In Situ Electrochemical Behavior of Aluminum Chemical Mechanical Polishing at Low Down Pressure in Environmentally Friendly and Weakly Alkaline Slurry

Abstract

The lower pressure tendency in chemical mechanical polishing (CMP) process requires a lower adhesive inhibitor with environmentally friendly corrosion properties to replace the conventional benzotriazole (BTA) inhibitor for aluminum (Al) CMP. Open circuit potential test, potentiodynamic polarization curve test, linear sweep voltammetry and potential drop investigated by in-situ electrochemical mechanical polishing (ECMP) platform were used to reveal the controlled evolution process of corrosion inhibitor films at low pressure during Al CMP. The comparison between BTA and 1,2,4-triazole (TAZ) shows that TAZ has lower current density, wider potential inhibition interval, and high planarization efficiency, although TAZ has lower adhesion on Al surface. Finally, the surface roughness of Al after CMP with TAZ in weakly alkaline slurry at pressure of 1 psi was observed by atomic force microscopy (AFM) with a value of 0.19 nm. This studies demonstrated that the conventional BTA can be replaced by environmentally friendly corrosion inhibitor TAZ, which is a promising alternative candidate to the Al CMP at low down pressure.

Structure-Performance Relationships of Complexing Agents on the Chemical Mechanical Polishing of 6063 Aluminum Alloy

“…Therefore, the mild alkaline polishing slurry is desirable for the CMP of Al alloy. [17][18][19] According to the obtained experimental results, the pH of the polishing slurry was determined at 10.…”

“…16 In order to solve the problems of equipment corrosion and environmental pollution of acidic polishing fluid, it is desirable to conduct CMP in alkaline polishing slurry. 17,18 Previous studies indicated high material removal rate (MRR) and good surface quality can be obtained in alkaline polishing slurry. [19][20][21] In the CMP of aluminum alloy, oxidant and complexing agents are critical additives, which have significant impact on material removal and surface quality.…”

“…However, the formation of passivation layer at high H 2 O 2 concentration can hinder further chemical etching and mechanical abrasion and thus decrease the polishing rate. 17,18,[22][23][24][25][26] Complexing agents commonly facilitate material removal by binding metal cations and facilitating the dispersion of formed nanoparticles during the CMP process. Amino and carboxyl groups are the representative functional groups of complexing agents, which can chelate various metal ions in CMP fluid, thus accelerating the corrosion process and achieving higher MRR.…”

Effect of Different pH in HKMG on the Selection Ratio of Al and Poly Removal Rates

“…The HKMG process is divided into two camps: the Gate first process represented by IBM and the Gate last process represented by Intel in the semiconductor industry. 5,6 HKMG Gate last process is the mainstream process route of HKMG process; 7 The manufacturing technology of metal gate structure is the key technology of HKMG back gate process; 8 The chemical-mechanical polishing (CMP) technology of metal gate is a breakthrough in the upgrading of HKMG process technology, 9,10 and mainly refers to the CMP technology of Al gate in the back-gate process, and the CMP technology of Al gate will become an important breakthrough in the future patent layout and technology upgrading in this field. 11,12 Compared with polysilicon gates, [13][14][15] Al gates have good conductivity, provide a stronger gate electric field, and effectively reduce gate capacitance.…”

Synergetic Effect of 1,2,4-triazole and Glycine on Chemical Mechanical Planarization of Aluminum at Low Polishing Pressure in an Eco-Friendly Slurry

“…2 As the feature size shrinks down to 28 nm and below, aluminum (Al) is commonly used in front-end-of-line (FEOL) structures as a feasible gate material. 5,6 Damage-free and atomically smooth surface of Al is required in the "gate-last" integration scheme for HKMG transistors. In addition, in the fabrication process of FinFET devices, the RMG gate material includes tungsten (W), aluminum (Al), nickel (Ni), cobalt (Co), and titanium (Ti).…”