A Feature-Scale Greenwood–Williamson Model for Metal Chemical Mechanical Planarization

2015

Self Cite

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...

mentioning

confidence: 99%

mentioning

confidence: 99%

A Material Removal Rate Model for Aluminum Gate Chemical Mechanical Planarization

2015

Self Cite

“…3 Therefore, CMP attracts numerous experimental, theoretical and numerical investigations on revealing the removal mechanism of different materials, improving the non-uniformity of wafer surface, and optimizing design layouts. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] These investigations demonstrate that understanding the removal mechanism, design pattern effects and thickness variation control is quite helpful for CMP process simulation and optimization of design for manufacturability (DFM).…”

mentioning

confidence: 85%

“…[1][2][3] In order to obtain a planar surface, various kinds of CMP models have been proposed in literature to address the removal mechanism [6][7][8][10][11][12]15 of different materials and achieve accurate surface topography simulation. 1,2,9,13,14,[16][17][18][19][22][23][24] The surface kinetic CMP models connect the total polish rates with kinetic processes and describe the wafer-scale variations of surface profiles. 1,2,6,11,[25][26][27] For the sake of elucidating the mechanical aspects of polishing systems, contact mechanics or fluid dynamics based CMP models have been developed to understand the fundamental phenomena at different length scales.…”

mentioning

confidence: 99%

An Oxide Chemical Mechanical Planarization Model for HKMG Structures

Yang

et al. 2018

Self Cite

In order to predict the surface topography, a chip-scale oxide chemical mechanical planarization (CMP) model is proposed in poly opening polishing processing of high-k metal gate (HKMG) structures. A geometrical chemical vapor deposition model is first constructed to describe the influence of design pattern effects on the initial surface profiles of dielectric oxides. Based on contact mechanics, the global pressure distribution is then computed to incorporate the long-range features of design structures and polishing pad deformation. The global pressure is further combined with local pattern effects to construct a feature-scale material removal rate model, which can be utilized for surface topography simulation of design chips. The predicted results of the proposed CMP model are consistent with the experimental data collected from the test patterns of HKMG CMP process. Consequently, the oxide CMP model has good potentials of predicting the surface planarity of polishing wafers and optimizing some design rules for HKMG design layouts.

“…[33][34][35][36] These waferscale CMP models can be used to capture the surface kinetic effects and relate the MRR to the contact behavior at different polishing conditions. 14,18,[37][38][39][40][41][42] In order to capture the slurry flow behavior in the CMP process, the interaction between the removal rate and the hydrodynamic pressure can also be studied by fluid hydrodynamicsbased models. [43][44][45] Furthermore, mixed lubrication models are developed to analyze CMP process characteristics by using contact mechanics and fluid hydrodynamics.…”

mentioning

confidence: 99%

A Wafer-Scale Material Removal Rate Model for Chemical Mechanical Planarization

Liu

et al. 2020

Self Cite

In this work, a new wafer-scale material removal rate (MRR) model is proposed to investigate the underlying removal mechanism of wafer surface in the chemical mechanical planarization (CMP) process. Based on the governing equation of the plate theory, chemical reaction kinetics and wear theory, an analytical CMP model has been constructed to capture the influence of mechanical abrasion and chemical reactions on the removal rate with high efficiency. The effect of the elastic modulus of the pad, platen rotational speed, polishing temperature and reactant concentrations on the removal mechanism is investigated in detail to elucidate the intrinsic removal behavior. It is found that the material removal rate is sensitive to the elastic modulus of pad, temperature distribution, and chelator concentration, more sensitive to the oxidizer concentration, and most sensitive to the platen rotational speed. The magnitude of the removal rate can be adjusted significantly by properly selecting a good configuration of these influencing factors. The model predictions of the MRR profiles are consistent with the published experimental data at different polishing conditions. Therefore, the present CMP model can give insights into the wear mechanism of polishing process and may be utilized as a simulation tool for further optimization of removal rate and surface uniform control.