Despite the fact that it’s done much of its manufacturing in nanoscale dimensions for years, the conservative semiconductor industry, with its extreme performance and manufacturing demands, hasn’t yet had much use for the unique nanoscale properties of the nanoparticles, fullerenes, nanowires, quantum dots, and the like usually considered nanotechnology. Nor have the nanoscale patterning processes developed by the chipmakers yet been of much use to the rest of the nanotechnology world.
But that may be starting to change. Among the emerging technologies selected by the volunteer committee of industry executives to highlight this year at SEMICON West’s Technology Innovation Showcase are modeling of nanoscale properties, nanoscale control of diamond thin films, and high-throughput nanoimprinting, all offering innovative nanotechnology solutions in use in real electronics products, and all with potential applications in other sectors as well.
Moving nanoimprint lithography into production
Nanoimprint lithography (NIL) looks like it’s starting to move from the lab into the factory at last. One customer is using Obducat AB’s NIL technology to produce an optical component that forms a part of a consumer product that’s now on the market. And other users are reportedly getting close to using the technology for producing high brightness LEDs, hard disks, and optical media.
Obducat says a new production model based on their NIL technology has a throughput of up to 30 wafers/hour, and asserts that the technology now looks scalable without major pain to higher volumes, with 90 wafers/hour its next goal. “Imprint is going to be the enabling lithography technique for people who want to print nanostructures in a very cost efficient way,” says Marc Beck, senior applications engineer at the Malmo, Sweden-based company.
Key to Obducat’s increased throughput is getting more mileage out of the costly wafer-scale master stamp, which has to be patterned very slowly with an e-beam. The company uses this permanent master to stamp out multiple disposable stamps on rolls of polymer to use for the actually imprinting. Pressing out the soft polymer stamps continually cleans the master, as any particles stick to the polymer. Pressing only the soft polymer prevents the damage to the master that occurs when a particle gets between the hard master and the hard target substrate. And using each polymer intermediary stamp only once prevents contamination. While one imprint head is stamping out the polymer stamps, a second head stamps the polymer stamps onto the substrate. Also potentially useful for scaling is Obducat’s use of a full-wafer stamp instead of a step and repeat system, and its soft press technology, which uses pressurized gas to apply pressure evenly across large and uneven substrates.
Screening new materials by modeling nanoscale effects
Plug the chemical elements of a material and a guess at its structure into Atomistix Inc.’s modeling software, and the computer will crunch out a prediction of the material’s electrical properties, based on the laws of quantum mechanics that govern electron transport at the nanoscale. The Copenhagen company says that modeling can screen new materials for desired properties considerably faster even than combinatorial synthesis experiments. Moreover, points out company president Kurt Stokbro, the model “shows how the material would work if it was perfect, and can quantify the impact of defects.” He notes that in a recent search for new spintronics memory structures, the model predicted what turned out to be the best material — though it took considerably longer to get the experiments to confirm that it worked.
“As geometries move further down the nanoscale, the costs of experiments continue to climb, but the cost of computing continues to plummet, so modeling becomes more and more cost effective,” points out Stokbro. He notes a recent study by market researcher IDC showing modeling software typically returned $3-$9 for every $1 invested in the pharmaceutical industry, where usage is more established, with the heaviest users getting the best returns.
The software allows researchers to build and manipulate atomic scale models of nanoelectronic devices, to calculate things like the transport properties of nanowires and carbon nanotubes, leakage voltage in semiconductor structures, and charge transfer in biological systems. It can also simulate how the measurement probe itself influences these nano systems, and calculate virtual measurement data that can be compared with experimental results.
The Atomistix models were developed over the last ten years at the Technical U. of Denmark, and have so far been used mostly by Ph.D.’s in theoretical physics or chemistry in research groups at universities and large companies. But the recent explosive growth in computer capability allows more intelligence to be built in to the model, and Atomistix is stepping up its efforts to make them easier for engineers to use, and offering training workshops and consulting help.
Adding diamond to the engineer’s toolkit
Advanced Diamond Technologies (ADT) aims to make diamond just another material for engineers to consider to get the performance they need. The Romeoville, IL, company is introducing diamond-on-insulator (DOI) wafers at SEMICON West, ready for sacrificial etching of MEMS devices, and it’s been releasing some diamond MEMS products of its own to show off the possibilities of devices designed to take advantage of diamond’s properties.
Diamond’s hardness means the structures — not just coated with diamond film, but actually made entirely out of diamond after the underlying oxide is etched away — don’t wear out as fast as silicon-based ones, and are naturally hydrophobic to prevent the micron-scale parts from sticking to each other, which are the source of major reliability issues. Diamond’s stiffness and light weight also means it vibrates at higher frequencies than most other materials, potentially making it an attractive material for things like MEMS radio frequency devices, pressure sensors, resonators, microphones, and AFM probe tips.
Diamond thin films have been around for some time, but they’ve typically been rough, highly variable, expensive, and in limited supply. ADT president Neil Kane says the company has shown it can meet very tight specifications with its patented diamond film technology, ultra-nanocrystalline diamond, which is grown one atom at a time in 3-5nm crystals by a CVD semiconductor process resulting in a highly smooth surface without polishing, and it’s now ramping up production to assure a reliable supply for MEMS makers to work with. “We’re making the wafers available, so designers can now start developing with diamond in ways that weren’t possible before,” he notes.
ADT has been working on exploiting the acoustic velocity of diamond for a high-frequency RF device for a rugged and broader-band wireless telecommunications system used in military and civilian applications in a DARPA-funded project. Also, the company is partnering with seal supplier John Crane Inc. to coat the surfaces of mechanical seals with the diamond film, to improve their friction and wear characteristics in extreme environments. And it’s working on diamond packaging and electrodes to improve the biocompatibility and reduce the size of implantable electronics, within the DOE’s efforts to develop an implantable electronic artificial retina or seeing-eye chip. — Dr. Paula Doe, SEMI
Reprinted with permission from Small Times.