半导体的CO2激光退火和合金化

本文主要研究连续CO₂激光对半导体的照射效应。实验结果与理论分析说明,用连续CO₂激光照射可将半导体样片加热到所需的温度。与其它短波长的激光不同,波长为10.6μm的连续CO₂激光照射半导体有如下特点:CO₂激光是借助于自由载流子吸收与半导体耦合;样片在深度方向被均匀加热;激光背面照射可以增强退火效果。连续CO₂激光照射可以固相外延再生长的方式使As离子注入Si的损伤层退火恢复。在再生长的过程中注入的As离子进入替位,电激活率很高,而且不发生杂质再分布。将连续CO₂激光背面照射成功地应用于GaAsFET制备欧姆接触,既可避免激光正面照射对器件结构的破坏,又能得到比热退火为好的电学性能。关键词：

CW CO2-LASER ANNEALING AND ALLOYING OF SEMICONDUCTORS

The effects of CW CO₂-laser irradiation on semiconductors are studied with primary emphasis on the physics of the process. Experimental results and theoretical considerations show that semiconductor sample can be heated to desired temperatures by CW CO₂-laser irradiation. The CW CO₂-laser irradiation with wavelength of 10.6 μm is different from the other short wavelength lasers in the following features: light absorption of laser radiation through free carrier absorption, uniform temperature distribution throughout the thickness of the wafer, enhancement of annealing efficiency by laser irradiation from back surface. The temperature profile produced by stationary CW CO₂-laser irradiation is capable of annealing As⁺ ion implantation damage in Si with a solid-state regrowth mechanism. During the regrowth process the implanted As⁺ ions are incorporated into substitutional lattice sites and can be made electrically active to a high degree without redistribution of the original profile. Using CO₂-laser irradiation from the back surface we have produced ohmic contacts with excellent electrical properties for GaAsFET without damaging the device structure on the front surface.