“Oxides Beyond SiO2”
Dr. Darrell G. Schlom, Cornell University
Until recently the word “oxide” could only mean one thing to anyone working in the semiconductor industry: SiO2. But the replacement of the SiO2 gate dielectric in silicon-based field-effect transistors in microprocessors produced by leading manufacturers by a hafnium-based dielectric has catapulted other oxides into the limelight. The incredible electronic properties of the SiO2/silicon interface are the reason silicon dominated the semiconductor industry and helped it grow to over $250 billion in annual sales. Accompanying over four decades of shrinkage of transistor dimensions has come tremendous improvements in circuit speed and computer performance. At the same time, however, it also led to exponential growth in the static power consumption of transistors due to quantum mechanical tunneling through an ever-thinner SiO2 gate dielectric. This spurred an intensive effort to find an alternative to SiO2 with a higher dielectric constant (K) to temper this exploding power consumption and enable Moore’s law to continue. In this talk the comprehensive materials analysis to identify silicon-compatible materials that go beyond SiO2 (i.e., with higher K and sufficient bandgap) will be described, together with how these materials have enabled improvements in MOSFETs, DRAM and emerging semiconductor devices. A glimpse of other enticing oxides and how their properties may be altered using thin film tricks will also be presented.
Darrell Schlom is a professor of materials science and engineering and the Hebert Fisk Johnson Professor of Industrial Chemistry at Cornell University. He received his PhD in materials science and engineering from Stanford University in 1990. His research concerns heteroepitaxial growth and characterization of oxide thin films (especially ferroelectric and multiferroic oxides) and oxides on semiconductors for increased functionality (e.g., spintronics) or as potential replacements for SiO2 as the gate dielectric in MOSFETs. He is a fellow of both the Materials Research Society and the American Physical Society, he has organized 32 major symposia/conferences, he holds eight patents, and he has co-authored more than 350 publications.