Experiment and simulation of single inhibitor SH110 for void-free TSV copper filling

Abstract

Three-dimensional integration with through-silicon vias (TSVs) is a promising microelectronic interconnection technology. Three-component additives are commonly used for void-free TSV filling. However, optimising the additive concentrations is an expensive process. To avoid this, a single-component additive was developed: 3-(2-(4,5-dihydrothiazol-2-yl) disulfanyl) propane-1-sulfonic acid/sulfonate (SH110). Sodium 3,3′-dithiodipropane sulfonate (SPS) and SH110 were used as additives for TSV electroplating copper filling. SH110 resulted in void-free filling, whereas large keyhole voids were found for SPS. To understand how the additives affect the filling mechanism, linear sweep voltammetry of the plating solutions was carried out. The interactions between the Cu surface and additives were simulated by molecular dynamics (MD) analysis using Materials Studio software, and quantum chemistry calculations were conducted using GAUSSIAN 09W. SH110 adsorbs to the Cu surface by both 4,5-dihydrothiazole (DHT) and 3-mercaptopropane sulfonate (MPS) moieties, while SPS is adsorbed only by MPS moieties. MD simulations indicated that the adsorption of the coplanar MPS moiety is the main factor governing acceleration. Quantum chemistry calculations showed that DHT provides an inhibitory effect for TSV filling, while MPS acts as an accelerator for SH110. SH110 is an excellent additive exhibiting both the acceleration and the suppression necessary for achieving void-free TSV filling.

Ultra-Uniform Copper Deposition in High Aspect Ratio Plated through Holes via Pulse-Reverse Plating

“…So, the addition of SH110 enables depolarization of copper deposition. With a SH110 concentration increase, the concentration of inhibitor fragments decomposed by SH110 gradually increased, and the cathodic polarization increased [30,31]. Different potential changes were gradually displayed under strong and weak convection.…”

“…Wang et.al. [31] showed that SH110 was an excellent additive exhibiting bi-role as the accelerator and the inhibitor, and exhibits superior performance than the conventional additive, SPS. Meanwhile, SH110 exhibited higher bottom-up filling ability than SPS over a wider potential range.…”

Advanced 3D Through-Si-Via and Solder Bumping Technology: A Review

“…To increase the coverage of the barrier/seed layer steps, they used the TSV shape with scallop-free taper-ends and effectively filled the TSV with defect-free copper. Wang et al added a single sulfonic acid derivative (3-(2-(4,5-dihydrothiazol-2-yl) disulfanyl)-propane-1-sulfonic acid) and observed void-free TSV filling and suppression of outgrowths as compared to existing commercial complex additives [114]. Typical parameters for various TSV technologies are given in Table 2.…”

A Review on the Fabrication and Reliability of Three-Dimensional Integration Technologies for Microelectronic Packaging: Through-Si-via and Solder Bumping Process

“…Therefore, to improve the efficiency and simplify the Cu-filling process, some researchers reported using a single additive to the plating solution. Wang et al [59] have reported by using single inhibitor material, 3-(2-(4,5dihydrothiazol-2-yl)disulfanyl)propane-1-sulfonic acid (SH110) shown in Figure 12a, they were able to perform defect-free Cu filling at the current density of 1 mA/cm 2 . Le et al [60] suggested another additive material of 3-(1-pyridinio)-1-propanesulfonate (PPS), as shown in Figure 12b; using the current density of 0.2 A/dm 2 and 5 g/L concentration of PPS, they successfully filled the TSV with Cu.…”