温度场的分布对多晶硅酸腐蚀绒面形貌的影响

Effect of Temperature Distribution on Acid-Etched Texturing of Multi-Crystalline Silicon

通过热传导方程,根据不同的边界条件,分别计算了多晶硅酸腐蚀反应时腐蚀坑周围的温度场分布。模拟计算表明:如在酸腐蚀液中采用制冷措施,使酸腐蚀液本体温度维持在15℃,会使硅表面腐蚀坑底部与腐蚀坑开口温度差变大,有利于绒面获得开口小深度大的陷阱坑;如不控制酸液温度,则会导致腐蚀坑底部与坑开口温度差较小,从而使硅片表面产生深度浅、开口大的陷阱坑。在不同的温度下对多晶表面进行酸腐蚀制绒,样品表面的扫描电子显微镜(SEM)图显示,低温下绒面腐蚀坑密度大、深度大且开口小,与模拟分析结果基本相符。

Using heat conduction equation, the temperature distributions around pits on multi-crystalline silicon surface are calculated under different boundary conditions during etching reaction. The simulation results show that the solution temperature of 15 ℃ controlled by cooling measures can result in an obvious temperature difference between the pits bottoms and multi-crystalline silicon surfaces. This difference is helpful to reduce the pits opening size as well as increase the pits depth. On the other hand, etching the multi-crystalline silicon surface without temperature control will make little temperature difference between the pits bottoms and multi-crystalline silicon surfaces, which produces the trap pits with the shallow and large opening. Silicon surfaces are textured under different temperature conditions in the experiment. Scanning electron microscope （SEM） image of experimental sample surface etched under the low-temperature condition shows the high-density distributions of trap pits with large pits depth and small opening. The experimental results can match the theoretical prediction well.