包含偏硅酸影响的3D NAND磷酸湿法刻蚀动力学  

Kinetics of 3D NAND flash wet etching with phosphoric acid under the influence of H2SiO3

作　　者：彭子林 周蕾 邓庆航 叶光华[1] 周兴贵[1] PENG Zilin;ZHOU Lei;DENG Qinghang;YE Guanghua;ZHOU Xinggui(State Key Laboratory of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化学工程联合国家重点实验室,上海200237

出　　处：《化工学报》2025年第2期645-653,共9页CIESC Journal

基　　金：国家自然科学基金项目(22378115)。

摘　　要：以磷酸为刻蚀剂选择性刻蚀Si_(3)N_(4)和SiO_(2)堆叠结构中的Si_(3)N_(4),是3D NAND闪存芯片制造过程中最关键的步骤之一。随着3D NAND存储单元堆叠层数的不断升高,扩散限制越来越严重,刻蚀产物偏硅酸浓度梯度不断加大,致使刻蚀工艺面临刻蚀选择性低、氧化物回沾等问题。针对上述3D NAND湿法刻蚀问题,结合表征和动力学实验,获得了有无偏硅酸影响的磷酸刻蚀Si_(3)N_(4)和SiO_(2)动力学模型。结果显示Si_(3)N_(4)刻蚀过程是水和磷酸等含氧亲核试剂对Si原子的亲核攻击过程,磷酸刻蚀Si_(3)N_(4)和SiO_(2)的反应活化能分别为60.71 kJ·mol^(-1)和66.90 kJ·mol^(-1),亲核试剂破坏Si—O键所需能量高于Si—N键。包含偏硅酸影响的Si_(3)N_(4)和SiO_(2)刻蚀动力学显示偏硅酸浓度越高Si_(3)N_(4)和SiO_(2)的刻蚀速率越小,并且SiO_(2)刻蚀速率对偏硅酸浓度的变化更敏感。本工作的研究结果可为3D NAND磷酸湿法刻蚀工艺的设计优化提供一定的基础数据和理论认识。Selective etching of Si_(3)N_(4)in a stacked structure of Si_(3)N_(4)and SiO_(2)using phosphoric acid as an etchant is one of the most critical steps in the manufacturing process of 3D NAND flash memory chips.With the increasing number of stacked layers,diffusion limitation becomes important and the concentration gradient of the etching product H2SiO3 becomes large,which brings the problems of low etching selectivity and serious oxide regrowth in this etching process.Facing these above-mentioned problems,this work combines characterizations and kinetics experiments to obtain the kinetics models of Si_(3)N_(4)and SiO_(2)etched by phosphoric acid with or without the influence of H2SiO3.The results show the etch of Si_(3)N_(4)is the nucleophilic attack of Si by the nucleophilic reagents,like water and phosphoric acid.The activation energies for etching Si_(3)N_(4)and SiO_(2)by phosphoric acid are 60.71 kJ·mol^(-1)and 66.90 kJ·mol^(-1),indicating the energy required to break Si—O bond is larger than that to break Si—N bond under the attack of nucleophilic reagents.The etching kinetics of Si_(3)N_(4)and SiO_(2)with the influence of H2SiO3 concentration show that the etching rates of Si_(3)N_(4)and SiO_(2)decrease with the increase of H2SiO3 concentration,and the etching rate of SiO_(2)is more sensitive to the change of H2SiO3 concentration.The results in this work should provide some fundamental data and theoretical understanding for the optimal design of phosphate wet etching process for manufacturing 3D NAND.

关 键 词：3D NAND闪存 湿法刻蚀 氮化硅 氧化硅 偏硅酸 化学反应 动力学 动力学模型 

分 类 号：TQ031[化学工程]