Semiconductor processes and nanofabrication

High-efficiency photo-electron conversion devices

Semiconductor processes and nanofabrication

Characterizations and applications of nanomaterials

Light harvesting and light extraction

Optical analysis techniques

Eco-friendly devices and sensors

Fabrication of sub-wavelength antireflective structures in solar cells by utilizing modified illumination and defocus techniques in optical lithography

We demonstrate a simple method, which is combining modified illumination and defocus techniques to fabricate sub-wavelength antireflective structures for solar cells. The optimum pyramid resist and silicon profiles can be obtained after exposure, development and common dry etching processes. The reflection and transmission properties are analyzed by the rigorous coupled-wave analysis in two-dimensional microstructure and find the reflectance is dramatically increased as consideration of all diffraction orders. Therefore, patterning the sub-wavelength texturing structures for eliminating the diffraction order light is important. Patterning sub-wavelength structures should use the short wavelength combining defocus exposure or using a suitable modified illumination exposure system. The optimized pyramid structures are simulated in dosage-focus matrix with different types of light source. Results show the quadrupole modified illumination system with large process latitude is suitable for patterning sub-wavelength pyramid structures. 2007 Elsevier B.V. All rights reserved.