We live in a world of miniaturization and personal power. From desktop publishing and printing in the 1970s, we've gone to individual cell phones, to your own portable music library via MP3 players and to desktop audio and video editing, to cite just a few. You can even buy a small-scale machine shop with CAD software that routes, drills and turns parts with minimal intervention, for both prototyping and small production runs.
But one important technology--semiconductor fabrication--has run counter to the smaller, cheaper, do-it-yourself trend. Like its cousin, the particle physics lab, fabrication takes ever-larger machines to deal with ever-smaller dimensions, and costs have increased by several orders of magnitude in recent decades.
To be financially viable, fabs have to run large volumes, reach for 100 percent utilization and yield, and minimize odd or special runs. Orders must be carefully scheduled to keep production moving, so specialty designs, test layouts and student projects have nowhere to go--save for costly specialty fabs.
But what about radically rethinking the problem of huge fabs? Suppose we set a challenge, perhaps similar to the Kremer or Antari X aviation prizes, and get some student teams to build a practical desktop fab? By setting some reasonable constraints, it might be doable. Once you redefine the objective and change the ground rules, then radical new ideas may emerge.
If the fab's objective is to make only a few parts, perhaps it should lock the wafer in place and then robotically bring the process steps to the wafer in sequence. Maybe it doesn't use masks, but direct beam-writing. Limit wafer size to 3 inches. Have critical gases and fluids come prepackaged, in small canisters, like ink for a desktop printer. Restrict the die size as well as the packaging options. Support only a few processes, and don't go below 100-nanometer geometry (most designs don't need tighter geometry for performance; they need it primarily to achieve die-per-wafer density). Back-end processing could be done by an adjacent desktop unit.
This desktop fab would suit the needs of education, low-volume production runs and some industry niches. The challenge could be sparked with some prize money from the industry, perhaps along with seed money to qualified teams.
In short, let's dramatically rescale the objectives, and perhaps we can get some ideas that make innovative use of today's small-scale, high-precision technologies.
By Bill Schweber, editor of Planet Analog, a sister Web site and publication of EE Times