Plasma-based processes and thin film equipment for nano-scale device fabrication

Plasma-based thin film equipment and processes have been widely used for micro-electronics, information storage sensors, and energy harvest/storage devices. To achieve higher package density, large storage capacity, and to meet other specific stringent design criteria, the film layer thickness is often reduced to a few nanometers or even to a few angstroms, while the device dimension has been shrinking to sub-micrometer scales. As the material thickness (h) approaches atomic dimension and the device dimension (w x d) approaches a few tens of nanometers, thin film layer uniformity and inter-layer mixing, as well as device edge damage control are crucial for its performance and reliability. In this review paper, we will discuss briefly vacuum and plasma aspects, followed by a detailed review on various plasma-based thin film deposition and removal techniques. The deposition methods discussed here include magnetron sputtering, ion beam deposition (IBD), and plasma enhanced chemical vapor deposition (PECVD). We focus on the advantages and disadvantages of various hardware configurations and how to achieve uniform film growth over large area with minimized interlayer mixing for any specific process. The device patterning aspects cover ion beam etching (IBE), reactive ion etching (RIE), and various techniques for end-point detection of etching processes. We discuss how the definition technique affects edge damage, profile, and dimension (w x d) control, as well as post-definition corrosion behavior. Some specific examples will be presented to highlight how the physical principles can be used in practice for film/device property control.