Mechanical features of copper coatings electrodeposited by the pulsating current (PC) regime on Si(111) substrate

Implementation of the Chicot–Lesage Composite Hardness Model in a Determination of Absolute Hardness of Copper Coatings Obtained by the Electrodeposition Processes

“…The fine-grained mat coating obtained from the basic electrolyte showed clear boundary between Cu grains, while boundary among grains was not visible in smooth mirror bright Cu coating obtained in the presence of additives. The higher coating hardness of Cu coatings obtained from additive free electrolyte can be attributed to numerous boundaries among grains representing a disruption site for dislocation motion, or better said, the boundaries among grains prevent a movement of the dislocations [30,37]. Each grain boundary acts as a mini-resistor when the indenter penetrates in the volume of the coating material.…”

“…From Figure 4a it can be seen that the composite hardness of the mat coating obtained from the basic electrolyte was larger than that obtained from the electrolyte with additives. Furthermore, it follows from the same Figure that the Hc values were mainly in the RID range between 0.1 and 1, indicating a necessity of application of the composite hardness models for the determination of absolute coating hardness [11][12][13]21,[28][29][30]. With a hardness of 1.41 GPa, the brass belongs to the group of relatively hard substrates, while Cu coatings electrodeposited on it belong to "soft film on hard substrate" composite system type [22].…”

Application of the Composite Hardness Models in the Analysis of Mechanical Characteristics of Electrolytically Deposited Copper Coatings: The Effect of the Type of Substrate

“…The direct approach is suitable for thick coatings excluding any contribution of a substrate to measure the hardness value, but the limit of this approach is the insufficient precision of a diagonal size measurement at the low indentation load. The indirect approach takes into account the contribution of substrate hardness to measure the hardness value [24,25]. The main disadvantage of the application of these models is the absence of their universal character, with numerous limitations to the calculation of true (or absolute) hardness from the measured composite hardness.…”

“…For the same metal coating, the choice of the composite hardness model is determined by the type of used substrate. The following substrates are the often applied in the Cu electroplating processes: silicon [20,25,35,38], nickel coatings [14,21], copper [9,10,19,38], polyimide [5], graphite [23] or brass [21].…”

“…The creep resistance of the coatings gives very valuable information related to the timedependent flow of materials [40], i.e., to an evaluation of their reliability. It is necessary to stress that aside from the data obtained for the Cu coatings electrodeposited on the Si(111) substrate by the PC regime [25], other data dealing with the analysis of this mechanical characteristic are not found in the literature for the copper coatings.…”