NH_(3)和N_(2)混合等离子体预处理对锗MOS器件性能的影响  

Effect of NH_(3)/N_(2) Mixed Plasma Pretreatment on the Performance of Ge MOS Devices

作　　者：乌李瑛 柏荣旭 瞿敏妮 付学成[1] 田苗 马玲 王英[1] 程秀兰 WU Liying;BAI Rongxu;QU Minni;FU Xuecheng;TIAN Miao;MA Ling;WANG Ying;CHENG Xiulan(Center for Advanced Electronic Materials and Devices,School of Electronic Information and Electrical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Beneq Oy Shanghai Rep.Office,Shanghai 200135,China)

机构地区：[1]上海交通大学电子信息与电气工程学院先进电子材料与器件平台,上海200240 [2]芬兰倍耐克有限公司上海代表处,上海200135

出　　处：《材料导报》2021年第14期14012-14016,共5页Materials Reports

基　　金：国家科技部“十三五”高性能计算重点研发计划项目子课题(2016YFB0200205);2018年度上海研发公共服务平台建设项目(18DZ2295400);上海交通大学决策咨询课题(JCZXSJB2019-005,JCZXSJB2018-022)。

摘　　要：对锗衬底进行NH 3和N 2混合等离子体(V(NH_(3))∶V(N_(2))=5∶1)原位预处理,其自然氧化层GeO_(x)反应生成GeO_(y)N_(z)。XPS结果显示,随着预处理时间的延长,GeO_(y)N_(z)厚度稍有增加。结构为500 nm Al/20 nm Ti/10 nm HfO_(2)/Ge的锗MOS电容样品,在1 V的偏压下,未经过原位等离子体预处理的样品的漏电流密度为10^(-4) A/cm^(2)量级,而120 s NH_(3)/N_(2)混合等离子体预处理后的样品的漏电流密度减小到10^(-5) A/cm 2量级;所有等离子体预处理样品的C-V曲线不存在明显的翘曲变形,表明样品的界面陷阱电荷密度较低;通过C-V曲线计算可得,NH_(3)/N_(2)混合等离子体预处理60 s后样品的等效电容约为17,小于理想HfO_(2)的介电常数值,说明预处理条件下仍有不可忽略的层间电容。与其他预处理方法相比,NH_(3)/N_(2)混合等离子体原位预处理锗衬底可以更加有效地提高锗衬底上原子层沉积HfO_(2)层间界面的质量,抑制Ge向HfO_(2)的扩散,对界面的陷阱电荷有重要的限制作用。在提高锗MOS器件的性能方面,NH_(3)和N_(2)混合等离子体原位预处理的方法在工业生产中更具有潜在优势。The germanium substrates were pretreated in situ with a mixture of NH_(3) and N_(2) plasma,and the native oxide GeO_(x) were transformed to GeO_(y)N_(z).The XPS results showed that with the increase of pretreatment time,the thickness of GeO_(y)N_(z) increased slightly.For the germa-nium MOS capacitor samples with structure of 500 nm Al/20 nm Ti/10 nm HfO_(2)/Ge at the bias voltage of 1 V,the leakage current of the samples without in-situ plasma pretreatment were an order of 1×10^(-4) A/cm^(2),while the leakage current of the samples under the condition of 120 s NH_(3)/N_(2) mixed plasma pretreatment were reduced to an order of 1×10^(-5) A/cm^(2).The C-V curves of all samples pretreated by NH_(3)/N_(2) plasma showed no obvious warpage deformation,indicating that the interface trap charge density of the samples was low;according to the calculation of C-V curve,the equivalent capacitance of the sample for 60 s NH_(3)/N_(2) mixed plasma pretreatment is about 17,which is less than the dielectric constant value of ideal HfO_(2),indicating that there is still a non-negligible interface capacitance under the pretreatment condition.Compared with other pretreatment methods,in-situ pretreatment of germanium substrate by NH_(3)/N_(2) mixed plasma can more effectively improved the quality of interface of atomic layer deposited HfO_(2) on germanium substrate,inhibited the diffusion of Ge to HfO_(2),and played an important role in limiting the trap charge the interface.It had more potential advantages in improving the performance of Ge-MOS devices in industrial production.

关 键 词：锗MOS 原子层沉积 原位等离子体预处理 二氧化铪薄膜 高介电常数 漏电流密度 

分 类 号：TM21[一般工业技术—材料科学与工程]