Original Date: 01/27/1997
Revision Date: 01/18/2007
Best Practice : Semiconductor Technology
As a world expert in laser recrystallization and doping of silicon for semiconductor devices, Lawrence Livermore National Laboratory’s (LLNL’s) Advanced Process Development Group has been developing and demonstrating technologies which may replace ion implantation for 0.18-micrometer and below generations of integrated circuits. Those LLNL programs with the greatest potential for quantum-leap impacts in the semiconductor industry include gas immersion laser doping (GILD); poly-silicon electronics on plastic; micron thin crystalline silicon electronics; and two-dimensional ion implant and heat flow modeling.
GILD applies LLNL’s technology base of GILD to shallow junction formation in submicron CMOS integrated circuit processing and low power electronics. GILD has proven to be superior over other doping techniques primarily because of its improved reduction in thermal budgets. The technique is adaptable to a step-and-repeat laser process which can result in the combination of the doping and lithographic processes into one step.
Poly-silicon electronics on plastic applies LLNL’s technology base of low temperature depositions, pulsed laser crystallization, and doping to silicon thin film transistor fabrication on plastic substrates for low-cost, flexible rugged electronics. LLNL’s fabrication techniques produce processing temperatures of less than 100°C on polyester, a laser crystallized channel, and a laser doped source-drain which resulted in thin-film transistor yields of 90% on a four- inch wafer.
Micron thin crystalline silicon electronics applies LLNL’s technology base of silicon circuit transfer on arbitrary substrates to high-performance flexible silicon and thin electronics on any material. By converting crystalline silicon wafers to flexible circuits on plastic or metal-foil holding substrates, this technology achieves very large scale integration density circuits at low power and light weight. The final product is a robust sheet of micron thin flexible silicon microelectronics.
Two-dimensional implant and heat flow modeling applies LLNL’s technology base of modeling and simulation to focused ion beam machining and GILD two-dimensional, non-equilibrium melting and heat flow. The technology incorporates heat flow data into SUPREM IV; however, the method has not been fully tested. Two-dimensional melt and solidification modeling has had limited testing on a square heat-flow mesh. This modeling has produced laser material interaction from a simple model.
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