To address the difficult challenges associated with ultra-shallow junction semiconductor fabrication, high power CO2 lasers are being employed for rapid thermal processing of silicon wafers. During semiconductor fabrication, doping agents are implanted within a ciystal lattice structure. These implanted dopants are electrically inactive because they reside on interstitial sites after the implantation. A thermal activation step is necessary to activate the doping agents and repair the damage done to the crystal structure during the semiconductor ion-implantation process. Laser Spike Anneal (LSA) technology combines a continuous-wave (CW) laser with projection optics and active beam feedback controls (uniformity, temperature, dwell time) to enable the ultra shallow junction formation. Mounted on an X-Y stage, the wafer is scanned under a stationary, shaped laser beam to locally heat and anneal exposed areas as it passes. The localized region reaches temperatures just slightly below the silicon melting point of 1412°C in a submillisecond time frame. The LSA process heats up only a thin layer of the silicon without causing damage to the whole wafer. This results in low resistivity and near diffusion-less junctions. The annealing process requires nano-scale precision while maintaining beam process yield quality under demanding through-put requirements.
Potential hazards involved during LSA processing include robotic motion, beam access, Laser Generated Air Contaminants (LGACs,) hot surfaces, confined space entry and high voltage. This paper will provide a brief introduction to how LSA is being applied to current semiconductor fabrication. Additionally, it investigates how engineering controls have been applied to product development to reduce potential risk while providing remote process analysis. Preventative measures include system User Interface (UI) controls, enclosures, interlocks, sensors, automation, including remote process analysis tools to evaluate real-time wafer transfer, positioning, beam process quality and error correction, while preventing operator access to potential hazards.