Study On The Alkaline Cleaner In Post-CMP Cleaning Of Copper Interconnection For GLSI

With the development of micro electronics technology and the dimension of Cu wafer trends to be large,the integrated circuit?IC?feature size becomes smaller and has entered the great large integrated circuit?GLSI?era.The post chemical mechanical polishing?CMP?cleaning is an important process in the process of preparing the IC.The ability of post-CMP cleaning is seriously affects the performance of electronic devices.The traditional acid cleaning agent cannot meet the needs of producing of the tiny wire,becouse of it has the weakness of complex composition,single cleaning object,and more cleaning steps.Therefore,the research and development of alkaline cleaner has become the main research direction of the microelectronics industry.In this paper,it was analyzed the adsorption mechanism of impurities,the main cleaning object and also discussed the disadvantages of the main CMP cleaner.At the same time,the different cleaners such as NH₄OH,TMAH and FA/O cleaner which was created by project team were compared in this paper.The study focused on the removal effect of particles which represents the physical adsorption of impurities and BTA as the representative of the chemical adsorption of impurities.The surface and interface corrosion of the multi-layer Cu wiring wires and the optimization of the surface roughness of the wafer surface were also studied in this paper.At the same time,the influences of the pH value and temperature value of the cleaning effect were also studied.The study was showed that the removal effect of FA/O cleaner in post-CMP was behave better than the mainstream NH₄OH and TMAH alkaline cleaner.The main components of the FA/O cleaner are FA/O?chelating agent and FA/O non-ionic surfactant.Comparing with other alkaline cleaners,FA/O?chelating agent has more than thirteen high stability of chelate rings,which can form stable chelats with dozens of different metal ions.Because it has the same C-N key with organic matter,according to the principle,which has the same structure can dissove each other.It can effectively dissolve the residual organic pollutants such as BTA.With the increase of FA/O?chelating agent concentration,the cleaning ability is becoming more stronger.But,if the chelating agent concentration was too high in the cleaner,it would cause to corrosing of wiring surface and the defects would increases.FA/O surfactant is a kind of macromolecular non-ionic surface active agent.The surface tension is little,decontamination ability is strong and easy to adsorb on the copper surface to protecting the copper from etching.With the increase of surfactant concentration,surface tension decrease and gradually get CMC value,also the decontamination ability is enhancing.However,due to the FA/O surfactant is extremely easy to adsorb on the wafer surface,if the surfactant concentration is too high,it would cause the second organic matter pollution.The experimental results were showed that,when the concentration of FA/O chelating agent in the cleaning solution range from 150ppm to 200ppm,the concentration of FA/O non-ionic surfactant is close to 1500ppm,the pH value is greater than 10 less than 12,and the temperature is during 25³5?,the removal of impurities such as particles,BTA were better,the surface was almost no corrosion and the roughness value was nearer than1.39nm.