Novel integration of ultrathin Al2O3 with low-k dielectric as bilayer liner for capacitance optimization and stress mitigation in Cu through-silicon-via

作者：Zhang Lin; Li Hong Yu; Shang Yang; Yoo Woosik; Yu Hao; Tan Chuan Seng^*

来源：Japanese Journal of Applied Physics, 2016, 55(4): 04EC08.

DOI：10.7567/JJAP.55.04EC08

Through-silicon-via (TSV) used in three-dimensional (3D) stacked dies must present small electrical parasitic, such as capacitance, to allow for low latency signal transmission. Stable TSV capacitance is desired to overcome the spatial circuit performance variation caused by non-uniform hotspot heating. In this work, a novel combination of low-k with ultrathin Al2O3 bilayer liner is successfully integrated in the TSV. The TSV capacitance is reduced by similar to 26% as compared to plasma-enhanced tetrahydrothosilicate (PETEOS) oxide liner. Stable TSV capacitance within the operating voltage of interest (similar to 0-5V) is achieved by operating the TSV in a stable accumulation capacitance region. The positive shift in the flat-band voltage (Delta V-FB=+19V) is achieved by utilizing Al2O3-induced negative fixed charge (vertical bar Q(f)vertical bar = 1.3 x 10(12) cm(-2)) at the Si/low-k interface. Leakage current density of the bilayer liner is improved to a level comparable with the PETEOS oxide liner post annealing [forming gas (N-2/H-2) at 350 degrees C for 2 h or 400 degrees C for 0.5 h]. Low-k material with a smaller elastic modulus improves the thermo-mechanical stress exerted on the surrounding Si substrate compared with PETEOS oxide.

• 出版日期2016-4
• 单位南阳理工学院