InP晶圆背面减薄工艺中翘曲度的控制与矫正

Warpage Control and Correction of InP Wafer in Back-thinning Process

背面减薄是制备InP基光电子芯片的一道重要工艺。晶圆被减薄后失去结构支撑,会因应力作用产生剧烈形变,翘曲度大幅提高。严重的翘曲会使芯片可靠性降低甚至失效,应对晶圆的翘曲度进行控制和矫正。文章从"损伤层-翘曲度"理论出发,实验研究了晶圆厚度、粘片方式、研磨压力、磨盘转速、磨料粒径对翘曲度的影响。根据试验结果优化工艺参量,优化后晶圆的翘曲度降低了约20%;再通过湿法腐蚀去除损伤层,矫正已产生的翘曲,使晶圆的翘曲度降低约90%。优化减薄工艺降低损伤应力与湿法腐蚀去除损伤层分别是控制和矫正晶圆翘曲度的适用方法,可使翘曲度下降至之前的10%以内。

Back thinning is an important process for the fabrication of InP-based optoelectronic chips.When the wafer loses the structural support after thinning,its warping degree will increase due to the severe deformation caused by stress.Serious warping will reduce the chip reliability or even make it invalid,thus the warpage of the wafer should be controlled and corrected.In this paper,based on the theory of‘damage layer-warping degree’,the influences of wafer thickness,adhesive mode,grinding pressure,grinding speed and abrasive particle size on warping degree were analyzed.And the process parameters were optimized according to the test results,and the warping degree of the wafer was reduced by about 20%after optimization.Then wet corrosion was used to remove the damaged layer and correct the warping,which reduced the warping degree of the wafer by about 90%.Using the optimized thinning process to reduce the damage stress and wet-corrosion to remove the damage layer are the applicable methods for controlling and correcting the warping degree of the wafer,which can reduce the warping degree to be less than 10%of that before the back-thinning process.