RAISIN Workshop
We’re delighted to be attending RAISIN – Roadmap for Applications of Implanted Single Impurities Network.
We’re looking forward to seeing you at the University of Surrey, from 6 to 8 September!
We’re delighted to be attending RAISIN – Roadmap for Applications of Implanted Single Impurities Network.
We’re looking forward to seeing you at the University of Surrey, from 6 to 8 September!
We’re excited to be sponsoring, attending and exhibiting at the Annual Conference on Mass Spectrometry Imaging and Integrated Topics.
The conference will be held this October in Montreal, we look forward to seeing you there!
We’re excited to be sponsoring and attending the 2023 North American SIMS Workshop at Rice University in Texas!
We look forward to seeing you there!
We’re excited to be attending and exhibiting at the annual the ASMS conference once again in Houston!
You’re welcome to drop by booth 814 to learn more about how our products can benefit your research.
See you in Houston!
We’re delighted to announce that we will be exhibiting at the 66th International Conference on Electron, Ion, and Photon Beam Technology and NanoFabrication (EIPBN) in beautiful San Francisco.
Our project engineer Dr Gianfranco Aresta will be talking about our single ion implantation platform, the Q-One. Feel free to drop by Booth 420 and chat with us!
We are really looking forward to seeing you there.
We’re delighted to announce that we will be attending the Pittcon Conference and Exposition in Philadelphia. This will be our first time at this exciting conference, and we are really looking forward to engaging with a new audience and learning all about their applications.
See you in Philadelphia!
We are excited to announce that we will be sponsoring, attending and exhibiting at the Regional Mass Spectrometry Imaging Spring Workshop in Uppsala, Sweden, this March.
Don’t miss our lunch talk on the 29th about the applications of the J105, we look forward to seeing you there!
Ion implantation is a process whereby dopant ions are accelerated in intense electrical fields to penetrate the surface of a material, thus changing the material’s properties.
An essential technique in the semiconductor industry, it is used for modifying the conductivity of a semiconductor during the fabrication of integrated circuits. It is also heavily used for making silicon-on-insulator devices and in many other industries, including physics, materials science, and metallurgy.
Virtually all ion implantation applications involve implanting vast numbers of ions over a large area to modify the bulk properties of a material. In contrast, Q-One is designed for implanting single ions with extremely high precision to fabricate quantum devices. However, many of the same concepts apply.
Ion implanters consist of a source region that forms the ions, an accelerator region that electrostatically accelerates them to high energy, and a target chamber. Instruments must be pumped to a high vacuum to prevent contamination of the target and breakdown under high voltage.
Ion sources often generate multiple ions depending on design, including different elements, their isotopes, and multiple charge states for each. A magnetic filter, also known as a Wien filter, is often used to select specific ions based on their velocity.
The implanting species, also called dopants, vary considerably with the application. Boron, arsenic and phosphorous are the most common dopants in semiconductor applications, while oxygen and nitrogen are used to process metals. Dopants for quantum applications include phosphorous,1 nitrogen,2–5 silicon,6–8 and germanium,9, and rare earth elements such as erbium.10
Implanters are often categorised by the ion beam current at the target, either low, medium or high. High-current systems for commercial applications operate at up to tens of milliamps and process hundreds of wafers per hour. On the other hand, Q-One operates at extremely low currents when implanting single ions, often tens of femtoamps.11
The ion dose is the integral of the ion current per unit area over time, measured in ions per square centimetre (ions/cm2). The dose determines the concentration of the dopant in the target. Common dose values are in the range 1016 – 1018 ions/cm2.
The energy of the ion beam is a crucial parameter in ion implantation processes as it has several significant effects. The energy is the product of the accelerator voltage and the ion’s charge state, measured in electron volts (eV). For example, a Bi2+ ion accelerated in a 30 kV field has an energy of 60 keV.
Ions hitting a target lose their kinetic energy through collisions with the nuclei and electrons of the material until they stop. The depth to which the ions penetrate depends on their energy and mass, the target mass, and the beam’s angle to the crystal plane in the case of a single crystal. Higher energies penetrate further for a given mass, while lighter elements penetrate further than heavy elements for a given energy.12
The energy range of ion implantation instruments can range from 1 keV to several MeV. Q-One operates in the range of 5 – 30 kV, with an option to extend this to 40 kV. In this range, the ions penetrate approximately 5 – 100 nm beneath the surface – suitable for most quantum applications.
As the ions stop, they become laterally displaced from their initial trajectory, known as straggle. Straggle is an important consideration when it comes to single-ion implantation. The precision with which ions are positioned is the sum of the beam diameter at the target plus the lateral straggle. In some instances, the straggle is much larger than the beam and, therefore, the limiting factor.
Straggle is proportional to the energy and inversely proportional to the mass. So lowering the implantation energy and selecting heavier elements results in greater precision by reducing the straggle.
Ion implantation is a violent process. The projectile transfers a large amount of its kinetic energy to the target atoms, displacing them from the lattice sites. The primary collisions result in secondary collisions, and so on, in a process known as collision cascade.
The collision cascade forms a variety of defects in the material, including vacancies, interstitials, amorphous zones, stacking faults, and dislocation loops, among others.12 Thermal annealing post-implantation restores the crystalline order and allows the device to function. High temperatures can also cause diffusion of the implanted atoms, so annealing steps must be designed carefully.
The beam energy also has an important effect on the sputter yield. Ions impinging on a surface do not just penetrate the surface. They also sputter material, which is an important consideration, particularly at low energy.
The sputter yield (Y) is the mean number of atoms removed from the target surface per incident ion. If Y > 1, the ions remove more target material per implanted ion, resulting in erosion. If Y < 1, the ions sputter fewer target atoms per implanted ion, and material builds up. When Y = 1, there is a one-for-one replacement of target atoms with implanted ions.
Holmes et al. use TRIDYN simulations to model the sputter yield of 28Si impinging natural silicon at various energies.6 They show that the three regimes are energy-dependent and that Y = 1 at two energies, 3 and 45 keV, resulting in a planar surface. However, operating at 45 keV produces a much deeper implant and is thus more suitable for device fabrication.
Want to know more about Q-One and how it can impact your research? Get in touch with our team today, and we’d be happy to help.
The 23rd secondary ion mass spectrometry (SIMS 23) conference was held in Minneapolis, MN, from 18 – 23 September 2022.
The biennial event is a forum for colleagues from academic, industrial, and national laboratories worldwide to exchange results and new ideas on Secondary Ion Mass Spectrometry and related techniques.
The banquet dinner was held on Wednesday of the conference week and was an opportunity for the attendees to relax, network, and catch up with old friends.
The dinner also hosted the Rowland Hill Awards. Rowland Hill was a founder and former managing director of Ionoptika, who sadly passed away in 2015. Ionoptika established the Rowland Hill Awards in his honour to recognise excellence in SIMS research and to promote young and early career researchers.
The winners of this year’s awards were Karolin Bomhardt and Svenja-Katharina Otto, both of Justus-Liebig-University Giessen, Alfred Fransson of the University of Gothenburg, and Matija Lagator, of the University of Manchester.
Many congratulations to all the winners!
For a list of all upcoming conferences, shows, and exhibits, see our Events page.
Ionoptika is delighted to sponsor the International Conference on Secondary Ion Mass Spectrometry, which will be held this year in Minneapolis. The conference is always an excellent forum for colleagues from academia and industry to exchange new results and ideas on SIMS and related techniques. This year will be no different. We hope to see you there!
We are proud to once again sponsor the PacSurf meeting. Bringing together the surface analysis community from across the Pacific and further afield, this is always a fascinating meeting and of course a wonderful location. Travel restrictions not withstanding, we are very much looking forward to seeing you there.