Selective and homo emitter junction formation using precise dopant concentration control by ion implantation and microwave, laser or furnace annealing techniques

摘要

We investigated phosphorus and boon implanted emitter and selective emitter junction formation comparing; 1) 15keV to 30keV implant energies, 2) implant dopant dose concentration between 3E14/cm2 to 1E16/cm2 and 3) various anneal conditions from high temperature (>1407°C) laser melt annealing to low temperature (<500°C) microwave annealing and furnace anneals between 750°C to 1050°C for dopant activation and diffusion. By engineering and optimizing dopant concentration with anneals we could realize homo emitter and selective emitter junctions from 0.25um to 1.5um depth with sheet resistance from 9Ω/□ to 2200Ω/□ and peak surface dopant electrical activation levels from 4E18/cm3 up to 5E20/cm3. Highest dopant activation efficiency was achieved with liquid phase junction diffusion formation method using laser melt annealing and was limited by the dopant source concentration if <2E16/cm2. The POCl3 dopant source concentration of 1E16/cm2 was only 15% efficient with furnace solid phase diffusion activation while laser melt liquid phase diffusion activation was 45% compared to implant which was 35% active with solid phase diffusion and 100% active with liquid phase diffusion.