The filling of micron through-holes (THs) in a printed circuit board (PCB) by copper electroplating was investigated in this study. The role of supporting electrolytes, such as H(2)SO(4), Na(2)SO(4) and K(2)SO(4), was explored using practical TH filling plating and linear-sweep voltammetry (LSV) analysis of plating solutions. The copper could selectively fill THs using one organic additive, namely, tetranitroblue tetrazolium chloride (TNBT), as an inhibitor. The inhibiting strength of TNBT depended on the supporting electrolytes. Although H(2)SO(4) could enhance the inhibiting strength of TNBT, it also decreased the filling capability of the copper plating solution; Na(2)SO(4) and K(2)SO(4) did not enhance the inhibiting strength of TNBT but they increased the filling capability of the copper plating solution. Additionally, the protons could chemically interact with TNBT to form precipitate, whereas sodium and potassium ions did not easily interact with TNBT. The filling capability of the copper plating solution using Na(2)SO(4) and K(2)SO(4) as supporting electrolytes could be greatly improved by adding a small amount of bis(3-sulfopropyl)-disulfide (SPS) and poly(ethylene glycol) (PEG) with a molecular weight of 600. (C) 2011 Elsevier Ltd. All rights reserved.

Through-holes (TH) filling of printed circuit board (PCB) by copper electroplating using single organic additive was carried out. The inhibition of the organic additive was sensitive to acid. We chose different kind of organic acids with different concentrations as supporting electrolytes to achieve TH copper filling, which was called butterfly technology (BFT). To reduce plating time, high current density was necessary but it had to combine with raising the concentration of chloride ions and force convection. These combinations can significantly improve the filling performance of the copper plating solution. All of the results of electroplating were observed by optical microscope (OM).

In this work, a copper plating formula that can directly and selectively fill the through silicon holes (TSHs) for 3D chip stacking packaging was developed. The copper plating technology reduced and simplified the process steps for fabricating through silicon vias (TSVs) and TSHs. The highly selectivity of copper fill in the TSHs also reduced the manufacture cost of 3D chip stacking packaging, because the copper plating technology reduced the loading of a post-copper chemical mechanical polishing (CMP) and did not need a post-thermal annealing treatment. The copper plating formula was very simple, just containing single organic additive.

Three new technologies for Cu coating and deposition in through silicon vias (TSVs) and through silicon holes (TSHs) were developed. One is to synthesize Cu nanoparticles (CuNPs) with a particle size of 3–5 nm and then coat the CuNPs onto the sidewall of TSVs by a wet process to act as catalysts for a seed layer formation through copper electroless deposition. The wet process for Cu seed layer formation can make sure of conformal coating and reduce the process cost of TSV. Second, we develop a new Cu electroplating formula that can make selective Cu fill (SCF) in TSVs, which leads to no increase in Cu thickness on the top surface after electroplating. The plating technique, SCF, can greatly reduce the loading of Cu CMP and the process cost of TSV. Finally, we develop a novel Cu plating technique for direct TSH filling, meaning that the conducting template assembled on one side of the TSH in advance is unnecessary. Cu can fill the TSH directly in a middle-up mode. This filling mode can make sure of no void after electroplating. In addition, the barrier layer employed herein was formed through CoWP electroless plating to replace the traditional dry process for cost cut.

A copper electroplating process using a single organic additive was developed for filling through holes of printed circuit boards. The organic additive acted as an inhibitor of copper deposition in the presence of chloride ions and H(2)SO(4). This copper electroplating formula resulted in center-up filling, which differs from the bottom-up filling exhibited by blind microvias. The inhibiting strength of the organic additive and the filling capability of the plating solution strongly depended on the concentration of H(2)SO(4). The electrochemical behavior of the organic additive was characterized by electrochemical analyses and imaging of TH cross sections. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3511757] All rights reserved.

In recent years, through wafer electrical connections have become important roles, which will be used in developing high-speed, compact 3D microelectronic devices in next generation. Although the electroplating copper is a well-established process, completely void-free electroplating in through silicon holes (TSH) with a high aspect ratio remains a big challenge. Naturally, local current distribution is not uniform from the hole opening to the hole center during traditional electroplating. Therefore, voids were easily formed in TSH after traditional electroplating. In this paper, using this center-up technique, we demonstrate successful filling of though holes with an aspect ratio of 7.6. A novel copper plating formula composed of a special inhibitor achieved void-free copper could fill in TSH. Due to this special adsorption and inhibition of the new additive (VF-S), that have resulted in a concentration gradient of VF-S from the hole opening to the center, the center-up filling mode was carried out, meaning that copper pillars can be directly formed by copper electroplating without the need of a conducting template assembly.