1. Sandia National Laboratories Materials & Processing for Si Compatibility Charles T. Sullivan ctsulli@sandia.gov, 505/844-9254 Center for Compound Semiconductor Science and Technology Microsystem Science, Technology and Components Center Shawn Lin and Jim Fleming Introductory overview Photonic Bandgap Materials Optical Interconnects for High Performance Computing Workshop Oak Ridge 11/8-9/99

2. Sandia National Laboratories Possible Options for On-Chip Waveguide Interconnects Hard dielectric waveguides –low-loss optical fiber compatibility »low index contrast  N ~ 0.005 »  = 0.1 dB/cm to < 0.01 dB/cm »e.g., LPCVD-based buried BPSG/TEOS –higher-index for higher-density routing »high index contrast  N > 0.1 »  < 0.1 dB/cm ? »e.g., LPCVD-based SiON/TEOS Polymeric waveguides –low-temperature post-processing »low index contrast  N ~ 0.05-0.005 »  ~ 0.1 dB/cm to 0.5 dB/cm, depending on »e.g., fluorinated acrylates or polyimides

3. Sandia National Laboratories Possible Applications of PBG Materials Wavelength (  m) Transmission Bandstop is Largely Independent of Angle

4. Sandia National Laboratories Simulated Electric Field Patterns for 90-degree Waveguide Bend 2D Square Lattice 3D Square Lattice

5. Sandia National Laboratories 90-degree Waveguide Bend at Millimeter-Wave Frequencies Transmission Efficiency Frequency (GHz) 7590801059585110100 theory experiment 1.2 1.0 0.8 0.6 0.4 0.2 0

6. Sandia National Laboratories The minimum feature size for a lattice with bandgap of 1.5 micron is 0.18 microns! The Microfabrication Challenge

7. Sandia National Laboratories 3D Silicon Photonic Crystal at Mid-IR Frequencies Side View Top View poly-Si Si substrate Technology Challenges - precise stacking; - smooth planarization; - large area uniformity. 4-layer crystal

8. Sandia National Laboratories Mold Process Flow

9. Sandia National Laboratories The Simple Cubic Structure Fabricated Using the Mold Process

10. Sandia National Laboratories Fillet Flow Process

11. Sandia National Laboratories 1.5µm Bandgap Fillet Structure 1.3 1.5 1.7 Wavelength (  m) 1.41.61.8 Transmission Efficiency 100 20 bandgap Measured Results 3L 4L

12. Sandia National Laboratories Novel Structures Under Investigation

13. Sandia National Laboratories Singlemode 3D Defect Cavity 1 2 3 4 5 6 7 6.4  m (0.6 ) 9.2  m (0.8 ) Defect Volume: 0.2 3 Modal Volume: 0.8 3 Higher-Q Results