Hostname: page-component-cd9895bd7-gvvz8 Total loading time: 0 Render date: 2024-12-28T20:11:42.649Z Has data issue: false hasContentIssue false
  • English
  • Français

Contact Pressure Distribution in the Chemical Mechanical Planarization of 450mm Wafers

Published online by Cambridge University Press:  01 February 2011

Padraig Timoney ,
Eamonn Ahearne  and
Gerald Byrne
Padraig Timoney
Affiliation:
padraig.timoney@ucd.ie, Advanced Manufacturing Science Research Centre, School of Electronic, Electrical and Mechanical Engineering, University College Dublin, Dublin, Ireland
Eamonn Ahearne
Affiliation:
eamonn.ahearne@ucd.ie, Advanced Manufacturing Science Research Centre, School of Electronic, Electrical and Mechanical Engineering, University College Dublin, Dublin, Ireland
Gerald Byrne
Affiliation:
gerald.byrne@ucd.ie, Advanced Manufacturing Science Research Centre, School of Electronic, Electrical and Mechanical Engineering, University College Dublin, Dublin, Ireland
Get access

Abstract

Optimisation of spatial uniformity of material removal in chemical mechanical planarization requires an understanding of the mechanics of the wafer carrier system. Finite element analyses have been carried out by researchers identifying relationships between von Mises stress distribution and material removal rate. However, in many of these wafer scale models, the derivation of the material properties of the polishing pad and sub pad is unclear and consequently a large variation in values used is observed. Models are generally validated with a procedure different to that simulated in the model and with different output variables. Few models have incorporated the industry standard method of pressurizing the backside of the wafer independently to the wafer carrier loading using a pressurized air chamber located directly behind the backside of the wafer. The anticipated introduction of 450mm diameter wafers has surprisingly not been accompanied by wafer scale models investigating the issues that will arise from the diameter and thickness scaling ratio of the wafer.

This paper presents a unique approach to finite element modeling of CMP incorporating realistic boundary conditions for the wafer carrier and platen assemblies. Model predictions of interfacial contact pressure for a 200mm wafer loaded by a lip seal type carrier head were validated by unique measurements of the contact pressure between the wafer and the pad using Fujifilm Prescale TM pressure measurement film and accompanying analysis software. The results demonstrated a close correlation between the model's prediction and the measured values. Results are presented for the upscaling of this validated model to 450mm wafer dimensions. The results indicate a doubling of the contact pressure maximum values compared to the 200mm wafer model. These results illustrate the extent of the challenge facing CMP tool vendors in increasing the level of control of the mechanical force distributed by the wafer carrier on 450mm wafers. The model can be used as a design tool to optimize machine and process parameters.

Keywords

CMPstress/strain relationshipelastic properties
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1249: Symposia E/F – Advanced Interconnects and Chemical Mechanical Planarization for Micro-and Nanoelectronics , 2010 , 1249-E05-05
Copyright
Copyright © Materials Research Society 2010

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1 Fu, G., Chandra, A., The relationship between wafer surface pressure and wafer backside loading in chemical mechanical polishing. Thin Solid Films, 2005. 474 (1-2): p. 217–221.Google Scholar
2 Wang, D. et al. , Von Mises Stress in Chemical-Mechanical Polishing Processes. Journal of the Electrochemical Society, 1997. 144: p. 1121.Google Scholar
3 Chen, K. et al. , Finite-element analysis on wafer-level CMP contact stress: reinvestigated issues and the effects of selected process parameters. International journal of advanced manufacturing technology, 2009. 42 (11): p. 1118.Google Scholar
4 Hollatz, M., Thieme, P., and Ullrich, A., Modeling of Wafer Pressure Distribution and Removal Uniformity for Lip Seal Carrier, in CMP-MIC Conference. 2001. p. 33–40.Google Scholar
5 Kim, Y. et al. CMP profile simulation using an elastic model based on nonlinear contact analysis. in International Conference on Simulation of Semiconductor Processes and Devices (SISPAD), p. 69–72. 1997.Google Scholar
6 Hoffmann, K., Decker, K., Inaccuracies in measurement of contact pressure due to the measuring grid of a foil sensor. Int. J. Intell. Syst. Technol. Appl., 2008. 3 (1/2): p. 80–94.Google Scholar
7 Fujifilm, , Fujifilm Pressure Distribution Mapping System for Prescale. 2.01 ed. 2008.Google Scholar
8 Lammer, D., ISMI 450mm Program Moving to Next Stage, in Semiconductor International – Wafer Processing. 2009, Reed Electronics.Google Scholar