05898190

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Advanced excursion control and diagnostics for CMP process monitoring Andrew Stamper Microelectronics Division IBM Corporation Hopewell Junction, NY 12533 Stamper@us.ibm.com

Abstract—This CMP processes are generally well known and established critical steps in semiconductor manufacturing, but must be very closely monitored and controlled to maintain process uniformity and minimize process induced defects. CMP processes are generally monitored using a combination of blanket test wafers, short loop patterned wafers and product wafers, along with a variety of in-situ controls. This paper talks about the techniques demonstrated for defect excursion monitoring in CMP module using short loop test wafers and an advanced dark Field inspection tool. These techniques enable effective control and monitoring of the CMP tools used for manufacturing advanced semiconductor logic devices. We talk about three approaches that helped accomplish this objective: (i) Pattern wafer inspection at M1 Cu CMP level using Puma 9550 DF inspector (ii) use of In-line Defect Organizer (iDO) to effectively and automatically extract and classify scratches – the key defect of interest to the CMP process engineer; and (iii) use of quick recipe templates to diagnose and make required recipe changes for 32 nm and 22 nm devices using ―Auto Derivative Recipe‖ feature on Puma 9550 to maximize engineering and tool efficiency Keywords-iDO(inline defect organizer), auto derivative,

I.

INTRODUCTION

This paper will discuss excursion control methodologies adopted at IBM using Puma 9550 DF wafer inspection system with Inline Defect Organizer for automatically classifying and monitoring scratches in the CMP module and Use of “Auto Derivative Recipe” feature to create multiple recipes to automatically monitor and diagnose issues due to small process changes on 32 nm and 22 nm product wafers. Having a functional, automated classifier will improve the Mean Time to Detect (MTTD) on the process tools and minimize product at risk to a potential tool or process issue. This paper will describe the methodology that enables fast and accurate defect detection and classification performance on Cu CMP short loop test wafers. II.

Gangadharan Sivaraman, Ravi Sankar KLA-Tencor Gangadharan.Sivaraman@kla-tencor.com, Ravi.Sankar@kla-tencor.com

scratches) from other real defects (CMP residual slurry, Foreign Material, embedded contamination) and come up with a novel way to monitor scratches in CMP module and shut off CMP process tools based on results from iDO classification.

Figure 1: Concept of iDO for binning defects Performance of iDO is measured by accuracy on purity of a bin. The accuracy and purity of a bin is defined based on Confusion matrix.

INLINE DEFECT ORGANIZER

iDO provides a way by which the user can use the classified defect data from inspection system and try to separate different defect types. We were able to use Puma 9550 + iDO to successfully bin scratches (polishing and handling

978-1-61284-409-1/11/$26.00 ©2011 IEEE

Figure 2: Confusion Matrix


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