A micro-contact and wear model for chemical–mechanical polishing of silicon wafers

Zhao, Yongwu; Chang, L.

doi:10.1016/s0043-1648(01)00871-7

Cited by 267 publications

(189 citation statements)

References 19 publications

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“…22) Thus, the silicon surface is polished by the two-body abrasion (i.e., sliding motion) of abrasives, which is induced by the strong elastic contact force between the abrasive particles and pad asperities. 23,24) Therefore, CMP with low abrasive concentrations can result in a high COF because of the low number of abrasive particles. In contrast, the abrasive particles are evenly distributed on the pad asperities when the abrasive concentration is relatively high (i.e., 1.5 to 3 wt %) in the CMP process.…”

Section: )mentioning

confidence: 99%

Experimental Investigation of Material Removal Characteristics in Silicon Chemical Mechanical Polishing

Park

Jeong

Lee

et al. 2009

Jpn. J. Appl. Phys.

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The material removal characteristics of a silicon wafer were experimentally investigated with respect to the chemical dissolution and mechanical abrasion of the wafer during silicon chemical mechanical polishing (CMP) using an alkali-based slurry. The silicon surface without native oxide is rapidly dissolved by the slurry containing an amine agent, which effectively leads to the reduced hardness of the loaded silicon wafer due to Si-Si bond breaking during polishing. The abrasive particles in the slurry easily remove the reacted silicon surface, and the removal rate and wafer non-uniformity for abrasive concentrations of 1.5 -3 wt % are better than those for other concentrations because of the low and steady coefficient of friction (COF) owing to the evenness of abrasive particles between the wafer and pad. Also, it was found that a high slurry flow rate of 700 -1000 cm 3 /min improves wafer non-uniformity owing to the reduced temporal variation of temperature, because the slurry acts as a good cooling source during polishing. However, the removal rate remains almost constant upon varying the slurry flow rate because of the effective dissolution characteristic of the slurry with abundant amine as an accelerator, regardless of the reduction of average temperature with increasing slurry flow rate. In the break-in process used to stabilize the material removal, the viscoelastic behaviors of the pad and the ground wafer surface with native oxide and wheel marks cause a temporal change of the friction force during polishing, which is related to the removal rate and wafer non-uniformity. As a result, the stabilization of removal rate and wafer non-uniformity is achieved through a steady-state process with elevated temperature and reduced COF after a total polishing time of 60 min, based on the removal process of the wafer surface and the permanent deformation in the viscoelastic behavior of the pad. #

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Section: )mentioning

confidence: 99%

Experimental Investigation of Material Removal Characteristics in Silicon Chemical Mechanical Polishing

Park

Jeong

Lee

et al. 2009

Jpn. J. Appl. Phys.

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“…Mechanic-based models have been widely utilized to calculate the load transferred by the particles and pad onto the wafer as a function of typical CMP parameters. [6][7][8][9][10][11][12] The influence of applied pressure, pad properties, particle size and concentration, wafer hardness, and their interactions on the MRR is also expressed.13 A wafer-level MRR model was proposed by combining a hierarchical model of the particle-wafer-pad interactions and an adhesive wear model. 14 For z E-mail: xuqinzhi@ime.ac.cn in-depth understanding the slurry flow at the wafer-pad interface, 15,16 fluid hydrodynamics with mass transport model was also developed to depict the importance of the slurry flow to the CMP process.…”

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confidence: 99%

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

Chen

2015

ECS J. Solid State Sci. Technol.

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In this work, a new aluminum gate chemical mechanical planarization (CMP) model for material removal rate (MRR) is proposed in high-k metal gate (HKMG) process. Using the basic principles of steady-state oxidation reaction and mechanical abrasion mechanism, the combinational interaction of chemical and mechanical coupled effects on MRR was systematically described by process parameters, pad properties and concentration of oxidizer, and then balanced to construct an overall polishing rate. Because of the great significance of the slurry pH on MRR in CMP process, the effects of surface forces, including the influences of van der Waals (vdW) and double-layer (DL) forces simultaneously acted between the wafer and the particles were investigated. Meanwhile, the influence of particle sizes, abrasive loadings and zeta potentials of the wafer and particles on MRR was also analyzed. It is found that the attractive vdW forces strengthen the MRR, while the DL forces, calculated to be repulsive, lower the MRR. The magnitude of surface forces increases with a smaller particle size compared with the pad-particle force. When zeta potentials of the wafer and particles are considered as a function of slurry pH, the experimental trends for the MRR with slurry pH, applied pressure and abrasive loading were predicted well by the present model. Therefore, the governing equation of aluminum removal reveals some insights into the HKMG CMP process and can be utilized for optimizing and controlling the polishing rate of aluminum gate structures and performing sensitivity analyses of operating parameters. With the steady shrinkage of the feature size and device geometry of modern integrated circuits (ICs), chemical mechanical planarization (CMP) has become the most important process choice for the surface planarization in the fabrication of advanced multilever ICs in microelectronic industry.1 A variety of materials and structures, including copper damascene metallization, oxides in shallow trench isolation (STI) and inter-level dielectrics (ILD), replacement metal gate for high-k metal gate (HKMG) structures and fin field effect transistor (FinFET) devices are polished with different slurries. [2][3][4] In CMP process, a rotating wafer with different types of design structures is pushed against a rotating polishing pad which is immersed in slurries containing chemicals and abrasive particles. Pattern structures on the wafer surface are first chemically passivated by slurry chemicals and then removed by effects of contact interactions of abrasive particles which are trapped between the pad and the wafer. The contact mechanism of the particles in the slurry provides the opportunity to remove the material from the wafer surface at an acceptable production rate. 5The material removal rate (MRR) which has been studied extensively from both a modeling and experimental standpoint depends sensitively on pattern geometry, process parameters, chemical reactions, pad properties and mechanical abrasion. If the CMP process is not properly controlled...

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“…Tam et al [5] investigated the influences of processing parameters such as rotating speed, abrasive size on the surface roughness of optical devices. Zhao and Chang [6] examined the influence of polishing parameters on material removal rate by the chemical mechanical polishing method where they used silicon as the material to improve surface roughness for their research. Yang and Lee [7], on the other hand, introduced method of lapping to a smaller aspherical lens die by using a spherical tool.…”

Section: Introductionmentioning

confidence: 99%

Pressure variation of developed lapping tool on surface roughness

Hussain

Lee

Aung³

et al. 2018

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Improving the surface roughness is always one of the major concerns in the development of lapping process as high precision machining caters a great demand in manufacturing process. This paper aims to investigate the performance of a newly designed lapping tool in term of surface roughness. Polypropylene is used as the lapping tool head. The lapping tool is tested for different pressure to identify the optimum working pressure for lapping process. The theoretical surface roughness is also calculated using Vickers Hardness. The present study shows that polypropylene is able to produce good quality and smooth surface roughness. The optimum lapping pressure in the present study is found to be 45 MPa. By comparing the theoretical and experimental values, the present study shows that the newly designed lapping tool is capable to produce finer surface roughness.

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A micro-contact and wear model for chemical–mechanical polishing of silicon wafers

Cited by 267 publications

References 19 publications

Experimental Investigation of Material Removal Characteristics in Silicon Chemical Mechanical Polishing

Experimental Investigation of Material Removal Characteristics in Silicon Chemical Mechanical Polishing

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

Pressure variation of developed lapping tool on surface roughness

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