Effect of Basicity of Amino Group at Side Chain in Diallylamine-Type Copolymer Additive on Via-Filling by Copper Electrodeposition

Abstract

We achieved the bottom-up via-filling by copper electrodeposition using a single diallylamine-type copolymer additive instead of the four types of additives, Suppressor Leveler Accelerator and Chloride ions. We newly synthesized and used four additives modified side chains to research more the function of this additive. We observed vias cross sections, performed an electrochemical analysis and conducted quartz crystal microbalance (QCM) measurements. By comparing the amino group at the end of the side chain with the one near the main chain, it was found the basicity of the latter is weak due to the neighboring group effect. However, when the distance between these two amino groups is long, the basicity of the amino group near the main chain is strong. The use of a polymer additive with a strong amino group near the main chain had the effect of suppressing the electrodeposition outside vias and achieving a good bottom-up filling.

Superconformal Copper Deposition in Through Silicon Vias by Suppression-Breakdown

“…Localized breakdown on the sidewalls is a transient state that subsequently converts to bottom-up filling like that previously reported for Cu systems. [16][17][18][19][20][21][22][23][24] The bottom-up filling process has been understood and modeled to be associated with growth rate dependent disruption of the polymer suppressor. [16][17][18][19][20][21][22] In contrast, a sustained sidewall bifurcation process has previously been observed and captured in PEI suppressed systems by models employing transport limited consumption or deactivation of the suppressor species at the passive-active boundary.…”

“…While filling has often been reported and analyzed for multicomponent additive packages, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] the demonstrated ability of suppressor-only systems to yield bottom-up filling is of particular interest for determining the essential processes that underlie this unusual superconformal filling evolution. [16][17][18][19][20][21][22][23][24][25] In the most extreme form of bottom-up filling, active deposition is localized to the bottom surface of recessed features while the immediately adjacent sidewall and free surface are maintained in the passive state by suppressor adsorption as shown for Cu deposition in the bottom row of Fig. 1.…”

Polyethylene Glycol-Based Single Organic Additive for Through Silicon Via Filling and its Structural Modification Effect

“…A naphthalene ring was also added to each quaternary ammonium cation of the additive to obtain a strong suppression effect of the aromatic ring. [44][45][46][47] Moreover, the additive performance was optimized by modifying its chain length using polyethylene glycol (PEG) of various molecular weights as the starting material (Fig. 1).…”