脉冲镀金在半导体激光器中的应用及工艺优化

Application and process optimization of pulse Au-plating in semiconductor laser

为提高半导体激光器芯片的焊接成功率以及器件的性能寿命，采用脉冲电镀技术在半导体激光器芯片 P 面沉积了厚金层，详细研究了镀金液 pH 值和电流通断比对镀金层组织形貌、表面粗糙度、内应力、沉积均匀性以及粘附力的影响规律。结果表明，表面粗糙度随 pH 值的升高或通断比的提高而增大。沉积均匀性随 pH 的增大先降低后升高，而随通断比的增大而变差。pH 较大（＞10．0）或较小（＜8．5）时，镀金层粘附性均不理想。而通断比对镀金层的粘附性影响不大。不同条件下，金膜内应力均为张应力，大小为29～88 MPa。

In order to increase the welding yield,the property and the life of semiconductor laser,thick Au films were deposited on the P-side of semiconductor laser chip by pulse electroplating technology.The effects of pH and on/off ratio of gold plating liquid on the morphology,surface roughness,intrinsic stress,uniformity and adhesion of the Au films were studied comprehensively.The results show that the surface roughness increases with the increase of pH or on/off ratio.The deposition uniformity firstly decreases then increases with the pH increasing from 8.0 to 1 0.0,while becomes worse with the increase of on/off ratio.The adhesions between the Au films and laser chips are not excellent when the pH is too high（〉1 0.0）or too low（〈8.5）.However,the on/off ratio has a weak effect on the adhesion of Au films.The intrinsic stresses of Au films platted under different conditions are tensile with the range from 29 to 88 MPa.