Bore-DOOM.

Have nothing better to do? Watch a sputtering rig from start to finish:

It has time annotations so you can skip the uneventful bits.

Plasma starting is quirky:

  • With too low pressure, plasma won’t start.
  • With too high pressure, arcing will happen.
  • With too low voltage (below 300V), plasma won’t hold in the trap as pressure drops.
  • With too high voltage, but not low enough pressure yet, plasma will arc, then fade and won’t restart.

A current meter must be added to complete the graph, and see what is this thing doing. Next week, probably.

For now I ca n get away with hand-eye coordination.

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Pride and Depositionize.

Today I finally started to characterize the vacuum chamber. Time vs Thickness, A-K voltage vs plasma current and Vacuum.

One thing I found out, is that my newly installed 50/100Ω ballast resistor was not performing well. It just didn’t allow the machine to operate properly (but without characterization, I am not sure where it acted)

With it, all tries ended up like the center piece. Looking like copper oxide, and with 250ohm resistance. Without the resistor, it was easier to achieve and mantain the plasma, and copper sputtered easily. (left and right, copper on glass)

The copper passed the tin-wetting and finger tests (it doesn’t smear when you rub the finger on it).

It’s also so shiny, the camera won’t focus on it, but rahter on the reflected image (ceiling)


That’s a really odd picture!

For fun, I tried to do a simple circuit on glass:


So proud!

However, the copper film was simply too thin, and the solder paste destroyed it when melting. In any case, that just requires more time in the chamber. I’ll have proper deposition figures soon.

See ya!

The Goblet of Fire

Plasma, that fourth state of matter:

-“When an ionised gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate its behaviour.”
(wikipedia)

As you know, plasma is a quite hot stuff. Usually it’s density is so low that thermal transfer quickly reaches an equilibrium much lower than the melting point of materials. However, in a sputtering machine, you do concentrate plasma in a small area, so, continuous operation requires a bit more than just having a passive aluminium heatsink.

And yes, you can just powermelt the target:

An aluminium plate with concentrated plasma heats quickly, as I have found out. After medium sputtering runs (20/25 minutes, NO Argon), the magnets are so hot you can barely hold them in your hand. That must be around 40/50ºC, wich obviously can only get worse. Normal (cheap) neodimium magnets have a curie point of just 100ºC, so it’s better not to risk damaging them. And just because fuck yeah, I want to liquid cool it to allow extended operating time.

Let’s have some water channels cut into the plasma trap plate:

At first I was thinking about machining it by hand in stainless, as having a rotary table makes it a fairly easy task. However, later on, I realized I could simply make it in aluminium wich is a better heat conductor AND my 3020CNC can machine it, if you are patient. I’ll still have to tap all the holes by hand, but that’s a minor nuisance.

Having a laser cutter helps immensely with reducing waste (milling acrylic is a pain in the ass)

Some might say so many screws are overkill, and might be true, however, given the diameters involved, and that I am using viton O-rings wich are not super flexible either, I have just preferred going all the way. The acrylic is 7mm to ensure minimum deflection.

Yeah, I should have made the utside border a tad larger. (The inside diameter has to fit the magnets, so there’s not much room there.)

The screws are stainless steel, so I don’t think they will affect the shape of the magnetic trap.


Test fit on top of a non machined plate (with recess for the magnet)

Since I received my new 3D printer before machining the plate, I printed a 15mm section to test fit the magnets and general visual guidance, plus screw check.

The magnet slot had a bit too much room left (2mm) so it was reduced 1,25mm in Fusion. (to 40,75mm). The screw lenght allowance was correct.

Overall fit was good, so the minor changes where validated and saved.

Machining!

Spot drilling.
I was too lazy to actually make a separate program for this, so I used the same drilling program, but added a +6.5mm offset so it would only peck 1.5mm with the 90º spot drill, I know, extremely ineficient, but it would have taken longer to start the computer and actually make the program.

After drilling, the o-ring recesses where cut.

Quick seal check, just in case y messed up, or the o-rings where wrong.

As an afterthought, I could ave made the slots 0,5mm deeper, so the acrylic would fully compress the rings and sit flat against the plate, but well, as I said, an afterthought.

The magnet slot was cut first:

Then the water channels:


I know the pic is shaky, but I was busy, you know…

Little misshap with mach 3 going first to Z-Ø instad of X/Y-Ø, and a not-so-exact Z height setup. Fortunatey, the cut was ony 0,15 deep, so it doesn’t affect the overall performance, just my inner pride. (I tested a newish 2-flute endmill instead of the oldish 4-flute I was using, but it underperformed, so I changed back, and messed with the paper thickness Z height procedure. This part is not critical in the Z axis, so I wasn’t particularly worried.

Anyhow, everyone hail the awesome cooling plate:

I accept the fact that there will be some blow-by between inlet and outlet, but most of the water should still flow along the path.

Magnets!

The CNC part took 6.5h to machine in a cheap (ballscrew) 3020CNC router, with the following setup:

  • 2mm carbide 90º spot drill, 2,5mm carbide drill.
  • 8mm depth, 0,25 pecking depth. Lube between holes.
  • 2mm (R1) carbide ball endmill.
  • 4mm-4flute carbide endmill, flat, center cutting.
  • 0.5mm depth of cut up to 5mm depth (6mm for magnet), 1.25mm stepover. 75mm/min plunge. 150mm/min feed.
  • LUBE as if there was no tomorrow. Also make sure all the router bolts are tight.

These kind of machines are not particularly rigid, so this is the absolute limit of what they can do. If you are patient, tough, you will be able to squeeze it to the very last drop.

Using a locating setup, one could just machine the outside border and flip the part to machine the lip, however, since I have a lathe, I just prefer to do it there and avoid the hassle.

First, bandsaw the corners.

Chuck the plate from the inside…

…and slowly carve the diameters away.

After polishing all the important surfaces:

Oh! Also some custom fittings should be made, amirite?

So gorgeous.

In the heat exchanging department I would like to employ some passive cooling like this:

I know I could try to hook it up to one of my beer refrigeration units, however I pretty much prefer not to, because the vacuum chamber is at potential, and having liquid wiring around is…well, not my thing. Also it will make for a standalone unit (not that it is going to go anywhere, but hey, what if I want to sputter in the living room?) Should that not suffice, I can always connect it to one of the machines later, or make a heat exchanger or something.

In any case, the particulars of the radiator are irrelevant, any liquid computer cooling setup should work (to some extent, if you put a small one). So, pick your poison, as some say.

See ya!

Gatekeeper.

In the aftermath of the oil backstream, I finally set myself to give some attention to the pneumatic HVAC valve I had bought. I found this one on ebay for cheap, it was 1/3 the price of any other mechanical valve, and I figured it would not be that difficult to operate.

As I have mentioned before, from time to time, I binge-buy parts, just in case. Here, my pneumatics tray, with couplers, pressure reducers, pneumatic switces, one way valves, Y splitters and miniature manometers. Half are RC supplies and half have industrial origins.

I also had this cheap diaphragm pneumatic pump, wich, combined with some of the tray elements and spare parts from my RC  drawer, amount for a standalone pneumatic system:

Max pressure is 2 BAR, enough to operate the valve. I added a miniature reservoir so the pump only has to run briefly at machine start-up. The valve is a VM1000-4NU-00 pneumatic microswitch. (a lucky find allowed me to buy 8 of those very cheap, normally they are kidney-expensive)

The Y splitter, reservoir and manometer, are all RC air retract parts. As a bonus, here you have an X-ray of the manometer and microswitch (from my dead chanel X-Ray playground):

Once all the pieces for the control panel arrive, I’ll install the whole pneumatic circuit too.

See ya!

The Colour of Magic.

…Is Argon plasma white.


Finally! The KF-16 coupling arrived and I could test the vacuum chamber again! But first, some build pics:

Plate holding.

Drillset. 7-10-13-15-16mm  and then the boring head up to 19mm

Finishing the hole. It’s an interesting device, I must say. Bought it years ago, and never used it (but knew someday it would come in handy).

TIG welded and began assembling the vacuum lines.

Crudely put everything together.

Quickly reached 160 microns and drove up the voltage…but past 1000V no plasma was to be seen. I verified connections in case a cable was loose (highly doubted that, but one must check everything). and finally, tried increasing Ar pressure to 1000/1200 microns, wich obviously arced. Then decreased the vacuum again…and had to go waaay up (voltage wise) than before (with the cheap pump) to get some plasma glow.

With my cheap multimeter maxed out, an arc current spike fried it out, so I don’t really know what voltage this thing required to light up at 160/140 microns. All I can say is that my guesstimate on the cheap pump’s ultimate vacuum was probably waay out, more in the range of 500/800 microns (can’t know for sure).
In the end it was very late and had to stop the pump, so I left it unvented as a test for the integrity of the whole vacuum circuit.

Aaaaaand…

Yup! I forgot this pump doesn’t have a non-return valve, so the oil was sucked up the circuit. The whole vacuum chamber was soaked in oil when I arrived from walking the dogs, it must have went up quite far, however, the rest of the circuit hoses apear to be clean, so I guess it bubbled up in the chamber. Well, this is not worse than having a blow-by with an oil difussion pump. Luckily I already bought a vacuum valve, so this shouldn’t happen again. ^^U

Anyhow, this morning i decided to try some sputtering (yes, without cleaning the oil mess…it was just a quick and dirty test).

Aaaaaand…


¡¡SUCCESS!!

This was in the adhesive side of a smartwatch glass screen protector, so the copper crackeled, hence the small test point and it was retired from the chamber after a few minutes, so the copper thickness was small.

Also accidentally deposited copper in the centering seals XD!

Anyways it’s definitely good copper. Aplied some Sn/Pb solder with the soldering iron and it wetted perfectly:

Now, yes, I’m surely cleaning the vacuum circuit from all the oil. XD

See ya!

 

Doc Ock (part 2)

When we left, the manipulator prototype moved, but that was me, crudely twisting the tubes. For this to work, some kind of haptic controller has to be built. For a test, it doesn’t have to be particularly intuitive or ergonomic, so I made this chunk:

Each gearwheel holds 2 magnets inside and raceways for 3mm bearings. Individual control is achieved with a pushbutton coupled to a gear rack. The fourth axis (shoulder) is controlled twisting the main body. It should look like this:

15 hours later:

I only had few 3mm balls wich allowed for only three per stage, AND two couplings from the previous test, but it should serve to prove the point. Also, since I didn’t have the glass tube, I improvised with some teflon lining I had around (yes, I buy all kinds of materials just in case)

Proof-of-concept:
(yeah, it’s a vertical video, deal with it. XD)

it is a bit too small for my hand to grasp, so a bigger version will be made, also with better grips and such, but this will work for tests.
Now I only need for the post to deliver the rest of the materials.

See ya!

Semiconductors @ Home

Well, for some it was obvious, anf if not, well, now you know.
For a while I’ve been hiding the real purpose of my latest projects, why? Because I didn’t want to be laughed at, because of my somewhat low tech setup and such. But since I was told to sign up my project in the Hackaday 2018 Price, there is no much point denying what I am really doing, also, I can’t update anymore without it being obvious (like building a tubular oven) XD

The project page is here:

https://hackaday.io/project/107598-semiconductors-home

If you want to drop a like for the project, that would be awesome, if not, that’s awesome too!

Project status:

  1. Sputtering setup: Working, waiting for some parts for better performance, but it’s done.
  2. Tubular oven: Already ordered all the parts I need, waiting for them to arrive and start building.
  3. Fume Hood: In planing, should be fairly easy to build.
  4. Safety: Sourced nitrile gloves and Calcium gluconate. Also designing my own HDPE tweezers (because I can)
  5. Semiconductor components: Sourced all the acids needed, wafers should not be difficult to obtain online.

And now, some beauty shots, because yes: