激光退火工藝能夠對硅片背面進行局部加熱，形成極高的溫度，可以有效修復離子注入破壞的晶體結構，獲得比傳統退火工藝更好的離子激活效率和激活深度，同時硅片正面的溫度較低，不損傷硅片正面器件，是絕緣柵雙極型晶體管（IGBT）背面工藝的重要步驟。該項目采用多光束合束技術，將10臺20W的532nm綠光分別耦合到1根圓光纖內，然后通過19X1光纖合束器將10根光纖合成一束200W的532nm激光，合束后的激光通過光束整形技術得到均勻的方光斑，照射到硅基表面進行激光退火，目前本項目已完成原理樣機的研制。相關的激光退火工藝的研究正在進行之中，并取得了較好的實驗結果，在硼注入的硅基上，經過激光退火后，其方塊電阻為60歐姆，激活深度0.6微米，激活效率>80%。通過本項目的研究，攻克了綠光激光的光纖耦合、19X1光纖合束、高斯光束轉平頂光束的光學整形系統、IGBT綠激光退火工藝等相關關鍵技術，提升了我國在IGBT器件生產的技術水平，在這一領域縮小了與國外發達國家的差距。

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.