Effect of organic amine alkali and inorganic alkali on benzotriazole removal during post Cu-CMP cleaning

Benzotriazole(BTA), an anticorrosion agent of slurry, is the main organic pollutant remaining after CMP of multilayer copper wiring, and also the main removal object of post CMP cleaning. The adsorption of BTA onto the copper could form a dense Cu-BTA film, which makes the copper surface strongly passivated. According to this characteristic, quantitative analysis of BTA residue after cleaning is carried out by contact angle measurement and electrochemical measurement in this paper. A scanning electron microscope(SEM) with EDX was used to observe and analyze the BTA shape and elements. The efficiencies of organic alkali and inorganic alkali on the removal of BTA were studied. The corresponding reaction mechanism was also analyzed. The results show that the adsorption structure of Cu(I)-BTA cannot be destroyed in an alkaline environment with a pH less than 10; the effect of BTA removal by inorganic alkali is worse than that of the organic amine alkali with the coordination structure under the same pH environment; the FA/O Ⅱ chelating agent with the fraction of 200 ppm can effectively remove BTA residue on the surface of copper wafer.

Optimization of cleaning process parameters to remove abrasive particles in post-Cu CMP cleaning

The cleaning of copper interconnect chemical mechanical polishing(CMP) is a key process in integrated circuits(ICs) fabrication. Colloidal silica, which is used as the abrasive material in copper CMP slurry, is considered as the main particle contamination. Abrasive particle residuals can cause device failure which need to be removed efficiently. In this paper, a type of CMP cleaner was used for particle removal using a cleaning solution consisting of FA/O Ⅱ chelating agent and FA/O Ⅰ surfactant. By varying the parameters of brush rotation speed, brush gap,and de-ionized water(DIW) flow rate,a series of experiments were performed to determine the best cleaning results. Atomic force microscope(AFM) measurement was used to characterise the surface morphology of the copper surface and the removal of abrasive particles. A scanning electron microscope(SEM) with EDX was used to observe and analyze the particles shape and elements. The optima parameters of CMP cleaner were obtained. Under those conditions, the abrasive silica particles were removed effectively.