Performance of Sodium Dodecyl Sulfate in Slurry with Glycine and Hydrogen Peroxide for Copper-Chemical Mechanical Polishing

Abstract

The performance of sodium dodecyl sulfate ͑SDS͒, an anion surfactant, in a slurry with glycine and hydrogen peroxide ͑H 2 O 2 ͒ for copper-chemical mechanical polishing ͑Cu-CMP͒ was studied. The wettability and surface tension of the slurry for copper and the zeta potential of SiO 2 were examined. The influence of SDS on the static corrosion, material removal rate, and the surface roughness was studied. The results showed that SDS improved Cu-CMP performance by changing the physical characteristics of the slurry and protecting the copper surface from corrosion and scratches. A surface with the lowest amount of scratches and corrosion after polishing was obtained when concentration of the SDS surfactant was 0.78 mM/l in the glycine-H 2 O 2 solution. The mechanism of action between the SDS and copper surface was investigated by electrochemical polarization and X-ray photoelectron spectroscopy. Finally, a physical model was developed to describe the interactions between SiO 2 particles, the copper surface, and SDS in the slurry.In order to achieve higher performance of microelectronic devices, the planarization of copper interconnect lines is very important. 1 Chemical mechanical polishing ͑CMP͒ has proven to be a very profitable method in the IC manufacturing industry. [2][3][4] In the CMP process, the polishing slurry is a critical factor in determining the quality of the polished surface. The slurry provides both chemical and mechanical actions to the wafer planarization. Abrasive particles in the slurry play a role in removing the copper mechanically and taking away abraded copper from the surface. 5 Chemical components such as oxidizing agents, 2,6 complexing agents, 3,4,7 corrosion inhibitors, 8-11 surfactants, 12-14 and pH buffering agents are the essential components of ideal slurries. Hydrogen peroxide ͑H 2 O 2 ͒ and glycine are widely used as an oxidizer and complexing agent in the CMP slurry, respectively, 15 and benzotriazole ͑BTA͒ has been used as the most common inhibitor. 10,15,16 During the copper-chemical mechanical polishing ͑Cu-CMP͒, physical properties of the slurry, such as surface tension, dispersion and suspension stability of abrasives, interaction between the particles and the polished surface, and the rheological characteristics, affect the planarization efficiency dramatically. Surfactant is added to the slurry to avoid the agglomeration of particles which would result in scratches and other defects on the surface. 17,18 Selecting a high-performance surfactant is of great importance to the CMP process. 13 There is some literature about particles dispersion and slurry stability. The synergistic effects of a mixed surfactant system were carried out by Shah. 19 A proper concentration of anion surfactant sodium dodecyl benzene sulfonate and nonionic surfactant polyethylene glycol 4000 can make CeO 2 -coated SiO 2 nanoparticle suspension stable, that is, without sedimentation. 20 The effects of several different nonionic surfactants on the performance of copper-CMP were studied by Tsai et al. 2...

Effect of Intermolecular Interaction of Compound Surfactant on Particle Removal in Post-Cu CMP Cleaning

“…2 and Table IV, the minimum JFC-E has good wettability as it has the branched structure and hydrophilic group in the middle of the molecule. 21,22 The wettability of the compound of JFC-E and AES is not as good as that of pure JFC-E. However, the cleaning effect is not completely consistent with the wettability, so it is necessary to test the particle removal effect of the compound surfactant in next step.…”

A review on chemical and mechanical phenomena at the wafer interface during chemical mechanical planarization

“…Tseng et al [86] reported that the silica abrasives in the presence of methyl methacrylate were stabilized by either electrostatic barriers or steric barriers between the particles, resulting in an excellent uniformity of the oxide thickness across the wafer. Pan et al [87] suggested that sodium dodecyl sulfate (SDS), an anionic surfactant, could improve the dispersion stability of silica-based slurries for Cu CMP. Indeed, free SDS surfactants remaining in the slurry were very useful to suppress Cu corrosion and lead to good surface quality.…”

Synergistic Action Mechanism and Effect of Ammonium Dodecyl Sulfate and 1,2,4-triazole in Alkaline Slurry on Step Height Reduction for Cu CMP

“…The slurry designed for Cu CMP is usually composed of an oxidizer to form porous unstable surface oxides, complexing ligands to dissolve surface oxides from the sample surface in the form of water-soluble Cu complexes and dissolution inhibitors to prevent the surface from further corrosion. 4,5 As is well known, inhibitors have been used to protect the concave of Cu surface from chemical dissolution, while the convex regions are selectively flattened by both mechanical polishing and chemical dissolution, so that global planarization and satisfactory Cu surface quality can be realized. 6,7 Surface reactions of these individual chemicals often change significantly in the presence of other co-additives in the slurry.…”

“…6,7 Surface reactions of these individual chemicals often change significantly in the presence of other co-additives in the slurry. 4,8 Thus, the combined performance of the chemical mixture is more important than those of the individual additives, which can not only reduce the use of additives, but also achieve better polishing properties. For Cu film CMP, inhibitors play a very important role to realize local and global planarization.…”

“…They also proposed a result of complementary "space-filling" adsorption mechanism, but acidic media is not friendly to the environment and it is corrosive certainly to the equipment. Liang Jiang et al 10 proposed that by the synergy of BTA and Pluronic ® P103, low Cu RR, satisfactory Cu surface quality and desirable RR selectivity can be realized in KIO 4 -based alkaline slurries. However, in the presence of BTA, fragile Cu interconnection structures can be easily damaged.…”