LOCOS Dielectric Fillet Layout for High-Voltage Breakdown Relief

The patent applies curvature by adding fillets at the corners of the thick portion of the dielectric layer. Instead of sharp corners, the fillets create rounded transitions that eliminate the neck or bird's-beak regions where dielectric breakdown previously occurred. This curvature modification redistributes the electric field more evenly, preventing concentration at sharp corners and thereby improving dielectric reliability without significantly complicating the manufacturing process.

The patent implements local quality by creating a non-uniform dielectric layer thickness with a thick portion strategically positioned to provide field relief at high voltage regions. The thick portion has lateral dimensions and corner fillets that locally increase dielectric strength where electric field concentration occurs, while other regions maintain standard thickness. This localized thickening with filleted corners provides targeted protection against dielectric breakdown without requiring uniform thickness increase throughout the entire dielectric layer.