Effect of Guanidinium Ions on Ruthenium CMP in H₂O₂-Based Slurry

Abstract

With the development of integrated circuits (IC), ruthenium (Ru) has been selected as one of the most promising barrier metals for copper interconnects to replace traditional Ta/TaN bilayer. The present work investigates certain chemical aspects of this strategy of Ru-CMP by using guanidinium ions (Gnd+). And the experiments are designed to study Ru CMP in pH 9 using colloidal silica-abrasive based slurry with an oxidizer (H2O2), Gnd+. Zeta potential, electrochemical and atomic force microscopy are employed to probe the surface effects that facilitate material removal in chemically prevailing CMP of Ru. The results of CMP show that Gnd+ are better than that of potassium ions (K+) on the removal rate (RR) of Ru under the same conditions; and the improvement of Ru RR has a guiding significance for the development of next generation IC in the addition of Gnd+, which is proven by zeta potential increasing, open circuit potentials decreasing, corrosion current density increasing and corrosion potential decreasing.

Effect of ethylenediamine on CMP performance of ruthenium in H2O2-based slurries

“…However, when the concentration of H 2 O 2 exceeds a certain value, the dense and thick oxide lms are generated, resulting in the lower removal rate. 24 It can be seen from Fig. 1b that the surface roughness of ruthenium becomes signicantly smaller as the concentration of the added H 2 O 2 is more than 0.15 wt%, indicating that the oxide lms on the ruthenium surface is denser and smoother in this case.…”

“…In contrast, the use of H 2 O 2 could obtain the negligible corrosion potential difference between ruthenium and copper while forming a smooth and dense ruthenium surface. [22][23][24] Turning to the slurries with H 2 O 2 as oxidant, L. Jiang et al 19 reported that the added potassium ion could achieve the higher removal rate of ruthenium. This was mainly because the introduction of potassium ion increased the intensity of the reactions between H 2 O 2 and ruthenium and the mechanical action in CMP process.…”

“…H. P. Amanapu et al 8 investigated the effect of guanidine carbonate (GC) on ruthenium CMP using H 2 O 2 -based slurries, indicating that the increasing removal rate of ruthenium was because GC interacted with ruthenium oxides via the lone pair electrons on its nitrogen atoms to generate complexes. Subsequently, Y. C. Du et al 24 conrmed that guanidine ion (Gnd + ) was the main factor for promoting ruthenium removal by comparing several common guanidine salts. Most research on ruthenium CMP is mainly centered on the ruthenium oxidizers in the last decades of industrial research, but few studies on effective complexing agents for ruthenium.…”

Stable Hydrogen Production from Water on an NIR‐Responsive Photocathode under Harsh Conditions

“…Because the photo-electrodeposition time was fixed at 15 min in the case of the sample used for Figure 1, the estimated RuO 2 deposition rate was 2 nm min −1 . However, the theoretical deposition rate estimated from the applied current, calculated using Equation (1) [30] and the density of crystalline RuO 2 (6.97 g cm −3 ), is only 1.1 nm min −1 , which is just over half the observed value. Considering the roughness of the photocathode surface, the actual difference could be even larger.…”

Chemical Mechanical Planarization of Ruthenium Using Sodium Hypochlorite Based Titania Slurry

“…2 The major advantage of Ru is its low resistivity (∼7 μ cm) as compared to Ta (∼14 μ cm) and TaN (∼200 μ cm). [2][3][4][5][6] Ru allows direct electrodeposition of Cu which eliminates the need of Cu seed layer. [6][7][8][9] During CMP, both Ru and Cu have challenges in slurry environment.…”