We report Photonic Crystal (PhC) designs fabricated in silicon-on-insulator wafers (SOI) using 248 nm & 193 nm DUV lithography. Emphasis was on demonstrating unique PhC effects through the use of standard CMOS equpiment and process development of an optical test chip using a high-volume manufacturing facility. Most of the planar 2-D PhCs waveguides were designed using a triangular lattice of holes. An extensive range of test structures were also designed, including W1 and W3 waveguides in both triangular and square lattices. The use of optical proximity correction (OPC) and variations of pitch and hole dimensions allowed for a large design-of-experiment not practical using the more conventional e-beam direct-write approach. Smart Cut SOI wafers with a thin epitaxial Si layer on a 2μm buried SiO2 layer were first processed and characterized using 248 nm lithography. Preliminary pitch/hole patterning requirements were 400nm/200nm. Resist was changed from high- to low-contrast resist to compensate for the high sensitivity of critical hole dimension to exposure dose. Optical characterization data of PhC test structures were used to map band structure calculations and more accurately determine the PhC effective index; results were used to model more accurate pitch/hole values. Successful processing results were also obtained using 193nm lithography to resolve PhC pitch/hole dimensions of ~280/180nm. Optical characterization data are being used to refine next-generation PhC designs.
Silicon photonics, especially that based on silicon-on-insulator (SOI), has recently attracted a great deal of attention. The mature industrial infrastructure of CMOS fabrication offers an opportunity for low cost silicon based opto-electronic solutions for applications ranging from telecommunications to chip-to-chip interconnects. The high volume and high performance manufacturing disciplines are advantageous to electro-optics application development and fabrication. However, many technical hurdles still need to be addressed. This paper will give an overview of these opportunities as well as discuss some practical issues and challenges concerning processing silicon photonic devices in a high volume CMOS manufacturing environment.
In this paper the optical characterization of a novel, metal-oxide-silicon (MOS) capacitor-based, high speed, silicon optical modulator is presented. By using a capacitor based rather than the conventional p-i-n junction based architecture to modulate the free carrier density inside the waveguide, we show the realization of a fast, 2.5-GHz, optical modulator.
Optomechanical actuation was achieved reversibly using highly oriented pyrolytic graphite intercalated with bromine (1.9 mol% Br2). White light from a 150 W tungsten-halogen lamp was used for optomechanical switching. The displacement was approximately 4 micrometers and occurred only along the c-axis of the graphite. The rise and fall times were approximately 15 s. The origin of the optomechanical effect is the reversible exfoliation of the near surface region of the intercalated graphite.