Tom Thieme graduated from the University of Applied Sciences Berlin (Germany) in process and environmental engineering. Thereafter, 15 years as a professional in the global electronic and semiconductor industry gave him a distinguished experience in semiconductor related product support, marketing and sales.
Initially, as global product manager of TOTAL’s special chemical division, he approached the Asian silicon memory and CMOS semiconductor industry. This gave him a strong technical background on metal deposition processes for silicon and compound semiconductor application and wafer level packaging technologies. Since 2010 Tom is with LayTec and contributed very successfully to LayTec’s extraordinary success in the Greater China’s LED industry. As business development manager he helped our customers to take the full advantage of LayTec’s in-situ metrology products for compound semiconductor MOVPE processes. Based on his profound understanding of both, compound semiconductor customer needs and technology of integrated metrology he efficiently communicates the requests of our customers in the field back to LayTec’s R&D and application engineering teams. Since 2012 Tom is General Sales Manager of LayTec’s compound semiconductor division and since 2013 director marketing and sales.
Currently the LED industry is heading towards a period of competitive consolidation. As both the performance and efficiency of today’s LEDs are already good enough to outrun all conventional light sources, leading players in the field are now targeting a rigorous cost reduction throughout the complete LED supply chain in order to become also price competitive to the established light sources. Cost per lumen has to be reduced much faster than initially predicted. Especially the epitaxial growth process as the first and most critical part of LED production provides significant potential for cost reduction. The straight forward approach to cost reduction therefore is increasing the metal organic chemical vapor phase deposition (MOCVD) tool capacity and throughput. This is typically combined with increased wafer sizes (6” in case of sapphire substrates) and more recently also with lowering material cost by using silicon wafers (allowing 8” substrates to be used as well). All these measures require advanced in-situ monitoring to improve production yield and ensure process stability. In our paper we will focus on tight control of III-N LED processes and best practice strategies for process optimization by advanced in-situ metrology.
In-situ measurements provide real-time access to key parameters the epitaxial growth process, which can be used for quality improvement and cost reduction in the entire LED supply chain. Precise growth temperature measurements with an accuracy of ± 1K and wafer bow measurements during GaN buffer and active layer growth, as well as growth rate and morphology measurement of the individual layers of the compound semiconductor structure are key process information for statistical process control (SPC) and equipment engineering. SPC is typically used to narrow down process deviations between different production systems in a fab, as well as to improve the production quality from run to run. The ongoing trend to increase wafer size and consider alternative substrate materials to reduce manufacturing cost, necessitates the understanding of wafer stress root causes and their compensation. Such process know-how enables experienced engineers to set tight process specifications, which can be used to control the growth by advanced real-time in-situ data analysis. Hence, the process quality control and supervision of all LED production systems by fab wide in-situ metrology, using standardized interfaces for data transfer, will help to improve LED production yield substantially and to reduce cost.