Measuring Surface Uniformity in Chemical Mechanical Polishing

2009 ◽  
Vol 76-78 ◽  
pp. 459-464
Author(s):  
Jae Won Baik ◽  
Chang Wook Kang
Keyword(s):  
Chemical Mechanical Polishing ◽  
Geometric Mean ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Semiconductor Wafer ◽  
Statistical Process ◽  
Significant Step ◽  
The Difference ◽  
Thickness Variations ◽  
The Stability

Chemical mechanical polishing (CMP) is a technique used in semiconductor fabrication for planarizing the top surface of an in-process semiconductor wafer. Especially, Post-CMP thickness variations are known to have a severe impact on the stability of downstream processes and ultimately on device yield. Hence understanding how to quantify and characterize this non-uniformity is significant step towards statistical process control to achieve higher quality and enhanced productivity. The main reason is that the non-uniformed interface between the wafer and the machine-pad adversely affects the polishing performance and ultimate surface uniformity. The purpose of this paper is to suggest a new measure that estimates the uniformity of wafer surface considering the difference of the amount of abrasion between the center and the edge. This new measure which is called the Coefficient of Uniformity is defined as the following ratio: Geometric Mean (GM) / Arithmetic Mean (AM). This metric can be evaluated regionally to quantify the non-uniformity on the wafer surface from the center to the edge. Further simulations show that this new measure is insensitive to shift of the wafer center and sensitive to shift of the wafer edge. This trend indicates that this new measure is a very useful to test the non-uniformity of wafer after CMP polishing.

Modeling and Analyzing on Nonuniformity of Material Removal in Chemical Mechanical Polishing of Silicon Wafer

2004 ◽  
Vol 471-472 ◽  
pp. 26-31 ◽  
Author(s):  
Jian Xiu Su ◽  
Dong Ming Guo ◽  
Ren Ke Kang ◽  
Zhu Ji Jin ◽  
X.J. Li ◽  
...  
Keyword(s):  
Silicon Wafer ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Removal Mechanism ◽  
Particle Movement ◽  
Material Removal Mechanism ◽  
The Relationship ◽  
Nonuniform Material

Chemical mechanical polishing (CMP) has already become a mainstream technology in global planarization of wafer, but the mechanism of nonuniform material removal has not been revealed. In this paper, the calculation of particle movement tracks on wafer surface was conducted by the motion relationship between the wafer and the polishing pad on a large-sized single head CMP machine. Based on the distribution of particle tracks on wafer surface, the model for the within-wafer-nonuniformity (WIWNU) of material removal was put forward. By the calculation and analysis, the relationship between the motion variables of the CMP machine and the WIWNU of material removal on wafer surface had been derived. This model can be used not only for predicting the WIWNU, but also for providing theoretical guide to the design of CMP equipment, selecting the motion variables of CMP and further understanding the material removal mechanism in wafer CMP.

Analysis on the Contact Pressure Distribution of Chemical Mechanical Polishing by the Bionic Polishing Pad with Phyllotactic Pattern

2011 ◽  
Vol 215 ◽  
pp. 217-222 ◽  
Author(s):  
Y.S. Lv ◽  
Nan Li ◽  
Jun Wang ◽  
Tian Zhang ◽  
Min Duan ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Boundary Edge ◽  
Contact Pressure Distribution ◽  
Element Analysis ◽  
Pressure Distributions ◽  
Polishing Pad

In order to make the contact pressure distribution of polishing wafer surface more uniform during chemical mechanical polishing (CMP), a kind of the bionic polishing pad with sunflower seed pattern has been designed based on phyllotaxis theory, and the contact model and boundary condition of CMP have been established. Using finite element analysis, the contact pressure distributions between the polishing pad and wafer have been obtained when polishing silicon wafer and the effects of the phyllotactic parameter of polishing pad on the contact pressure distribution are found. The results show that the uniformity of the contact pressure distribution can be improved and the singularity of the contact pressure in the boundary edge of polished wafer can be decreased when the reasonable phyllotactic parameters are selected.

Modeling the Motion of Slurry Nanoparticles During Chemical Mechanical Polishing

Tribology ◽  
2005 ◽  
Author(s):  
Elon J. Terrell ◽  
Venkata K. Jasti ◽  
C. Fred Higgs
Keyword(s):  
Mathematical Model ◽  
Particle Motion ◽  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Surface Wear ◽  
Particle Collisions ◽  
Nanoscale Particles ◽  
Interparticle Collisions ◽  
Global Surface

Chemical mechanical polishing (CMP) has emerged as a commonly used method for achieving global surface planarization of micro-/nano-scale systems during fabrication. During CMP, the wafer to be polished is pressed against a rotating polymeric pad that is flooded with slurry. The motion of the wafer surface against the asperities of the pad and the abrasive nanoscale particles in the slurry causes the surface of the wafer to be polished to an atomically smooth level. Past studies have shown that the wear distribution is a function of the distribution of slurry particles in the wafer/pad interface, and thus it is desirable to model the migration of particles in order to predict the wear of the wafer surface. The current study involves the creation and simulation of a mathematical model which predicts the paths of slurry particles in a Lagrangian reference frame. The model predicts the effects of the various forces on each particle to determine its motion. The model also accounts for interparticle collisions and wafer/particle and pad/particle collisions. It is expected that the particle motion that is predicted from this model will allow for a more accurate correlation of the wafer surface wear distribution.

Effect of abrasive material properties on polishing rate selectivity of nitrogen-doped Ge2Sb2Te5to SiO2film in chemical mechanical polishing

2008 ◽  
Vol 23 (12) ◽  
pp. 3323-3329 ◽  
Author(s):  
Jin-Hyung Park ◽  
Hao Cui ◽  
Sok-Ho Yi ◽  
Jea-Gun Park ◽  
Ungyu Paik
Keyword(s):  
Crystal Structure ◽  
Material Properties ◽  
Chemical Mechanical Polishing ◽  
Fumed Silica ◽  
Colloidal Silica ◽  
Mechanical Polishing ◽  
Abrasive Material ◽  
Nitrogen Doped ◽  
The Difference ◽  
Abrasive Hardness

We investigated the polishing rate and selectivity of nitrogen-doped Ge2Sb2Te5(NGST) to SiO2film for different abrasive materials (colloidal silica, fumed silica, and ceria abrasives). They both were strongly dependant on abrasive material properties. The polishing rate of nitrogen-doped NGST decreased in the order ceria, fumed silica, and colloidal silica abrasives, which was determined by abrasive material properties, such as abrasive hardness, crystal structure, and primary and secondary abrasive sizes. In addition, the polishing rate slope of NGST film was not significantly different for different abrasive materials, indicating that the polishing of NGST film is mechanical dominant polishing. In contrast, the polishing rate slope of SiO2film decreased in the order ceria, fumed silica, and colloidal silica abrasives, indicating that the polishing of SiO2film is chemical dominant polishing. Furthermore, the difference in polishing rate slopes between NGST and SiO2film gave a polishing rate selectivity of NGST to SiO2film higher than 100:1 with colloidal silica abrasive.

Evaluation of the Stability on the New Alkaline Copper Bulk Slurry

2015 ◽  
Vol 645-646 ◽  
pp. 352-355
Author(s):  
Juan Wang ◽  
Ru Wang ◽  
Guo Dong Chen
Keyword(s):  
Integrated Circuit ◽  
Chemical Mechanical Polishing ◽  
Chelating Agent ◽  
Cost Effective ◽  
Mechanical Polishing ◽  
Oxidizing Agent ◽  
Low Dielectric ◽  
The Stability ◽  
Copper Polishing ◽  
Integrated Circuit Processing

At present, the chemical mechanical polishing is the only means for global planarization of an integrated circuit. After the node of the integrated circuit processing comes into 45nm, the diameter of wafer is 300mm, and the copper interconnect layer is above the 10 layer. In the same time the new low dielectric constant materials are used to the integrated circuit processing. That requires the property of the slurry used in the chemical mechanical polishing stricter. So the domestic and international companies carry out a series research works. Based on investigation and research for many years, the new alkaline copper rough slurry has been developed by the teachers and students in the Hebei University of Technology. The slurry has advantages as disadvantages. The composition of cost-effective slurry is simple and the effect of chemical mechanical polishing is good. But its stability is poor. In order to improve the stability, the compositions of the slurry need to adjust.The new alkaline copper rough slurry composed by abrasive, surface, chelating agent, oxidizing agent and deionized water. Experiments investigate the influence rule of copper polishing rate by the concentration of abrasive, the content of surface, the content of oxidizing agent and the content of chelating agent. The conclusion is arrived. When the concentration of abrasive is 4%, the content of surfactant is 10ml/l, the content of chelating agent is 10ml/l and the content of oxidizing agent is 5ml/l, the copper polishing rate keep 5000 Å /min.

Analysis of Chemical Action of Oxidants in Chemical Mechanical Polishing of SiC Crystal Substrate

2014 ◽  
Vol 1027 ◽  
pp. 213-216
Author(s):  
Su Fang Fu ◽  
Jian Guo Yao ◽  
Li Jie Ma ◽  
Jian Xiu Su
Keyword(s):  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Removal Rate ◽  
Mechanical Polishing ◽  
Key Factors ◽  
Chemical Action ◽  
Crystal Substrate ◽  
The Stability ◽  
Polishing Efficiency

Chemical mechanical polishing (CMP) had been considered as the most practical and effective method of achieving an ultra-smooth and non-damage surface in manufacturing SiC crystal substrate. CMP slurry was one of the key factors of CMP technology. In this paper, through investigating the changes of several core factors to evaluate the performance of CMP, such as the material removal rate (MRR), surface roughness Ra, 3D surface profiler, etc., the influence of various slurry and its content on the polishing efficiency and surface finish quality had been studied. The research results showed that different oxidant had different chemical action mechanism, also affecting the stability of CMP slurry and surface quality of specimen; adding suitable an oxidant to slurry could effectively improve the CMP performance.

Colloidal Silica based High Selectivity Shallow Trench Isolation (STI) Chemical Mechanical Polishing (CMP) Slurry

2005 ◽  
Vol 867 ◽  
Author(s):  
Kyoung-Ho Bu ◽  
Brij M. Moudgil
Keyword(s):  
Silicon Nitride ◽  
Chemical Mechanical Polishing ◽  
Colloidal Silica ◽  
Sodium Dodecyl ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Shallow Trench Isolation ◽  
Pattern Size ◽  
Trench Isolation ◽  
Silica Slurry

AbstractAmong various properties of chemical mechanical polishing (CMP) slurry, selectivity plays a key role in global planarization of high density and small pattern size shallow trench isolation (STI) process. Lack of adequate selectivity can lead to defects such as dishing and erosion. To improve the selectivity of STI CMP process, CMP characteristics of silica and silicon nitride wafer were investigated using colloidal silica slurry as a function of slurry pH. Sodium dodecyl sulfate (SDS), an anionic surfactant, was added to increase the selectivity of the slurry. As a result, selectivity increased from 3 to 25. It was concluded that selective passivation layer formed on silicon nitride wafer surface at acidic slurry pH range was responsible for the observed selectivity increase. Adsorption characteristics of SDS on silica and silicon nitride were measured as a function of slurry pH and concentration of SDS. As indicated by zeta potential behavior under acidic pH conditions, SDS adsorption on silicon nitride was significantly higher han silica due to the electrostatic forces. Significantly higher SDS coating on silicone nitride seems to have resulted in lubrication layer leading to increased polishing selectivity.

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