Low‐Temperature Deposition of Reactively Sputtered SiN_x Films Applicable to TSV Process

Abstract

In the through silicon via (TSV) process, which is a key technology for a three-dimensional large-scale integration (LSI), particularly in the "via-last process," SiN x films of high density are urgently needed for fabrication at low deposition temperatures. However, it is generally known that a SiN x film prepared at low temperatures shows low film density, resulting in poor insulating barrier properties. As a solution to this issue, we propose the use of the SiN x films deposited by reactive sputtering. We can obtain sputtered SiN x films at high density (2.78 to 2.99 g/cm 3 ) in spite of deposition without substrate heating. The 20-nmthick SiN x films passed an experimental check on barrier properties with respect to Cu diffusion upon annealing at 700°C for 1 h. The films also show good step coverage for a TSV with an aspect ratio of 1.5. The SiN x films prepared by reactive sputtering are a candidate for a good insulating barrier applicable to the via-last TSV process. C⃝ 2016 Wiley Periodicals, Inc. Electron Comm Jpn, 99(9): 101-107, 2016; Published online in Wiley Online Library (wileyonlinelibrary.com).