EngD Project Update 1: An Introduction

Throughout this blog I aim to provide updates on the work that I will be undertaking throughout my EngD. I thought I would begin with a brief introduction to my project, beginning with the title: Single Ion Multispecies Positioning at Low Energy (SIMPLE) Quantum Materials Metrology and Development: SIMPLE QMMaD. See, simple.

I am currently working with Ionoptika Ltd. to develop a new tool and imaging capability that will enable the deterministic implantation of single atoms in materials with sub-20nm spatial resolution.
In simpler terms: I will be part of the development of an ion gun that will implant single phosphorus atoms into a silicon substrate, (other combinations of elements will also be used) and we aim to be able to place them within 20nm of our desired target. For those unaware 20nm (nanometers) is around 10,000 times smaller than the width of a human hair. The spacing between silicon atoms in
a lattice is 0.543nm! So we are working at the physical limits, in terms of the precision of our targets. 

A C60 gas cluster ion gun. Whilst the pictured gun greatly differs to the one described, from the outside they look much the same. 

I’ll now delve into how an ion gun creates a beam of ions to ‘fire’ at a substrate. Taking the bottom of the gun to be where the ions end up last before being fired, at the top of the gun you have a reservoir of the element you wish to implant, in this example gallium (which at room temperature is a solid metal). The gallium reservoir will first be heated; this will melt the reservoir which will travel down a fine needle tip where single atoms that have become charged will be extracted from the reservoir by an applied electric field. All this happens in the emitter, which I will explain in more detail in a later post. These extracted ions will then be accelerated along the column of the ion beam by strong electromagnets, which will also act to direct the beam of ions toward the intended target.

I think it all sounds quite simple when you describe the workings of an ion gun as just a heater and some electromagnets, however the reality is much, much more complicated. You might think the development of ion beams and Implantation tools would be modern cutting edge science, but in fact most of the technology of Ion beam systems hasn’t changed much since its development in the 1970s! What makes this project special is that we are pushing the technology to the physical limits. 

I hope you enjoyed this brief introduction. In my next project update I will explain in much more detail the ion emitters.