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

Abstract

In this study, a multi-step current density method was investigated to fill TSVs with different aspect ratios (⌀20 µm × 120 µm, ⌀30 µm × 130 m, ⌀40 µm × 140 µm and ⌀50 µm × 150 µm) simultaneously without voids. First, the effects of current density and TSV size on the growth mode of electrodeposited Cu were investigated. The experimental results indicated that low current density (1 mA cm−2) was favorable to bottom-up filling for TSVs with small size (⌀20 µm × 120 µm). The medium current density of 6 mA cm−2 was favorable to bottom-up filling for the TSVs with large sizes (⌀40 µm × 140 µm and ⌀50 µm ×150 µm). The high current density of 9 mA cm−2 could only be used for bottom-up filling in the ⌀50 µm × 150 µm TSV. Second, three kinds of initial shape of Cu-TSV at the beginning of electroplating were proposed to discuss the growth mechanism of electrodeposited Cu in TSVs. Then, the effect of temperature on the filling mode of the TSVs was investigated. It was found that the deposition rate at different locations of the TSV sidewall was more uniform at low temperature, which was helpful to form the bottom-up filling mode. Finally, all the TSVs with different aspect ratios were simultaneously filled void free at 20 °C when the current densities of 3 and 6 mA cm−2 were applied for 90 min.

Modeling the Copper Electrodeposition of Through-silicon-vias Corresponded to Linear Sweep Voltammetry

“…According to our former research, the current of peak and valley in LSV curves corresponds to that on upper and lower section of via in model respectively. 4,26 Figure 3(a) show linear sweep curves of electrolyte with different components of additives. With increasing concentration of SPS, the small peak shifts towards more negative potential and the size of small peak increases.…”

“…Through-Silicon via (TSV) filling in the form of copper electrodeposition has become an important process technology for interconnecting the 3D stacked layer. [1][2][3][4] Under correct condition, the copper electrodeposition provides via filling in the form of superconformal and bottom-up. [5][6][7] Under the condition, including performance of electrolyte and status of electrode, is widely investigated to make copper electrodeposited properly.…”

Effect of current density on microstructure and mechanical property of Cu micro-cylinders electrodeposited in through silicon vias

“…For the Cu-TSV electrodeposited at 1mA/cm 2 , a weak signal of C 1s was observed. In contrast, the C 1s signal was obviously strong for the sample A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 15 electrodeposited at 9mA/cm 2 .…”

“…The electroplating bath used for TSV filling was a methanesulfonate solution with commercial additives. Details on the electroplating process have been reported in our previous work [15]. The current density of 1, 3, 6 and 9mA/cm 2 was used for electrodeposition, respectively.…”

Effect of External Factors on Copper Filling in 3D Integrated Through-Silicon-Vias (TSVs)

“…According to our previous study, the environment temperature in a small range (16∼28 • C) has an effect on the via filling efficiency. 30 However, the effect of environment temperature in a large range on the via filling model has rarely investigated at present.…”