Method of Performing Wafer Centering in Encore II Ta(N) Chambers by Measuring Backside Deposition
Publication Date: 2016-Mar-08
The IP.com Prior Art Database
Disclosed is a technique to measure and adjust wafer centering that allows for traceable controls and standards using an automated measurement. The measurement is accomplished while the chamber remains under vacuum and in process ready condition.
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Method of Performing Wafer Centering in Encore II Ta (N) Chambers by Measuring Backside Deposition
Wafer level arcing in Encore II Ta(N) chambers can result in wafer scrap and reduced yield, premature process kit failures, reduced target lifetimes, reduced tool availability, increased parts usage, and increased cost of ownership for Endura* platforms. A leading cause for wafer level arcing is inaccurate wafer centering on the pedestal, which allows metal deposition on the edge of the dep ring. Upon accumulation of this metal build-up, the potential for an arc event between the dep ring and the wafer increases. Wafer centering to date has been a manual process with no measurable standard or traceable control; it is subjective in nature and highly variable based on the experience of the engineer.
The novel contribution is a technique to measure and adjust wafer centering that allows for traceable controls and standards using an automated measurement. The measurement is accomplished while the chamber remains under vacuum and in process ready condition. Through improvements in wafer placement and centering on the pedestal, wafer level arcing events can be significantly reduced.
A test wafer is deposited with a Ta film in the chamber that is to have wafer centering optimized. The test wafer is analyzed on a tool called a VisEdge*, which produces an image of the Ta film which has deposited on the backside of test wafer.
Figure 1 displays a side view of an Encore II Ta(N) chamber and the relationship between the wafer, the pedestal, and the dep ring.
Figure 1: Encore II Ta(N) chamber setup
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Figure 2 displays the three distinct backside deposition regions measured by the VisEdge tool, and shows how these regions align with the tooling of the Encore II Ta(N) chamber. Also shown in Figure 2 is a "before" image of an out-of-center wafer. Note the sign wave profile of the VisEdge image and the range between wave peak and trough.
Figure 2: VisEdge scan of backside deposition
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Figure 3 displays an exaggerated view of the wafer placement from which the VisEdge image was taken. It can be seen that the point of least overhang occurs at abou...