Analysis of a metal filling and liner formation mechanism of the blind via with nano-Ag particles for TSV (through silicon via) interconnection

Abstract

We investigated a metal filling and liner formation mechanism with a nano-Ag particle for the blind Si via, which is used in the via first process of through silicon via (TSV) interconnection. Using the deep reactive ion etching process, we produced the blind Si via (which is called the blind via hole or via) with a nearly vertical profile. The diameter and depth of the blind Si via were about 10 and 71 µm, respectively. The blind via holes were filled with a nano-Ag particle solution to form a metal plug or a metal liner. At this time, the Ag filling properties were monitored as a function of the volatilization rate of the Ag particle solution in the evacuating chamber. In the fast volatilization of the nano-Ag particle solution, an Ag liner formed on the inner wall of via holes. Meanwhile, both an Ag liner at the sidewall and the Ag plug at the bottom were obtained by the slow volatilization process. Finally, blind via holes fully filled with nano-Ag particles were obtained using four repetitions of the slow volatilization filling process. The proposed TSV filling process can fill large-diameter via holes over 100 µm without a seed layer and chemical mechanical planarization for TSV interconnection at low temperature. This is a simple and cost-effective TSV filling process.

A Novel Seedless TSV Process Based on Room Temperature Curing Silver Nanowires ECAs for MEMS Packaging

“…In recent years, great efforts have been made to improve the TSV fabrication process. The focus is mainly on the research of new filling methods and materials, including seedless electroplating [20,21], liquid-metal injection (SnZn, SnAu) [22,23], metal paste printing (Ag, Au, Cu) [24,25,26,27,28], etc. Among these improved methods, interest in liquid-metal injection and paste printing is currently growing apace and great progress has been made.…”

“…For instance, Jiebin Gu et al developed an efficient TSV technology based on liquid-metal injection with a customized nozzle wafer for MEMS packaging [23]. Lee Mi Do and co-workers reported a cost-effective via metallization method using a nano-Ag particle solution through four cycles of printing and heat evaporation [24]. Nevertheless, the aforementioned TSV fabrication methods are limited by complex processing steps, drastically reducing the efficiency of fabrication and universality of the approaches.…”

Simultaneous filling of through silicon vias (TSVs) with different aspect ratios using multi-step direct current density

“…As one of the key processes in the fabrication of a three-dimensional integrated circuit (3D-IC), filling of through silicon vias (TSVs) has been extensively focused on, especially by electroplating Cu. Many studies have been carried out, including simulation of the electrodeposition process of Cu [2][3][4], and optimization of the electrodeposition bath [5][6][7][8][9][10][11]. In addition, the pulse current for TSV filling has also been investigated in detail [12,13].…”