This paper presents novel approaches on fabrication technology for micromachined spatial light modulators that are based on thin deformable viscoelastic layers. These layers are formed between two chips. The bottom chip contains an array of interdigitated electrode structures, where each structure represents one pixel. The top chip contains the mechanical layers which are transferred to the elastic layers by means of bulk etching techniques. This results in a high quality reflective surface with a 100% optical fill factor over the active region. Flexibility in choice of coatings gives the devices the potential to operate in specific spectral ranges with high load handling capability. The top chip is coated with a 50nm nitride layer onto which a 80nm aluminum layer is deposited. After curing of the intermediate viscoelastic layer, the entire device is placed in an elastomer holder and the bulk silicon is etched away in a 33wt% KOH solution. Devices were fabricated with electrode sizes in the range of 10 to 100μm and a 5μm thick viscoelastic layer. Experiments have shown far-field scattering as a result of 300V potential difference applied between the electrode. Biasing the membrane will lower this potential requirement to make integrated electronics possible. Applications can be found in high-end projection displays, optical lithography and optical communication networks.

Date Published: 3 April 2003
PDF: 8 pages
Proc. SPIE 4944, Integrated Optical Devices: Fabrication and Testing, (3 April 2003); doi: 10.1117/12.472009

Published in SPIE Proceedings Vol. 4944:
Integrated Optical Devices: Fabrication and Testing