Nonuniform Silicon Backside Edge-to-Center Plasma Thinning Process Using Low Global Warming Potential Gas for High Bandwidth Memory (HBM)

Abstract

Conventional SF6 based etching in HBM packaging faces low yield and edge breakage due to poor profile control and high GWP. To address this, a multi-step strategy using ClF3, IF7, and C4F6 is proposed. While ClF3 enables efficient thinning, a combination of ClF3/IF7/C4F6 with a localized magnetic field precisely modulates the wafer edge profile. Plasma diagnostics show that IF7 induces electron scavenging, reducing plasma reactivity via iodine species to prevent over-etching at the periphery. This approach ensures high yield, minimal surface damage, and tailored silicon profiles. Ultimately, this low-GWP chemistry provides a high-performance, sustainable alternative to SF6, meeting the stringent mechanical and environmental requirements for next-generation HBM integration.