| Research Abstract |
Acceleration and inhibition effects on via filling electrodeposition were discussed.
1.Acceleration effect
(1) Through mask electrode of electrode only at via bottom was used to measure the via bottom acceleration effects. The via bottom current increases with additives of Chloride(Cl^-), Polyethylen Glycol (PEG), Janus green B(JGB) and Bis(3-sulfopropyl) disulfide(SPS) if compared with Cl^-, PEG and JGB. With increasing via aspect ratio, the via bottom current also increases.
(2) The via bottom current also increases with narrower via opening size. The cross section of electrodeposits deposited on via bottom electrode was observed. These elctrodeposits are always flat and does not show the curvature even with the narrower via opening size which shows the acceleration effects. This contradicts with the adsorption model proposed by T.Moffat et. Al..
(3) This indicates that the free accelerator, not the adsorbed, shows the via bottom acceleration effect.
2.Inhibition effect
(1) Inhibition addi
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tives of PEG molecules was discussed next. The granular deposit shows higher FEAUGER peak intensity if compared with other flat areas. The PEG molecule is polymer containing oxygen and the granular deposits observed with the secondary electron image are the PEG molecules.
(2) The QCM substrates which has been pre deposited with copper was dipped into the PEG and Cl^- containing copper electrolytes. The differential frequency increases with the increase in the dipping time. With 200 second dipping time, numerous fine 10nm in diameter PEG molecules can be observed.
(3) The current shows constant and lower value of 4.3mA/cm^2 with the PEG and Cl^- containing copper electrolytes regardless of electrodepositiontime. With adding 1ppm of SPS, however, the current increased drastically. SPS has the acceleration effect of increasing current. Before adding 1ppm of SPS, the copper electrodeposit surface has numerous PEG molecules. However, no PEG molecules could be observed on the copper electrodeposit surface of 3000second and 5400sedond. The copper electrodeposits also show refinement of granular size to 100nm. The SPS additive has the PEG molecules removing and copper electrodeposit refinement effects.
*Three dimensional packaging technology is to stack the silicon chips in three dimensions. Through chip electrodes form on the silicon chips and these high aspect ratio vias are filled by copper electrodeposition. As an application of the research, we developed complete electrodeposition of these high aspect ratio vias. We achieved extremely short electrodeposition time of 2.5hrs. Less
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