金刚石丸片与固结磨料抛光垫研磨硅片的比较研究

采用金刚石丸片和固结磨料抛光垫两种方式研磨加工硅片,以硅片的材料去除率(MRR)和表面粗糙度(Sa)为指标对金刚石丸片和固结磨料抛光垫的研磨性能进行了评价.结果表明:固结磨料抛光垫研磨硅片的材料去除率高于金刚石丸片;研磨后硅片的表面粗糙度也优于金刚石丸片,且表面粗糙度(Sa)在中部和边缘相差不大.最后分析了研磨硅片的产物-磨屑的形状特征,得出固结磨料抛光垫研磨硅片时的塑性去除量远高于金刚石丸片.     

固结磨料抛光LiB3O5晶体的抛光液优化

LiB3O5(LBO)非线性光学晶体软、脆的特点增加了超精密加工的难度.采用固结磨料抛光技术对LBO晶体(110)面进行抛光,研究酸性、中性和碱性抛光液pH值调节剂及pH值对晶体抛光材料去除率、表面形貌和表面粗糙度的影响.结果表明:酸性抛光液对LBO晶体表面的腐蚀作用太大,中性抛光液的腐蚀作用太小,不适合抛光LBO晶体;乙二胺配制pH值为11的无磨料碱性抛光液固结磨料抛光LBO晶体(110)面,获得高的晶体表面质量,表面粗糙度Sa为1.94 nm,表面损伤小.     

不同粒径磨料对蓝宝石晶片及其抛光过程的影响

采用不同粒径的W28和W7碳化硼(B_4C)磨料对蓝宝石晶片进行研磨和化学机械抛光。研究了不同粒径的B_4C磨料对蓝宝石晶片研磨和化学机械抛光后的移除率、粗糙度、平坦度、弯曲度、翘曲度等参数的影响。结果表明:W28和W7的磨料有不同的研磨和抛光性能,在相同的加工条件下,使用W28的B_4C磨料,移除速率较快,但研磨所得蓝宝石晶片的损伤层较深,单面抛光20μm不足以去除其损伤层,抛光后表面划痕较多,粗糙度较大(R_a=1.319 nm,R_t=2.584 nm),表面有明显起伏;而W7磨料的移除速率慢,研磨时间长,在单面抛光移除20μm后其损伤层全部移除,抛光所得蓝宝石晶片平坦度略佳,抛光表面平整,粗糙度较小(R_a=0.194 nm,R_t=0.361 nm),无明显起伏,表面质量相对较高,适于精修平坦度。     

不同粒径磨料对蓝宝石晶片及其抛光过程的影响EI北大核心CSCD

采用不同粒径的W28和W7碳化硼（B4C）磨料对蓝宝石晶片进行研磨和化学机械抛光。研究了不同粒径的B4C磨料对蓝宝石晶片研磨和化学机械抛光后的移除率、粗糙度、平坦度、弯曲度、翘曲度等参数的影响。结果表明：W28和W7的磨料有不同的研磨和抛光性能,在相同的加工条件下,使用W28的B4C磨料,移除速率较快,但研磨所得蓝宝石晶片的损伤层较深,单面抛光20μm不足以去除其损伤层,抛光后表面划痕较多,粗糙度较大（Ra=1.319 nm,Rt=2.584 nm）,表面有明显起伏;而W7磨料的移除速率慢,研磨时间长,在单面抛光移除20μm后其损伤层全部移除,抛光所得蓝宝石晶片平坦度略佳,抛光表面平整,粗糙度较小（Ra=0.194 nm,Rt=0.361 nm）,无明显起伏,表面质量相对较高,适于精修平坦度。     

固结磨料研磨镁铝尖晶石的平均切深和亚表面损伤行为EI北大核心CSCD

根据接触力学原理建立了固结磨料研磨的平均切深模型,估算了不同粒径磨料作用下平均切深。依据磨粒平均切深值,采用离散元法对镁铝尖晶石固结磨料研抛的过程进行了模拟,并以此预测了固结磨料研磨条件下工件的亚表面损伤深度。采用角度抛光方法对亚表面损伤层深度的预测值进行了验证。结果表明:W5FAP研磨下工件亚表面损伤层深度的预测值为1.32μm、实测值为1.37μm;W14FAP研磨下的预测值为3.93 m,实测值为4.56μm;W50FAP研磨下的预测值为9.07μm,实测值为9.12μm;离散法的亚表面损伤层的预测结果与实测结果基本一致,验证了该方法的可靠性。     

固结磨料研磨镁铝尖晶石的平均切深和亚表面损伤行为

根据接触力学原理建立了固结磨料研磨的平均切深模型,估算了不同粒径磨料作用下平均切深。依据磨粒平均切深值,采用离散元法对镁铝尖晶石固结磨料研抛的过程进行了模拟,并以此预测了固结磨料研磨条件下工件的亚表面损伤深度。采用角度抛光方法对亚表面损伤层深度的预测值进行了验证。结果表明:W5FAP研磨下工件亚表面损伤层深度的预测值为1.32μm、实测值为1.37μm;W14FAP研磨下的预测值为3.93 m,实测值为4.56μm;W50FAP研磨下的预测值为9.07μm,实测值为9.12μm;离散法的亚表面损伤层的预测结果与实测结果基本一致,验证了该方法的可靠性。     

Nd:Y3Al5O12透明陶瓷的超精密加工

用化学机械抛光法加工掺钕钇铝石榴石(Nd:Y3Al5O12,Nd:YAG)透明陶瓷.为了提高加工效率,在研磨阶段逐步减小B4C磨料的粒径,精密研磨和抛光阶段采用粒度为3,1 μm和0.3 μm氧化铝粉;最后,选用胶体二氧化硅作为抛光液进行化学机械抛光,以获得更好的表面光洁度.采用Wkyo激光干涉仪测量加工样品的平面度,光学显微镜观察表面宏观损伤,原子力显微镜测量表面粗糙度和微观形貌.结果表明:采用该工艺可实现高效率、高精度Nd:YAG透明陶瓷的超精密加工,加工后的Nd:YAG陶瓷表面粗糙度<0.2 nm RMS(root mean square),平面度<λ/10 (λ=633 nm),微观损伤少.     

两种加工方式磨抛SiC陶瓷的对比实验研究

文章以SiC工程陶瓷为研究对象，通过游离磨料和固结磨料两种抛光方式的实验，分析了磨料粒度、抛光盘、抛光工具以及抛光工艺参数对工程陶瓷的表面粗糙度及表面形貌的影响，并对比了游离磨料和固结磨料的抛光效果，实验发现，一种新型的固结磨料磨抛盘在加工效率和加工质量上具有优越性。     

介孔氧化硅微球的合成及其在化学机械抛光中的应用

利用阳离子表面活性剂(十六烷基三甲基溴化铵)胶束与硅源(正硅酸乙酯)的协同组装过程,通过改进的St?ber法制备具有放射状孔道的介孔氧化硅(Mesoporous silica,Sm)微球。结果表明:所得Sm微球粒径在260~480 nm范围,样品的BET比表面积为1 300~1 500 m2/g,其内部孔道孔径集中在2~3 nm。利用原子力显微镜比较了Sm磨料与常规实体氧化硅(Solid silica,Ss)磨料对热氧化硅片的抛光特征。经Sm磨料抛光后,衬底表面粗糙度均方根值RRMS为0.240 nm,表面微观轮廓起伏在±0.70 nm范围内,抛光材料去除率γMRR可达93 nm/min。与Ss磨料相比,Sm磨料有利于降低抛光衬底粗糙度,提高材料去除率,并有效避免出现微划痕等表层机械损伤。     

磨料粒径对铝栅CMP去除速率和粗糙度的影响

在铝栅化学机械平坦化(CMP)中磨料直接影响去除速率和表面粗糙度。采用不同粒径的磨料配置抛光液对铝栅进行CMP实验,对去除速率和表面形貌测试结果进行分析。结果表明,去除速率与参与抛光的磨料颗粒数目和单个颗粒去除速率有关,表面粗糙度与单个磨料颗粒机械作用和抛光后磨料颗粒表面吸附有关,并对抛光液稳定性进行了研究。最终选用粒径70 nm,质量分数为5%的磨料,去除速率可达到181 nm/min,表面粗糙度为9.1 nm,对今后铝栅CMP的研究提供了参考。     

Synthesis and characterization of nanocomposite Fe3O4/SiO2 core–shell abrasives for high-efficiency ultrasound-assisted magneto-rheological polishing of sapphire

A functional Fe₃O₄/SiO₂ core–shell abrasive was synthesized via hydrolysis of tetraethyl orthosilicate. A silica shell was successfully coated on a Fe₃O₄ core, resulting in a core-shell particle with an average diameter of 140 nm. The prepared core–shell abrasives was utilized for ultrasound-assisted magneto-rheological polishing (UAMP) of sapphire substrate. The experimental results showed that the Fe₃O₄/SiO₂ core–shell abrasives exhibited a remarkable polishing performance for the sapphire material, resulting in smooth and detect-free surfaces with a high material removal rate (MRR) compared to mixed abrasives (Fe₃O₄ and SiO₂) and pure Fe₃O₄ particles. The application of ultrasonic vibration to the sapphire wafer further improved the MRR, which was approximately 3.4 times higher than that of traditional magneto-rheological polishing. The largest MRR (1.974 μm/h) and comparatively low surface roughness (0.442 nm) of the polished sapphire wafer were achieved by UAMP with the Fe₃O₄/SiO₂ core–shell abrasives. The polishing mechanism of the sapphire wafer is discussed in terms of chemical reactions and mechanical polishing.     

Chemical-mechanical polishing performance of core-shell structured polystyrene@ceria/nanodiamond ternary abrasives on sapphire wafer

Driven by electrostatic attraction, Ce⁴⁺ ions or/and positively charged detonation nanodiamond (DND) particles can absorb onto negatively charged polystyrene (PS) spherical colloids. Three types of core-shell structured composite abrasives, PS@CeO₂, PS@DND and PS@CeO₂/DND, can thus be assembled. When PS@CeO₂ and PS@DND were used to polish sapphire wafer at pad rotating speed of 120–150 r/min and load pressure of ~3 kg, the material removing rate (MRR) exceeded 1.0 μm h⁻¹, 10–20 % higher than unitary abrasives. The surface profile roughness (Ra) for wafer polished by these two composite abrasives was respectively 1.25 and 0.63 nm, which is superior to CeO₂ (Ra = 1.38 nm) and DND (Ra = 1.29 nm). When using PS@CeO₂/DND, the polishing interface area can be increased owing to the combined effect of elastic PS spheres and intensively coated CeO₂ and DND. Meanwhile, the synergistic mechanism of sapphire-CeO₂ chemical reaction and the strong mechanical abrasion of DND particles benefit the polishing efficiency. MRR for this ternary composite abrasive attained 1.4–1.7 μm h⁻¹ while sapphire can be smoothed to a sub-nanoscale roughness.     

Surface planarization of zirconia ceramic achieved by polyacrylamide grafted nanodiamond composite abrasives through chemical mechanical polishing

Zirconia ceramics are the promising materials for cell phone backplanes in the 5G era, and smoother surfaces and higher removal efficiency are sought after for their precision machining. Although nanodiamond abrasives have high polishing rates, it is easy to bring mechanical scratches and pits on the ceramic surface because of their high hardness, resulting in degradation of the surface quality of the finished workpiece. Therefore, polyacrylamide grafted nanodiamond particles were prepared by solution polymerization method for polishing ceramic wafers. As confirmed by Fourier transform infrared spectroscopy (FTIR), the polyacrylamide has been grafted on the nanodiamond surface. According to the scanning electron microscopy (SEM) and particle size distribution, the composite abrasives have better dispersion than pure nanodiamond abrasives. The results of chemical mechanical polishing (CMP) experiments showed that the composite abrasives could reduce the average surface roughness (Sa, arithmetic mean height) of zirconia ceramic from 28.31 nm to 2.68 nm (scanning area is 500 μm × 500 μm), and the polishing rate remained high compared to pure nanodiamond abrasives, showing superior CMP performance. X-ray photoelectron spectroscopy (XPS) demonstrated that solid-phase chemical reactions occurred during the polishing process to form ZrSiO₄. Meanwhile, contact-wear model combined with contact angle testing indicates that the introduction of polyacrylamide increases the contact area of the nanodiamond on the zirconia wafer surface, thereby significantly enhanced the mechanical effect.     

Polishing behaviors of ceria abrasives on silicon dioxide and silicon nitride CMP

The effects of ceria (CeO₂) abrasives in chemical mechanical polishing (CMP) slurries were investigated on silicon dioxide (SiO₂) and silicon nitride (Si₃N₄) polishing process. The ceria abrasives were prepared by the flux method, using potassium hydroxide (KOH) as the grain growth accelerator. The primary particle size of the ceria abrasives was controlled in the range of ~ 84-417 nm by changing the concentration of potassium hydroxide and the calcination temperature without mechanical milling process. The removal rate of silicon dioxide film strongly depended upon abrasive size up to an optimum abrasive size (295 nm) after CMP process. However, the surface uniformity deteriorated as abrasive size increases. The observed polishing results confirmed that there exists an optimum abrasive size (295 nm) for maximum removal selectivity between oxide and nitride films. In this study, polishing behaviors of the ceria abrasives were discussed in terms of morphological characteristics.     

Mechanistic difference between Si-face and C-face polishing of 4H–SiC substrates in aqueous and non-aqueous slurries

The traditional aqueous-based polishing slurries have been extensively used in the ultra-precision machining process of SiC substrates, but their processing efficiency remains a major challenge in making SiC wafers with high surface quality. SiC polishing slurries based on non-aqueous solvents have been explored and reported, however, the mechanism for the accelerated SiC material removal rate (MRR) remains unknown. In this work, the Si-face and C-face of the SiC wafer were polished with water and methanol as polishing liquid carriers, respectively. The MRR of Si-face using the methanol-based slurry, can reach 260.9 nm/h, and the polished Si-face surface roughness Ra reduces to 0.150 nm. In contrast, the MRR of Si-face by using the aqueous-based slurry, is 66.8 nm/h, the polished Si-face surface roughness Ra is 0.691 nm. However, the results of MRR and Ra for C-face are opposite. The reaction between the polishing liquid carriers and the atomic structures of Si-face and C-face lead to differences of the MRRs by analyzing contact angle, XPS, and molecular dynamics (MD) simulation results. The newly revealed polishing mechanisms shined light for speeding up the development of SiC polishing slurries based on the specific aspects of the polishing surface of SiC.     

Deterministic Microgrinding, Lapping, and Polishing of Glass–Ceramics

We report a series of microgrinding and polishing experiments on glass–ceramics. Microgrinding includes deterministic microgrinding (two-body abrasion at fixed infeed rate) and loose abrasive lapping (three-body abrasion at fixed pressure). We correlate material mechanical properties (Young's modulus, hardness, fracture toughness) and chemical properties (chemical susceptibility or mass loss under chemical attack) with the quality of the resulting surface (surface microroughness and surface grinding-induced residual stresses). We compare deterministic microgrinding (at fixed infeed) and loose abrasive microgrinding (at fixed pressure) in terms of material removal rates and resulting surface quality.     

Molecular dynamics simulation of SiC removal mechanism in a fixed abrasive polishing process

Precision polishing of mono-crystalline SiC wafers on a fixed abrasive pad is investigated by double-nano-abrasives cutting at micro/nano scale in this report. Prior to this report, a single abrasive approach in molecular dynamics simulation had been employed to illustrate the material removal mechanism in SiC polishing process, which is quite different from the real situation of the fixed abrasive polishing process. Cutting depth and spacing of abrasive particles in a fixed abrasive pads were tested to gain insights on phase transformation, subsurface damage, surface quality, material removal and friction characteristics of polished SiC wafers by molecular dynamics simulation. By following the coordination number and radial distribution function, we clearly see that the number of phase transformation atoms caused by cutting and abrasion increases with the cutting depth of nano-abrasives on the surface of SiC workpiece. Simulation results also suggest that the phase transformation of the SiC crystal phase increases with the lateral spacing of abrasive particles in pads, while does not change much with the increase of the longitudinal spacing. It is also found that the deeper the abrasive cutting depth, the deeper subsurface damage, resulting more materials’ removal from SiC workpiece. The lateral and longitudinal abrasive spacings lead to little change the depth of subsurface damage on the wafer in MD simulation for a fixed double abrasive polishing. The surface roughness is better with the larger lateral abrasive spacing, but no clear correlation with the longitudinal abrasive spacing.     

Parameter optimization of ultrasonic vibration polishing K9 optical glass based on ultrasonic atomization

To further improve the surface finish and processing efficiency of optical components, ultrasonic vibration technology is frequently combined with conventional processing and the process parameters that play a critical role in this composite processing are identified. This research proposes an ultrasonic vibration polishing method based on ultrasonic atomization (UA-UVP). The polishing performance of K9 optical glass is increased by ultrasonic atomization (UA) assisted by polishing solvent for ultrasonic vibration polishing (UVP). Orthogonal experiments are used to study the effects and variation laws of the flow rate of ultrasonic atomization (Q), the gap distance between the polishing tool and workpiece (G), ultrasonic electro spindle speed (W), abrasive particle size (D) and ultrasonic amplitude (A) on surface roughness (SR) and material removal rate (MRR), respectively. When these two polishing characteristics are considered together, the optimization of polishing parameters becomes complicated. Therefore, the principal component analysis (PCA) and grey relational analysis (GRA) methods were employed to the optimal experimental combination as Q:18 ml/min, G: 5 μm, W: 4000 r/min, D: 0.5 μm, A: 8 μm. The experimental results showed that Ra and MRR were measured as 10.466 nm and 0.473*10^8 μm³/min, respectively. Compared with the best experimental combination of orthogonal experiments, the improvement rates of SR and MRR were 26.65% and 25.80%, respectively. Overall, the application of ultrasonic vibration technology contributes to enhancing the uniform distribution of polished abrasive particles and improving the polishing characteristics.     

Ultra-precision finishing of low expansion ceramics by compliant abrasive technologies: A comparative study

Advanced ceramics have many attractive features such as high stability and wear resistance that find broad applications in various fields, e.g. optics, aerospace, etc. However, the accompanying difficult-to-machine property with complex geometry brings great challenges to the commonly used laser machining and rigid wheel based grinding in industry. To achieve optical surface quality with surface roughness below 10?nm Ra, three promising ultra-precision compliant machining technologies using adaptive elastic tools are presented in this paper, including bonnet polishing, compliant pitch polishing and shape adaptive grinding with fine grain size. A comparative study was conducted by machining three different low thermal expansion ceramics while continuously increasing attack angle, spindle speed and tool offset across rectangular regions. Material removal rate (MRR) and surface roughness (Ra) with respect to different process conditions are compared. With sufficient data, the processing ability using above three compliant machining technologies is summarized based on the MRR-Ra plots for different ceramics. In addition, microscopic observation and X-ray diffraction analysis are conducted to characterize differences in material behavior.