Superfilling of Cu-Ag Using Electrodeposition in Cyanide-Based Electrolyte

Abstract

Superfilling of Cu-Ag for metal interconnection was investigated in cyanide-based electrolyte. Superfilling was successfully achieved using the combination of KSeCN and thiourea. The trenches having widths in a range between 120 nm and 1.7 μm (depth: 400 nm) were filled without any voids. The continuous acceleration effect of KSeCN on Cu-Ag electrodeposition in the concentration range between 3.75 and 20 μM was confirmed, and thus the accumulation of KSeCN at the bottom of trench was surmised to be the main reason of Cu-Ag superfilling. Dissimilar to the previous superfilling of Ag or Au, which could be characterized as the fast surface diffusion of KSeCN, remarkable bumps and convex profiles at the corners of low-aspect-ratio trenches were developed. The proposed formula has led to defect-free superfilling of Cu-Ag with the Ag concentration in the range of 4.6 to 7.9 atom%.

Bottom-Up Electrodeposition of Zinc in Through Silicon Vias

“…15,16 The additive combinations of accelerator and suppressor associated with Damascene copper superfilling of submicrometer features have also been applied to much larger, lower aspect ratio microvias and more recently higher aspect ratio Through Silicon Vias (TSVs). [17][18][19][20][21][22][23][24][25] However, at these larger length scales electrical and compositional gradients begin to exert a much more important role on feature filling behavior.…”

Morphological Transitions during Au Electrodeposition: From Porous Films to Compact Films and Nanowires

“…[4][5][6][7] Of particular interest is the substantial literature on solution or vapor processing to yield a wide variety of nanostructures including high aspect ratio nanowires. 4,8,9 Solution-based, chemical reduction processes are attractive because they are inexpensive and scalable.9-18 Subsequent processing involving particle packing and/or substrate interactions can lead to higher order organization and colloidal crystals.19 Alternatively, nanostructures can be grown on or in surfaces that have been shaped by lithography or other means to obtain control of orientation and/or placement.8 Electrochemical processing may involve throughmask plating in patterned templates 20,21 or superconformal electrodeposition of metals and alloys [22][23][24][25][26][27][28][29][30][31] including gold 32-34 in high aspect ratio features. However, these processes require nanoscale patterned topography to create such structures and the associated patterning often comes with increased processing complexity.…”

Accuracy Improvement in Cyclic Voltammetry Stripping Analysis of Thiourea Concentration in Copper Plating Baths

“…1,2,[6][7][8][9][10][11][12][13][18][19][20][21][22][23][24][25][26][27][28][29] TU is a common additive in Cu and Ag electrodeposition baths and induces leveling and grain refining properties.…”

“…20,21,23,24 Various applications of TU as an additive have been studied, including the formation of the Cu twin, Ag superfilling, and the fabrication of CuS nanowire structures. 18,19,[23][24][25][26] TU is known to form thiolate complexes such as [Cu-(TU) ions. [27][28][29] Owing to the various derivatives and their different electrochemical responses, TU shows unique electrochemical behavior unlike typical suppressors or levelers.…”

“…1,2,6-13, [18][19][20][21][22][23][24][25][26][27][28][29] TU is a common additive in Cu and Ag electrodeposition baths and induces leveling and grain refining properties. [18][19][20][21][22][23][24][25][26] TU has been used as an additive either solely or in combination with Cl − (TU-Cl − ) in baths used for electrodeposition processes involving various current/potential waveforms such as direct current, pulse-, or pulsereverse waveforms.…”