A Model for Effect of Colloidal Forces on Chemical Mechanical Polishing

Mazaheri, Alireza; Ahmadi, Goodarz

doi:10.1149/1.1554730

Cited by 37 publications

(33 citation statements)

References 18 publications

(9 reference statements)

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“…Unless otherwise indicated, the specific values of the following parameters are set to be V = 0.5m/s, E p = 3M Pa, υ = 0.2, k 1 = 4.87×10 −6 m/s, M = 27g/mol and ρ 0 = 2.7g/cm 3 for convenience in the following simulation and verification. 12,26,27,65,69,70 In CMP process, it is really very difficult to accurately measure the specific model parameters. For simplicity and convenience, these parameters in the present model are mainly selected from some published literatures.…”

Section: Resultsmentioning

confidence: 99%

“…For simplicity and convenience, these parameters in the present model are mainly selected from some published literatures. 12,26,27,65,69,70 These values are generally adopted in CMP simulation or experimentally used for recipe configuration except for parameter k 1 . The chemical reaction rate parameter k 1 is fitted from the experimental values of the following subsections.…”

Section: Resultsmentioning

confidence: 99%

“…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%

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confidence: 99%

“…48 Furthermore, the DL forces were further considered in an extension of this model to understand the effect of slurry pH and DL forces at abrasive-wafer contact including their adhesion and repulsion. 12 As for HKMG structures, none of aluminum CMP (Al-CMP) models have been proposed to incorporate the surface forces in the process of constructing the MRR model. As we know, for integrating the metal gate as well as the high-k gate oxide, HKMG technology is widely adopted by most of IDM and foundries due to its associated lower thermal budget, more stable threshold voltage, and improved performance from strain induced dummy gate removal.…”

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confidence: 99%

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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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