More than 10 million elements are processed in the nanometer scale on computer chips. In the factory, the elements are processed by projecting an image of the wiring pattern on a semiconductor wafer. This method is called photolithography and has achieved miniaturization of electronic circuits by projecting light with a shorter wavelength.
A device that transfers a wiring pattern to a semiconductor wafer is called a stepper. A wiring pattern is processed on the reticle and projected onto the wafer using a large number of lenses and mirrors.
Smaller wiring patterns can be projected by using shorter-wavelength light such as ultraviolet light, but this approach too is reaching its limits.
- Light having a shorter wavelength than this does not pass through the lens but requires a mirror instead. The image created by the mirror is very dark, and the reduction rate of the image is low.
- Even a small amount of dust on the reticle causes the projected wiring to break or short circuit. (requires large-scale equipment to improve cleanliness)
If an image can be projected using a hologram, there will be no need for a lens or mirror. Dust on the hologram surface does not adversely affect the image.
In this laboratory, we are developing holograms called "quasicrystal holograms" and "photon sieve holograms" that can directly project microscale images without a lens or mirror. When a hologram pattern is designed from a base layout that combines diamonds and circles, process it onto glass, and shine light on it, a microscale image appears.