: Photo: Dave Bullock
LOS ANGELES -- As nanomachines move beyond just prototypes, a potential industry of microscopic mass production awaits its own Henry Ford to make it a reality. In anticipation of this demand, researchers at a nanotech lab at UCLA are mass-producing billions of customizable microparticles using a machine normally found in the microchip fabrication industry. Lead by Dr. Thomas Mason, the team has created microscale letters to illustrate the possibilities of this new process.
"The idea is to make a powerful statement about a new class of materials that exist. Solid particles that have human-designed shapes. We can design millions of different kinds of shapes, highly uniform, highly precise," explains Mason.
Mason's ultimate goal is to quickly create large quantities of parts for complicated nanomachines. These parts would include nanogears, nanoengines and other small-scale parts that are currently created one at a time in an assembly line fashion. Click through the gallery to go behind the scenes of microfabrication.
Billions of microscale letters on a silicon wafer reflect light like a diffraction grating.
: Photo: Thomas G. Mason and Carlos J. Hernandez Zoomed in, one can see the microscale alphabet soup and the potential for information and codes embedded in various substances. Though each letter is a few microns across, this new mass production technique will be able to produce objects on the scale of nanometers with upgraded equipment.
: Photo: Dave Bullock/Wired.comThis is the unglamorous beginning of nanoletter production.
The white box at left is the spin coater, which applies the nanoletter polymer on a silicon wafer (see first slide), like the kind used to make microprocessors. First, a drop of the polymer is placed on a silicon wafer. Then the wafer spins and the centrifugal force spreads the liquid evenly over the silicon.
The polymer is photosensitive and hardens under exposure to ultraviolet light. In the next steps, the UV light takes on the shape of the desired micro-object and exposes that exact design in the polymer. The unexposed polymer washes away, leaving the hardened shapes, in this case letters, behind -- almost like cutting cookies from a sheet of dough.
: Photo: Dave Bullock/Wired.comThis lamp enclosure emits strong UV light. The light bounces through a series of mirrors into the machine that exposes the nanoletters, called a stepper (shown in next slide).
: Photo: Dave Bullock/Wired.comUCLA nanotech professor Dr. Thomas G. Mason explains the basic operation of the stepper -- so named because it steps, or repeats, an image multiple times over the silicon wafer. The machine prints a microscopic version of the image at each step by shining UV light onto the photosensitive polymer, like the way positive film is exposed.
: Photo: Dave Bullock/Wired.comInside the stepper sits a 200-pound lens encased in stainless steel (center) which very accurately imprints a shrunken image onto the polymer. This lens is ground to an extremely high level of precision to avoid introducing errors into the image being exposed.
: Photo: Dave Bullock/Wired.comA robotic assembly inside the stepper grabs the silicon wafers and exposes it one section at a time. It exposes an entire wafer in roughly one minute, creating billions of micro-objects.
: Photo: Dave Bullock/Wired.comThe stepper rests on a pneumatic dampening system (black cylinders with blue tops) to virtually eliminate vibrations. Just as you donít want your camera shaking when you take a photo, you donít want your stepper shaking when you make billions of nanoletters.
A positioning platform (middle, illuminated in pink) precisely moves the wafers between exposures.
: Photo: Dave Bullock/Wired.comThis scrapped stepper system sits outside the clean room. It's now used for spare parts, just like that old car on cinder blocks in your front yard.
: Photo: Dave Bullock/Wired.comMason and Kun Zhao don gloves before entering the clean room where the Ultratech XLS stepper resides. Dust particles can ruin the nano and microscale patterns the stepper images on the silicon substrate.
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