DEVELOPMENT OF ONE-STOP MACHINING SYSTEM AND CORE TECHNOLOGIES FOR LARGE-DIAMETER Si WAFER BEING POTENTIALLY USED FROM YEAR 2003

本研究项目开发了一套φ 300 mm硅片的集成制造系统，采用固定磨料替代传统的游离磨料，提供了一套完整的解决方案，使表面粗糙度Ra <1 nm（Ry < 5 μ 6 nm），整体平坦度< 0.2μm/φ 300 mm。除了节省空间外，与目前用于φ 200 mm硅片的工艺相比，该集成系统还显著降低了70%的总能耗。四大核心技术：本研究发展了复合式制程机械、超磁致伸缩材料驱动的定位/对准装置及环保的冷却剂循环系统。得到的结果总结如下：磨削系统有两个自由度。工作主轴沿着X方向移动，而砂轮主轴沿着Z方向移动。空气静压轴承应用于主轴和其他导轨，因此在主轴和导轨之间没有接触。 ...更多信息 对立的部分。通过分离丝杠螺母，Z轴工作台在本质上是浮动的，并且通过低摩擦气动缸移动。该功能可产生低至20 gf/cm ^2的恒定磨削力/压力，并为最终抛光提供类似抛光的条件。为实现延性磨削，提高整体平面度，研制了工作主轴定位找正机构。在工作主轴和X轴工作台之间安装有两套600 x600 mm的板。底板用于找正，顶板用于定位。该设备由GMM驱动器提供动力，在750 kgf的有效载荷下能够提供6.25 μ m的步进响应，同时在± 1.5度的范围内以10^s的分辨率将工作主轴对准砂轮<-2>。大多数硅磨削系统采用切入方法保持接触面积不变，从而在整个磨削过程中提供稳定的磨削性能。结果，在晶片中心形成的切割路径比边缘处的切割路径密集得多。通过运动学分析，提出了提高加工表面粗糙度的速比组合准则、减小加工轮廓误差的砂轮对中方法、获得均匀切削轨迹密度的最佳砂轮几何形状，从而彻底消除亚表面损伤。该项目组正在进一步开发一种称为“CMG ;化学机械研磨”的新工艺，其中，化学活性添加剂被应用于机械研磨工艺。除了表面粗糙度的提高，在晶片亚表面的位错由CMG工艺完成显着减少到1/30相比，传统的精密磨削。少

This research project has developed an integrated manufacturing system for φ300mm silicon wafer, using fixed abrasive instead of conventional free slurry, to provide a totally integrated solution for achieving the surface roughness R_a < 1nm(R_y < 5〜6nm) and the global flatness < 0.2μm/φ300mm. In addition to the space saving, this integrated system also significantly reduces the total energy consumption by 70%, compared with the current process used for φ200mm Si wafer. Four core technologies : the hybrid process mechanics, the GMM (giant magnetostrictive material) actuated positioning/alignment device and the ecologically friendly coolant circulation system have been developed in this research. The results obtained are summarized as follows ;The grinding system has two degrees of freedom. The work spindle moves along X-direction, while the wheel spindle moves along Z-direction. Aerostatic bearings are applied to the spindles and other guideways so that no contact is made between the c … More ounterparts. By disengaging the lead screw nut, the Z-axis table is floating in nature, and movable by a low friction pneumatic cylinder. This function creates a constant grinding force/pressure as low as 20gf/cm^2, and offers a polishing-like condition for the final finish. In order to achieve ductile mode grinding and improve the global flatness, a positioning and alignment mechanism is particularly developed for the work spindle. There are two sets of plates (600x600mm) installed between the work spindle and the X-axis table. The bottom plate is used for alignment, while the top plate for positioning. Powered by GMM actuators, the device is able to offer 6.25 Å step response at the payload of 750kgf, while to align the work spindle against the grinding wheel at the resolution of 10^<-2> seconds over the range of ± 1.5 degrees.Most of the silicon grinding system utilizes the plunge method to keep the contact area unchanged and thereby to deliver a stable grinding performance throughout the grinding process. As a result, the cutting path formed in the wafer center is much denser than that at the fringe. A kinematical analysis has been done in this research and the results lead to 1) the criteria for speed ratio combination to improve the surface roughness, 2) a proper alignment between the wheel and wafer to effectively reduce the profile error, 3) an optimal wheel geometry to attain a consistent cutting path density.In order to completely remove the subsurface damage, the project team is further developing a new process called as "CMG ; chemo-mechanical grinding", in which, the chemically active additives is applied to the mechanical grinding process. In addition to the surface roughness enhancement, the dislocation at the wafer subsurface finished by CMG process is significantly reduced to 1/30 as compared to the conventional precision grinding. Less