Low-Temperature Deposition of Reactively Sputtered SiNx Films Applicable to TSV Process

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," SiNx films of high density are urgently needed for fabrication at low deposition temperatures. However, it is generally known that a SiNx 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 SiNx films deposited by reactive sputtering. We can obtain sputtered SiNx films at high density 2.78 to 2.99i¾?g/cm3 in spite of deposition without substrate heating. The 20-nm-thick SiNx films passed an experimental check on barrier properties with respect to Cu diffusion upon annealing at 700i¾?i¾?C for 1i¾?h. The films also show good step coverage for a TSV with an aspect ratio of 1.5. The SiNx films prepared by reactive sputtering are a candidate for a good insulating barrier applicable to the via-last TSV process.