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Stamp of approval
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02/05/2008
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Recent studies by the US National Institute of Standards and Technology (NIST) have helped resolve two important questions about nanoimprint lithography. According to NIST, the approach not only allows delicate insulating structures to be stamped accurately on chips, but also makes them better.
Nanoimprint lithography (NIL) is an embossing process in which a stamp with a nanoscale pattern in its surface is pressed into a soft film on the surface of a semiconductor wafer. The film is hardened, retaining the impressed pattern. NIST says that, using NIL, it has created features as small as 10nm across with relatively complex shapes.
NIL is being considered for building complex patterned insulating layers in future ics. One candidate is a porous glassy material called spin on organosilicate glass (SOG).
When heated, SOG turns into a thin glass film laced with nanometer pores that enhance the electrical insulation. But SOG is relatively delicate and conventional photoresist etching processes can compromise it. NIL, on the other hand, might be able to pattern SOG layers with wiring trenches and eliminate several time consuming and expensive photolithography steps.
A recent paper from NIST studied the effect of the embossing process on the nanopore structure in the glass. Researchers found the NIL embossing process had beneficial effects – including increasing the population of small pores and creating a protective skin across the surface of the material.
This and an earlier paper suggest that NIL can produce superior nanoporous insulator layers in advanced semiconductor devices with significantly fewer – and easier – processing steps than conventional lithography.
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Author
Graham Pitcher
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Source
photo: NIST
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