Semiconductor researchers gaze at purple atoms

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Semiconductor researchers gaze at purple atoms

Madison (WI) – A company called Imago has developed a technology that can peer deep into the semiconductor landscape, seeing individual atomic placement of doping atoms like arsenic. The research being carried out by Imago will help companies like IBM push future process technologies beyond the hard limits seen today.

When we consider the scale at which semiconductor products are constructed today, it’s almost mind boggling. Intel is ready to release a 45nm process technology with internal electrical wires carrying a current so small that individual transistor switching is on the order of ½ a billionth of a watt. In order to move electricity with such precision is a feat of itself. But what about the future? What about the upcoming 32 nm node? The 22 nm node? 16 nm, 12 nm and beyond? Will things continue on scaling forever? If the are manufactured in the way they are today, they won’t.

There are real, hard limits coming that scientists must overcome, if they want to see scaling down to the truly atomic levels. And that’s what this new tool from Imago is helping to address. It’s called, ironically enough, an “Atom Probe” machine and is designed to scan the surface of silicon looking for arsenic deposition. Arsenic is used as a doping agent, something that changes the electrical characteristics of silicon and makes it work with electricity. That’s why it’s called a “semiconductor”. It is only semi-conductive, and without the doping agent it would not work at all.

When manufacturers implant doping agents into the silicon, they use a machine called an “implanter”. That machine attempts to disburse the doping agent (arsenic) in a very uniform manner. Based on the process, it should hit the surface like rain drops, scattered all about like polka dots. But what the Atom Probe is revealing is that the doping agents are grouping together like social junkies. They hang out in the worst parts of the silicon city. In fact, whenever there is a defect, you will find them all grouped around. And just like what is often true in society, it is this grouping that causes problems.

When the doping agents are gathered together it alters the electrical characteristics of the semiconductor. At very small scales this grouping would cause it to fail and become unusable. Today at current process technologies like 90 nm, 65 nm and even 45 nm it isn’t an issue. But when the things of tomorrow get really, really small, today’s technology just won’t cut it. And it’s research like this which may propel us forward.

Imago was the first to develop the scanning Atom Probe machine. It’s a tool that hands researchers the ability to visualize (in 3D even) what had been theorized previously. Today, they can see the smallest possible depositions from their dopant implant process. And tomorrow, they’ll be able to take that data and adapt their manufacturing process to remove defects from silicon growth in order to allow for a better deposition process and to advance the state of the art to the point where Moore’s Law will continue to scale further.

Imago developed this machine in Madison, Wisconsin. The company said it is currently performing research for IBM on substrates like these. The idea is to advance the future technology of manufacturing.  The September 7 issue of Science magazine will cover the full details of this finding.