Question

What do you think the most pressing issue(s) are in further reduction of the feature size in today’s state-of-the- art lithography?

Answer 1

state-of-the-art process is called 193-nm immersion lithography. Light with a wavelength of 193 nm shines through a patterned surface called a photomask. That process casts the pattern through water onto the silicon wafer, where it is fixed by a photosensitive chemical and then etched onto the wafer.

problem is that light can’t directly define features smaller than its own wavelength. And 193 nm is so much longer than the size of the features modern chips need. These days it takes a host of optical tricks and work-arounds to make up the difference. The most costly of these is the use of as many as three or four different photomasks to produce a single pattern on a chip. With today’s most complex processors, that means a wafer could need some 80 trips though the lithography tool.

According to Moore’s law of doubling functionality on a chip every two year as the feature size on an integrated circuit decreases, fabricating the chips becomes increasingly difficult due to high cost and complexity of fabrication process.