Millisecond annealing with flash lamps: tool and process challenges

Sub-second annealing is one of the key issues to meet the requirements of the 45 nm technology node according to the ITRS roadmap. Therefore, over the past decade there has been great interest in techniques such as laser and flash lamp annealing (FLA). In addition, advanced ultra-fast annealing shows promise for technologies that are not directly related to Si device processing. The main reason for using FLA in alternative applications is the reduced thermal budget because of the short annealing time, which enables one to achieve high temperatures (> 500°C) in the near-surface region while keeping the substrate bulk relatively cold. This is of particularly high importance for the development of novel polymer-based electronics and flexible solar cell technologies, where the substrates cannot withstand temperatures in excess of 150°C. An overview of theoretical simulations and related results from FLA experiments for a variety of layered systems is given. The influence of the flash duration and intensity on the heat distribution and the resulting physical properties is considered. Design and performance issues of the FLA tools depending on the specific uses and technical requirements are addressed. Furthermore, topics covered include high-throughput applications e.g. for roll-to-roll production of polymer substrates. Results of a prototype tool for multi-flash processing up to a frequency of 1 Hz using a pulse duration of 1 ms are also discussed.