Microwave based technique for ultra-fast and ultra-high temperature thermal processing of compound semiconductors and nano-scale Si semiconductors

The 'hotter and faster' trend in rapid thermal processing (RTP) of semiconductors requires RTP equipment to be capable of reaching very high temperature along with very fast ramping and cooling rates. To fulfill the critical needs of the future RTP technology, LT technologies (LTT) has been developing a solid state, cavity-less and variable frequency based microwave technology capable of generating high-power, short-duration, spatially uniform, and material-specific microwave pulses. Ultra-high temperatures above 2000°C can be reached within a fraction of second. Moreover, the use of microwaves has an advantage of selectively heating the targeted features within the wafer volume while essentially having no significant thermal effects on other parts of wafer materials with different electrical properties. A PC based control system is also developed to regulate temperature uniformity and stability. In this paper, the results on post implant annealing of Al⁺ implanted 4H-SiC, and Mg⁺ implanted GaN using LTT's microwave RTP apparatus are discussed. These results demonstrate that microwave RTP technology offers significant improvements in performance and quality of SiC and GaN compound semiconductors including: (1) unprecedented ultra-low sheet resistance (2) very high carrier mobility and (3) perfect lattice damage recovery and defects elimination. Discussion will also be given to address the potentials and advantages of LTT's microwave technology in applications of millisecond annealing of Si based ultra-shallow junction (USJ) devices.