激光退火工艺能够对硅片背面进行局部加热，形成极高的温度，可以有效修复离子注入破坏的晶体结构，获得比传统退火工艺更好的离子激活效率和激活深度，同时硅片正面的温度较低，不损伤硅片正面器件，是绝缘栅双极型晶体管（IGBT）背面工艺的重要步骤。该项目采用多光束合束技术，将10台20W的532nm绿光分别耦合到1根圆光纤内，然后通过19X1光纤合束器将10根光纤合成一束200W的532nm激光，合束后的激光通过光束整形技术得到均匀的方光斑，照射到硅基表面进行激光退火，目前本项目已完成原理样机的研制。相关的激光退火工艺的研究正在进行之中，并取得了较好的实验结果，在硼注入的硅基上，经过激光退火后，其方块电阻为60欧姆，激活深度0.6微米，激活效率>80%。通过本项目的研究，攻克了绿光激光的光纤耦合、19X1光纤合束、高斯光束转平顶光束的光学整形系统、IGBT绿激光退火工艺等相关关键技术，提升了我国在IGBT器件生产的技术水平，在这一领域缩小了与国外发达国家的差距。

Laser annealing

Laser annealing can locally heat on the back of wafer to reach a high temperature, so the crystal structure damaged by ion implantation can be effectively repaired. And laser annealing can obtain higher activation efficiency and deeper activation depth than the traditional annealing process. Because the temperature is low on the front of wafer, the devices are not damaged on the front. Laser annealing is the important processing step of the back of insulated gate bipolar transistor (IGBT).

The process uses multi-beam combination technology that ten light beams of 20W green light of 532nm are coupled to one light beam of 200W through fiber combiner. Then Gauss beam is shaped to flattened beam to irradiate silicon base surface for annealing. Currently, we have completed development of prototype and achieved good experiment results. After boron-implanted silicon are annealed, the lowest sheet resistance reaches 60Ω, activation depth reaches 0.6 µｍ and activation efficiency is greater than 80%. The study of the project conquers multi-beam combination technology, Gaussian beam shaped to flattened beam, laser annealing process of IGBT and other related key technologies, improves Chinese technical level of production of IGBT devices, narrows the gap with other developed countries in this field.