Because the polishing of different materials is required in barrier chemical mechanical planarization(CMP) processes,the development of a kind of barrier slurry with improved removal rate selectivity for Cu/barrier/TEOS would reduce erosion and dishing defects on patterned Cu wafers.In this study,we developed a new benzotriazole-free barrier slurry named FA/O barrier slurry,containing 20 mL/L of the chelating agent FA/O,5 mL/L surfactant,and a 1:5 concentration of abrasive particles.By controlling the polishing slurry ingredients,the removal rate of different materials could be controlled.For process integration considerations,the effect of the FA/O barrier slurry on the dielectric layer of the patterned Cu wafer was investigated.After CMP processing by the FA/O barrier slurry,the characteristics of the dielectric material were tested.The results showed that the dielectric characteristics met demands for industrial production.The current leakage was of pA scale.The resistance and capacitance were 2.4 kΩ and 2.3 pF,respectively.The dishing and erosion defects were both below 30 nm in size.CMP-processed wafers using this barrier slurry could meet industrial production demands.
There is a lot of hydroxyl on the surface of nano SiO2 sol used as an abrasive in the chemical mechanical planarization(CMP) process, and the chemical reaction activity of the hydroxyl is very strong due to the nano effect.In addition to providing a mechanical polishing effect, SiO2 sol is also directly involved in the chemical reaction.The stability of SiO2 sol was characterized through particle size distribution, zeta potential, viscosity, surface charge and other parameters in order to ensure that the chemical reaction rate in the CMP process, and the surface state of the copper film after CMP was not affected by the SiO2 sol. Polarization curves and corrosion potential of different concentrations of SiO2 sol showed that trace SiO2 sol can effectively weaken the passivation film thickness. In other words, SiO2 sol accelerated the decomposition rate of passive film. It was confirmed that the SiO2 sol as reactant had been involved in the CMP process of copper film as reactant by the effect of trace SiO2 sol on the removal rate of copper film in the CMP process under different conditions. In the CMP process, a small amount of SiO2 sol can drastically alter the chemical reaction rate of the copper film, therefore, the possibility that Cu/SiO2 as a catalytic system catalytically accelerated the chemical reaction in the CMP process was proposed. According to the van't Hoff isotherm formula and the characteristics of a catalyst which only changes the chemical reaction rate without changing the total reaction standard Gibbs free energy, factors affecting the Cu/SiO2 catalytic reaction were derived from the decomposition rate of Cu(OH)2 and the pH value of the system, and then it was concluded that the CuSiO3 as intermediates of Cu/SiO2 catalytic reaction accelerated the chemical reaction rate in the CMP process.It was confirmed that the Cu/SiO2 catalytic system generated the intermediate of the catalytic reaction(CuSiO3/in the CMP process through the removal rate of copper film, infrared spectrum and AFM diagrams in d
