The experiment of PCD cutter and YG6X cutter milling SiCp/Al matrix composites was conducted, and the effect of tool material and machining parameters on cutting force and surface roughness was investigated, and the milling process of PCD tool was simulated with finite element software. The results showed that the axial thrust force was larger than the other two while precision milling 45% volume SiCp/Al matrix composites by YG6X tool, which resulting from great compressive strength of the material. The cutting force of PCD tool was much smaller than that of the YG6X, and the surface roughness of PCD tool was also smaller. Considering the cutting force and machining surface quality, YG6X should be used for rough machining, and PCD should be used for precision machining. The results of finite element simulation of PCD tools were in good agreement with experimental results, which can provide basis for production.
Low dielectric constant materials/Cu interconnects integration technology provides the direction as well as the challenges in the fabrication of integrated circuits(IC) wafers during copper electrochemical-mechanical polishing(ECMP). These challenges arise primarily from the mechanical fragility of such dielectrics, in which the undesirable scratches are prone to produce. To mitigate this problem, a new model is proposed to predict the initiation of scratching based on the mechanical properties of passive layer and copper substrate. In order to deduce the ratio of the passive layer yield strength to the substrate yield strength and the layer thickness, the limit analysis solution of surface scratch under Berkovich indenter is used to analyze the nano-scratch experimental measurements. The modulus of the passive layer can be calculated by the nano-indentation test combined with the FEM simulation. It is found that the film modulus is about 30% of the substrate modulus. Various regimes of scratching are delineated by FEM modeling and the results are verified by experimental data.
Electrochemical mechanical polishing(ECMP)is a new and highly promising technology.A specific challenge for integrating Ru as barrier in Cu interconnect structures is the galvanic corrosion of Cu that occurs during ECMP.To mitigate the problem,the benzotriazole(BTA)and ascorbic acid(AA)were chosen as selective anodic and cathodic inhibitors for Cu and Ru,respectively.The optimization of electrolytes at different pHs including BTA,hydroxyethylidenediphosphoric acid(HEDP),and AA were investigated using electrochemical methods.The Ru/Cu removal rate and the planarization efficiency during Ru/Cu ECMP can be approximated using electrochemical measurements of the removal rate,with and without surface abrasion.Chemical systems that exhibit a 1:1 selectivity between the barrier layer and copper would be ideal for the barrier removal step of ECMP.Optimized slurry consists of 20.0 wt%HEDP,0.5 wt%BTA,and 0.3 wt%AA at pH 2.2.Using the optimized slurry,the selectivity of Ru to Cu is near 1.Electrochemical measurements of open circuit potentials,potentiodynamic polarization,and impedance spectroscopy were performed to investigate the galvanic corrosion between ruthenium and copper.
为确定苯并三唑(BTA)在铜的电解抛光液中的腐蚀抑制作用,研究铜在30%(质量分数)H3PO4+0.01 mol/L BTA抛光液中的电化学行为,测试铜在该抛光液中的极化曲线以及静态腐蚀量.应用原子力显微镜和能谱分析,观测不同阳极电势下静态腐蚀后的铜表面形貌并分析CuBTA膜的形成过程.结果表明,一定阳极电势范围下铜先行溶解,表面粗糙度加大,之后铜离子吸附BTA分子在表面逐渐形成CuBTA覆盖层,铜的溶解速度受到抑制,表面粗糙度稳定于一较低值.为保证CuBTA膜的形成,铜片所加的静态阳极电势应在0.5 V以下,本实验条件下形成稳定的CuBTA膜需要2 min.
