Research About Metal Interconnection Process Based On Self-aligned Graphic Technology

With the rapid development of integrated circuits semiconductor manufacturing technology,the critical dimension(CD)of device is shrinking and the integration of chips is increasing.The closer the CD is to the 14 nm,the more restricted it is by the development of lithography.The self-aligned graphics technology has become an important feasible solution for achieving 14 nm process.The paper researched on the metal interconnection process based on self-aligned pattern technology.Firstly,based on the SADP technology,the self-aligned quadruple pattern(SAQP)technology is implemented utilizing the pure pitch division method to meet the miniaturization of the device.Two kinds of SAQP flow designs are implemented,one is the mandrel-sidewall-sidewall process with oxides and titanium nitride as core materials which have good step coverage and selective etching ratio,and the other is mandrel-sidewall-mandrel-sidewall process which uses different material and different thicknesses of the same material as etch stop layer.The SAQP technology can reduce the lithographic pattern' s pitch to a quarter,combined with the immersion 193 nm lithography technology,and get a significant improvement compared with the SADP technology.The two SAQP process simulations are realized and optimized through the TCAD simulation tool to lay the foundation for the 14 nm process.The small size metal interconnection,which obtained utilizing the self-aligned double pattern technology,has the problem of low breakdown voltage and poor reliability.The tantalum barrier film is deposited through reverse sputtering physical vapor deposition technique,and utilizing the reflow process to get uniformity.The silicon nitride is used as the main material to deposit the capping layer through chemical vapor deposition.Finally,the resistance and breakdown voltage of the tantalum barriers with different thickness are compared and analyzed.And the adhesion of silicon nitride is analyzed by providing different flow rates of ammonia during the ammonia treatment stage,changing the pre-deposition time and increasing the transition stage in the pre-deposition stage.The experimental results show that because of the hard Ta material's effect,interconnection resistance and line-to-line breakdown voltage increase as the thickness of the tantalum decreases,and an excessively thin barrier layer results in bad performance of barrier ability and wafer uniformity.The increase of ammonia flow rate,the decrease of pre-deposition time and t the addition of the transition stage can improve the adhesion of silicon nitride and the performance of the barrier layer.And the research improves the performance of metal interconnection barrier based on SADP technology.