Proceedings Article | 23 March 2011
KEYWORDS: Semiconducting wafers, Optical alignment, Double patterning technology, Manufacturing, Scanners, Control systems, Immersion lithography, Overlay metrology, Computer programming, Lithography
At SPIE2010, excellent performance of the cutting edge immersion lithography scanner, the NSR-S620D, which is based
on the new "Streamlign" platform was demonstrated. Last year's work focused mainly on machine evaluation data[1].
Now, many S620Ds are employed at customers' sites and being used in device manufacturing. In this paper, the authors
will introduce the latest factory data, as well as various techniques that enable superior yield and enhance productivity in
IC manufacturing.
It is well understood, that in order to achieve further device shrinks without using traditional techniques such as NA
expansion or wavelength reduction, several practical issues must be overcome. Extremely tight overlay performance will
be required for pitch splitting double patterning, for example. In addition, it is also necessary to control the image plane
and the aberration of the optics much more carefully. Of course these improvements must also be achieved with
sufficient productivity (throughput). In order to satisfy all of the requirements for mass production at customer factories,
many variable factors must be dealt with.
One of these variable factors is the characteristics of the processed wafers that include on-flatness, grid distortion, steep
topology around the edge, or topography of the previous layers' patterns. These factors typically impact overlay and/or
auto focus accuracy. Another variable is the difference in exposure conditions between layers, which include
illumination conditions, dose, reticle transmittance, and the alignment marks. Exposure induced heating in particular is
the key issue for today's enhanced throughput capabilities, with regards to achieving both optimal accuracy and
productivity. In some IC production facilities, and often foundries, many different kinds of products are manufactured in
parallel. However, in order to enhance performance and accuracy, it is sometimes necessary to optimize machine
parameters for each product. Cleary this requires quick tuning capabilities to minimize overhead affects for each product.
As discussed earlier, various techniques must be utilized to minimize the gap between machine inspection data and
manufacturing performance at customer sites. This paper discusses such technologies and provides the supporting data.
