thanks for sharing! I loved seeing the process and SEM pics. This is def promising for home chip fab. If the resistance goes down then the doping is working! For a while all my PN junction curves looked like that too, fixed it by using Al with a few % Cu mixed in for both P and N contacts and annealing at 450c. Pure aluminum tends to alloy with the silicon and forms spikes that go deep into the wafer and shorts your junction to the undoped silicon below. Not sure if this is a problem with Ti/Al. Also, your sputtered metal electrodes overhang the doped regions. Is there thick oxide on the non-overlapped regions? If the doped regions are 1x1mm, maybe try sputtering metal only on the center 0.5x0.5mm of each to be safe

This makes me think that there should be a sub-section of each scientific field (similar to this one at least) that focuses exclusively on the minimization/simplification of all techniques, tools, etc. needed to do certain experiments or create certain devices. It would be interesting to see a scientific group that actually worked to figure out the minimal setup needed to create usable chips and to shrink those needs.

Ion Implant process engineer here. Your description of my process was spot on! I'm impressed how you succinctly and thoroughly explained what I do in just over a minute and might have to steal your explanation when people ask me what I do! You also mention that ion implant will probably never be feasible in a home fab setup, and that's probably true under one condition... if you are concerned with purity of the energies and species being implanted. If you are OK just implanting everything in your source gas, it may be feasible for someone to setup a "shotgun" implanter, which is basically a plasma chamber fed by some dopant-containing gas over the wafer with an acceleration grid in between that sends all the positive ions into the wafer, dopant included. This was actually the first type of implanter ever used in industry. One issue with this design may be uniformity, not sure how this was solved in industrial applications. Another issue is that you still have to anneal the silicon to "activate" the dopant... speaking of, have you considered sending your laser doped wafers through an anneal furnace to "wash out" some of the nonuniformities?

If you input an AC wave into the wafer while using x/y deflection on the scope, you can apply the the AC signal to the x probe, while reading the output with the y probe. You will get a hysteresis curve telling the function of the pn junction at that AC frequency. The freq to use will depend on the capacitance of the junction.

5:08 I am in tears. What a wonderful image. Edit: Just saw that you were trying to make a diode. Well, the contacts are of paramount importance. Who on earth did tell you to use Al as a p contact???!!! Generally, you need high Workfunction (Φ) if you need an ohmic contact to a p-type semiconductor. You can think of it like this: the n-type semiconductor has a high fermi level and generally likes to give electrons, so you match it with a metal that likes to give electrons, such as: Cesium, Na, K, Aluminium. On the other hand, you match a p-type semiconductor with a metal that likes to retain its electrons, such as: Platinum, Selenium, Copper, Gold. Platinum and Selenium are kings with a work-function Φm being 6.35eV!!!!

This channel is amazing and deserves a lot more followers. If a video starts with "Hey folks, short video today talking about doping silicon with phosphoric acid and lasers" it's guaranteed to be good.

I love seeing work-in-progress content! It's really cool to watch projects evolve

Multi-layer contacts can be done using, for example, one or more of Mo/W/Ti/Cr as a Shottky or Ohmic contact, depending on your application and diffusion layer doping. Consider making a four probe resistance measurement setup (linear or square) for example with tiny pogo pins. You could also make the opposite side of the wafer back side electrode and measure your diode structures (e.g. pnn or even pin with more pure silicon) through the wafer.

This is dope! No, really - it's doping silicon. Will you be making a video about transistors with this technique?

If you want to play around with it.. I have a 600W (1 joule/pulse x 600hz) 308nm XeCl laser used for surface annealing flat panel displays in OLED production.

I always find that it's amazing that you can make garage-semiconductor

Oh yeah, work-in-progress is always awesome to me! I mean, with a fully perfected video, while very nice, it does feel a bit like magic. Seeing work-in-progress and sometimes simply failures, makes it real, makes me feel like maybe I can do it as well. So I'm all for it! :) I'll become a Patreon as well in the new year as I finally will have a bit more to spend again. :)

As someone who binge watches youtube videos on whatever subject I'm interested in that day, I very much appreciate your meticulously planned and edited videos. As I am usually searching for explanations of certain phenomenon, or in the case of many of your videos, diy versions of expensive processes or simply exposure to those processes I wouldn't normally get to see, I personally don't care so much that you put out videos on a strict schedule. I watch your videos because of how detailed you get and seeing what results you can achieve (and issues you had to resolve) once you've dialed everything in. Needless to say it's still fun to see everything you get to play with.

Nah, you've done it! looks great and it's so cool your having a go and showing us, I worked as final test for Applied Materials their Implant division and know what you have is great and you should keep going ...wow ! just as writing this you showed your hat and yeah keep going ! my two favourite subjects Mass Spec and semiconductor stuff, oh yeah and microscopy ! can we have a lab tour soon please ? have a great holiday and I can't wait for more, blistering hot channel by the way....cheers.

This is really interesting. I wouldn't have thought something like this could remotely work in a home shop at all. I do love that you're talking about it even though it's not quite there yet, I really hope that some other more knowledgeable people help you figure it out. I like these sorts of "work in progress" videos.

In college when we built mosefts, diodes, and capacitors we purged the chamber with nitrogen at the end of annealing. I think the final aneal had some hydrogen to get rid of dangling bonds. Been years since I have done it tho. I look forward to your content and my own lab once I can afford to set up my own lab.

The algorithm brought me here because the intricacies of all this is all way over my head but the general gist of it absolutely fascinating. Thanks.

Work in progress stuff is important. It's a big reason why I think the internet is even useful at all.

The fact I can follow what you’re saying for the most part, shows how good you are at these educational videos. Thanks for sharing. 😄

18:09 The laughter at the end, was the best part!

Enjoying your content! I always chuckle when you say "There are a lot of better explanations on the internet about this topic, but..." quickly followed by the best explanation of said topic on the internet, lol.

"short video" - 18 minutes.... Mmmmmmm. Yummy science content

My parents always told me doping was bad but this seems pretty cool

This is unbelievable , thanks for your effort. These are perhaps the first stones for free as freedom semiconductors technology for humanity. The same as Linus did for software. We are far far away from industry but this is a start. Fiber pulsed lasers are great and cheap, now we need more frequency, it would be a god send if we could double or triple the frequency with crystals.

Wow! I bet this kind of thing would really help for small scale retro chip production.

If you have a 1064 nm fibre laser you could just use SHG to generate 532 nm pulses. Should work if you only need like 40 % max power at 1064 nm. And you should probably get a system to remove those white clouds when you're doping, maybe immerse the wafer in phosphoric acid and use a small pump to circulate the fluid?

Kind sir, you are making beautiful and highly engaging videos. As a videographer I really appreciate the great looking floating head setup you got going - great looking grading! Keep doing what you’re doing!

"I dont really know what I'm talking about" the honesty of that statement is underappreciated.

Nice work, Cant wait to see the first garage-semiconductor CMOS chip-collab

Whoever does the lighting/set design is a genius. It's absolutely beautiful.

Wish you had taught my semi conductor physics class, because this video was 100x more interesting than any of my professor's lectures.

Christmas came early!

I like how 18 minutes counts as a short video

Bro. Keep up the good work. See something like this in a home lab gives me mad hope for the future.

Thank you for taking the time to inform me on such an understandable manner i had not heard of any of this despite my interest in electronics and diy hobbies

I can help you with some ion implantations. We have a 1.7MV NEC tandem accelerator, we don't get the very high currents like a implanter would. But we can go deep and do direct write without the lithography.

Definitely appreciate the updates along the way on projects!

A video list that a high school STEM teacher can use for some courses would be great. Maybe put together a equipment list for a high school lab so we can propose a budget. How to make diodes, and such. I recommend for Jr. high school how to make capacitors (big ones) as a lab. Having to write reports on what they find interesting will help develop the other skills a person needs to succeed in life. My hope is for the next generation, as the current one has lost ground vs. what our grandparents did in the past.

For your resistance measurements, you should really be using a 4 wire measurement

On the chalkboard in the background: "Photo litho nano particles Potato" Yes...potato!

The supporting tech tree needed to actually do this is probably too much for me to attempt myself, but it's amazing that garage-scale IC fab is becoming a reality. Who knows, in 10-20 years someone might have come up with a simple and cheap high vacuum solution that makes MSI fab on the scale of a small 5 axis CNC machine feasible.

please let us see behind the scenes and the ones that you don't finish. This is where most of the learning is done!

This was really great. Thank you for sharing it with us. I can't wait to see more.

You dig into such interesting projects, love your channel, thanks

I'll say it if nobody else will. This is pretty dope.

This was a great video

I like the worn out hats! It gives them character and a story to tell!

Really cool effort towards individual / garage scale integrated circuits. Me and friends have dreamed about simplified processes to make this possible for many years. BTW I've watched a whole bunch of your videos and never even noted your hat :)

DIY transistors. Hell yeah! Fastest path to rebuilding a civilization after we do ourselves in.

@Breaking Taps, "Design of Experiments" may help you optimize your parameters.

as a patron, i can't care any less about any perks. the only benefit i want from supporting you is you continuing to make good videos.

I dont know how I got here, but this is very cool. Love the explanation and details.

FINE! I'LL WATCH THIS VIDEO! Just a heads up, youtube has been pushing this video for days.

Glad for the shift, as seeing what does not work well or work at all, is a good way to document paths in the road with "warning" signs, though with caveats that someone might go "well that is excellent that is what I needed" and not just "ah that does not work ok let me try this other direction, since I don't have a good *this works for sure* path". I really wish more people would do this documentation of everything including what does not work and what it actually did as far as they can tell. Thanks a bunch, one of these days I will have some money I can spare to throw your way, and this is why you and others doing this will get first crack at that extra money :) Hopefully I will soon have my lab and workshop moved too so I can offer trade of skill and tool set with people since I really need an electron microscope, but access to one might be even better as it would add the validity of the person doing the scanning to the already valuable view of what is accomplished (or not accomplished) to make up for the pestering others and then having to wait for shipping and the like (and trusting the shipper to not damage or alter the item being scanned or something LOL) That bit if the person has good reputation for just showing the work and not trying to alter it's results for any particular reason, well makes up for the negatives I would say.

Another way to test junctions is by probing in the dark. Take millivolt / micro volt reading of a junction in the dark and then shine infrared light source at junction and measure the voltage generated. Even light emitting diodes behave like micro solar panels when put in sunlight and the voltage can be measured with a basic voltmeter. This is how photo-diodes and photo-transisters work. Well actually photo-diodes lower their resistance when illuminated by the correct wavelength (usually infrared). Theres no doubt in my mind that hobbyist will eventually produce customized semiconductors at home in the comming years.

I just started a job as a technician for marking lasers... found a fun experiment to do :D

I've been interested I making integrated circuits at home lately, this tech is good to know about!

It's funny how some of the most interesting and insightful information comes from people who also say "I don't know"/'I'm not an expert"/"These are just my results"

Awesome content. Nice micrographs too. I never know what to expect when you post a new video, but I'm always glad you did. It's so fascinating to watch you work through the issues and figure out what your data is telling you.

I don't have any idea about this niche of computing, however the lasers are cool. Subscribed, hopefully I can learn more!

5:51 - whoa that is cool. This means means this is a valid alternative for precision wafer sensitizations which today uses ion implantation. This means the laser method is much more affordable and doable. I wonder why big companies haven’t done this before…

Kick ass work! I love watching people smarter then me, it pushes me to advance to new levels. There was a time this would have been like listening to people having a conversation in Mandarin, but now I actually understand what you're talking about. I hope one day I will be doing these experiments on my own in my own homemade lab. The way I view things is if an apocalypse happened I'm not smart enough to rebuild our world with what I know now and I want to have those skills even though that won't ever happen it's better to know as much as you can about everything you don't already understand.

Tips from Jeri??? That's awesome!

looks like some nano scale weld beads

Oh my, this video is a gem ! I've been interested by the Silicon world for more than 2 decades and yet never heard about this technique :-O

This is very exciting! Please keep going

So glad I found your channel! Very interesting stuff!!

Awesome new hat, with dope science content

I like the old hat. But the new one is fantastic. Also the doping stuff is dope. Love your projects and vids about them regardless the outcome.

Loved seeing WIP

this is really dope!

Thank-you. The one time I am thankful for the creepy web tracking. I was searching for this.

Why am I watching this? It’s completely above my head lol

Enjoying your channel. Merry Christmas! Oh, nice hat. The old one rocks, too.

"Very cool micrographs but not necessarily good devices"... gradschool flashbacks

Best Christmas present

He needs StyroPyro to build a UV laser setup. That would be the colab of the decade!

I work at Intel in a module that uses thermal diffusion to do the nmos and pmos wells. It's the main way the big boys dopent into processors

The amount of thermal damage as evidenced by the ripples, etc., would seem to be counter to the process of making "good" diodes, since the junction is no longer particularly single crystal, so is likely to have leakage and soft breakdown characteristics. It may be possible that lower power for longer durations could allow the dopant to gradually get incorporated into the wafer. You only need around 900C local temperature for boron doping as I vaguely recall from the process used a job from over 40 years ago. Ditto phosphorous, I think, although that might have needed a higher temperature, say closer to 1000C local temp. But otherwise, that was the approach, we coated the wafers with dopant and popped them into the furnace for an hour or so. However, I also vaguely recall that our diffusion process resulted in growing kind of a doped oxide layer, possibly, which then had to be removed.

I am excited to see Jeri featured in your video :D

Does the liquid or oxide layer impact the laser optically? Not quite sure how you focussed your beam - but I feel like that focussing through like 3mm of fluid could be rather difficult

I work in a wafer fab on ion implant, my guess would be that laser doping isn't used bc ion implantation gives better results with finer control, but if I remember I'll see if I can find someone who knows why we don't use laser diffusion.

1:00 what a pretty shot, wow

color me surprised and highly interested to try this on my own, thanks a lot for the great content as always!

Great Christmas morning watching this vid!

I have an old beat up hat also that I love. Hats like that are earned I have only ever worn a hat to the point of destruction twice and it sucks switching to a new hat. The new one never feels right.

very interesting video. I learned a lot from it. Thank you!

if you have only a good n-type contact, you can make an n-p-n transistor(maybe even a field transistor) to test if that works!

Your projects are always inspiring! Love your presentation style. Ah and your old cap is epic, don't stop wearing it!

[precious] I hear you. But I think you're making the right decision.

Found your channel just now and you immediately received a sub and bell turned on, Great content and presentation.

As mentioned by other guys, be careful of your aluminium lest it diffuses through the Titanium layer and form unwanted silicates on the silicon layers below although i do not expect it to be serious as you are dealing with lasers. And 4 point probe is your friend for measuring/calculating resistances at these scales

A Kickstarter with the most famous SID chip would be nice :)

hey, you making exceptionally great content! keep on going!

Such technology will open possibility for really open source hardware.

Cool. Thanks for sharing.

As this method would be very good for low cost/low volume fabrication and would scale fairly well for a medium volume fab. Maybe one day the first self-sustaining colony on Mars will be using this method to make semiconductors.

I have done my first tests with laser doping and my results where around 10-25 ohm per sequare centimeter with a xtool f1 ir laser. and i have been able to do this multiple times in a row. also trough 360 nm termal oxide. Also the hot probe test works well

How in the hell have I never seen your content? SUBBED!

glad i found ur channel, great content.