A complex for nuclear doping of silicon with an extremely large diameter of more than 200 mm was put into commercial operation at the TPU research reactor. There are no nuclear facilities in the world yet, where it would be possible to irradiate ingots of a larger diameter.
Doping can significantly improve the properties of silicon as a semiconductor. This is the first production in Russia, and there are only a few of them in the world. Large-diameter silicon will allow the creation of more powerful electronics, including its use in green energy complexes, as well as reduce its cost. With the help of the new complex, it will be possible to irradiate up to four tons of silicon per year. Russian and Chinese semiconductor manufacturers are already showing interest in the new product.
The launch took place on September 7 as part of the Days of Atomic Science and Technology. It was dedicated to the 55th anniversary of the TPU research reactor. This is the only operating university reactor in the country and the only research reactor beyond the Urals.
The launch ceremony was attended by representatives of Rosatom State Corporation, TVEL Fuel Company, and the Siberian Chemical Combine.
Doping is a process in which atoms of other materials are introduced into a material in order to change or improve its properties. Nuclear doping means that these additives have appeared as a result of material irradiation. In this case, the feedstock is cylindrical ingots of superpure single-crystal silicon. After pre-treatment, silicon ingots are packed into containers and loaded into an experimental channel in the reactor core. There, under the influence of a neutron flux, uniform inclusions of phosphorus atoms appear in silicon. This makes silicon a good semiconductor, along with high resistance. This is important for use in electronics.
“The transition to large silicon diameters is a request of all global solar panel manufacturers. Within five years, TPU has created a channel that enables irradiating more than 200 mm silicon rods. For the next ten years, this is a good start for new technologies and manufacturing,” Vyacheslav Pershukov, special representative of Rosatom for International and Scientific and Technical Projects, said.
After being removed from the reactor core, silicon ingots are additionally “baked” in a special furnace at a temperature of about 800 degrees Celsius. This is necessary for the silicon atoms to fall into the right places after irradiation. Finished silicon is also sent to the customer in the ingot form. Ingots are cut into thin plates, and then into fragments of the desired size.
“We make technologically high quality silicon with more stable properties due to irradiation in a nuclear reactor. With the new complex, we are a unique technological facility within the country in this area. I warrant that this will help us to strengthen technological sovereignty.
At the same time, we do not focus on a specific area of ??further use of silicon. In this case, we are working with raw materials. We have seen a steady interest in large diameters in recent years from the market. Previously, the maximum diameter we worked with was 128 mm. This production line will continue to work, it is also in demand,” the Acting Rector of Tomsk Polytechnic University, Dmitry Sednev, said.
The new complex includes a 9-meter-long irradiation facility itself, most of which is hidden under the water of the reactor pool. It also includes neutron filters, silicon containers, a set of equipment in the accompanying rooms, such as a new furnace for post-reactor processing of ingots. This was preceded by serious calculating and preparatory work for several years, including two years of trial operation.
The total cost of the complex is a little more than 50 million rubles. These are federal budget funds allocated, in particular, within the framework of the federal targeted program, as well as TPU's own funds.