The Search For New Materials
It makes sense that the first chips were built out of silicon. It’s hard to think of a more abundant material than sand, or one that’s so easily accessible in so many places. It’s like building the first homes out of earthen bricks. There was never a shortage of materials.
Even aluminum and copper for the wires and interconnects in these chips are readily available, despite the rising price of copper in recent years. And, in theory, anything that is carbon-based, such as graphene or other nanowires, should be readily available for use. Most of us burn enough toast each year to provide a steady stream of carbon for these ventures.
But as we move down process nodes, the semiconductor industry has been pushing steadily deeper into the Periodic Table using a group known as transition metals—and with mixed results. Consider element No. 73, for example—Tantalum. It has become a mainstay in capacitors, but the supply has been in jeopardy since the early part of the millennium due to mine closings in Australia, Canada and Mozambique and political uncertainties in Central Africa. And as the co-CEO of Synopsys quipped back several years ago, “Does anyone really know the world’s supply of Hafnium?”
These are more than just amusing questions. Just because an element looks good on paper based on electrical properties—its ability to resist breaking down over time under constant bombardment of electrons, in extreme temperatures, or under the stress of semiconductor manufacturing and polishing—that doesn’t mean it will be a good candidate for mass-produced chips.
The problem is that this kind of supply chain information isn’t necessarily available to researchers. Understanding what works electrically, physically and over time has nothing to do with what works in a global supply chain. At the forefront of science, anything is possible. Across a geopolitical spectrum, many things are subject to negotiation.
We’ve heard plenty about co-design and co-development, but most of this has been inside the semiconductor world. As we reach out to find new materials, we will have to forge an understanding between science and economics—is there sufficient quantity available from a stable government at a reasonable price? These are questions the semiconductor has not had to wrestle with in any serious way in the past, but as we move to new and more exotic materials, they are questions that will need to be asked.
There are 118 elements in the Periodic Table, and there are thousands of compounds and isotopes that can be made from these elements. Understanding availability and price up front would save a lot of effort and speed up research on materials that could really make a difference.