Cu CMP with orbital technology: summary of the experience

Gotkis, Yehiel; Schey, D.; Alamgir, S.; Yang, Ji Chul; Holland, Karey

doi:10.1109/asmc.1998.731619

Cited by 10 publications

(10 citation statements)

References 2 publications

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“…Under such circumstances, CMP will maintain the feature profile without any further step height reduction. The dishing model by Saka et al [12] follows the approach of Gotkis et al [5] and is also similar to the contact mechanics model due to Vlassak [16]. It can also deliver the complete dishing profile, but will also require an iterative numerical solution procedure.…”

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confidence: 97%

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An analytical dishing and step height reduction model for chemical mechanical planarization (CMP)

Chandra

2003

IEEE Trans. Semicond. Manufact.

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An analytical model for dishing and step height reduction in chemical mechanical planarization (CMP) is presented. The model is based on the assumption that at the feature scale, high areas on the wafer experience higher pressure than low areas. A Prestonian material removal model is assumed. The model delineates how dishing and step height reduction depend on slurry properties (selectivity and Preston's constants), pad characteristics (stiffness and bending ability), polishing conditions (pressure, relative velocity and overpolishing) and wafer surface geometry (linewidth, pitch and pattern density). Model predictions are in good agreement with existing experimental observations. The present model facilitates understanding of the CMP process at the feature scale. Based on the proposed model, design avenues for decreasing dishing and increasing the speed of step height reduction may be explored through modification of appropriate parameters for slurry, pad and polishing conditions. The proposed model may also be used as a design tool for pattern layout to optimize the performance of the CMP process.

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confidence: 97%

“…The physical insight for feature scale model based on direct wafer-pad contact is given by Warnock [17] and Gotkis et al [5]. Warnock points out that depending on the pad flexibility, polishing rate at any given point is affected by its surrounding topography, i.e., high area will experience higher removal rate because of higher pressure at that point.…”

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confidence: 99%

An analytical dishing and step height reduction model for chemical mechanical planarization (CMP)

Chandra

2003

IEEE Trans. Semicond. Manufact.

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“…Based on the understanding of the CMP process, researchers have modeled the feature scale surface evolution in two different ways: one group (e.g., Runnels 1996 andYao et al 2000) assumes there is a fluid layer between wafer and pad while the other group assumes direct wafer-pad contact. For the latter, there are also two kinds of models: one implies only high areas on the wafer feature have direct contact with pad and low areas are free of any loading and is not polished (e.g., Elbel et al 1998, Chekina 1998and Saka et al 2001; the other assumes both high and low areas contact with pad (e.g., Gotkis et al 1998, Chen and Lee 1999, Vlassak 2001and Saka et al 2001. The major assumptions in Chen and Lee (1999) model are: (a) the pressure difference between the high area and the low area is proportional to the step height; (b) higher area will experience higher pressure.…”

Section: Literature Reviewmentioning

confidence: 99%

“…However, the model does not show the effects of wafer feature geometry, such as linewidth, pitch and pattern density, and pad bending influ ence. Gotkis et al (1998) and Saka et al (2001) have the same dishing model and it only con siders the case when the removal rates on metal region and on dielectric region are the same.…”

Section: Literature Reviewmentioning

confidence: 99%

“…The physical insight for feature scale model based on direct wafer-pad contact is given by Wamock (1991) and Gotkis et al (1998). Warnock points out that depending on the pad flexibility, polishing rate at any given point is affected by its surrounding topography, i.e., high area will experience higher removal rate because of higher pressure at that point.…”

Section: Literature Reviewmentioning

confidence: 99%

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Modeling of chemical mechanical polishing at multiple scales

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Chemical Mechanical Polishing (CMP) has grown rapidly during the past decade as part of mainstream processing method in submicron integrated circuit manufacturing because of its global or near-global planarization ability. However, CMP process is influenced by many factors and is poorly understood. It makes process control and optimization very diffi cult. This study focuses on the modeling and simulation to facilitate better understanding and better control of the CMP process. The thesis outlines the modeling of CMP process in three scales: particle scale for material removal mechanism, wafer scale for within wafer nonuniformity issues and feature scale for dishing and erosion in metal CMP. At the particle scale, material removal mechanism is assumed to be due to local plastic deformation of wafer surface at the abrasive-wafer interface. Pad is assumed to deform like a beam to obtain an approximate force partition between abrasives and direct wafer-pad contact. A mechanistic material removal model is derived that delineates the influence of abrasive (shape, size and concentration), pad (rigidity) and process parameters (pressure and relative velocity) on the material removal rate (MRR). Wafer scale model is based on the solution of indentation of elastic half space by a rigid fhctionless polynomial punch. The elastic solution is derived through potential theory and complex analysis method. It is valid for any polynomial punch with integer power or noninteger power. The load-displacement relationship is also derived and the conditions for unbonded or bonded contact are obtained from the boundary condition at punch edge. The corresponding viscoelastic solution is obtained through Laplace transform and elastic-viscoelastic analogy. The elastic solution is used to explain the edge effect. The elastic analytical vi solution is first verified against numerical results from Finite Element Method (FEM) simula tion. It shows wafer curvature, indentation depth and load will influence the interface pressure distribution throughout the wafer surface and it introduces parameters control as a potential avenue for completely eliminating the within wafer nonumifonnity. Viscoelastic solution is used to explain within wafer nonuniformity, i.e., edge effect and wafer to wafer nonuniformity, i.e., removal rate decay for unconditioned pad. The relationships among wafer-pad interface pressure, wafer shape and wafer loading condition are also investigated. Feature scale model for dishing and erosion is based on Preston's relationship for material removal and constant downforce. It shows dishing will reach a limit and is governed by polishing conditions (overpolishing, pressure, velocity), slurry (selectivity), pad character istics (pad stiffness and bending ability), as well as wafer surface feature topography (pattern density, linewidth and pitch). This model is also valid for step height reduction when the same surface material is polished. Due to process complexity and coupling of various parameters, more fundamental research needs...

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Effects of pattern characteristics on copper CMP

Ruan

Chen

et al. 2009

J. Semicond.

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Copper chemical mechanical polishing (CMP) is influenced by geometric characteristics such as line width and pattern density, as well as by the more obvious parameters such as slurry chemistry, pad type, polishing pressure and rotational speed. Variations in the copper thickness across each die and across the wafer can impact the circuit performance and reduce the yield. In this paper, we propose a modeling method to simulate the polishing behavior as a function of layout pattern factors. Under the same process conditions, the pattern density, the line width and the line spacing have a strong influence on copper dishing, dielectric erosion and topography. The test results showed: the wider the copper line or the spacing, the higher the copper dishing; the higher the density, the higher the dielectric erosion; the dishing and erosion increase slowly as a function of increasing density and go into saturation when the density is more than 0.7.

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Cu CMP with orbital technology: summary of the experience

Cited by 10 publications

References 2 publications

An analytical dishing and step height reduction model for chemical mechanical planarization (CMP)

An analytical dishing and step height reduction model for chemical mechanical planarization (CMP)

Modeling of chemical mechanical polishing at multiple scales

Effects of pattern characteristics on copper CMP

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