Nanophotonic waveguides in silicon-on-insulator (SOI) fabricated with complementary metal-oxide-semiconductor (CMOS) technology are key for ultracompact photonic integrated circuits (PICs). This paper demonstrates the fabrication of nanophotonic waveguides using deep ultraviolet (UV) lithography and CMOS processes. It compares photonic wires and photonic-crystal waveguides, showing that photonic wires have significantly lower propagation losses (0.24 dB/mm) compared to photonic-crystal waveguides (7.5 dB/mm). The study highlights the potential of CMOS technology for commercial nanophotonic integration, emphasizing the need for high-resolution fabrication to achieve nanoscale features with sub-nanometer accuracy. Nanophotonic waveguides are crucial for PICs, enabling compact, high-performance components. They rely on high refractive index contrast for tight light confinement. Two main techniques are used: photonic wires, which guide light via total internal reflection, and photonic crystals, which use photonic bandgap effects. Photonic wires are more efficient for low-loss waveguiding, while photonic crystals offer unique optical properties but suffer from higher losses due to scattering. SOI is ideal for nanophotonic waveguides due to its high refractive index contrast and compatibility with CMOS processes. The fabrication process involves deep UV lithography and dry etching, with careful control of sidewall roughness to minimize scattering. Two etching approaches are discussed: deep etching through both silicon and oxide, and silicon-only etching. The latter reduces sidewall roughness but requires mask corrections to account for optical proximity effects. Photonic-crystal waveguides are more complex to fabricate and characterize due to their periodic structures and sensitivity to sidewall roughness. The study shows that silicon-only etching reduces losses in photonic-crystal waveguides, achieving propagation losses as low as 7.5 dB/mm. However, photonic wires offer significantly lower losses (0.24 dB/mm) and are more suitable for nanophotonic integration. The paper also discusses other nanophotonic structures, including ring resonators and fiber couplers, fabricated using similar techniques. These components demonstrate the versatility of CMOS-based nanophotonic fabrication for integrated photonic systems. The results highlight the potential of CMOS technology for commercial nanophotonic integration, emphasizing the need for detailed process characterization and optical proximity correction to achieve high-quality nanoscale structures.Nanophotonic waveguides in silicon-on-insulator (SOI) fabricated with complementary metal-oxide-semiconductor (CMOS) technology are key for ultracompact photonic integrated circuits (PICs). This paper demonstrates the fabrication of nanophotonic waveguides using deep ultraviolet (UV) lithography and CMOS processes. It compares photonic wires and photonic-crystal waveguides, showing that photonic wires have significantly lower propagation losses (0.24 dB/mm) compared to photonic-crystal waveguides (7.5 dB/mm). The study highlights the potential of CMOS technology for commercial nanophotonic integration, emphasizing the need for high-resolution fabrication to achieve nanoscale features with sub-nanometer accuracy. Nanophotonic waveguides are crucial for PICs, enabling compact, high-performance components. They rely on high refractive index contrast for tight light confinement. Two main techniques are used: photonic wires, which guide light via total internal reflection, and photonic crystals, which use photonic bandgap effects. Photonic wires are more efficient for low-loss waveguiding, while photonic crystals offer unique optical properties but suffer from higher losses due to scattering. SOI is ideal for nanophotonic waveguides due to its high refractive index contrast and compatibility with CMOS processes. The fabrication process involves deep UV lithography and dry etching, with careful control of sidewall roughness to minimize scattering. Two etching approaches are discussed: deep etching through both silicon and oxide, and silicon-only etching. The latter reduces sidewall roughness but requires mask corrections to account for optical proximity effects. Photonic-crystal waveguides are more complex to fabricate and characterize due to their periodic structures and sensitivity to sidewall roughness. The study shows that silicon-only etching reduces losses in photonic-crystal waveguides, achieving propagation losses as low as 7.5 dB/mm. However, photonic wires offer significantly lower losses (0.24 dB/mm) and are more suitable for nanophotonic integration. The paper also discusses other nanophotonic structures, including ring resonators and fiber couplers, fabricated using similar techniques. These components demonstrate the versatility of CMOS-based nanophotonic fabrication for integrated photonic systems. The results highlight the potential of CMOS technology for commercial nanophotonic integration, emphasizing the need for detailed process characterization and optical proximity correction to achieve high-quality nanoscale structures.