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Modeling of Feature-Scale Planarization in STI CMP Using MESATM
Published online by Cambridge University Press: 18 March 2011
Abstract
MESA is a feature-scale planarization model that predicts the changing topography of the wafer surface during the chemical mechanical polishing (CMP) process used in IC manufacturing. This model has previously been applied to the polish of inter-level dielectrics and copper. The present study is part of a model validation procedure for shallow trench isolation (STI) using experimental feature-scale data. It was carried out using the SpeedFam-IPEC Auriga polisher with SKW Associates 200-mm wafers (SKW3 MIT-STI-mask), Rodel IC 1000/1400 pads and Cabot SS-12 slurry. MESA accounts for observed differences in planarization using Rodel IC1000 with and without foam backing as well as the pattern-density dependence within each die. The data were obtained and plotted in such a way that the active-area and trench-oxide levels are displayed throughout the whole polish, including the points where active area clears to nitride and silicon as well as where trench oxide dishes below the silicon level. The pattern density effect is evident in both cases, but a comparison between the two pads shows less pattern density effect and improved planarization with the single IC 1000 pad.
MESA is shown to predict the details of the topographical evolution for STI CMP on the feature scale. When validated by fitting the pad constants k1 and k2 to describe the planarization, MESA provides reasonably accurate predictions for the polish of any oxide pattern structure as long as the same CMP process is used.
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- Copyright © Materials Research Society 2001
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