Bottom Coverage of Cu Deposit for 200-nm-Class Circular Vias with High Aspect Ratios Investigated by Magnetron Sputtering Activated Using Superconducting Bulk Magnet

• Published in: Japanese Journal of Applied Physics 2004-09, Vol.43 (9R), p.6026
• Main Authors: Hazama, Hirofumi, Matsuda, Takashi, Mizutani, Uichiro, Ikuta, Hiroshi, Yanagi, Yousuke, Itoh, Yoshitaka, Sakurai, Kazuo, Sekiguchi, Atsushi, Imai, Atsuo
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.43.6026

We have investigated the bottom coverage effect of circular vias with different aspect ratios patterned on Si substrates by depositing Cu using a magnetron sputtering apparatus equipped with a superconducting bulk magnet. The superconducting SmBa 2 Cu 3 O 7-δ bulk of 60 mm diameter was magnetized up to 4.5 T at 52 K and cooled to 40 K in a refrigerator. It served as a permanent magnet producing magnetic fields about 10 times as strong as that obtained from a conventional Nd–Fe–B permanent magnet, resulting in a marked enhancement in plasma density on the Cu target. Indeed, the present magnetron sputtering apparatus was capable of sputtering under Ar gas pressures of at least 3.33 ×10 -3 Pa with a throw distance D st of 300 mm when a Cu target of 150 mm diameter was employed. Practical sputtering was possible under 2.66 ×10 -2 Pa even when D st was extended to 500 mm. Under this condition, a uniform Cu film with a bottom coverage of 58% was successfully deposited at the bottom of a circular via of 250 nm diameter and 1.15 µm depth with an aspect ratio of 4.6 within a circle of 120 mm diameter on the substrate.