not classified as a human carcinogen, but when inhaled it can cause kidney and liver damage.
Possible "central nervous system effects" are also noted, whatever that might mean.
We cannot just focus on only wafer fabrication as well. We would be ignoring an entire half of the
manufacturing process. Many of the same health and environmental concerns apply to the back-end too.
Here, each chip on a wafer is cut, tested, wired up, and then placed in an exterior shell. Relevant
subtasks include die preparation, wire bonding, molding, plating, soldering, and chip testing.
Broadly speaking, there are two types of tasks here:
Operations and maintenance. Operators today have relatively low exposure
to toxic chemicals, though workplace advocates have concerns about repetitive tasks and the like.
Maintenance workers on the other hand have to take apart equipment,
exposing them to high concentrations of potentially toxic chemicals.
The most common type of chemicals used in packaging subtasks
are epoxy molding compounds. Mostly made of epoxy resin,
hardeners, and silica, they are used to protect circuits from the outside.
These ingredients are not known to be toxic,
but it has been reported that the actual molding process can generate toxic byproducts
like phenol, formaldehyde and benzene. The latter two are carcinogens.
They say that safety regulations are written in blood. What we know today about the effects
of semiconductor manufacturing come from studying the suffering of those before us.
Silicon Valley is today known for housing the designers and engineers who make our
slick gadgets and social networks. But before that, it had been an industrial
manufacturing location for companies like Fairchild Semiconductor and Intel.
Fairchild Semiconductor was a semiconductor pioneer. The Traitorous Eight and all that jazz.
One of the first companies to experiment with making chips out of silicon rather than germanium.
The company used a chemical called 1,1,1-Trichloroethane as an organic
solvent. It is helpful for cleaning circuit boards and as a photo-resist. It is not toxic,
per se, but can cause birth defects in pregnant women.
Today, the chemical is being phased out of use because of its ozone-depletion properties.
Fairchild had been storing this stuff in underground fiberglass tanks
at their San Jose site. From 1977 to 1981,
the tanks leaked the solvent into the ground water, contaminating well #13.
What did this stuff do to the population there? Well,
investigators were not sure. Pregnant women in the Los Paseos neighborhood of San Jose
showed higher rates of spontaneous abortion and congenital malformation.
But this was all indirect evidence and the timing was uncertain.
And some 69 women in the Los Paseos area did not show any birth issues at all.
Regardless, this data as well as a university study linking the chemical to congenital
heart defects in rats led Fairchild to pay out a multi-million dollar settlement with the families.
A later report in 1988, "Pregnancy Outcomes in Santa Clara County 1980-1985,"
found that pregnant women in a neighboring city also drank water contaminated with
1,1,1-Trichloroethane but suffered no unusual effects. So, unnecessary concern?
BUT wait! A counter-study a few years later pointed out that the 1988 study did not count
for the effects of showering or washing your hands with Trichloroethane water. The saga marches on.
The 1981 Fairchild incident goes to show just how complicated human health studies
are - tying cause and effect are much more difficult than at first glance.
When workers at a facility start getting unexplained health issues and believe the
company is at blame, tracing what exactly happened gets really complicated. This has been repeatedly
the case throughout the years as companies and workers clash over their individual positions.
Examples include a 1979 event with Signetics,
IBM in 1985, National Semiconductor UK in 1998 and a 2008 cancer cluster amongst Samsung Electronics.
The standard method has been to look at statistics - the mortality rates, the incidence ratios, and
so on. But the cohorts tend to be small (one to five thousand at the most), classification errors
do happen, and confounding factors are everywhere. So, it can be hard to avoid unusual results.
Cancer has been the single biggest focus of various industry healthcare studies.
The industry's connection to cancer has been and remains hotly debated
since the 1980s across the UK, South Korea, Taiwan, and the US.
For instance, in the case of those 1985 IBM workers. A 2006 study looked at standardized
incidence ratios of cancers in semiconductor and storage device manufacturing workers.
They found no causal associations between semiconductor manufacturing and cancer.
But cut the same data a different way, like researcher Richard Clapp did that same year,
and you find an elevated incidence of kidney, skin, and brain/nervous system cancers.
But that study lacked exposure data, so we do not know what might have caused this.
Okay, last one. A 2010 study of the National Semiconductor UK plant
showed no elevated rates of cancer in both men and women, except for lung cancer.
The lung cancer incidence rates were high enough to be statistically significant. But the report
also notes that they did not know the population's smoking rates. So that's something to think about.
Anyway, to sum it up. It is tough to prove causation from correlation.
And yet harder to do it in one of the human body's most complicated diseases.
With that being said, one connection with relatively strong links is that of
reproductive health. Female reproductive health is a special concern because
the majority of the factory workforce tends to be women of child-bearing age.
A 1980 Finnish study was the first to identify an elevated risk of spontaneous
abortion amongst female electronics workers. The Fairchild Semiconductor case a year later
got scientists started on further studying the industry's reproductive health risks.
A series of studies have identified elevated risks of spontaneous abortion,
especially amongst workers working in the masking and photo-lithography processes.
Studies suspected the use of a chemical - ethylene glycol ether a known repro-toxin,
as well as other organic solvents. Exposure to this chemical
can also cause lower fertility and more variable menstrual cycles.
This was replaced with propylene glycol monomethyl ether,
a known neurotoxin. But even so, elevated spontaneous abortion risks continue,
leading scientists to continue trying to figure out what else might be causing
reproductive issues. As always, more studies are needed but this risk is widely acknowledged.
There is no denying that semiconductor companies back in the 1960s and 70s
had a rather ... cavalier approach towards handling ingredients and wastes.
Microelectronics firms dumped their acids and solvents into the sewers. Those often flowed
into the San Francisco Bay. Toxic chemicals were tossed into city dumps, pits, and dry wells.
Crews working on Intel's first facility in Mountain View
found that acids had eaten through the bottoms of all the nearby sewer lines.
You can’t do that stuff anymore in the USA. The 1970s saw the start of the environmental movement,
the creation of the EPA and the tightening of toxic waste regulations.
Things have vastly improved since then.
Companies have also realized the value of recycling.
I talked a little about this in my video on semiconductor water usage,
but these facilities run at such scale that recycling and reuse technologies are essential.
Semiconductor wastewater often has acids, alkalines, fluorides, ammonia, and wafer polish.
Companies will apply a series of treatments include reverse osmosis,
oxidation, carbon filters, and more to clean the water enough for possible reuse.
That being said, these facilities use over 400 ingredients and far more compounds.
One researcher found that only 10% of the ingredients were being monitored.
Including none of the byproducts produced from reactions - like plasma. A particular concern.
TSMC mentions they specifically treat for 25 chemicals in their wastewater,
which sounds like a lot, but in context is not.
One sustainability study in 2018 looked at how several American semiconductor
facilities across the US disposed of seven chemical wastes. Some companies did well,
others not so well. And a few really not so well.
Which is kind of wild considering how much focus local governments have on this stuff.
And regulations going forward do not do anything about the toxic legacies of
those early wild west years. For instance, all the SuperFund sites in Silicon Valley,
scattered amongst some of the world's richest cities.
Or the groundwater contamination damage from a former RCA plant operating from 1968 to 1992
in Taoyuan, Taiwan. These legacies remain
and somebody gets stuck with the job of cleaning it up for years thereafter.
I remember staying at a hotel near a TSMC plant, and being specifically told by the locals
not to stay too long around it - even if you don’t smell anything there.
Silicon manufacturing has gradually moved out of the Silicon Valley
to new locations inside and out of the United States.
Arizona and Texas, inside the US. South Korea, Taiwan and China outside the US.
Regulators are in a poor position to monitor these facilities’ impact. Despite their best
efforts, these places often have less resources and regulatory knowledge
to properly track what is going on inside these fabs.
Heck, not like the Silicon Valley authorities were doing that well anyway.
Beyond that, semiconductor manufacturing is an immensely profitable and high value activity
that governments value and protect. In 2019, South Korea exported over $93 billion in chips, some
15% of the country's total exports. The same goes for Taiwan. These are powerful constituencies.
Right now, there is a big semiconductor shortage
going on. Companies and consumers cannot get the chips they need.
Fab construction crews are rushing to put shovels into the ground to get going on these facilities.
Considering all the hurry, environmental surveys and evaluations might not seem all that important.
TSMC just passed one for their 2nm Hsinchu facility, for instance.
But this stuff should be taken seriously, because there is still a lot that we do not
know about semiconductor manufacturing and its effects on the environment and people.