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Combined XRR and XRF gives absolute film thickness accuracy |
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Sep 27, 2005 at 07:51 PM |
 Product Briefing Outline: Bede has launched
the latest variant of the "BedeMetrix" F X-ray metrology tool, which
delivers non-destructive, high speed film thickness measurement on
patterned wafers through combined XRR (X-ray Reflectivity) and XRF
(X-ray Flourescence). The result is an extended thickness measurement
range
of 1 nm to 10 μm on a wide range of material types. Proprietary small
spot X-ray optics enable measurement on test pads and in scribe lines
down to 100 μm for XRR and 30 μm for XRF, for in-line measurement on
product wafers.
Problem: The measuring of layer thickness with
traditional techniques such as optical, opto-acoustic and XRF is
already exceeding the process control limits of advanced process nodes.
Greater attention is now required in examining the cyrstalline
structures, such as interconnect barrier layers in root cause failure
analysis. Traditional inspection techniques are not able to measure
thickness at the atomic level. Ellipsometry is not best suited for this
application as it cannot measure
non-transparent films and analysis is strongly influenced by changes in
the optical properties of a given film. AFM's cannot measure layer
thickness without special sample preparation and have slow throughput.
Solution: Combining XRR and XRF provides much improved
complimentary information about barrier films and their cyrstalline
structures. X-rays incident at a low angle to the layer surface. As
incident angles are increased X-rays begin to penetrate the surface and
are transmitted into the film. At a critical point the X-rays will be
partially reflected from interfaces in the layer structure causing
interference. By scanning the incident angle and measuring the X-rays
scattered through twice this angle, an interference pattern is obtained
which provides data on the layer structure. Measurements are absolute
and only rely on the measurement of angles, rather than reliance on
optical constants or monitor wafers.
Applications: Thin film thickness
Platform: The BedeMetrix family of X-ray
metrology tools consists of the BedeMetrix-L process development tool
and the BedeMetrix-F tools for dedicated process control. The
BedeMetrix-F is available in three primary configurations for strained
silicon, metal film structure determination, and high-speed thickness
measurement.
Availability: 2005 onwards.
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Comment by GUEST on 2007-12-18 10:33:07
OK!
but nothing gives absolute accuracy I guess |
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Wafer Processing 