钌表面上锡及其氧化污染物的原位清洗研究

Investigation of in-situ cleaning for tin and its oxidized contaminants on ruthenium

本文介绍了在多层反射镜钌表面原位清洗锡及其氧化污染物的实验研究.实验通过物理气相沉积(PVD)方法制备颗粒状和薄膜状锡及其氧化污染物,并采用朗缪尔探针和减速场离子能量分析仪(RFEA)对不同功率的氢等离子体进行了系统分析.对比颗粒状和薄膜状锡及其氧化污染物的清洗速率后发现,颗粒状污染物顶部的清洗速率最高,其平均清洗速率次之,而薄膜状污染物的清洗速率最低.XPS结果表明经过低功率(1 W)等离子体清洗后,锡氧键断裂并发生了化学还原过程.扫描电镜截面图像显示低功率清洗后底部的薄膜厚度增加,指明清洗过程中的再沉积现象.TRIM模拟说明高功率(10 W)下氢注入深度超过钌膜厚度,而低功率(1 W)下氢注入深度小于钌膜厚度.钌膜的粗糙度在1 W照射10 h后仍保持稳定.在化学还原和刻蚀过程中,氢离子和氢自由基分别起到断裂化学键和反应物的作用.根据上述结果推断,低功率(1 W)氢等离子体可实现对锡及其氧化污染物的无损原位清洗.

An experimental study of in-situ cleaning of tin and its oxide contaminants on the surfaces of the ruthenium layers of multilayer mirrors.Granules and thin films of tin with oxide contaminants were deposited on ruthenium surfaces by a physical vapor deposition(PVD).The hydrogen plasma for cleaning at different powers was systematically diagnosed by a Langmuir probe and a retarding field ion energy analyzer(RFEA).Comparisons of the cleaning rates of the tin granules and thin films with oxide contaminants revealed that the cleaning rate on top of the granular contaminants was the highest,while the cleaning rate of contaminants on the tin thin film is the lowest.The XPS analyses of the Sn 3d peaks demonstrated a breakage of tin-oxygen bonds and a process of chemical reduction after 1 W cleaning.The SEM cross-section images showed an increase of the base film thickness after 1 W cleaning,indicating a phenomenon of redeposition during the cleaning processes.The TRIM simulations illustrated that the hydrogen injection depth was larger at the high power(10 W),whereas was lower at the low power(1 W)than the ruthenium film thickness.The roughness of the ruthenium film substrate remained stable during the 10 h and 1 W irradiation.During chemical reduction and etching,hydrogen ions and hydrogen radicals play roles of breaking chemical bonds and reactants,respectively.According to the above results,it is found that the low-power(1 W)hydrogen plasma can achieve a non-destructive in-situ cleaning of tin and its oxide contaminants.