Effect of Potassium Ions on Tantalum Chemical Mechanical Polishing in H₂O₂-Based Alkaline Slurries

Abstract

Tantalum has been used as the barrier material for copper interconnects for decades. This paper mainly investigated the effect of potassium ions on tantalum chemical mechanical polishing in H2O2-based alkaline slurries. The results reveal that, with the increase in the H2O2 concentration, the tantalum material removal rate (MRR) gradually increases via forming a structurally weak oxide film mainly composed of Ta2O5 and small amount of soluble tantalum species. On the basis of H2O2, with the increase in the concentration of potassium ions, the tantalum MRR first linearly increases and then becomes saturated, while Ra keeps almost unchanged. Additionally, the change of the tantalum MRR is independent of the anions of the potassium salts. The enhancement of the tantalum MRR is due to the slight increase in Icorr and the anodic current density possibly, and more significantly, the remarkable increase in the interactions between silica particles and the tantalum surface caused by the decrease in the absolute value of the zeta potentials and the thickness of the electrical double layers of both silica particles and the tantalum surface. Moreover, a tunable MRR selectivity of Ta vs. Cu can be obtained by adjusting H2O2, potassium ions and the copper chelating agent/inhibitor.

An Alkaline Slurry Design for Co-Cu CMP Systems Evaluated in the Tribo-Electrochemical Approach

“…Due to this reason and, also due to the reusable feature and easy availability of such samples, continued use of polycrystalline discs/coupons is routinely found in the current literature of metal CMP. [83][84][85][86][87][88] The significance of the data recorded here with metal discs is ingrained in the latter's utility for experimentally mimicking the mechano-chemical features of the CMP process. The obtained results demonstrate how this capacity of tribo-electrochemical measurements can translate to the capability of correlating various mechanical and (electro)chemical aspects of complex CMP systems.…”

Exploring the role of −NH2 functional groups of ethylenediamine in chemical mechanical polishing of GCr15 bearing steel

“…(1). The cathodic reactions can be depicted as follows [39] 7and (9) could be either from the dissolved oxygen in the solution or from the decomposition product of H 2 O 2 [40]. The oxidation function of O 2 in Eq.…”

Chemical-Mechanical Impact of Nanoparticles and pH Effect of the Slurry on the CMP of the Selective Layer Surfaces

“…Since CMP MRR is dependent on the nanoparticle size and concentration in the slurry, the effects have been investigated by many researchers [26][27][28][29][30][31][32][33][34][35][36]. The reported results are often contradictory and are explained based on the selected ranges of the nanoparticle size and concentration, as well as by their behavior during the CMP process.…”

“…In the literature, there are numerous studies on similar topics [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] applied to the copper CMP of integrated circuits. It is worth mentioning that the present study intends to extend to other fields, namely to surfaces coated through selective transfer (the surfaces of the selective layer) in the friction process, considering the slurry pH (important for removal through CMP of the selective layer) [7,[22][23][24][25][26], H 2 O 2 (the most common oxidant) [27][28][29][30][31][32][33], size [21,[28][29][30][31], and concentration [12,21,34] of nanoparticles used in the CMP slurry. Thus, this paper explores the pH effect at a constant H 2 O 2 concentration on the etching and polishing behavior of the selective layer and the influences on size and concentration of nanoparticles during selective layer surface CMP.…”