铌酸锂晶体的研磨亚表面损伤深度

针对光学材料研磨过程引入的亚表面损伤层(SSD)深度对工件的抛光工序效率和表面质量的影响,探索了光学材料在研磨过程中的亚表面损伤规律。采用角度抛光的方法测量了软脆材料铌酸锂(LN)晶体的损伤层深度,分析了研磨方式、磨粒粒径和研磨压力对工件亚表面损伤层的影响规律。结果表明:研磨方式对损伤缺陷的影响最为显著,相同研磨条件下游离磨料研磨后的损伤层深度约为固结磨料研磨的3~4倍,游离磨料研磨后工件亚表面存在多处圆弧形裂纹,固结磨料研磨后主要显现细小裂纹和"人"字型裂纹;当磨粒粒径从W28下降到W14后,游离研磨的亚表面损伤层深度下降至原来的45%,而固结研磨的损伤层深度下降至30%;另外,研磨压力的降低有利于减小工件的亚表面损伤。该研究对LN晶体研磨方式及研磨工艺的选择具有指导意义。     

蓝宝石晶体双面研磨加工的实验研究

为了实现对蓝宝石晶体的高效低损伤研磨加工,对蓝宝石晶体的双面研磨加工表面粗糙度、研磨均匀性和亚表面损伤层的深度进行试验研究。采用280#碳化硼磨粒双面研磨(0001)面蓝宝石晶体,首先考察了研磨时间对材料去除速率、表面粗糙度的作用规律,根据蓝宝石晶体切割表面状态确定了双面研磨的加工余量,接着,通过WYKO粗糙度仪从微观上分析了蓝宝石晶体表面的研磨均匀性,最后应用纳米压入测试分析了亚表面损伤层的深度。实验结果表明：蓝宝石晶体经过120分钟的双面研磨加工后可以获得Ra0.523μm,Rt<6.0μm的表面,亚表面损伤层小于1μm。     

游离磨料和固结磨料研磨后亚表面裂纹层深度研究

不同研磨方式加工K9玻璃产生不同的亚表面裂纹层深度,亚表面裂纹层深度的测量对确定材料下一步的加工去除量和提高加工效率具有重要意义。利用磁流变抛光斑点法测量游离磨料和固结磨料两种方式研磨后的亚表面裂纹层深度,每种研磨方式选用粒径分别为W40和W14的两种磨料。结果表明:磨粒粒径为W40和W14的游离磨料研磨后K9玻璃的亚表面裂纹层深度分别为20.1μm和3.646μm,而对应固结磨料研磨后的深度分别为3.37μm和0.837μm。固结磨料研磨在加工过程中能有效减小K9玻璃的亚表面裂纹层深度,提高加工效率和工件表面质量,改善器件的性能。     

蓝宝石基片的单面研磨工艺研究

为了实现蓝宝石基片的快速平坦化,对蓝宝石基片进行系统的单因素单面研磨试验,研究了磨料种类、磨料粒径、研磨盘转速、研磨压力以及磨料质量分数等研磨工艺参数对蓝宝石基片材料去除率和表面粗糙度的影响规律。试验结果表明:金刚石磨料适合蓝宝石基片的单面研磨;随着磨料粒径的增大,材料去除率逐渐增大,表面越来越粗糙;随着研磨盘转速的增大,材料去除率先增大后减小,表面粗糙度值在20～60 r/min区间变化不大,稳定在Ra 0. 12～Ra 0. 13μm之间,而在60～100 r/min区间波动较大,当研磨盘转速为60 r/min时,材料去除率最大;随着研磨压力的增大,材料去除率逐渐增大,而表面粗糙度值越来越低;随着磨料质量分数的增大,材料去除率先增大后减小,表面粗糙度先增大然后趋于平缓,当磨料质量分数为3 wt%时,材料去除率最大,且表面粗糙度值相对较小;最后通过正交试验优化了工艺参数,在优化的工艺条件下依次选用粒径为W40、W14、W3的金刚石磨料对蓝宝石基片进行粗研、半精研及精研,取得了表面粗糙度为Ra 7. 9 nm的平坦表面。     

蓝宝石衬底双面研磨亚表面损伤双片式角度抛光法检测

针对传统角度抛光法检测的不足,提出将双片式角度抛光法用于蓝宝石衬底双面研磨亚表面损伤层深度的检测。双片式角度抛光法采用双晶片重合黏结的实验晶片组测量抛光斜面腐蚀裂纹,避免了传统角度抛光法因抛光斜面和原晶片平面分界边缘难以辨别而造成的测量误差;使用数显测长仪对实验晶片组抛光斜面加工轮廓进行测量,测量结果代入相应计算公式得出准确的斜面倾角,消除角度取值不准确带来的方法误差,提高了测量精度。经检测得到,单晶面抛光斜面平均裂纹宽度约为175μm、平均斜面倾角为4.91°,双面研磨单晶面亚表面损伤层深度约为15μm,双晶面亚表面损伤层深度约为30μm。双面研磨工艺参数:研磨液采用320#碳化硼磨粒煤油溶液,研磨初始压力为30g/cm2,研磨终止压力为110g/cm2,研磨盘转速为13r/min。     

蓝宝石衬底双面研磨亚表面损伤分布研究

在前人对硬脆性材料亚表面损伤预测理论研究的基础上,建立了蓝宝石衬底双面研磨亚表面损伤层深度与表面划痕深度之间的理论模型(DNR)。通过对双面研磨后的衬底晶片进行KOH轻度化学腐蚀并结合VK-X100/X200形状测量激光显微系统,得到了晶片表面划痕随深度的分布情况,进而得出了晶片亚表面损伤层随深度的分布情况。研究表明：亚表面损伤层随深度变化的分布规律为随着深度的增大呈递减趋势,集中分布在距离外层碎裂及划痕破坏层下方0～12.9μm深度范围内,所占比例达96.7%左右。研究结果有利于优化双面研磨工艺参数来控制亚表面损伤层的深度。     

粘结Fe＋SiC磁性磨料的研究

研究了粘结Fe SiC磁性磨料的成分、粒度以及研磨时间对几种钢件研磨表面粗糙度的影响,并通过扫描电镜分析研磨表面形貌,探讨了研磨机理。试验结果表明：该磁性磨料具有良好的研磨效果,而磨磨机理是SiC粒子对钢件表面的低应力磨料磨削。     

SiO_2/CeO_2复合磨粒的制备及在蓝宝石晶片抛光中的应用

采用均相沉淀法制备了SiO2/CeO2复合磨料,并利用X射线衍射仪(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FT-IR)等对样品的相组成和形貌进行了表征。将所制备的SiO2/CeO2复合磨料用于蓝宝石晶片的化学机械抛光,利用原子力显微镜检测抛光后的蓝宝石晶片表面粗糙度。结果表明:所制备的SiO2/CeO2复合磨粒呈球形,粒径在40-50nm;在相同条件下,经过复合磨料抛光后的蓝宝石晶片表面粗糙度为0.32nm,材料去除速率为16.4nm/min,而SiO2抛光后的蓝宝石晶片表面粗糙度为0.92nm,材料去除速率为20.1nm/min。实验显示,复合磨料的材料去除速率略低于单一SiO2磨料,但它获得了较好的表面质量,基本满足蓝宝石作发光二极管(LED)衬底的工艺要求。     

光学硬脆材料固结磨料研磨中的亚表面损伤预测

研磨过程中亚表面损伤层深度的正确预测是研磨工艺参数制定的重要依据。针对固结磨料的研磨特点,选择两种典型光学硬脆材料(镁铝尖晶石和石英玻璃),采用离散元仿真技术,分别建立了两种材料的二维离散元模型,分析了工艺参数对光学硬脆材料亚表面损伤(裂纹)层深度的影响。而后,采用角度抛光法测量了镁铝尖晶石和石英玻璃的亚表面损伤层深度,进行了实验验证。结果表明:采用固结磨料研磨时,磨粒粒径对光学硬脆材料亚表面损伤的影响相当显著,在相同研磨工艺条件下,随着磨粒粒径的增大,亚表面损伤层深度和微裂纹密集程度明显增加。离散元仿真结果与实验结果的对比表明:采用离散元技术可以对光学硬脆材料的亚表面损伤深度进行快速有效的预测,从而为后续的研磨抛光工艺提供参考与指导。     

蓝宝石衬底研磨加工中研磨盘材质的影响

采用W14、W3.5的B4C磨粒对蓝宝石衬底进行粗研磨和精密研磨的试验研究.对比分析铸铁、合成铜和合成锡盘粗研磨蓝宝石衬底的表面粗糙度和研磨表面均匀性,试验结果表明,铸铁研磨盘获得的蓝宝石衬底宏观表面均匀性和平面度均优于合成铜盘和合成锡盘,经铸铁研磨盘加工后的蓝宝石衬底面型峰谷值误差小于5 μm、中心线平均表面粗糙度Ra<0.82 μm.精密研磨试验结果表明,采用合成铜盘和W3.5B4C磨粒有效地改善了蓝宝石衬底表面的均匀性,获得了Ra<20 nm、面型峰谷值误差小于1.6 μm的均匀表面,为蓝宝石的超精密研磨奠定了良好的基础.     

磨粒粒径对蓝宝石研磨均匀性影响的试验研究

通过蓝宝石衬底的单面研磨试验研究,分析了W14和W3.5的B₄C磨粒研磨后蓝宝石表面的微观形貌和宏观形貌,W14的B₄C磨粒加工后蓝宝石表面微观裂纹密集且交错分布,体现了以滚轧和挤压为主的材料脆性去除作用,相同条件下,W3.5的B₄C磨粒加工的蓝宝石表面划痕均匀,表面无微观裂纹,实现了以切削为主的材料延性去除形式。测试分析结果表明：磨粒粒径的选择对蓝宝石的研磨表面状态具有重要影响,其选择准则除考虑要达到的粗糙度等级之外,还必须同时考虑与研磨盘的嵌入作用及其对加工表面状态的影响;W3.5的B₄C磨粒研磨加工后的蓝宝石表面宏观和微观均匀性良好,表面粗糙度、平面度等符合抛光前道工序的要求。     

Self-dressing effect using a fixed abrasive platen for single-sided lapping of sapphire substrate

Single-sided lapping is crucial in sapphire wafering processes for improving flatness and achieving the target wafer thickness using loose abrasives. In single-sided lapping process, the Material removal rate (MRR) is a key factor for reducing process time and cost. However, the MRR is limited when using loose abrasives because abrasives mostly act by rolling and sliding. Many researchers have studied fixed abrasives to increase the MRR, but the MRR decreases with time. To solve this problem, the self-dressing effect was studied with various pressures, velocities, cutting fluids and wafers. The MRR decreased due to the wear of abrasives, and the pressure and velocity have little effect on the self-dressing. Lapping experiments were done using cutting fluid with a lapped wafer and sawed wafer. The MRR, plate roughness and thickness were measured to study the wear of the abrasive and the self-dressing effect. The cutting fluid delayed the wear of the abrasives and thus improved the decrease in MRR, but it had little effect on the self-dressing effect, like in the case when water was used. When using cutting fluid and a sawed wafer, the MRR was high and did not decrease. A concentrated load on the plate caused by shape error and saw marks on the sawed wafer could produce the self-dressing effect. We verified that a sawed wafer could produce the self-dressing effect on even a worn plate.     

单晶蓝宝石的延性研磨加工

为实现单晶蓝宝石的延性研磨加工,采用纳米压痕和划痕法测试并分析了单晶蓝宝石(0001)面的微纳力学特性,建立了单颗圆锥状磨粒的压入模型并计算了延性研磨加工的受力临界条件,分析了金刚石磨粒嵌入合成锡研磨盘表面的效果.对单晶蓝宝石进行了延性研磨加工试验,采用NT9800白光干涉仪、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等方法分析了单晶蓝宝石的延性研磨表面特征.试验结果表明:采用纳米压痕和划痕法可以为单晶蓝宝石的延性研磨加工提供工艺参数,单晶蓝宝石的延性堆积的极限深度为100 nm,金刚石磨粒的嵌入及在适当载荷下可以实现蓝宝石的延性研磨加工,实验条件下的最佳载荷为21 kPa,延性研磨后单晶蓝宝石表面划痕深度的分布情况较好,分散性小,研磨后的表面发生了位错滑移变形.     

研磨压力对固结聚集体磨料垫自修正影响

固结磨料研磨过程中磨料的微破碎是实现固结磨料垫自修正特性的主要途径,研磨压力是影响磨粒微破碎的关键参数。选用单晶金刚石和聚集体金刚石作为磨粒制备固结磨料垫,在15 kPa压力下以石英玻璃为加工对象进行研磨实验,比较两者的材料去除率及加工稳定性;制备了4种陶瓷结合剂含量的聚集体金刚石,并制备成固结聚集体金刚石磨料垫,探索了不同压力下的固结聚集体金刚石磨料垫的自修正性能;分析了研磨后的工件表面粗糙度和表面微观形貌。结果表明:采用固结聚集体金刚石磨料垫,研磨后工件表面粗糙度低,去除效率稳定;在15~21 kPa的压力下,结合剂含量次高的聚集体金刚石研磨效率高,材料去除率达到8.94~12.43μm/min,加工性能较稳定,研磨后的工件表面粗糙度R a在60 nm左右;在3.5~7 kPa压力下,结合剂含量次低的聚集体金刚石研磨性能较稳定,材料去除率在2.67~3.12μm/min,研磨后的表面粗糙度R a在40 nm左右。高结合剂含量的聚集体金刚石磨粒更适合高研磨压力条件,而低结合剂的聚集体金刚石磨粒更适合于低研磨压力。     

A study of material removal amount of sapphire wafer in application of chemical mechanical polishing with different polishing pads

The study mainly explores the fabrication mechanism for fabricating sapphire wafer substrate, by using chemical mechanical polishing (CMP) method. A slurry containing the abrasive particles of SiO₂ is used to contact with the sapphire substrate polish and to produce chemical reaction for removal of sapphire wafer substrate when CMP method is used. The study observes the changes of the removal amount of sapphire wafer substrate when the pattern-free polishing pad and hole-pattern polishing pad are used under different down forces, polishing velocities, abrasive particle sizes and slurry concentrations. Employing regression analysis theory, the study makes improvement of the equation of material removal rate (MRR) to be the material removal height per 30 minutes (MRRh), and develops a compensation parameter C_rv of the error caused by the volume concentration of slurry. The results of experimental analysis show that under a certain down force, if the polishing velocity is greater, the material removal amount will be greater. Generally speaking, the material removal amount of hole-pattern polishing pad is greater than that of pattern-free polishing pad. As to the relationship between abrasive particle size and slurry concentration, when particle size is smaller, the volume concentration of slurry will be higher, and the number of abrasives for polishing wafer will be greater. As a result, a better material removal depth can be acquired. Through the above analytical results, considerable help is offered to the polishing of sapphire wafer.     

Basic observations in the flat lapping of aluminum and steels using standard abrasives

This research studies the characteristics of aluminum 2024, 304 stainless steel, and 1018 steel during lapping with three different types of abrasives, namely, garnet, silicon carbide, and white aluminum oxide, through detailed experimental analysis. Specifically, the effects of different abrasives on material removal rate and surface finish were evaluated. It was found that silicon carbide and white aluminum oxide abrasives removed more material per minute than garnet. A higher mean frictional force and mean coefficient of friction were obtained in aluminum lapped with SiC and white Al₂O₃ abrasives, and a lower mean frictional force was obtained in 304 stainless steel lapped with SiC. From geometric and energy-dispersive spectroscopy analysis obtained using scanning electron microscopy, it was confirmed that some abrasives became embedded into the lapped metal substrates. No burn was observed on the lapped samples, and scratches and unfinished lapped parts were observed mainly in 304 stainless steel. In order to determine the quantitative influence of each variable, an analysis of variance was performed. It was found that the main effects of abrasive types, size of abrasives, and type of work material had statistically significant influence on material rate and surface finish. In addition, there was a highly significant two-way interaction between abrasives and workpiece.     

氮化硅陶瓷球精加工表面缺陷的研究

将3种不同直径的氮化硅球坯采用循环加工方法研磨成G5级轴承用陶瓷球。研究了研磨过程中陶瓷球的磨损行为并将磨损缺陷按光学显微镜下的形貌分成5类。采用扫描电子显微镜观察分析各种缺陷并用陶瓷材料断裂力学解释凹坑与裂纹缺陷的形成。研究结果表明，异常的磨粒作为尖锐压头产生凹坑。各种裂纹主要是由起钝压头作用的上研磨盘产生的。材料的晶体结构变化产生雪花缺陷，雪花缺陷抵抗磨粒磨损的能力较差。精研过程中不正确的加工压力和没有破碎的硬磨粒产生擦伤和划痕缺陷。提高球坯圆度，降低粗研加工的载荷和速度可以减少裂纹缺陷。提高磨粒质量可以减少精研中各种机械加工缺陷。