IBM breathes new life into chip-making technique

IBM Corp. may have figured out a way to extend the life of a popular method for manufacturing semiconductor chips, potentially deferring for several years the costly transition to newer production methods, it said on Monday.

Scientists at IBM’s Almaden Research Labs created what it says are the smallest circuit patterns yet made using a technique called deep-ultraviolet (DUV) optical lithography. They are 29.9 nanometers wide, or about one-third the width of the smallest computer circuits being mass produced today. One nanometer is a billionth of a meter.

The chip industry has been trying for years to come up with a new way that’s both reliable and practical for etching circuits on silicon wafers. Current methods are approaching fundamental physical limits as circuits become more and more minute.

Chip companies have come up with several alternatives, but most require expensive equipment upgrades and none are guaranteed to work well in mass production. The transition is important because the ability to print smaller and smaller circuits is essential to making ever faster, more powerful chips.

IBM’s results show that a variant of DUV lithography called “high-index immersion” will allow the industry to use its current production methods for seven more years before it has to make a radical change, Dr. Robert D. Allen, manager of lithography materials at IBM’s Almaden Research Center, said in a statement.

The tiny circuit was made on a piece of test equipment dubbed Nemo, which was designed and built at the Almaden Labs by IBM and a partner, JSR Micro Inc. of Sunnyvale, California. The companies will discuss the achievement in detail this week at the SPIE Microlithography 2006 chip conference in San Jose, California.

Circuits are made by projecting a laser beam through a “shadow mask” to create patterns on photosensitive film on silicon wafers. These are then etched and treated with material deposits to build up the tiny wires that link transistors. In recent years, very pure water has been inserted between the optics and the silicon wafer to allow finer resolutions, a technique known as immersion lithography.

IBM’s Nemo tool uses intersecting laser beams to create light-and-dark interference patterns with spacings closer than can be made with current chip-making equipment.

“As a result, Nemo is ideal for researching, testing and optimizing the various high-index fluids and photoresists being considered for use in those future DUV systems that would create such fine features,” the company said.

The scientists still have to create suitable high-index lens materials to allow commercial use of the process, IBM said. It also hopes that future research will further reduce the size of the circuits it has managed to draw.

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