In the Soviet era this factory produced crystals for microcircuits KR1821RU55B, M1821VI85A, M1821VI54, 1564IE19. The Soviet factory was closed in 1993 and remained abandoned for more than 25 years. However, as you may see on photos the site has been preserved very well.
Silicon monocrystals were grown in special production facilities, and then cut into thin wafers with a diamond saw. Further, the plates went through several stages of grinding and only after that they were sent to the areas of production of integrated circuits. In the manufacture of integrated circuits, a group production method was used, which implies the production of a large number of integrated circuits of the same type on one semiconductor wafer and the simultaneous processing of dozens of such wafers. The photo below shows what technnicians finally got – a round plate with a matrix of chips. After the completion of the manufacturing cycle, the wafers were cut in two mutually perpendicular directions into separate crystals, each of which was a separate integrated circuit.
To create the regions of an integrated circuit, a photolithography process is used. Since in this case it is not necessary to process the entire surface of the substrate (plate), then it is necessary to use the so-called masks, which affect only certain areas. Integrated circuits have dozens of layers, and each layer requires its own mask. In the photo you can see masks for different chips.
Chip production involves the imposition of thin layers with a complex “pattern” on silicon substrates. By applying and removing special substances on (and with) different areas, we obtain a certain structure on the silicon surface. To automate processes in the USSR, Lada-Elektronika installations were created. Outwardly, they stand out in orange and white housings. Plates can be washed on the lines; etching of layers; removal of photoresist from oxidized and metallized substrates.
After that, additional photolithography processes are carried out, with different materials, until the desired three-dimensional structure is obtained. Diffusion thermal installations are used to introduce impurities into the silicon layers. Depending on the gas, they allow for oxidation of substrates, forcing phosphorus or boron, annealing, gas etching. The trays with substrates are loaded into a quartz tube, the working zone of which is located inside a high-temperature furnace. A diffusant carried by a carrier gas (argon or nitrogen) and an oxygen flow are fed into the pipe. The photographs show an automated diffusion system of the ADS-6-100 model.
