A research team led by U. of Massachusetts Chemical Engineer James Watkins has developed a new method of depositing copper films within tiny channels etched in silicon wafers.
The technique offers an efficient way to create the ever-smaller circuitry demanded by the microelectronics industry, the journal Science reported. The conventional fabrication methods deposit metals and other materials onto silicon from either a gas or liquid solution. Both approaches have their own advantages and disadvantages, according to Science.
But Watkins’ group took a different view. “We reasoned that individually, each of the methods is probably limited in a fundamental way, but if you could combine the most desirable attributes of the methods into a single process, then you could solve the problem,” Watkins said. “This is possible by depositing the materials from a supercritical fluid.”
This is a substance that has some properties of a liquid and some properties of a gas, Watkins explained.
“If you heat and compress a gas like carbon dioxide, it can be used to dissolve a wide range of compounds. The solution, however, does not behave like a liquid, but rather like a gas, and therefore flows easily over complex surfaces and into narrow gaps.”
Watkins called this combination of properties “chemical fluid deposition” and said it was ideal for the fabrication of tiny devices with complicated features.