scholarly journals A Decreasing Mechanism of the Removal Rate in Wafer Polishing Process

2006 ◽  
Vol 72 (4) ◽  
pp. 517-522
Author(s):  
Tetsuo OOKAWA ◽  
Masami MASUDA ◽  
Hirotaka SASAKI ◽  
Takashi NISHIGUCHI
Keyword(s):  
Removal Rate ◽  
Polishing Process ◽  
Wafer Polishing

Study on Effect of Composite Particles in Polishing Process and Its Mechanism

2007 ◽  
Vol 24-25 ◽  
pp. 155-159 ◽  
Author(s):  
Xue Feng Xu ◽  
B.X. Ma ◽  
Feng Chen ◽  
Wei Peng
Keyword(s):  
Removal Rate ◽  
High Surface ◽  
Composite Particles ◽  
Particle Interactions ◽  
Polymer Particles ◽  
Layer Model ◽  
Polishing Process ◽  
High Surface Quality ◽  
Wafer Polishing ◽  
Double Layer Model

In this paper, mixed slurries containing silica abrasives and polystyrene (PS) polymer particles in deionized water at pH 10.5 have been evaluated for silicon wafer polishing. By applying the theory of electric double layer model, the effect of the particle interactions in mixed slurry is investigated. Zeta potential measurements and TEM images have been used to show the formation of composite particles. The polishing mechanism with composite particles slurries is discussed. Polishing experiments with the mixed slurries formed by coating smaller (~30nm) abrasives onto softer and larger (~2000nm) polymer particles have shown the superior characteristic with higher removal rate and high surface quality.

scholarly journals Effect of Conditioner Type and Downforce, and Pad Surface Micro-Texture on SiO2 Chemical Mechanical Planarization Performance

Micromachines ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 258 ◽  
Author(s):  
Jeffrey McAllister ◽  
Calliandra Stuffle ◽  
Yasa Sampurno ◽  
Dale Hetherington ◽  
Jon Sierra Suarez ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Polishing Process ◽  
Wafer Polishing ◽  
The Coefficient Of Friction

Based on a previous work where we investigated the effect of conditioner type and downforce on the evolution of pad surface micro-texture during break-in, we have chosen certain break-in conditions to carry out subsequent blanket SiO2 wafer polishing studies. Two different conditioner discs were used in conjunction with up to two different conditioning downforces. For each disc-downforce combination, mini-marathons were run using SiO2 wafers. Prior to polishing, each pad was broken-in for 30 min with one of the conditioner-downforce combinations. The goal of this study was to polish wafers after this break-in to see how the polishing process behaved immediately after break-in. One of the discs used in this study produced similar micro-texture results at both downforces, which echoed the results seen in the mini-marathon. When comparing the different polishing results obtained from breaking-in the pad with the different discs used in this study, the coefficient of friction (COF) and SiO2 removal rate (RR) were uncorrelated in all cases. However, the use of different discs resulted in different COF and RR trends. The uncorrelated COF and RR, as well as the differing trends, were explained by pad micro-texture results (i.e. the differing amount of fractured, poorly supported pad asperity summits).

Mechanochemical Polishing of Single Crystal Diamond with Mixture of Oxidizing Agents

2006 ◽  
Vol 315-316 ◽  
pp. 852-855 ◽  
Author(s):  
Cheng Yong Wang ◽  
C. Chen ◽  
Yue Xian Song
Keyword(s):  
Surface Roughness ◽  
Single Crystal ◽  
Smooth Surface ◽  
Removal Rate ◽  
Polishing Process ◽  
Iron Plate ◽  
Oxidizing Agents ◽  
Single Crystal Diamond ◽  
Lower Temperature ◽  
And Control

In order to achieve the smooth surface of diamond, several kinds of mixture oxidizing agents have been used to polish the single crystal diamond by a designed polishing apparatus. The existing of graphite and amorphous carbon has been found in the surface of diamond after polishing. The mechanochemical actions of oxidizing agents and the polishing iron plate have been proved. The mixture of oxidizing agents can decrease the polishing temperature so that the super-smooth surface of single crystal diamond can be achieved at lower temperature. The method provided is benefit not only to simplify polishing device and control the polishing process, but also to improve the removal rate and surface roughness.

Achieving Highly Stable Removal Rate in Small Tool Polishing of Glass Lenses

2020 ◽  
Author(s):  
Urara Satake ◽  
Toshiyuki Enomoto ◽  
Teppei Miyagawa ◽  
Takuya Ohsumi
Keyword(s):  
Removal Rate ◽  
Industrial Applications ◽  
Polishing Process ◽  
The Stability ◽  
Sudden Decrease ◽  
Polishing Pads ◽  
Glass Lenses ◽  
Polishing Pressure ◽  
Small Tool

Abstract The demand for improving the image quality of cameras has increased significantly, especially in industrial applications, such as broadcasting, on-vehicle, security, factory automation, and medicine. Surface of glass lenses, which is a key component of cameras, is formed and finished by polishing using small tools. However, the existing small tool polishing technologies exhibit serious problems including an unstable removal rate with the accumulated polishing time. In concrete, low removal rate at the beginning of the polishing process and sudden decrease in the removal rate during the polishing process significantly deteriorate stability of the removal rate. To improve the stability of the removal rate, we proposed a vibration-assisted polishing method using newly developed polishing pads with titanium dioxide particles in the previous work. Polishing experiments on glass lenses confirmed that the variation in the removal rate was suppressed by the developed polishing method; however, the reason for the improvement, in concrete, the relation between the vibration of polishing pressure and the stability of the removal rate remains unknown. In this study, we investigated and clarified the effect of the vibration of polishing pressure on the surface conditions of polishing pads, which strongly affected removal rate.

Effects of the Profile of Workpiece Surface on Material Removal Rate Distribution in Polishing Process

2016 ◽  
Vol 851 ◽  
pp. 149-154
Author(s):  
Zhen Gang Wu ◽  
Dong Shan He ◽  
Ping Zhou ◽  
Dong Ming Guo
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Surface Profile ◽  
Prediction Method ◽  
Quantitative Prediction ◽  
Polishing Process ◽  
Workpiece Surface ◽  
Coefficient Distribution ◽  
Polishing Pad

Accurate prediction of the material removal rate (MRR) distribution is very important for the control of the polishing process. However, the widely used prediction method of MRR based on the Preston equation is still incapable of predicting the roll-off phenomenon in polishing process. One of the reasons is that many of the researchers’ neglected the effect of the surface profile of the workpiece on the MRR. In this paper, the evolutionary process of MRR distribution with the change of surface profile using two different polishing pad is studied, it is found that MRR varies gradually with the change of surface profile and tends to be uniform finally. Based on the analysis of contact pressure considering the actual surface profile of workpiece and modified Preston equation, the distribution of MRR is analyzed. It is found that the Preston coefficient distribution on workpiece surface is stable when the surface profile variation is small and shows obvious differences from the center to the edge of the workpiece. Through the comparison it is found that correlation between the regularities of Preston coefficient distribution and the type of polishing pad is significant. The research results in this paper will play an important guiding role in the quantitative prediction method research of polishing process.

Fundamental Studies on the Mechanisms of Oxide CMP

2000 ◽  
Vol 613 ◽  
Author(s):  
Uday Mahajan ◽  
Seung-Mahn Lee ◽  
Rajiv K. Singh
Keyword(s):  
Surface Roughness ◽  
Particle Size ◽  
Wear Rate ◽  
Removal Rate ◽  
Polished Surface ◽  
Electrostatic Repulsion ◽  
Polishing Process ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Slurry Stability

ABSTRACTIn this paper, results of studies on the addition of salt to a polishing slurry, in terms of its effect on slurry stability, SiO2 polishing rate and surface roughness of the polished surface are presented. Three salts, viz. LiCl, NaCl and KCl were selected, and three concentrations were tested. Polishing rate measurements using these slurries show that adding salt leads to increased removal rate without affecting surface roughness significantly. Based on these results, we can say that the agglomerates formed by adding salt to the slurry are fairly soft and easily broken during the polishing process. In addition, turbidity and particle size measurements show that significant coagulation of the particles in the slurry occurs only at the highest salt concentration, and is fastest for LiCl and NaCl, with KCl showing the slowest coagulation. From these results, it can be concluded that the enhancement in polish rate is due to increased contact at the wafer-pad-slurry interface, and not due to formation of larger agglomerated particles in the slurry. This is because of reduced electrostatic repulsion between these three surfaces, due to the screening of their negative surface charge by the metal ions in solution, resulting in a higher wear rate.

Experimental Investigation on Wafer Polishing of Oxide and Copper Layers

2002 ◽  
Author(s):  
Jhy-Cherng Tsai
Keyword(s):  
Process Parameters ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Removal Rate ◽  
Back Pressure ◽  
Copper Layer ◽  
Wafer Polishing ◽  
Critical Technology ◽  
And Performance ◽  
Polishing Pressure

Polishing, in particular chemical-mechanical polishing (CMP), is a critical technology for the planarization of wafers. This paper investigates, via experiments, and compares the performance of CMP process with different process parameters for wafers with silicon-dioxide (SiO2) layer and for wafers with copper (Cu) layer. Polishing pressure (P), speed (V), and back pressure (BP) are used as process parameters in this study. Different pads and slurries are also experimented for copper layer as its properties are different from that of conventional oxide layer. Material removal rate (RR) and non-uniformity (NU) are used as indices to measure the performance. Experimental data on oxide layers show RR increases as P and V increase but NU gets worse at the same time. This condition can be improved, for both oxide and copper layers, with suitable BP. Experiments on copper CMP using slurry with abrasives show that RR increases with higher P and V. While NU gets worse with higher P, it can be reduced as V increases using a soft pad. Better NU can be obtained using soft pad though RR is lower in this case. For abrasive-free polishing of copper layer, RR, though relatively lower compared to CMP with regular slurry, is unstable using hard pad despite that NU becomes better at higher P. NU of polished wafer is best at certain pressure but becomes worse at low pressure for hard pad and at high P for soft pad. It is also observed that NU of AFP can be improved with BP and softer pad. Soft pad gives better polishing quality and performance though RR is lower than that using slurry with abrasives.

Investigation on Smoothing Silicon Carbide Wafer With a Combined Method of Mechanical Lapping and Photocatalysis Assisted Chemical Mechanical Polishing

2018 ◽  
Author(s):  
Zewei Yuan ◽  
Kai Cheng ◽  
Yan He ◽  
Meng Zhang
Keyword(s):  
Silicon Carbide ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Removal Rate ◽  
Mechanical Polishing ◽  
Combined Method ◽  
Polishing Process ◽  
High Quality ◽  
Quality Surface ◽  
High Quality Surface

The high quality surface can exhibit the irreplaceable application of single crystal silicon carbide in the fields of optoelectronic devices, integrated circuits and semiconductor. However, high hardness and remarkable chemical inertness lead to great difficulty to the smoothing process of silicon carbide. Therefore, the research presented in this paper attempts to smooth silicon carbide wafer with photocatalysis assisted chemical mechanical polishing (PCMP) by using of the powerful oxidability of UV photo-excited hydroxyl radical on surface of nano-TiO2 particles. Mechanical lapping was using for rough polishing, and a material removal model was proposed for mechanical lapping to optimize the polishing process. Several photocatalysis assisted chemical mechanical polishing slurries were compared to achieve fine surface. The theoretical analysis and experimental results indicate that the material removal rate of lapping process decreases in index form with the decreasing of abrasive size, which corresponds with the model developed. After processed with mechanical lapping for 1.5 hours and subsequent photocatalysis assisted chemical mechanical polishing for 2 hours, the silicon carbide wafer obtains a high quality surface with the surface roughness at Ra 0.528 nm The material removal rate is 0.96 μm/h in fine polishing process, which is significantly influenced by factors such as ultraviolet irradiation, electron capture agent (H2O2) and acidic environment. This combined method can effectively reduce the surface roughness and improve the polishing efficiency on silicon carbide and other hard-inert materials.

A New Permanganate-Free Slurry for GaN-SiC CMP Applications

2020 ◽  
Vol 1004 ◽  
pp. 199-205
Author(s):  
Treliant Fang ◽  
Ping Chung Chen ◽  
Ming Hsun Lee
Keyword(s):  
Removal Rate ◽  
Waste Water Treatment ◽  
High Hardness ◽  
Wide Band ◽  
Sodium Chlorite ◽  
Toxic Heavy Metal ◽  
Wafer Polishing ◽  
Single Crystal Sic ◽  
Buffer Control ◽  
Ph Buffer

Single crystal SiC wafers are known to be extremely difficult to polish by conventional CMP slurries because of their high hardness and chemical resistance. Previously only those manganese-containing CMP slurries are capable of producing measurable and useful polishing rates with this versatile wide band-gap substrate. A new permanganate-free SiC polishing slurry containing a generic formula of MXO2 etchant, where M is an alkali metal, X is a halogen, O is oxygen is disclosed. When mixed with an abrasive powder in an aqueous slurry form, the tribochemical reactant that activates under pressure, etches SiC effectively, rendering an enhanced Material Removal Rate (MRR) when processing CMP SiC wafers. The MRR can sometimes go up to a few order of magnitudes, as compared to the abrasive slurry without these chemical etchants. The series of MXO2 compounds that can activate SiC polishing belong to the chemical family of halites. Sodium chlorite, NaClO2, the simplest and most available member of the halites family, is a good example. The accelerated polishing rates offer increased throughput of the slow SiC CMP process. The new slurry is particularly useful for non-oxide wafer polishing, which includes SiC, GaN and AlN wafers. An outstanding character of the new halite-based polishing formulation that is different from the current permanganate-based slurries is that the waste stream produced from the CMP process can be easily treated in the waste water treatment facilities because they do not contain toxic heavy metal ions such as manganese and permanganate in the polishing formulations. Continuous exhaustive CMP polishing test with 32 4” 4H-N SiC wafers using a production CMP tool containing 32L of the alumina-chlorite slurry has demonstrated an MRR of 1.7um/hr (Si-face) when the slurry is fresh, and a final MRR of 1.0um/hr after 16 hours polishing at 800mL/min slurry flow rate with pH buffer control without fresh oxidant addition. The resulting 32 polished 4H-SiC test wafers show overall excellent smooth surface roughness with the best Ra of 0.05nm by AFM after fine CMP polishing.

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