Study On BTA Removal Of Post CMP Cleaning Of Noval Barriers For GLSI

The birth of the dual-damascene process brought integrated circuits into the age of copper interconnection,Co and Ru have become the new barrier materials for copper interconnection system under 14nm technical node due to their better physical and chemical properties.CMP processing can achieve global planarization of copper interconnect and barrier layer with the wide use of BTA in slurry for GLSI barrier CMP,taking the advantage of excellent corrosion resistance of BTA to copper.But the adsorption of BTA on the surface of copper lines is very stable,and there is still a certain amount of BTA residues on the surface of the wafer after CMP,so that BTA became one of the main removal objects for post CMP cleaning.In the acid cleaning environment,Ru is easily vaporized to the toxic RuO₄ which will pollute the ultra clean environment,and the galvanic corrosion of copper and cobalt is extremely serious,so the research and development of the novel alkaline cleaning agent for BTA removal in the application of new barrier layer has become the focus of the current IC manufacturing field.In this paper,the mechanism of BTA film formation and adsorption is introduced.Three methods of BTA residue detection are developed,including contact angle detection,electrochemical detection and infrared spectroscopy detection.The standard characteristic infrared spectrum of Cu?II?-BTA was determined,the location and distribution of the standard characteristic infrared absorption peak of Cu?II?-BTA has been calibrated by experiment,which made infrared detection as a qualitative or semi-quantitative characterization of BTA residues after cleaning possible.The effects of alkali and pH changes on the removal of BTA,the effect of surfactant and concentration changes on the removal of BTA and particles were studied in this paper.The effect rules and action mechanism of organic amine base and inorganic base,anionic surfactant and non-ionic surfactant in the post-cleaning process were analyzed,and the composition scheme of novel alkaline cleaner was determined.Then through the actual cleaning effect after CMP and the detection of copper-cobalt galvanic corrosion,the novel alkaline cleaning solution with a pH of 10.35?consisting of a mass fraction of 200 ppm FA/O II chelating agent,500 ppm LABSA,a trace amount of cesium hydroxide as a pH regulator?has been shown to effectively remove BTA and particles,strong inhibition of copper and cobalt galvanic corrosion,suitable for post CMP cleaning of novel barrier layers.