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    Native oxide is stripped off the wafer with a quick dilute HF dip and then they are extensively cleaned in Piranha solution (H2SO4:H2O2), RCA 1 (H2O:NH3:H2O2), RCA 2 (H2O:HCL:H2O2), followed by another dilute HF dip.

    An obvious reminder: despite the context, do NOT try this at home unless you really know how to handle these chemicals. Sulfuric and hydrochloric acids are fairly benign when dilute… which these are not. Ammonia is toxic, concentrated hydrogen peroxide is caustic and can form all sorts of excitingly flammable and explosive substances if not handled with care, and killing you is probably the best thing HF can do to you.

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      Yup. You definitely should not mess with any of these without all the appropriate safety equipment (acid gloves, apron, and face mask, calcium gluconate gel, safety shower) and someone else available to help in the case of an emergency. HF is crazy dangerous. Direct contact with a 50% HF puddle the size of your palm is enough to kill you if not treated immediately, and even with immediate rinsing and calcium concatenate gel, treatment might require amputation. And it won’t hurt immediately. Once it starts to hurt, it’s already too late, and you’re in for a world of pain as it dissolves your bones.

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      Super impressive, especially for someone still in highschool! I still love everything about semiconductors, even though I found working in the industry too stressful. There’s just so much interesting physics, mathematics, and hardware, and its impact cannot be understated. It has impacted every other industry so thoroughly. And the number of man hours put into understanding silicon and how it interacts with basically every other element on the periodic table, with light, with heat, etc. boggles the mind.

      For others interested in the topic, I highly recommend the book “The Story of Semiconductors” by J W Orton. It’s an interesting history set in a broader context.

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        especially for someone still in highschool

        oh my goodness I did not notice that. Wow.

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        There’s some nice links and details in the HN comments. Particularly this sub-thread about the site’s author.

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          Meanwhile I never got the hang of etching PCBs…