Zachary Tong's "Cobbled Together" Laser Lithographic Etching Machine Draws One-Micron Lines
YouTuber and former neurobiologist turned software engineer Zachary Tong has published a video on a homebrew machine designed for laser lithography down to micron-sized features, as part of the "MakerFoundry" project for DIY semiconductor fabrication.
"Photolithography is simply a process to create a pattern onto a photoresist," Tong explains. "Most people are probably familiar with PCB development and etching, and it's the same idea — just shrunk down to a very small scale so that you can fabricate transistors, or MEMS, or microfluidics, anything at the micron level. This is a form of maskless lithography, meaning that it directly writes the pattern onto the substrate rather than using an intermediate mask that you first generate and then project through."
In effect, what Tong has put together is a laser etcher — only operating at scales an order of magnitude smaller than the width of a human hair. In testing, the device was proven to etch lines between one and three microns wide — around the size of a bacteria.
"[That] gives you an idea of the capabilities of a machine like this," Tong says, "essentially cobbled together with aluminum extrusions and 3D-printed parts."
The device itself is split into three key sections: An optical system at the rear, an electronics section in the middle, then an XY stage and microscope objective at the front — all driven by a low-cost ultraviolet diode laser, cleaned up by passing the beam through what Tong describes as " a kind of optical breadboard" with a metal pinhole to round off the elliptical beam shape and improve the final result.
Full details of the build are available on the Breaking Taps YouTube channel, along with a look at the problems remaining to be solved with the design, with additional information available on the MakerFoundry Hackaday.io page.