Superconformal Filling of High Aspect Ratio through Glass Vias (TGV) for Interposer Applications Using TNBT and NTBC Additives

Citation

Ogutu, P., Fey, E., & Dimitrov, N. (2015). Superconformal Filling of High Aspect Ratio through Glass Vias (TGV) for Interposer Applications Using TNBT and NTBC Additives. Journal of The Electrochemical Society, 162(9), D457–D464. https://doi.org/10.1149/2.0641509jes

Keywords

  • Through glass vias (TGV)
  • Superconformal filling
  • Tetranitroblue tetrazolium Cl− (TNBT) and Nitroblue tetrazolium Cl− (NTBC)
  • Butterfly mechanism
  • Void formation
  • Current density
  • Acidic CuSO4/Cl− formulations
  • Interposer applications

Brief

This article presents a method for achieving superconformal filling of through glass vias (TGV) with copper using tetranitroblue tetrazolium Cl− (TNBT) and nitroblue tetrazolium Cl− (NTBC) additives for glass interposer applications.

Summary

The article, published in 2015 in the Journal of The Electrochemical Society, details a method for filling through glass vias (TGVs) with copper (Cu) using electroplating. This process is important in the creation of glass interposers, which are used in electronic packaging to connect different components.

Here are the key findings of the article:

  • Superconformal filling, where the deposition rate inside the vias is higher than on the surface, was achieved using two different additives: TNBT and NTBC.
  • This filling mechanism is referred to as the "butterfly" effect due to the shape of the copper deposit in the early stages of filling.
  • TNBT with acetic acid (CH3COOH) resulted in complete filling of 6:1 aspect ratio TGVs in 3 hours and 10:1 aspect ratio TGVs in 12.5 hours.
  • NTBC with sulfuric acid (H2SO4) achieved similar results, filling 6:1 aspect ratio TGVs in 4-5 hours and 10:1 aspect ratio TGVs in 12-13 hours.
  • The presence of chloride ions (Cl-) and the choice of acid are critical for controlling the plating process.
  • The authors investigated the role of additive reduction during the plating process but did not find conclusive evidence to support it as the primary mechanism of action.

The article concludes that both TNBT and NTBC can effectively fill high aspect ratio TGVs, paving the way for their use in the production of glass interposers. The research highlights the importance of carefully controlling plating parameters, such as additive concentration, current density, and acid type, to achieve optimal results.

Origin: https://iopscience.iop.org/article/10.1149/2.0641509jes/meta

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