WEBVTT - How Microchips Are Made 0:00:00.320 --> 0:00:02.880 Brought to you by the reinvented two thousand twelve camera. 0:00:03.200 --> 0:00:08.920 It's ready. Are you get in touch with technology with 0:00:09.039 --> 0:00:17.880 tech Stuff from how stuff works dot com. Hello again, everyone, 0:00:17.960 --> 0:00:21.439 welcome to tech stuff. My name is Chris Boulette and 0:00:21.440 --> 0:00:23.959 I am an editor here in how stuff works dot Com. 0:00:24.000 --> 0:00:27.200 Sitting across from me cracking up at my goofiness is 0:00:27.400 --> 0:00:31.440 senior writer Jonathan Strickland. Seriously, guys, if you could hear 0:00:31.520 --> 0:00:34.880 our pre show and post shows, you would you would 0:00:34.920 --> 0:00:37.640 just you would think that the goofy stuff we do 0:00:37.760 --> 0:00:44.360 during the show is nothing in embarrasson nothing. Yeah, let's 0:00:44.400 --> 0:00:48.160 turn this episode off with a little oh listener mail. 0:00:53.600 --> 0:00:56.760 This listener mail comes from Jacob a k. A. Booger, 0:00:58.080 --> 0:01:02.480 and Jacob gave himself that name. I'm catching up to 0:01:02.520 --> 0:01:06.440 the present day podcasts and them on USB versus FireWire, 0:01:06.600 --> 0:01:09.240 and I still haven't heard you guys mentioned a m 0:01:09.319 --> 0:01:12.479 D yet. Please talk about them since I think they're 0:01:12.520 --> 0:01:15.640 better than Intel in more than a few ways. Thanks 0:01:16.040 --> 0:01:20.039 Jacob Booger, Well Booger, we thought we'd talked a little 0:01:20.040 --> 0:01:23.520 bit about kind of microchips in general and how they're made. Um, 0:01:23.720 --> 0:01:27.319 we don't tend to to break things down to company 0:01:27.319 --> 0:01:30.400 by company. But of course Intel on a m D 0:01:30.440 --> 0:01:35.400 are both known for their microchip architecture. Yeah they uh. 0:01:35.600 --> 0:01:39.199 For the uninitiated, these two are pretty much the big 0:01:39.240 --> 0:01:42.919 guys in the computer segments like the personal computer. Intel 0:01:42.959 --> 0:01:45.119 an m D are wrestling back and forth with one 0:01:45.120 --> 0:01:47.680 another on a day to day basis. Now, there are 0:01:47.720 --> 0:01:49.720 lots and lots and lots and lots of other companies 0:01:49.720 --> 0:01:53.880 who make microprocessors of different kinds. Right, Let's let's be fair. Yes, 0:01:54.640 --> 0:01:59.240 when you say wrestling, Intel's kind of the enormous sumo 0:01:59.280 --> 0:02:04.080 wrestler and a m D is like the luchador. Yes, 0:02:04.160 --> 0:02:07.000 but that doesn't necessarily mean that in this case the 0:02:07.080 --> 0:02:11.520 luchador is you know, a lesser. Oh no, no no, no, 0:02:11.840 --> 0:02:15.480 I'm just saying by market share, okay, yes, by market share, yes, 0:02:15.600 --> 0:02:19.799 until has the the lion's share of the market. Um. 0:02:19.919 --> 0:02:25.560 But there there are many many other microprocessor manufacturers out there, um, 0:02:25.600 --> 0:02:29.080 you know, some of whom are limiting their their work 0:02:29.120 --> 0:02:33.240 to one or you know, one or two different products. 0:02:33.840 --> 0:02:37.000 You can find microprocessors and just about everything anything that 0:02:37.000 --> 0:02:39.520 that's electronic these days, because we've come to roll eye 0:02:39.600 --> 0:02:43.079 on them. Yeah, we also had another listener asked us 0:02:43.120 --> 0:02:45.880 about microchips, and I would like to apologize to that 0:02:45.960 --> 0:02:49.440 listener because I could not find your email and or tweet. Um, 0:02:49.480 --> 0:02:51.280 I know that you sent it to me. And so 0:02:51.400 --> 0:02:54.840 we wanted and this listener wanted to know what microchips were, 0:02:55.360 --> 0:02:57.840 and you know, what they did and how they were made. 0:02:58.360 --> 0:02:59.960 And so we were going to kind of talk about 0:03:00.880 --> 0:03:03.480 a little bit of of what they do, but not 0:03:03.560 --> 0:03:07.160 a whole lot because we've talked about it before. But uh, 0:03:07.320 --> 0:03:09.960 a microchip. You know, when you hear that term, you 0:03:10.040 --> 0:03:12.519 might think, well, what the heck is that. Technically it's 0:03:12.600 --> 0:03:16.200 an integrated circuit. Yes, that's what a microchip is. And 0:03:16.280 --> 0:03:18.880 so if you remember when we talked about the basics 0:03:18.880 --> 0:03:23.480 of electronics and electronic theory, a circuit is a pathway 0:03:23.639 --> 0:03:26.600 for electrons to flow through, Yes, and of course the 0:03:26.639 --> 0:03:31.200 flow of electrons we know better as electricity. At least 0:03:31.200 --> 0:03:36.320 that's the current definition. Oh my gosh, I totally forgot 0:03:36.320 --> 0:03:39.400 that we went down that road last time. Alright, So, yes, 0:03:39.480 --> 0:03:43.840 a circuit is a pathway for electricity. Integrated circuit is 0:03:44.160 --> 0:03:47.960 a special kind of circuit. Now, let's let's I guess 0:03:48.200 --> 0:03:50.320 you want to are we gonna take the way back 0:03:50.360 --> 0:03:53.320 machine here, or you want to just talk about the past. Oh, 0:03:53.440 --> 0:03:55.320 we could just talk about the past, all right. So 0:03:56.400 --> 0:03:58.480 I don't think anybody gassed up the way back, Yeah, 0:03:58.520 --> 0:04:00.840 I think, well, right, yeah, I I noticed the last 0:04:00.840 --> 0:04:04.280 time I was pulling the cord, it wasn't really it 0:04:04.400 --> 0:04:06.560 wasn't really starting up the way you would expect it to. 0:04:07.320 --> 0:04:11.600 So anyway, back in the day, the day being a 0:04:11.600 --> 0:04:16.320 long time ago. Uh, circuits were much larger than they 0:04:16.360 --> 0:04:19.719 are today. Um, they you could actually see each of 0:04:19.720 --> 0:04:23.159 the discrete elements pretty clearly because it was all on 0:04:23.200 --> 0:04:26.960 a much larger scale. And we're going all the way 0:04:26.960 --> 0:04:31.880 back to vacuum tubes here talking about So vacuum tubes 0:04:32.440 --> 0:04:37.680 acted the way transistors do. Now, so let's let's talk 0:04:37.720 --> 0:04:40.440 a little bit about what exactly they did. The whole 0:04:40.480 --> 0:04:43.760 purpose of it was to control the flow of electricity. 0:04:43.800 --> 0:04:46.920 It would be to allow electricity to flow through that 0:04:46.960 --> 0:04:48.800 part of the circuit, and you could even use it 0:04:48.839 --> 0:04:54.640 to amplify the electricity if you needed to. Okay, you're 0:04:54.680 --> 0:04:56.640 just staring at me now. I wasn't planning on talking 0:04:56.640 --> 0:05:02.680 about vacuum tubes, so I didn't at any rate, Uh, 0:05:02.880 --> 0:05:05.719 The problem with vacuum tubes is they were really big 0:05:05.880 --> 0:05:08.240 and they produced a lot of heat. They do produce 0:05:08.240 --> 0:05:09.839 a lot of heat. I can tell you that right now. 0:05:09.880 --> 0:05:13.520 I have a a beaten up old amplifier that uses 0:05:13.600 --> 0:05:15.960 vacuum tubes. And not only do they produce a lot 0:05:16.000 --> 0:05:18.560 of heat, they're really heavy and unwieldy because they take 0:05:18.600 --> 0:05:22.080 up a lot of space. Yes, so those are all problems, right, 0:05:22.120 --> 0:05:24.200 I mean, you've got it, produces a lot of heat, 0:05:24.440 --> 0:05:26.839 takes up a lot of space, and they're really heavy. 0:05:26.880 --> 0:05:31.479 So the early computers were these enormous machines that generated 0:05:32.640 --> 0:05:35.279 uh so much heat that it was hard to be 0:05:35.320 --> 0:05:37.880 in the same room as them. Um, of course, it's 0:05:37.880 --> 0:05:39.320 hard to be in the same room anyway, because they 0:05:39.320 --> 0:05:41.440 pretty much took up an entire room. Well, but it 0:05:41.480 --> 0:05:43.160 this way. You're not going to see a vacuum tube 0:05:43.160 --> 0:05:46.000 powered iPod anytime soon because they take up a lot 0:05:46.040 --> 0:05:50.680 of space, right, So you can't put that in your pocket, Yeah, no, 0:05:50.960 --> 0:05:53.600 you can't that. And and in fact, the development of 0:05:53.640 --> 0:05:58.320 the semiconductor was what led to you know, transistor radios, 0:05:58.320 --> 0:06:00.000 and that's when we started getting a lot of portable 0:06:00.000 --> 0:06:03.640 electronics because it was possible to to throw a portable 0:06:03.720 --> 0:06:06.520 radio in your pocket instead of you know, having to 0:06:06.560 --> 0:06:08.400 deal with the one that was plugged in you know, 0:06:08.440 --> 0:06:10.919 at home, on on the desk, right, the one that 0:06:10.960 --> 0:06:12.680 was almost the same size as the desk it was 0:06:12.720 --> 0:06:18.320 on the Yeah. So, so vacuum tubes were limiting us 0:06:18.400 --> 0:06:21.760 quite a bit, uh because of their size, because they 0:06:21.760 --> 0:06:24.400 would also burn out, and if one burnt out, that 0:06:24.440 --> 0:06:26.720 meant that your whole system was no longer working and 0:06:26.760 --> 0:06:28.800 you would have to replace the burnt out tube. So 0:06:29.240 --> 0:06:32.359 we needed to find something that was smaller, generated less heat, 0:06:32.920 --> 0:06:38.799 was more reliable, and that ended up being the transistor. Now, uh, 0:06:38.920 --> 0:06:42.760 that was invented back in It would still be quite 0:06:42.760 --> 0:06:46.040 a while before we got transistors small enough to put 0:06:46.080 --> 0:06:48.760 them on like a circuit board. The earliest transistors were 0:06:48.760 --> 0:06:54.120 actually pretty large. Um. And then even then, you're still 0:06:54.160 --> 0:06:58.279 talking about a bunch of discrete elements that you wired 0:06:58.279 --> 0:07:01.720 together to create a circuit. Yeah right, So yeah, I mean, 0:07:01.800 --> 0:07:03.960 if you've done this, you might have a physics classes 0:07:04.000 --> 0:07:06.640 you've done where you've created an electric circuit this way, 0:07:07.200 --> 0:07:10.560 where you know, you're using wires to connect various elements 0:07:10.600 --> 0:07:12.120 together and then you hook it up to a battery. 0:07:12.720 --> 0:07:15.160 So if you haven't, you should because it's a lot 0:07:15.160 --> 0:07:18.560 of fun. It's a good learning experience. But that's an aside, right, 0:07:19.000 --> 0:07:24.400 so the sorry, yeah, I know, now I'm throwing off 0:07:24.440 --> 0:07:30.880 down like okay with notes notes, So let's talk about 0:07:30.920 --> 0:07:35.280 the complex circuits here. Um, there was an issue called 0:07:35.320 --> 0:07:38.440 the tyranny of numbers. The tyranny of numbers? Have you 0:07:38.480 --> 0:07:42.800 heard about this? Wasn't that a mystery novel? Uh? No? Not? Well, 0:07:42.840 --> 0:07:45.960 I mean I'm gonna say no, it could be true. 0:07:46.040 --> 0:07:48.800 I'm gonna write it if there wasn't one. Right, now, 0:07:49.840 --> 0:07:53.480 here's the here's the definition. Advanced circuits contained so many 0:07:53.600 --> 0:07:57.800 components and connections they were virtually impossible to build. This 0:07:57.920 --> 0:08:01.120 problem was known as the tyranny of number burrs. So that, 0:08:01.240 --> 0:08:02.800 in other words, we get to a point where we 0:08:02.800 --> 0:08:05.840 can build circuits, right, but in order to build them 0:08:05.840 --> 0:08:08.600 at the complexity that we need, the tools we have 0:08:08.640 --> 0:08:11.880 are two crude, right, using it, building it by hand. 0:08:11.920 --> 0:08:13.840 It's just there's no way you can have the level 0:08:13.840 --> 0:08:16.400 of precision you need in order to build a circuit 0:08:16.480 --> 0:08:20.360 that's small. What could possibly be the solution to the 0:08:20.400 --> 0:08:27.280 tyranny of numbers problem? Let's see I've mentioned it before already, 0:08:28.080 --> 0:08:31.360 the integrated circuit. Just say the integrated circuit. Okay, the 0:08:31.400 --> 0:08:34.559 integrated circuit. Very good. So in nineteen fifty eight, you've 0:08:34.559 --> 0:08:38.800 got Jack Kilby. Yes, and Kilby was working at Texas Instruments, 0:08:39.360 --> 0:08:41.720 one of those aforementioned companies that makes lots and lots 0:08:41.720 --> 0:08:46.319 of different kinds of microprocessors. That's correct. And Kilby at 0:08:46.360 --> 0:08:49.800 the time was brand new to the company. You know, 0:08:49.800 --> 0:08:51.480 he'd only been working there for a little while and 0:08:51.520 --> 0:08:55.280 had not earned any vacation yet. So there was a 0:08:55.320 --> 0:08:58.200 point where pretty much everyone went on vacation except for Kilby, 0:08:58.280 --> 0:09:02.240 and he was left there pondering the tyranny of numbers problem, 0:09:02.280 --> 0:09:04.120 and he came up with this idea. He thought, well, 0:09:04.120 --> 0:09:07.520 what if you were to build an entire circuit out 0:09:07.520 --> 0:09:11.720 of one piece of material, and you would essentially carve 0:09:11.840 --> 0:09:15.080 out the different elements that you would need out of 0:09:15.120 --> 0:09:18.640 that material, overlay it with some metal to be the connectors, 0:09:19.160 --> 0:09:21.880 and then you would have an entire circuit printed more 0:09:21.920 --> 0:09:25.720 or less on one single piece and you wouldn't have 0:09:25.800 --> 0:09:29.240 to build the individual elements. That was the idea behind 0:09:29.280 --> 0:09:33.280 the integrated circuit. I apologize, so Essentially he found a 0:09:33.320 --> 0:09:36.600 way to make the whole thing fit in a much 0:09:36.640 --> 0:09:40.680 more compact space. Right, and by using this method of 0:09:40.800 --> 0:09:46.240 carving away from a single elements a single chip, really 0:09:47.000 --> 0:09:51.840 you could make the different individual um parts of the 0:09:51.880 --> 0:09:56.760 circuit much much smaller than you could before. Um. Which 0:09:56.800 --> 0:10:01.200 is good because it has led to lots and lots 0:10:01.240 --> 0:10:04.720 of very very small devices. Well this is this is yeah, 0:10:04.800 --> 0:10:08.600 this is what eventually led up to Gordon Moore taking 0:10:08.600 --> 0:10:11.840 a look at the number of transistors uh that engineers 0:10:11.840 --> 0:10:14.600 were able to fit onto a single one inch diameter 0:10:15.080 --> 0:10:19.199 chip and say, look every at the time, I think 0:10:19.240 --> 0:10:22.080 it was every twelve months, they were doubling, although of 0:10:22.080 --> 0:10:24.400 course today we talked about it being every two years. 0:10:24.880 --> 0:10:27.600 Um Gordon, So Moore's law has slowed down over time, 0:10:27.640 --> 0:10:31.160 but it's still you're still talking about doubling over a 0:10:31.640 --> 0:10:35.000 set time limit, which is pretty amazing because you know, 0:10:35.040 --> 0:10:39.760 we're in the we're in the billions now. So um 0:10:39.880 --> 0:10:42.080 so how well, first of all, we I guess we 0:10:42.080 --> 0:10:45.520 should talk about the material they use to build these chips. 0:10:45.600 --> 0:10:50.280 Its silicon. Yes, it's not just silicon, it's extremely pure 0:10:50.400 --> 0:10:52.920 silicon YEP. As a matter of fact, when I was 0:10:52.960 --> 0:10:56.480 doing research on this. I found a video by a 0:10:56.520 --> 0:11:00.800 different part of our company. The Science Channel did a 0:11:00.840 --> 0:11:05.600 piece on silicon and it's it's um really fascinating what 0:11:05.640 --> 0:11:09.560 they do because they have to to melt down lumps 0:11:09.600 --> 0:11:12.600 of the material to to get you know, basically to 0:11:12.920 --> 0:11:16.199 reform it in the shape that they need for microprocessors. 0:11:16.240 --> 0:11:19.600 But it has to be extremely pure, so they have 0:11:19.640 --> 0:11:22.480 to clear out the chamber chamber with argonne gas to 0:11:22.480 --> 0:11:24.319 make sure that there's no air in there at all, 0:11:25.160 --> 0:11:30.040 melted down and then uh, they create essentially what looks 0:11:30.040 --> 0:11:34.040 like a giant silicon pencil. Yeah, it's a big cylinder 0:11:34.520 --> 0:11:41.560 cylinder of silicon, and then they put the cylinder through Um, well, 0:11:41.559 --> 0:11:45.640 they use they use a very fine wire to cut wafers. Yes, 0:11:45.920 --> 0:11:49.199 it's water thin, Yes it is. As a matter of fact, 0:11:49.280 --> 0:11:53.360 it's it's just a few millimeters thick each each layer, 0:11:53.720 --> 0:11:57.160 right and and um, so there they cut these these 0:11:57.160 --> 0:12:00.920 slices off and each slice becomes its own the owner, 0:12:01.040 --> 0:12:04.679 its own silicon wafer that you used to imprint uh, 0:12:04.760 --> 0:12:08.959 circuitry onto and you could end up using one wafer 0:12:09.000 --> 0:12:12.240 to produce dozens and dozens of chips. Yes, it's a 0:12:12.280 --> 0:12:14.040 matter of fact, every once in a while you'll see 0:12:14.040 --> 0:12:17.719 a picture in the news of some dignitary visiting a 0:12:17.720 --> 0:12:20.360 computer plant and they'll hold up a what looks like 0:12:20.360 --> 0:12:22.319 a giant disk and you're going, wait a minute, that's 0:12:22.320 --> 0:12:24.480 way too big to fit in my computer. Well, yes, 0:12:24.600 --> 0:12:26.880 this is. This is a cross section of that giant 0:12:26.880 --> 0:12:30.560 cylinder imprinted with in general and one the ones I've seen. 0:12:30.559 --> 0:12:32.200 When they show where they're holding it up there, you 0:12:32.200 --> 0:12:35.240 can see that there's something etched on on the silicon. Well, 0:12:35.280 --> 0:12:39.240 those are all the different individual chips or what would 0:12:39.280 --> 0:12:42.720 become chips if they were you know, uncontaminated by whoever 0:12:42.760 --> 0:12:44.400 it is holding it up right at the at the 0:12:44.480 --> 0:12:47.280 end of the process, once everything's been printed, you you 0:12:47.480 --> 0:12:53.320 chop that wafer into the various, uh, actual individual chips. 0:12:54.040 --> 0:12:56.200 Shop I mean you actually use a very fine saw. 0:12:56.520 --> 0:12:58.080 It's a diamond saw as a matter of fact, that 0:12:58.120 --> 0:13:02.040 they used to cut the uh, the slice of silicon 0:13:02.160 --> 0:13:03.960 up into lots and lots of little chips. But we've 0:13:04.160 --> 0:13:08.960 we've left out stuff all right, So well, the process 0:13:09.000 --> 0:13:12.640 is known as photolithography, and it's been in use for 0:13:12.800 --> 0:13:16.280 several years several by several, I mean many, it's actually 0:13:16.360 --> 0:13:18.720 kind of a it's really a neat neat idea. All right, 0:13:18.760 --> 0:13:21.120 so let's let's start with you've got your your silicon 0:13:21.840 --> 0:13:23.920 um also, well, well we'll go ahead and say where 0:13:23.960 --> 0:13:29.480 the stuff takes place, because we're talking about elements on 0:13:29.640 --> 0:13:33.040 these chips that are just a few nnometers in width. 0:13:33.480 --> 0:13:37.280 So any kind of impurity, any mode of dust that 0:13:37.400 --> 0:13:39.560 got on this thing is going to ruin it. A 0:13:39.600 --> 0:13:42.360 mode of dust would be enormous compared to one of 0:13:42.400 --> 0:13:45.199 the transistors on these chips. Exactly. Yeah, so you can't 0:13:45.240 --> 0:13:48.240 have any sort of of dust in there. Well, think 0:13:48.280 --> 0:13:52.120 about your environment for a second. Uh, just the dust 0:13:52.160 --> 0:13:54.680 in the air alone in your environment right now, unless 0:13:54.679 --> 0:13:57.719 you're in a clean room, is gonna be way too 0:13:57.800 --> 0:14:01.840 much to ever try and produce. Use a microchip, ye, 0:14:01.960 --> 0:14:05.520 so at least one that will function. Right, And we're humans. 0:14:05.720 --> 0:14:08.480 We give off lots of lots of dust. Dead skin 0:14:08.559 --> 0:14:12.000 cells have tons of dust every day if you look 0:14:12.000 --> 0:14:15.880 at the entire human population, literally tons of dust. So 0:14:16.679 --> 0:14:21.360 the these clean rooms can't have that. They don't have 0:14:21.400 --> 0:14:23.360 the luxury of being able to have that sort of 0:14:23.480 --> 0:14:26.200 dust flying around. So in order to prevent it, they 0:14:26.240 --> 0:14:29.760 have massive air conditioning systems that circulate the air in 0:14:29.800 --> 0:14:32.280 these these clean rooms. These clean rooms can be enormous, 0:14:32.320 --> 0:14:35.040 by the way, like the size of a warehouse, but 0:14:35.800 --> 0:14:37.960 in most of them, the air conditioning system is so 0:14:38.000 --> 0:14:41.160 powerful that it can completely circulate all the air in 0:14:41.200 --> 0:14:46.200 that room under ten minutes. It's pretty impressive. And uh, 0:14:46.360 --> 0:14:50.520 this is where Intel's famous bunny suit campaign came from. 0:14:50.760 --> 0:14:55.120 Back in the sadly, not the kind of bunny suit 0:14:55.160 --> 0:14:57.800 I was thinking. No, no, the bunny and the bunny 0:14:57.800 --> 0:15:00.840 suits are actually they they look like they're in some 0:15:00.880 --> 0:15:04.400 sort of high tech firefighting gear because their suits that 0:15:04.440 --> 0:15:06.360 they wear where they have hoods over their heads with 0:15:06.360 --> 0:15:10.000 a visor in them, and this basically keeps dust out 0:15:10.000 --> 0:15:11.440 of the air by you know if you see in 0:15:11.480 --> 0:15:13.600 the humans. But yeah, it keeps it inside the suit. 0:15:14.040 --> 0:15:17.840 The humans then they can't shed inside the clean rooms. Yeah, 0:15:17.960 --> 0:15:20.360 and I remember in that video you were referencing, they 0:15:20.360 --> 0:15:22.360 actually talk about how the air in these rooms is 0:15:22.840 --> 0:15:25.760 cleaner than the air you'll find in hospitals. That doesn't 0:15:25.800 --> 0:15:28.680 surprise because of the way, the speed and the filters 0:15:28.720 --> 0:15:33.520 that they use. So we've got this this uh environment 0:15:33.600 --> 0:15:36.440 that is it's not dust free because you're never gonna 0:15:36.440 --> 0:15:39.200 get that unless you're in a complete vacuum. Um. But 0:15:39.280 --> 0:15:41.680 it's about as limited as you possibly can be and 0:15:41.720 --> 0:15:45.520 still be on on earth. Uh. Now, let's talk about 0:15:45.560 --> 0:15:48.680 the actual process of photolithography. Yeah, but as we get 0:15:48.680 --> 0:15:51.560 into this, you're gonna see that we have improved on 0:15:52.280 --> 0:15:54.640 Dr Kilby's process. I'm assuming he is a doctor. I 0:15:54.640 --> 0:15:58.200 didn't see that part on the engineer at any rate. Yeah, 0:15:58.240 --> 0:16:04.600 on Kilby's process for creating microprocessor micro microchips. Because this 0:16:04.680 --> 0:16:08.200 is a very very sophisticated way of doing it. Right. 0:16:08.560 --> 0:16:12.720 So you start with your your pure silicon uh wafer, Yes, 0:16:13.000 --> 0:16:17.400 that you have sliced off of the the whole uh cylinder. 0:16:18.360 --> 0:16:20.800 Then the next thing you need to do is you 0:16:20.880 --> 0:16:25.160 need to uh create a mask. Now, the mask is 0:16:25.240 --> 0:16:27.680 and this is not in all forms of lithography, but 0:16:27.720 --> 0:16:31.760 we'll get into that. The mask is essentially a pattern. Yes, right, 0:16:31.800 --> 0:16:34.440 it's the pattern. It's what the chip is supposed to 0:16:34.440 --> 0:16:37.320 look like at the end. If you if you've ever 0:16:37.320 --> 0:16:40.960 worked in photography and uh with film, not with with 0:16:41.040 --> 0:16:43.720 the with the digital camera, and you are trying to 0:16:44.640 --> 0:16:47.880 make part of the picture a little darker when you're 0:16:47.880 --> 0:16:52.240 developing it, you would hold up something basically to block 0:16:52.440 --> 0:16:56.480 the light from getting to that part of the uh, 0:16:56.560 --> 0:16:59.400 to the photosensitive paper. Well that's basically what the mask 0:16:59.560 --> 0:17:03.840 is is blocking light from a very high energy ultra 0:17:03.920 --> 0:17:08.920 violet source which is going to shine onto the silicon wafer. Uh, 0:17:08.960 --> 0:17:11.800 and the mask is blocking that. Now why would we 0:17:11.840 --> 0:17:14.439 do this, Well, it's because the silicon is not just 0:17:14.600 --> 0:17:18.200 silicon at that point. They have also overlaid on top 0:17:18.240 --> 0:17:23.040 of that a piece of uh, photosensitive film right right, 0:17:23.119 --> 0:17:26.119 So you've got this, You put the photos intoitive film 0:17:26.240 --> 0:17:29.040 on top of the wafer, and then you've got this uh, 0:17:29.119 --> 0:17:34.400 this mask that ah that ultraviolet light shines through. When 0:17:34.400 --> 0:17:38.199 the ultraviolet light contacts the wafer, like, there's gonna be 0:17:38.240 --> 0:17:40.520 some parts that the mask blocks in, some parts that 0:17:40.560 --> 0:17:42.880 the mask lets through, right right, So the parts where 0:17:42.920 --> 0:17:45.880 the mask let's through the light, the light hits the wafer. 0:17:46.040 --> 0:17:49.240 And when you when you are finished with this first 0:17:49.280 --> 0:17:53.240 process and you wash the film uh away, the it 0:17:53.359 --> 0:17:56.680 takes anything that that the light has contacted gets essentially 0:17:56.680 --> 0:18:00.400 carved away. Well, basically what happens is that the high 0:18:00.680 --> 0:18:04.760 energy ultraviolet light causes that film to break up, you 0:18:04.800 --> 0:18:08.440 know it, Uh, the film doesn't react to the light 0:18:08.720 --> 0:18:10.879 very well. So that's the point. They wash it with 0:18:10.960 --> 0:18:15.840 water and that washes away the broken away bits, but 0:18:15.880 --> 0:18:17.960 you still have that protective film on the places where 0:18:17.960 --> 0:18:20.600 the light didn't touch because of the mask. Well right, right, yeah, 0:18:20.600 --> 0:18:23.720 I worded it incorrectly. Well no, no, no, I was 0:18:23.800 --> 0:18:29.280 just clarifying. And then um, they once they rinse that away, 0:18:29.320 --> 0:18:32.199 they bake it. Then they use a process called etching, 0:18:32.640 --> 0:18:37.480 in which they use chemicals to dissolve the remaining protective film. 0:18:38.880 --> 0:18:42.920 Uh to Basically, you know, now you have just the 0:18:42.960 --> 0:18:47.440 etched wafer of silicon, right, so are film there and 0:18:47.440 --> 0:18:49.680 and also and also the stuff that was no longer 0:18:49.800 --> 0:18:51.720 covered by the film which had been you know, the 0:18:51.720 --> 0:18:54.560 film got zapped away wherever the light touched it. Yes, 0:18:54.760 --> 0:18:57.719 that gets etched away. Yes, so that's where you've actually 0:18:57.800 --> 0:19:01.840 carved away the the material. What's left standing is the 0:19:01.880 --> 0:19:05.320 stuff that was not touched by the light. That's just 0:19:05.440 --> 0:19:08.960 one round. You may have to do this dozens of 0:19:09.080 --> 0:19:12.600 times before you have actually carved out all the elements 0:19:12.760 --> 0:19:16.520 on your your your circuit. So well, there's another part 0:19:16.560 --> 0:19:18.719 of the process to the doping part, in which they 0:19:18.800 --> 0:19:22.200 change the electrical properties of the silicon. Right, doping means 0:19:22.240 --> 0:19:26.679 that you are purposefully introducing impurities into the material in 0:19:26.760 --> 0:19:30.000 order to change it's it's um well, the way it 0:19:30.119 --> 0:19:34.639 what either conducts or insulates. I mean, that's that's what 0:19:34.720 --> 0:19:38.200 a semiconductor is. Under certain circumstances that can conduct electricity 0:19:38.200 --> 0:19:40.439 and others it does not, right, and where it can 0:19:40.440 --> 0:19:43.760 conduct some electric electricity, but a not at a rapid 0:19:43.880 --> 0:19:47.280 rate as rapid as it was maybe at just certain temperatures. 0:19:47.880 --> 0:19:50.280 So again, this all depends upon the impurities that you 0:19:50.400 --> 0:19:53.080 introduce into it. So at the base you have to 0:19:53.119 --> 0:19:55.720 have the pure system so that it doesn't conduct electricity 0:19:55.720 --> 0:19:58.720 at all. Otherwise you do you have a chip that's 0:19:58.760 --> 0:20:02.960 not gonna work. Again, the ultimate goal here is to 0:20:03.000 --> 0:20:05.480 be able to direct the flow of electrons in a 0:20:05.560 --> 0:20:07.840 very specific way, and of course if your entire chip 0:20:07.880 --> 0:20:10.840 does that, If it doesn't, it's it's not specific at 0:20:10.840 --> 0:20:16.200 that point, and so you'd have a broken chip. So um, they, 0:20:16.240 --> 0:20:19.639 as Jonathan pointed out a moment ago, they continue to 0:20:19.640 --> 0:20:22.680 do this layer by layer by layers, so that um, 0:20:22.720 --> 0:20:25.800 again you're taking up less space because you have layers 0:20:26.880 --> 0:20:30.239 of material on top of one another, which you know 0:20:30.280 --> 0:20:32.879 there it's no longer and no longer requires it to 0:20:33.080 --> 0:20:35.399 take up so much physical space because it's all basically 0:20:35.440 --> 0:20:38.840 sandwiched on top of one another. But then there's the 0:20:38.840 --> 0:20:43.960 the metallization process, right, so you've carved away everything that 0:20:44.040 --> 0:20:47.040 doesn't need to be there. It's kind of like a sculptor. Yeah, 0:20:47.080 --> 0:20:49.639 it didn't carve everything away that doesn't look like a circuit. 0:20:50.920 --> 0:20:53.840 Very nice, it's essentially that's what how it works. I'm 0:20:53.880 --> 0:20:56.439 on board with that. But again it's on an incredibly 0:20:56.480 --> 0:20:58.359 tiny level. And the reason it can be so tiny, 0:20:58.440 --> 0:21:00.879 you know, we've talked about before that the nano scales 0:21:00.920 --> 0:21:03.760 so small that you cannot view it through a light microscope. Yes, 0:21:04.040 --> 0:21:06.439 well that's because they're not using the way they can 0:21:06.480 --> 0:21:08.760 get at a small as. They're not using visible light. Again, 0:21:08.800 --> 0:21:12.640 they're using ultra violet light. Yes, and in fact, Intel 0:21:13.400 --> 0:21:17.959 uses um is using a process called extreme ultra violet 0:21:18.359 --> 0:21:22.080 lithography in their latest processors, which are the ones that 0:21:22.160 --> 0:21:26.240 have like the thirty two nnometer transistors, which is crazy. 0:21:26.480 --> 0:21:31.320 I figured they were building microchips sliding downhill on a 0:21:31.359 --> 0:21:38.760 street luge and that's not extreme, not that extreme. Yeah, 0:21:38.800 --> 0:21:40.879 it's not gonna be in the X games. But so 0:21:41.000 --> 0:21:44.400 the motalization, this is where you've built all these elements 0:21:44.400 --> 0:21:47.399 by carving away the stuff that doesn't belong, but you 0:21:47.440 --> 0:21:50.880 still have to connect them together, right, you know, this 0:21:50.920 --> 0:21:52.960 is normally where you would be building wires. Well, the 0:21:52.960 --> 0:21:57.040 way they build wires and uh in these transistor or 0:21:57.080 --> 0:21:59.960 in these uh these circuits, it's actually kind of similar 0:22:00.119 --> 0:22:03.040 to the process we just described, except what they do 0:22:03.119 --> 0:22:07.680 is they put a layer of metal UM on top 0:22:07.760 --> 0:22:10.760 of the wafer and then again you put the this uh, 0:22:10.840 --> 0:22:13.920 this UV sensitive photo resist on top of that metal, 0:22:14.920 --> 0:22:18.480 and you have another mask. This mask is going to 0:22:18.560 --> 0:22:22.720 block out all the places that where hiring actually blocks 0:22:22.720 --> 0:22:27.679 out the places where you do want wiring, right, so 0:22:27.760 --> 0:22:31.480 you want the places you want protected. Yeah, so it'll 0:22:31.520 --> 0:22:34.000 block it'll block light. Wherever it blocks light, that's where 0:22:34.000 --> 0:22:35.920 a wire is going to be. Wherever light comes through, 0:22:36.200 --> 0:22:38.960 that's gonna carve away this metal. So again you go 0:22:39.119 --> 0:22:42.960 through another process where you run it through the system. 0:22:43.000 --> 0:22:46.520 The light ends up hitting the certain the designated areas 0:22:46.600 --> 0:22:49.280 on the wafer UM and that ends up going to 0:22:49.480 --> 0:22:53.760 that's gonna end up breaking down the metal so that 0:22:54.000 --> 0:22:56.240 you are left with just the wires that you want 0:22:56.680 --> 0:22:59.800 you've carved away everything you don't want again, you may 0:22:59.840 --> 0:23:02.720 have to do this process several times because in order 0:23:02.760 --> 0:23:05.000 to get all the connections you need, Um, you may 0:23:05.040 --> 0:23:08.000 need to do several layers on wires up to I 0:23:08.000 --> 0:23:12.520 think five I think was the last I had read, right, 0:23:13.400 --> 0:23:18.840 But um, it's again very similar to the lithography process 0:23:18.880 --> 0:23:22.960 of actually carving out the chip itself. Yep, and uh 0:23:23.400 --> 0:23:27.160 see there. This is all very cool and it has 0:23:27.240 --> 0:23:30.320 led to a number of you know, all kinds of 0:23:30.359 --> 0:23:33.720