Real-time process control of molecular beam epitaxy using in situ optical sensors

Summary form only given. Molecular beam epitaxy (MBE) is currently the most powerful and flexible growth method available for the fabrication of advanced device structures for nanoelectronics. Sensor technology is now sufficiently mature to make real-time sensor feedback control of the major process parameters of MBE a realistic and practical possibility of fabricating resonant tunneling diodes (RTDs), and IR photodetectors. The design and operation of a system is described, beginning with a discussion of the individual sensors and the physical basis for their operation. Then, the system performance is illustrated through specific examples of real-time sensor-feedback control of substrate temperature and layer composition during the growth of InGaAs-InAlAs HBTs, and control of barrier layer thickness for AlAs-InGaAs RTDs, with quantitative results on the improved repeatability achieved through the use of sensor-based control.