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Co. s Founder, explains that for years, the semiconductor industry used silicon dioxide as its gate insulator. SiO2, with a dielectric constant, or k value, of 4.2, did the job perfectly because it was well understood and was highly compatible with the transistor s underlying silicon metal layer.

As semiconductor size shrinks in keeping with Moore s law, the SiO2 transistor gate must be made thinner and thinner to maintain adequate capacitance across it. But below 2 nm or so, Co. s Founder says, the gate becomes so thin that electrons can leak through and sap power from the device.

A product like hafnium oxide, with a k value of about 30, gets around this problem because it can form a thicker gate that blocks electrons while maintaining capacitance. But the use of hafnium oxide presents fabrication challenges. "The problem," Co. s Founder says, "is that silicon dioxide is a wonderful material to work with, and nothing else even comes close."

For example, although SiO2 can be formed on silicon by simple thermal oxidation, hafnium oxide must be deposited with sophisticated chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques. Furthermore, because the deposition process involves volatilization, the hafnium must be sold as a volatile, typically organic, precursor.




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