Semiconductors are more than just processors and GPUs

I spent most of the day yesterday chasing down crosses for P-Channel FETs.<p>They are all GONE. No stock of anything (except the crappy ones, super-tiny packages, high Vgs(th) or high Rds(on) and other leftovers).<p>I&#x27;ve never seen anything like this, it&#x27;s kind of frightening. Like walking into a grocery store and seeing the aisles all EMPTY except for a few scraps.<p>I don&#x27;t even know where they all went. It&#x27;s not like you need a TSMC slot to make a FET.<p>And <i>whatever</i> you look up, Chinese brokers have 10K-50K pieces of them for $25 each. Don&#x27;t know what to think of that, either.

Fun fact: Solar cells and the LEDs are the same element.<p>If you wire up a solar cell like an LED, it glows dimly in infrared. QA uses this to diagnose dysfunctional wafers.

CPUs and GPUs account for more dollars spent than solar cells, but solar cells account for most area&#x2F;mass of semiconductor devices made today.<p>A gigawatt of solar cells represents about 5 square kilometers of silicon wafers at 20% light conversion efficiency. The world installed 183 gigawatts of solar PV in 2021, almost all of it based on silicon wafers:<p><a href="https:&#x2F;&#x2F;www.pv-magazine.com&#x2F;2022&#x2F;02&#x2F;01&#x2F;bloombergnef-says-global-solar-will-cross-200-gw-mark-for-first-time-this-year-expects-lower-panel-prices&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.pv-magazine.com&#x2F;2022&#x2F;02&#x2F;01&#x2F;bloombergnef-says-glo...</a><p>That&#x27;s in the neighborhood of 915 square kilometers of wafers.<p>Silicon for solar has risen meteorically over the past 20 years.<p><a href="https:&#x2F;&#x2F;www.pv-magazine.com&#x2F;2021&#x2F;10&#x2F;26&#x2F;whats-next-for-polysilicon&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.pv-magazine.com&#x2F;2021&#x2F;10&#x2F;26&#x2F;whats-next-for-polysi...</a><p><i>Until the early 2000s, demand for polysilicon (often simply referred to as “poly”) was dominated by the semiconductor industry, which required a fairly steady 20,000 to 25,000 metric tons (MT) per year. But semiconductor demand for poly was quickly outpaced by PV as the solar industry began to grow rapidly, from a rounding error at the turn of the millennium to almost half of global polysilicon demand by the middle of the decade.</i><p>...<p><i>By the end of 2013, the manufacturing cost of polysilicon had tumbled to below $20&#x2F;kg among industry leaders. Meanwhile, capacity had grown from less than 50,000 MT per year in 2007 to over 350,000 MT per year by 2013.</i><p>Polysilicon capacity at the end of 2021 was in the neighborhood of 700,000 metric tons, with more big expansions on the way. The extra 350,000 metric tons added since 2013 is almost entirely for solar.

Good overview, but he&#x27;s missing one of the coolest applications of semiconductor &#x2F; photolithography.<p>MEMS. Micro-electromagnetic systems. The most common MEMS I can think of is the comb sensor, used for accelerometers in all of your cell phones.<p><a href="https:&#x2F;&#x2F;www.memsjournal.com&#x2F;2010&#x2F;12&#x2F;motion-sensing-in-the-iphone-4-mems-accelerometer.html" rel="nofollow">https:&#x2F;&#x2F;www.memsjournal.com&#x2F;2010&#x2F;12&#x2F;motion-sensing-in-the-ip...</a><p>The MEMS sensor for an accelerometer is quite simple. Take the nearest comb and smack it against a desk: you&#x27;ll notice that the comb vibrates in one direction. Now hook up two combs and interleave their teeth together so that they&#x27;re barely touching. When they touch, an electrical signal is sent through them to sense when they touch.<p>Add differently sized teeth, the larger the spacing the more acceleration is needed before they activate. (EDIT: Looks like the iPhone MEMS uses capacitance... similar concept though, the capacitance changes based off of how far away these teeth are from each other and you can measure that using college-level electronics)<p>Finally, have these teeth rotated in all directions, so that you can sense all the directions in one little device.<p>--------<p>MEMS are about using the physical properties of object, but just making these small physical objects really, really, really tiny thanks to the magic of photolithography.<p>You can see this literal comb structure by looking at any accelerometer under a microscope: <a href="https:&#x2F;&#x2F;memsjournal.typepad.com&#x2F;.a&#x2F;6a00d8345225f869e20148c7030795970c-pi" rel="nofollow">https:&#x2F;&#x2F;memsjournal.typepad.com&#x2F;.a&#x2F;6a00d8345225f869e20148c70...</a><p>------<p>If the accelerometer is too difficult for you to understand, the &quot;beginner MEMS&quot; is gears.<p><a href="https:&#x2F;&#x2F;www.sandia.gov&#x2F;app&#x2F;uploads&#x2F;sites&#x2F;145&#x2F;2021&#x2F;11&#x2F;1-1.jpg" rel="nofollow">https:&#x2F;&#x2F;www.sandia.gov&#x2F;app&#x2F;uploads&#x2F;sites&#x2F;145&#x2F;2021&#x2F;11&#x2F;1-1.jpg</a><p>You can make any shape you want with modern chip-making tools. The &quot;shape&quot; most people want is a transistor (gate, drain, source). But in many ways, a teeny-tiny gear is simpler to think about.<p>The practical applications of micro-scale MEMS (gears, combs, springs, etc. etc. ) is somehow harder to think about than computers, so there aren&#x27;t very many practical MEMS around. But still, practical MEMS help remind us that all of these chip-making tools exist in the real, physical world. Albeit at a very small scale.

I used to be a professional computer geek on weekdays and professional photographer on weekends; and 20 years on, it still blows my mind the similarities between the materials and manufacturing of the CPU doing heavy work in my laptop and the sensor gathering pixels in my camera :O

I almost always think of all the things on breadboards (e.g. in the second picture on the page). But it&#x27;s probably because of all the games I played had those kinds of things in their technology thumbnails. Or maybe it was because I was alive when Radioshack existed.<p>most recently: <a href="https:&#x2F;&#x2F;dyson-sphere-program.fandom.com&#x2F;wiki&#x2F;Microcrystalline_Component?file=Microcrystalline_Component.png" rel="nofollow">https:&#x2F;&#x2F;dyson-sphere-program.fandom.com&#x2F;wiki&#x2F;Microcrystallin...</a>

Those are diffraction-grating colors, not thin-film-interference colors.