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脉冲激光退火具有热积存小、高温影响深度浅等优点,用来制备Si C欧姆接触可以忽略高温对衬底背面结构的影响,更好地与减薄工艺兼容,从而提高器件性能。借助波长为532 nm的固态Nd∶YAG激光器退火Ni/4H-Si C结构,分析了激光脉冲能量与脉冲个数对欧姆接触的影响。实验表明,激光脉冲能量对于Ni/4H-Si C欧姆接触的形成起主要作用,只有脉冲能量高于1.8 J/cm2的激光束才有可能形成欧姆接触。对于能量过小的激光脉冲,即使增加脉冲个数也无法形成欧姆接触。当激光脉冲能量为2.3 J/cm2,脉冲数为60个时可形成良好的欧姆接触,比接触电阻为4.8×10-5Ω·cm2。当激光脉冲能量为3.6 J/cm2时,单脉冲就可实现欧姆接触,比接触电阻为7.0×10-5Ω·cm2。脉冲数越少、脉冲能量越高的激光退火方式总能量消耗相对较少、能效较高。
The pulsed laser annealing has the advantages of small heat accumulation and high temperature and shallow depth. The Si C ohmic contact can neglect the influence of high temperature on the back structure of the substrate and is better compatible with the thinning process to improve device performance. The influence of laser pulse energy and pulse number on the ohmic contact was analyzed by annealing the Ni / 4H-Si C structure with a solid-state Nd:YAG laser at a wavelength of 532 nm. Experiments show that the laser pulse energy plays a major role in the formation of ohmic contact of Ni / 4H-Si C, and only the laser beam with pulse energy higher than 1.8 J / cm2 is likely to form ohmic contact. For laser pulses with too small energy, ohmic contacts can not be formed even if the number of pulses is increased. When the laser pulse energy is 2.3 J / cm2, the number of pulses is 60, a good ohmic contact can be formed, and the specific contact resistance is 4.8 × 10 -5 Ω · cm 2. When the laser pulse energy is 3.6 J / cm2, a single pulse can achieve ohmic contact, the specific resistance is 7.0 × 10-5Ω · cm2. The smaller the number of pulses, the higher the pulse energy laser annealing total energy consumption is relatively small, high energy efficiency.