Gapfill Improvement with Helium /Argon Sputter Gas of HDP FSG in Power Device

Low dielectric constant (low-k) materials are crucial in advancing integrated circuit technology. Fluorosilicate glass (FSG), with a lower dielectric constant than pristine undoped SiO₂, is widely used as a dielectric material in the intermetal dielectric (IMD) layers of 180nm-130nm CMOS devices [1]. It reduces interconnect capacitance, mitigates RC delays, and enhances device performance. Traditional high-density plasma (HDP) FSG deposition processes utilize argon (Ar) as the primary sputtering gas, adjusting the deposition-to-sputtering (D/S) ratio for gapfill. However, Ar-Based one-step HDP deposition often struggles to achieve perfect gapfill, frequently resulting in voids or metal clipping. This study introduces helium (He) as the primary sputtering gas in a one-step FSG HDP process to enhance gapfill performance, achieving void-free and metal clipping-free results while significantly widening the D/S process window. Compared to conventional Ar-Based deposition, the helium-based process increased throughput on Lam Research Corp.’s SPEED® Max platform by 20% and improved sputtering rate uniformity from 4.7% to 1.0%.