激光退火形成Ni/4H-SiC欧姆接触

Ni/4H-SiC Ohmic Contact Formed by Laser Annealing

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。

Pulse laser annealing has the advantages of short thermal budget and shallow high tempe- rature impact depth, thus the impact of high temperature could be ignored for fabricating SiC ohmic con- tact, compatible with grinding process and therefore the performance of devices were promoted. The influences of the laser pulse energy and pulse number on the ohmic contact were analyzed by means of solidstate Nd ： YAG laser annealing Ni/4H-SiC with the wave length of 532 nm. The experimental results show that the laser pulse energy plays a more important role in forming Ni/4H-SiC ohmic contact, and only when the pulse energy is higher than 1.8 J/cm2, is it possible to achieve ohmic contact. The laser pulse without sufficient energy could not achieve ohmic contact even by increasing the number of laser shots. When the laser pulse energy is 2. 3 J/cm2 and the pulse number is 60, a good ohmic contact can be formed, and the specific contact resistance is 4. 8×10^-5Ω·cm^2. When the laser pulse energy is 3.6 J/cm2, the ohmic contact can be formed by the single pulse, and the specific contact resistance is 7. 0×10^-5Ω·cm^2. The laser annealing method performed with higher pulse energy and fewer shots owns smaller total power consumption and higher efficiency.