Study On The Correr Polution Removal In Post-CMP Cleaning Of Copper Interconection For GLSI

With the feature size shrinking constantly,the harm of impurity contamination to the performance of devices is increasing more and more seriously in GLSI(great scale integrated circuit).Therefore,the cleaning technology becomes the important factor to influence the coefficient of device.With Cu replaced Al to be the most effective metal interconnect layer material,chemical mechanical polishing(CMP)technology has been becoming the most effective means to achieve chip global planarization.But after CMP,there are a lot of abrasive,metal,organic pollution residues,especially the copper pollutant,which would have a great influence on performance and stability of device.Therefore,the removal of copper pollution is very important during post CMP cleaning progress.This paper analyzes the advantages and disadvantages of current post CMP cleaning technology and craftwork.In the light of he disadvantages of complex craftwork,efficiency and equipment corrosion in copper contamination removal,a novel alkaline cleaning solution is put forward to remove copper pollution.Chelating agent can remove CuO by its excellent chelating ability to Cu ions.By introducing surfactant,utilize its characteristic of preferential adsorption forming a layer of protective film on the copper surface,thus protecting copper surface from corrosion.The compound cleaning solution has effective efficiency in removing Cu pollution without corroding copper surface.In the research,the abilities of copper oxide film and Cu-BTA film removal on copper surface by FA/O II type chelating agent were studied through the single factor experiment firstly.The results show that the higher the concentration of chelating agent is,the more CuO and Cu-BTA can be removed.And the copper pollution can be removed completely when the concentration reaches 150ppm-200 ppm.But the single chelating agent will corrode the copper surface,causing new defects.Then,in the premise of fixed concentration of chelating agent,the effect of surfactant on the copper surface protection was studied by electrochemical experiments.The results show that the concentration of surfactant is higher,the protection ability is stronger.And when the concentration reaches a certain large,protective film tends to be saturated.At Last,the compound cleaning solution with corresponding concentration of chelating agent and surfactant is found has a good removal effect on CuO and Cu-BTA without surface corrosion.Then select several ratios with good cleaning effect to clean 12 inch CMP after cleaning multilayer copper wiring surface and analysis the surface defects after cleaning by SEM.The results show that the compound cleaning solution with 150 ppm chelating agent and 400 ppm surfactant can effectively remove copper pollution and have effect on colloidal silica and organic residues,which can make the total number of surface defects basically meet the requirement of industry.