Real-Time In Situ Parallel Detection of Elements and Molecules with TOFMS during ALD for Chemical Quality Control of Thin Films

The extraordinary properties of thin films result from their 2D structure, (i.e., one dimension is negligibly small when compared with the two others). Consequently, precise and well-established fabrication methods are required to provide appropriate functionality of these materials, such as hardness, resistance to mechanical stress, durability, or chemical/electrical stability. In this work, we present the potential of integrating a time-of-flight mass spectrometer (TOFMS) with atomic layer deposition (ALD) for real-time control of thin-film fabrication processes. This technique provides parallel detection of all ionized molecules and ionized fragments; therefore, the limitations of commonly used quadrupole mass spectrometers are overcome. Furthermore, since the chemical data acquisition is conducted in situ, the results of applied deposition parameters can be observed on-line allowing for immediate modifications, for example, in the case of process deviation from optimal or failure. The presented monitoring method is expected to be broadly applied in many deposition or etching processes, in which accurate chemical composition and strict end point control are demanded, such as manufacture of microdevices (for new energy solutions and microelectronics), protective surface coatings, actuators, sensors, and biomedical applications