A new method of applying thin layers of atoms has appeared. It was presented by scientists from the USA, they were inspired by the device of a household humidifier.
Researchers from the University of Alabama presented a new method of applying thin layers of atoms as a coating on the material at temperatures close to room temperature. The scientists used ultrasonic atomization technology to vaporize chemicals used in atomic layer deposition (ALD).
“ALD is a method of applying three-dimensional thin films, which plays an important role in the production of microelectronics, in particular, such elements as central processors, memory and hard drives,” the scientists noted. Each ALD cycle applies a layer several atoms deep.
ALD processes typically use heated molecules in the gas phase that evaporate from solid or liquid form – much like room humidifiers that use heat to evaporate water. However, in this process some chemical elements are unstable and can decompose before the vapor pressure begins.
“Ultrasonic spraying, developed by our research team, allows low vapor pressure precursors to be produced because evaporation was caused by ultrasonic vibration of the module. As with a domestic humidifier, ultrasonic spraying creates a mist consisting of saturated steam and microdrops. The micron-sized droplets continuously evaporate and are applied to the material surface,” the researchers noted.
In this process, an ultrasonic transducer is used, placed in a liquid chemical precursor. After start-up, the device starts to vibrate at a rate of several hundred times per second and creates a mist of material. Small droplets of liquid in the mist quickly evaporate in the gas collector under vacuum and mild heat treatment, leaving an even layer of applied material.