Cobalt (Co) has been identified as the promising candidate material due to the technology node goes down to 7nm and below. In this paper, the effect of diethylenetriamine pentaacetate pentapotassium (DTPA) on chemical mechanical polishing (CMP) of cobalt (Co) in H2O2 based slurry at pH 9 was studied. The roles of DTPA on the Co material removal process are discussed and a removal mechanism is proposed. The studied result shown that the removal rate (RR) was significantly improved by added DTPA, due to the Co and DTPA reaction Co-DTPA complex. The test results of electrochemical, UV-Vis and XPS also shows the DTPA has obvious chelation for Co.
When the technology node goes down to 7nm and below, cobalt (Co) has been identified as the promising candidate for the inter-connect/contact material. In this paper, we investigated the effect of amine based chelating agent and H 2 O 2 on cobalt contact chemical mechanical polishing (CMP) in colloidal silica based slurry at pH 8. It revealed that the combination of H 2 O 2 and FA/O II can significantly improve the cobalt removal rate (RR) by an order of magnitude. The electrochemical measurements, X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) spectroscopy experiments were applied to explore the removal machanism of Co film. The high removal rate of Co may be due to the formation of the water-soluble Co(III)-FA/O II complex. And relatively low dissolution (≤1 nm/min) and good surface quality was achieved by adding a novel corrosion inhibitor.
Co/TaN has been considered as one of the most promising candidates for barrier layers with the feature size of integrated circuit (IC) shrinking to 14 nm and below. The present work investigates the effect of chelating agent and non-ionic surfactant on Co/Cu/TaN CMP in weakly alkaline slurry without any oxidizer. The results show that TaN removal rate increases to the peak value 526 Å/min as the chelator concentration is 1ml/L. That is due to the formation of the water-soluble complex on the surface of TaN. What's more, the TaN removal rate reaches to 501 Å/min and the root mean square roughness (Sq) of TaN is 0.654 nm when non-ionic surfactant concentration is 10 ml/L under the system of 1 ml/L of the chelator. Meanwhile, by the cross-over experiment, it is when slurry is composed of 5 wt% abrasive content, 1 ml/L chelator and 10 ml/L non-ionic surfactant at pH 10 that removal selectivity of Co:Cu and TaN:Cu are comparatively higher and closer (Co:Cu∼2.74:1, TaN:Cu∼2.61:1) along with a good surface quality is obtained.
Palladium/nickel-foam (Pd/Ni) electrode is used as a typical efficient electrocatalytic electrode for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) in surface water and industrial wastewater. Many researches had reported how to enhance the dechlorination efficiency of the Pd/Ni electrode by using less Pd loading. However, there are few reports of choosing a suitable electrolyte solution to improve the efficiency of dechlorination. Efforts were made in this work of the different catholyte influenced the dechlorination efficiency. The results showed the fastest removal efficiency of 2,4-D in 34 mmol/L NaHCO3 than in 34 mmol/L NaCl, 34 mmol/L NaClO4, 17 mmol/L Na2SO4 catholyte, respectively on Pd/Ni electrode with pd loading of 0.202 mg/cm2 at constant potential of -0.55 V (vs saturated calomel electrode). The dechlorination current efficiency (CE) was 20.5% in the 34 mmol/L NaHCO3 catholyte more than three times that in 17 mmol/L Na2SO4 catholyte for that HCO3- was the most likely source of protons for adsorbed active hydrogen (H*) in Pd active centers.
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