Doing anything that requires measurements in nanometers is pretty difficult, and seems like it would require some pretty sophisticated equipment. But when the task at hand is growing oxide layers on silicon chips in preparation for making your own integrated circuits, it turns out that the old Mark 1 eyeball is all you need.
Alert readers may recall that [ProjectsInFlight] teased this process in his previous video, which covered the design and construction of a DIY tube furnace. In case you missed that, a tube furnace is basically a long, fused quartz tube wrapped in electrical heating elements and lots of insulation, which is designed to reach the very high temperatures needed when making integrated circuits. The tube furnace proved itself up to the task by creating a thin layer of silicon dioxide on a scrap of silicon wafer. Continue reading “Growing Oxides On Silicon On The Road To DIY Semiconductors”→
A member of the so-called “Traitorous Eight” who left Shockley Semiconductor in 1957 to form Fairchild Semiconductor, he and his cohort laid the seeds for what became Silicon Valley and the numerous companies, technologies, and products which have flowed from that. His name is probably most familiar to us through “Moore’s Law,” the rate of semiconductor development he first postulated in 1965 and revisited a decade later, that establishes a doubling of integrated circuit component density every two years. It’s a law that has seemed near its end multiple times over the decades since, but successive advancements in semiconductor fabrication technology have arrived in time to maintain it. Whether it will continue to hold from the early 2020s onwards remains a hotly contested topic, but we’re guessing its days aren’t quite over yet.
Perhaps Silicon Valley doesn’t hold the place in might once have in the world of semiconductors, as Uber-for-cats app startups vie for attention and other semiconductor design hubs worldwide steal its thunder. But it’s difficult to find a piece of electronic technology, whether it was designed in Mountain View, Cambridge, Shenzhen, or wherever, that doesn’t have Gordon Moore and the rest of those Fairchild founders in its DNA somewhere. Our world is richer for their work, and that’s what we’ll remember Gordon Moore for.
We’re going to go out on a limb and predict that future history books will note that the decision to invade a sovereign nation straight after a worldwide pandemic wasn’t exactly the best timing. Turns out the global electronics shortage the pandemic helped to catalyze isn’t just affecting those of us with peaceful intentions, as the Russian war machine is having a few supply issues with the parts needed to build modern weapons and their associated control equipment.
So what parts are we talking about anyway? The cheapest chip on the top priority list is the Marvell ‘Alaska’ 88E1322 which is a dual Gigabit Ethernet PHY costing a mere $7.10 USD according to Moscow. The most expensive is the 10M04DCF256I7G, which is an Altera (now Intel) Max-10 series FPGA, at $1,101 USD (or 66,815 Rubles, for those keeping score).
But it’s not just chips that are troubling them, mil-spec D-sub connectors by Airborn are unobtainable, as are all classes of basic passive parts, resistors, diodes, discrete transistors. Capacitors are especially problematic (aren’t they always). A whole slew of Analog Devices chips, as well as many from Maxim, Micrel and others. Even tiny logic chips from Nexperia.
Of course, part of this is by design. Tightened sanctions prevent Russia from purchasing many of these parts directly, which is intended to make continued aggression as economically unpleasant as possible. But as the POLITICO article points out, it’s difficult to prevent some intermediaries from ‘helping out’ without the West knowing. After all, once a part hits the general market, it is next to impossible to guarantee where it will eventually get soldered down.
Silicon has had a long run as the king of semiconductors, and why not? It’s plentiful and works well. However, working well and working ideally are two different things. In particular, electrons flow better than holes through the material. Silicon also is a poor heat conductor as we’ve all noticed when working with high-speed or high-power electronics. Researchers at MIT, the University of Houston, and other institutions are proposing cubic boron arsenide to overcome these limitations.
According to researchers, this material is a superior semiconductor and, possibly, the best possible semiconductor. Unfortunately, the material isn’t nearly as common as silicon. Labs have created small amounts of the material and there is still a problem with fabricating uniform samples.
Early experiments show the material has very high mobility for electrons and holes along with thermal conductivity almost ten times greater than that of silicon. It also has a good bandgap, making it very attractive as a semiconductor material. In fact, only diamond and isotopically enriched cubic boron nitride have better thermal conductivity.
However, there are still unknowns about how to use the material in practical devices. Long-term stability tests are as lacking. So maybe it will wipe out silicon or maybe it won’t. Time will tell.
We’re used by now to many of the more capable microcontrollers and systems-on-chip that we use having an ARM core at their heart. From its relatively humble beginings in a 1980s British home computer, the RISC processor architecture from Cambridge has transformed itself into the go-to power-sipping yet powerful core for manufacturers far and wide. This has been the result of astute business decisions over decades, with ARM’s transformation into a fabless vendor of cores as IP at its heart. Recent news suggests that perhaps the astuteness has been in short supply of late though, as it’s reported that ARM’s Chinese subsidiary has gone rogue and detatched from the mothership taking the IP with it.
It seems that the CEO of the Chinese company managed to retain legal power when sacked by the parent company over questionable ties with another of his ventures, and has thus been able to declare it independent of its now-former parent. It still has the ARM IP up to the moment of detatchment and claims to be developing its own new products, but it seems likely that it won’t receive any new ARM IP.
What will be the effect of this at our level? Perhaps we have already seen it, as more Chinese chips such as the cheaper STM32 clones are likely to get low-end ARM cores as a result. It seems likely that newer ARM IP will remain for now in more expensive non-Chinese chip families, but in the middle of a semiconductor shortage it’s likely that we wouldn’t notice anyway. Where it will have a lasting effect is in future Chinese joint ventures by non-Chinese chip companies. Seeing ARM’s then-owner Softbank getting their fingers burned in such a way is likely to provide a disincentive to other companies considering a similar course. Whether ARM will manage to resolve the impasse remains to be seen, but it can hardly be a help to the rocky progress of their Nvidia merger.
After spending much of the 20th century languishing in development hell, electric cars have finally hit the roads in a big way. Automakers are working feverishly to improve range and recharge times to make vehicles more palatable to consumers.
With a strong base of sales and increased uncertainty about the future of fossil fuels, improvements are happening at a rapid pace. Oftentimes, change is gradual, but every so often, a brand new technology promises to bring a step change in performance. Silicon carbide (SiC) semiconductors are just such a technology, and have already begun to revolutionise the industry.
Mind The Bandgap
Traditionally, electric vehicles have relied on silicon power transistors in their construction. Having long been the most popular semiconductor material, new technological advances have opened it up to competition. Different semiconductor materials have varying properties that make them better suited for various applications, with silicon carbide being particularly attractive for high-power applications. It all comes down to the bandgap.
Electrons in a semiconductor can sit in one of two energy bands – the valence band, or the conducting band. To jump from the valence band to the conducting band, the electron needs to reach the energy level of the conducting band, jumping the band gap where no electrons can exist. In silicon, the bandgap is around 1-1.5 electron volts (eV), while in silicon carbide, the band gap of the material is on the order of 2.3-3.3 eV. This higher band gap makes the breakdown voltage of silicon carbide parts far higher, as a far stronger electric field is required to overcome the gap. Many contemporary electric cars operate with 400 V batteries, with Porsche equipping their Taycan with an 800 V system. The naturally high breakdown voltage of silicon carbide makes it highly suited to work in these applications.
If we had a dollar for every exciting new device that’s promised to change everything but we never hear of beyond the initial hoopla, we’d own our own private islands in the sun from the beaches of which we’d pick out Hackaday stories with diamond-encrusted keyboards. The electronic engineering press likes to talk about new developments, and research scientists like a bit of publicity to help them win their next grant.
The Bizen transistor however sounds as though it might have some promise. It’s a novel device which resembles a bipolar transistor in which the junctions exhibit Zener diode-like properties, and in which the mechanism is through quantum tunneling rather than more conventional means. If this wasn’t enough, its construction is significantly simpler than conventional semiconductors, requiring many fewer support components to make a logic gate than traditional CMOS or TTL, and requires only eight mask steps to manufacture. This means that lead times are slashed, and that the cost of producing devices is much reduced.
The device’s originator has partnered with a semiconductor fab house to offer a service in which custom logic chips can be produced using the new devices in a series of standard building blocks. This is likely to be only of academic interest to the hacker at the moment, however the prospect of this cost reducing as the technology matures does show promise of reaching the means of some more well-funded hacker projects. It will be a while before we can order a chip with the same ease as a PCB, but this makes that prospect seem just a little bit closer.