Interference Lithography System

Custom automation for high capacity, accurate diffraction grating production

custom automation system for large, interference lithography substrates
© Photo Fraunhofer CMI

custom automation system for large, interference lithography substrates

custom automation system for large, interference lithography substrates - close up
© Photo Fraunhofer CMI

custom automation system for large, interference lithography substrates - close up

Customer & partners:

In partnership with the Massachusetts Institute of Technology and an industrial customer, Fraunhofer CMI developed custom automation for the efficient manufacture of high accuracy, large scale diffraction gratings.

Technical summary:

Applications such as high power lasers used for Inertial Confinement Fusion research require gratings that cannot be produced via current semi-conductor manufacturing techniques. These gratings are nearly a meter in length by half meter in width, with closely placed lines, typically on a 400 nm to 1000 nm pitch, with a phase accuracy of 10 nm over the entire length. The newly developed custom automation system writes the lines by scanning an interference pattern of two UV laser beams over the optical substrate. A high speed metrology system optically steers the interference pattern to correct for errors in the mechanical motion of the scan to ensure accuracy. This metrology system makes extensive use of Zerodur and Super Invar components to maximize accuracy and stability.

 

 

 

 

 

 

Results:

Constructed a high-performance system for large, interference lithography substrates

Substrate dimensions:1.0 m x 0.5 m

Maximum load: 100 kilograms

Diffraction grating periodicity: 0.2 - 5 micron

Line placement accuracy: 2.5 nanometers over entire substrate

Temperature control precision: ±0.005 °C.