Impurities in the Electroplated sub-50 nm Cu Lines: The Effects of the Plating Additives

Abstract

The impurities incorporated in the electrodeposited 40 nm Cu lines as well as in blanket Cu films were studied. Two different levelers were used in the study. While the impurity in the blanket films were found highly dependent on the leveler and its concentration, the leveler had no impact on the impurity in the narrow lines. Furthermore, the concentrations of suppressor and chloride showed little to no impact on the impurity in the narrow lines. An increase of accelerator concentration resulted in higher S and Cl contents in the lines. The increase in S incorporation was also observed for blanket wafers plated with incremental concentrations of accelerator. In addition, the impurity in the narrow lines was also found to increase with the increase of the applied plating current density. A correlation between a slow Cu grain growth and high impurity content was established by using Cu blanket films plated with different leveler concentrations or Cu films ion-implanted with different doses of impurities.

Impurity Effects in Electroplated-Copper Solder Joints

“…Researchers at IBM [53,54] reported that the impurity content increased as a high concentration of leveler was added in the plating solution. The impurities were carbon, oxygen, sulfur, and chlorine, and their concentrations increased by about one order of magnitude (from 10 18 atoms/cm 3 to 10 19 atoms/cm 3 ) as the leveler's concentration was increased by the same order of magnitude.…”

“…Once the impurity content is high (10 18 -10 20 atoms/cm 3 , depending on the impurity type), it will significantly affect the electrical property and microstructural evolution of the Cu layer [19,21,53,54]. In this section, we will review that the impurity incorporation in the electroplated Cu layer also has a significant effect on the interfacial reactions at the solder/Cu joints.…”

Oscillatory Behavior in Cobalt Electrodeposition with 3-Mercapto-1-Propanesulfonate

“…Organic additives are used in damascene Cu chemistries not only to achieve void-free metal filling process but also to control the impurity incorporation and grain structures of deposited Cu. − The former is achieved as a result of the interplay between multiple additive components . The metal cation reduction kinetics are thus altered upon various mechanisms, such as an interaction between metal cations and additives in bulk electrolytes, the adsorption, desorption, and breakdown of a catalytic or inhibitive intermediate species adsorbed on the electrode surface, or competitive adsorption between multiple intermediates on the electrode surface. , These mechanisms at certain conditions can trigger electrochemical oscillation, where either the potential or current changes periodically within a certain range during galvanostatic or potentiostatic deposition, respectively.…”

Determining instantaneous removal rates in metal chemical mechanical planarization

“…In the case of copper or tungsten CMP, film morphology, density and elemental composition change dramatically as function of thickness. [28][29][30][31][32] This is especially true in the case of copper-filled trenches of patterned wafers where topography-reducing, as well as deep trench filling additives in the electroplating bath, leave their elemental fingerprint inside the film. 28) Since film thicknesses get smaller with polish time, the above factors must also change as a function of polish time.…”