💡a journey into microchips: between transistors, resistors and bunny suits.
bits and pieces of my first hands-on exposure to the nano world.
hey! welcome to my newsletter.🌿 in case you do not know me: i’m mafer, a 19-year-old peruvian freshman at stanford university, climate tech enthusiast and boba tea connoisseur. i’m very glad to have you here.
(sorry — have been procrastinating on this post for a hot minute, but here it is!)
the latest scientific gossip about moore’s law and how its ending particularly surprised for these past months. if we already have transistors that boil down to 1 nanometer, how can we even surpass that now, while still maintaining the physical properties that the nanoscale enables? quantum effects below that threshold could potentially hinder their capacity:
quantum tunneling occurs when a particle’s wavefunction, described by the Schrödinger equation, is not required to be zero inside a barrier, allowing it to pass through the barrier.
electrons can now behave as a wave - instead of bouncing back, they can go through energy barriers. just imagine throwing a ball to a wall. in a “classical microchip environment”, the ball would bounce back. but at the quantum level, it goes through it.
and, the problem?
the location of the electron becomes (sadly) unrecognizable. to account for this, we employ a wave-like representation to determine its probabilistic whereabouts, known as a ‘wavefunction’. this is a mathematical entity that describes the probability distribution of finding the particle in various states or locations.
these past month , i had the opportunity to learn a bit more about the nano world. specifically, we delved into the world of chips, transistors, diodes, resistors, circuits… all of this at the nanoscale. amongst many others, we debated this same question of how much is there left to discover. is moore’s law really ending?
as a little milestone of what i learned (and a little attempt to answer the query), here are some interesting mechanisms that i learned along the way, and my biggest takeaways of each one.
⛏️what is a transistor?
let’s start from the basics.
transistors, in short, are very very very little “automated” switches. and i say automated, because you don’t need someone to control when it’s on and off! this is what makes them so compelling - they use the presence or absence of electrons to represent and manipulate information in electronic circuits.
but let me walk you through how they generally work.
transistors are made of a semiconductor (mostly silicon), since these can both insulate and conduct electricity. this characteristic is crucial, since the whole purpose of a transistor is to regulate current or voltage flow acting as a “switch”. these are incredibly important for the miniaturization of electronic devices, since the integrated circuits (ICs) contain millions to billions of transistors in a small chip, allowing for powerful computing and processing capabilities in compact devices like smartphones, laptops, and wearables.
🧐so… microchips?
a bunch (actually, millions or billions!) of transistors can be found in microchips. and the way they are produced was one of my favorite things this year. shadowing at the stanford nanofabrication facility, we could see the layered approach of microchip fabrication. overall, the process is as follows:
deposition for adding materials: it is an additive process, so you quite literally add the microchip material in a layer. there are a lot of cool examples for this one, like evaporation, sputtering, atomic layer deposition, and a lot more!
lithography for patterning (my fav): the wafer goes through a resist spinner, and photoresist is added on top. in the lab, we saw how some people did it with masks (meaning that the photoresist gets set in chosen parts of the wafer… look at this diagram i made!)
![](/img/missing-image.png)
etching for removing materials: developers dissolve the areas exposed to UV in positive photoresist. the unexposed areas under the black patterns are not dissolved.
doping for resistivity change: we introduce an electron donor or acceptor into crystal lattice
anneal for dopant activation
polishing to planarize wafers — and voila! you made your first microchip!
looking at this process and making a wafer design on my own was, quite simply, fun. my design was mega mind with a bunch of carbon buckyballs!
🦾my main takeaways.
the nanoscale world is full of incredible complexities and opportunities. and the more we understand about the behavior of materials and particles at this level, the more we can innovate and push the boundaries of technology.
despite the challenges posed by quantum effects, like tunneling, we are developing new techniques and materials to continue advancing. moore’s law may be evolving, but the spirit of relentless progress and discovery in nanotechnology remains as strong as ever. this journey into the nano realm has only just begun, and there’s so much more to explore and learn!
Hey, I'm very curious about something. As students, have you observed any practical applications of the latest microchip technologies in neuroscience or biology?