A Comparative Study on the Roles of Velocity in the Material Removal Rate during Chemical Mechanical Polishing

Tseng, Wei–Tsu; Chin, Jyh‐Hwa; Kang, Lee‐Chieh

doi:10.1149/1.1391872

Cited by 71 publications

(50 citation statements)

References 10 publications

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“…Expressing the removal rate as a linear function of both normal and shear stresses, Wang et al 8 and Tseng et al 9 proposed a modification to the assumption of linearity inherent in Preston's equation. Using the analogy of the removal process to a traveling indenter problem and the principles of elasticity and fluid mechanics, they derived a feature-scale model with and u 1/2 dependence on the removal rate.…”

Section: Introductionmentioning

confidence: 99%

Pad effects on material-removal rate in chemical-mechanical planarization

Bastawros

Chandra

Guo

et al. 2002

Journal of Elec Materi

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INTRODUCTIONAmong the newly developed planarization technologies for ultra-large-scale integration metallization, chemical-mechanical planarization (CMP) has emerged to be most promising because it can provide better local and global planarization of the wafer surface. 3 In recent years, CMP has emerged as an enabling technology for the next generation of chip manufacturing and has become the second fastest growing area of semiconductor-equipment manufacturing. Beside interlayer-dielectric planarization, CMP has also found applications in shallow-trench isolation, damascene technologies, 4,5 and other novel processing techniques, such as polishing of Si 3 N 4 balls for bearing applications. 6 In CMP, however, the manufacturing technique has outdistanced its underlying science. Current CMP practices focus more on empirical developments of polishing "recipes" for each specific application. This makes the CMP process design a trialand-error procedure. Moreover, valuable insights gained in one application cannot be readily used under a modified set of circumstances. Such lack of scalability and migratability of experimental data hinders the CMP process design efforts. The lack of physical understanding also makes the process difficult to control and results in suboptimal process performance. Accordingly, the present work aims at developing a mechanistic model of material removal during a CMP process by addressing the role of the employed porous pad.There exist several material-removal models for the CMP process. The oldest and most commonly used is Preston's model: 7 Ḣ ϭ C и P o и u, where Ḣ is the average thickness removal rate, P o is the applied pressure, u is the relative velocity between the pad and the wafer, and C is Preston's coefficient. Preston's equation is based on the observation in glass polishing and is an empirical model; however, it gives a good estimate of the material-removal rate (MRR) in CMP.Expressing the removal rate as a linear function of both normal and shear stresses, Wang et al. 8 and Tseng et al. 9 proposed a modification to the assumption of linearity inherent in Preston's equation. Using the analogy of the removal process to a traveling indenter problem and the principles of elasticity and fluid mechanics, they derived a feature-scale model with and u 1/2 dependence on the removal rate. Recently, Zhao and Shi 10 proposed a model of CMP based on elastic contact and soft-pad response. They proposed a dependence of for MRR and in-P 2/3 o P 5/6 o The role of a porous pad in controlling material-removal rate (MRR) during the chemical-mechanical planarization (CMP) process has been studied numerically. The numerical results are used to develop a phenomenological model that correlates the forces on each individual abrasive particle to the applied nominal pressure. The model provides a physical explanation for the experimentally observed domains of pressure-dependent MRR, where the pad deformation controls the load sharing between active-abrasive particles and direct pad-wafer contact. The pr...

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Section: Introductionmentioning

confidence: 99%

Pad effects on material-removal rate in chemical-mechanical planarization

Bastawros

Chandra

Guo

et al. 2002

Journal of Elec Materi

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“…[18] proved that the MRR in the chemical-mechanical polishing process is related to the normal and shear stresses. Tseng and Wang [19] modified the Preston's equation to express the MRR as a function of the normal stress of the wafer, the relative velocity of the polishing and the elastic deformation of the abrasive grains. Nanz [20] provided new MRR equation considers the bending of pad and flow of slurry.…”

Section: Materials Removal Ratementioning

confidence: 99%

Optimization of Single-Sided Lapping Kinematics Based on Statistical Analysis of Abrasive Particles Trajectories

Barylski¹,

Piotrowski²

2017

Kinematics

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The chapter presents the influence of selected kinematic parameters on the geometrical results of the single-sided lapping process. The optimization of these parameters is aimed at improving the quality and flatness of the machined surfaces. The uniformity of tool wear was assumed as main optimization criterion. Lapping plate wear model was created and in detail was analyzed. A Matlab program was designed to simulate the abrasive particles trajectories and to count their distribution. In addition, the influence of additional guiding movements of the conditioning ring has been verified and the idea of a flexible single-sided lapping system assisted with a robot, which ensures the optimal constant wear over the diameter was presented.

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“…Although the Preston equation (11) has been used with some success, there also are situations in which it does not well correlate the experimental data, thus motivating several experimental and modeling works aiming to modify (11) (see [23][24][25][26][27][28] for example). In particular, Runnels and Eyman [23,24] postulated that the local MRR is a function of the local normal and tangential stresses acting on the wafer surface by the flowing slurry.…”

Section: Slurry-impurity Transport Equationmentioning

confidence: 99%

“…Meanwhile, combining Runnels' postulate [24] with some heuristic arguments regarding the material removal process, Tseng and Wang [25] derived an expression relating the overall MRR to p 5/6 back V 1/2 , instead of the p back V dependence of the Preston equation (11). It is also worth mentioning that, to account for the deterioration in the shearing efficiency of abrasive particles, Tseng et al [26] replaced the constant C P in (11) by an exponentially decaying function of the sliding velocity V .…”

Section: Slurry-impurity Transport Equationmentioning

confidence: 99%

Modeling and calculation of slurry-chemistry effects on chemical–mechanical planarization with a grooved pad

Wang

Yang

2008

J Eng Math

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During chemical-mechanical planarization (CMP), a rotating wafer is pressed against a rotating pad, while a slurry is dragged into the pad-wafer interface. Here, taking into account the dependence of local material removal rate (MRR) on the slurry's chemical activity, the effects of pad groove geometry and various other process parameters on the spatial average and non-uniformity of MRR are examined. Technically, the slurry flow is calculated by following an existing approach that integrates two-dimensional fluid-film lubrication theory and contact-mechanics models. A slurry impurity transport equation is then used to calculate the impurity concentration that determines the slurry's chemical activity and hence the local MRR. The numerical results obtained here indicate that the presence of pad grooves generally decreases the average slurry impurity concentration, and increases the average contact stress on the pad-wafer interface. However, as a grooved pad has less contact area for effective interaction with the wafer surface, the average MRR may or may not be increased, depending upon the specific setting of process parameters. Meanwhile, it appears that the retaining ring generally used to keep the wafer in place also plays an important part in reducing the MRR non-uniformity.

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A Comparative Study on the Roles of Velocity in the Material Removal Rate during Chemical Mechanical Polishing

Cited by 71 publications

References 10 publications

Pad effects on material-removal rate in chemical-mechanical planarization

Pad effects on material-removal rate in chemical-mechanical planarization

Optimization of Single-Sided Lapping Kinematics Based on Statistical Analysis of Abrasive Particles Trajectories

Modeling and calculation of slurry-chemistry effects on chemical–mechanical planarization with a grooved pad

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