Tag: Epitaxy

Contributor Post Created with Sketch. How to Build a Computer 39: Epitaxy II: The Reckoning

 

I know y’all have been waiting eagerly with your wafer in the chamber, the temperature pumped down and your native oxide layer stripped off for me to finish this two-parter. Well, wait no longer! Okay, maybe wait some as you have to find a tank of dichlorosilane to hook up so you have something to epitax onto your wafer. Di-what now?

Dichlorosilane! Or Tri- or Tetra; really anything from SiH4 to SiCl4 works, though I’m told industry generally works with SiCl2H2. Alright, you pump in dichlorosilane gas and react it on the wafer and it puts silicon on top of your silicon. Neat, huh? That’s it! Join us fortnight next for —

Contributor Post Created with Sketch. How to Build a Computer 38: Epitaxy

 

Hello and welcome back to How to Build a Computer. If any of y’all are worried about my long absence, well, let that be a lesson to you: The bearded nogoodnik with the dimensional transportalponder does not have your best interests in mind. Sadly, the story is much less interesting than that; I ran out of processes that I either learned about in school or worked with on the job. I’m much less happy regurgitating textbooks than I am imparting actual experience. For instance, I don’t even know if “epitax” is a real verb, but I’m going to use it like such because it’s fun to say.

With the preliminaries out of the way, let’s take a look at the wonderful world of Epitaxy. From the Greek root it looks like we’re talking about a tax atop your other taxes, but however timely and relevant such a word might otherwise be that’s not what we’re working on. What we’re building here is a crystal on top of your other crystal. Recall way back from the start how wafers are sliced out of boules that are composed of one giant crystal. There’s some advantage to remember that that’s not a perfectly flat surface. Here, let me demonstrate: