Homebrew Electron Beam Lithography With A Scanning Electron Microscope

December 19, 2024 by Dan Maloney 3 Comments

If you want to build semiconductors at home, it seems like the best place to start might be to find a used scanning electron microscope on eBay. At least that’s how [Peter Bosch] kicked off his electron beam lithography project, and we have to say the results are pretty impressive.

Now, most of the DIY semiconductor efforts we’ve seen start with photolithography, where a pattern is optically projected onto a substrate coated with a photopolymer resist layer so that features can be etched into the surface using various chemical treatments. [Peter]’s method is similar, but with important differences. First, for a resist he chose poly-methyl methacrylate (PMMA), also known as acrylic, dissolved in anisole, an organic substance commonly used in the fragrance industry. The resist solution was spin-coated into a test substrate of aluminized Mylar before going into the chamber of the SEM.

As for the microscope itself, that required a few special modifications of its own. Rather than rastering the beam across his sample and using a pattern mask, [Peter] wanted to draw the pattern onto the resist-covered substrate directly. This required an external deflection modification to the SEM, which we’d love to hear more about. Also, the SEM didn’t support beam blanking, meaning the electron beam would be turned on even while moving across areas that weren’t to be exposed. To get around this, [Peter] slowed down the beam’s movements while exposing areas in the pattern, and sped it up while transitioning to the next feature. It’s a pretty clever hack, and after development and etching with a cocktail of acids, the results were pretty spectacular. Check it out in the video below.

It’s pretty clear that this is all preliminary work, and that there’s much more to come before [Peter] starts etching silicon. He says he’s currently working on a thermal evaporator to deposit thin films, which we’re keen to see. We’ve seen a few sputtering rigs for thin film deposition before, but there are chemical ways to do it, too.

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Darkroom Robot Automates Away The Tedium Of Film Developing

January 8, 2024 by Dan Maloney 14 Comments

Anyone who has ever processed real analog film in a darkroom probably remembers two things: the awkward fumbling in absolute darkness while trying to get the film loaded into the developing reel, and the tedium of getting the timing for each solution just right. This automatic film-developing machine can’t help much with the former, but it more than makes up for that by taking care of the latter.

For those who haven’t experienced the pleasures of the darkroom — and we mean that sincerely; watching images appear before your eyes is straight magic — film processing is divided into two phases: developing the exposed film from the camera, and making prints from the film. [kauzerei]’s machine automates development and centers around a modified developing tank and a set of vessels for the various solutions needed for different film processes. Pumps and solenoid valves control the flow of solutions in and out of the developing tank, while a servo mounted on the tank’s cover gently rotates the reel to keep the film exposed to fresh solutions; proper agitation is the secret sauce of film developing.

The developing machine has a lot of other nice features that really should help with getting consistent results. The developing tank sits on a strain gauge, to ensure the proper amount of each solution is added. To avoid splotches that can come from using plain tap water, rinse water is filtered using a household drinking water pitcher. The entire rig can be submerged in a heated water bath for a consistent temperature during processing. And, with four solution reservoirs, the machine is adaptable to multiple processes. [kauzerei] lists black and white and C41 color negative processes, but we’d imagine it would be easy to support a color slide process like E6 too.

This looks like a great build, and while it’s not the first darkroom bot we’ve seen — we even featured one made from Lego Technics once upon a time — this one has us itching to get back into the darkroom again.

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Polaroid Develops Its Pictures Remotely

August 16, 2023 by Bryan Cockfield 8 Comments

For those who didn’t experience it, it’s difficult to overstate the cultural impact of the Polaroid camera. In an era where instant gratification is ubiquitous, it’s easy to forget that there was a time when capturing a photograph meant waiting for film to be developed or relying on the meticulous art of darkroom processing. Before the era of digital photography, there was nothing as close to instant as the Polaroid. [Max] is attempting to re-capture that feeling with a modified Polaroid which instantly develops its pictures in a remote picture frame.

The build is based on a real, albeit non-functional, Polaroid Land Camera. Instead of restoring it, a Raspberry Pi with a camera module is placed inside the camera body and set up to capture pictures. The camera needs to connect to a Wi-Fi network before it can send its pictures out, though, and it does this automatically when taking a picture of a QR code. When a picture is snapped, it sends it out over the Internet to wherever the picture frame is located, which has another Raspberry Pi inside connected to an e-ink screen. Once a picture is taken on the camera it immediately shows up in the picture frame.

To help preserve the spirit of the original Polaroid, at no point is an image saved permanently. Once it is sent to the frame, it is deleted from the camera, and the next picture taken overwrites the last. And, for those who are only familiar with grayscale e-ink displays as the integral parts of e-readers, there have been limited options for color displays for a while now, as we saw in this similar build which was painstakingly built into a normal-looking picture frame as part of an attempted family prank.

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Hacking Film Processing With Coffee

December 24, 2021 by Al Williams 31 Comments

Years ago, doing your own darkroom work was the only way to really control what your pictures looked like. In those days, coffee was what kept you going while you mixed another batch of noxious chemicals in the dark and fumbled to load a tank reel by feel. But did you know that you can process black and white film with coffee? Not just coffee, of course. [Andrew Shepherd] takes us through the process using what is coyly known as Caffenol-C.

Apparently, the process is not original, but if you’ve ever wanted to do some film developing and don’t want exotic and dangerous chemicals, it might be just the ticket. The ingredients are simple: instant coffee, washing soda, water and –optionally — vitamin C powder. If nothing else, all of this is safe to pour down your drain, something you probably aren’t supposed to do with conventional developers that contain things like formaldehyde and methyl chloroform.

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They May Be For Developing Countries, But We Want A Concrete Lathe

September 27, 2011 by Brian Benchoff 59 Comments

At the 2009 Ghana Maker Faire, [Pat Delany] met a young carpentry student that saved for three months to buy a cheap Chinese wood plane. He was confounded by this distribution of resources, so [Pat] created the Concrete Lathe project that aims to get useful machine tools out to where they’re needed most.

The idea for concrete machine tools came out of the US involvement in World War I. America had been staunchly isolationist before committing to the war, and production of arms did not match the needed output. A man named L.I. Yeomans came up with the idea of building concrete lathes to produce artillery shells for the war effort.

Of course, the concrete lathe project is a bit more peaceful in its intentions. The concrete lathe is meant to be a cheap machine tool for developing nations. Both the concrete lathe and the Multimachine are meant to be built cheaply using scrap materials, reduce training time for machinists, and create other machine tools in a Reprap-like biological distribution.

There’s a ton of documentation on the concrete lathe wiki like the bed instructions torn from the pages of Ikea instructions, and the thread follower. While they’re still a lot of work and testing to be done, giving some manufacturing capability to those who need it most is a pretty noble cause.

Thanks [Rob] for sending this one in.