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在先进的多功能金属栅极MOSFET中作为湿法蚀刻停止层的氮化钽薄膜的结构表征

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发表于 2018-12-6 10:39:57 | 显示全部楼层 |阅读模式
Structural characterization of tantalum nitride films as wet etch stop layer in advanced multiwork function metal gate MOSFETs
在先进的多功能金属栅极MOSFET中作为湿法蚀刻停止层的氮化钽薄膜的结构表征

Journal of Vacuum Science & Technology B 36, 062904 (2018);

https://doi.org/10.1116/1.5044633
Petra Mennell1,a),b), Hamed Parvaneh2,b), Zeynel Bayindir2, Dong Hun Kang2, Frieder Baumann2, Anita Madan2, Abner Bello2, Ashawaraya Shalini3, and Mark Klare3
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1GLOBALFOUNDRIES Fab 10, 2070 Route 52, Hopewell Junction, New York 12533
2GLOBALFOUNDRIES Fab 8, 400 Stonebreak Extension Road, Malta, New York 12020
3Nova Measuring Instruments Inc., 3090 Oakmead Village Dr., Santa Clara, California 95051
a)Electronic mail: petra.mennell@globalfoundries.com
b)P. Mennell and H. Parvaneh contributed equally to this work.

ABSTRACT
摘要

As the dimensions of semiconductor devices become smaller, the use of high-k materials as gate oxides has become necessary for controlling gate leakage current. In addition, to achieve higher performance, conventional polysilicon metal gates have been replaced with multistack metal electrodes with engineered work functions. Thus, a suite of devices with different levels of performance and power usage is available. The integration scheme to create such structures involves an additional deposition step and selective wet etching of titanium nitride (TiN) in a complex patterning scheme following the high-k film deposition. Tantalum nitride (TaN) is one of the candidates used as an etch stop layer in a bilayer scheme of TaN/TiN. This prevents any exposure of high-k hafnium oxide (HfO2) gate oxide to wet etch chemistry in the patterning scheme, which could cause damage and/or skimming, resulting in undesirable effects on device characteristics and reliability. In order to accommodate for shrinking trench widths, these bilayer stacks are kept as thin as possible, which makes monitoring the thickness during various patterning steps very challenging. In this study, the authors present an approach to an offline and inline metrology setup. In order to gain insight into basic layer growth and interdiffusion characteristics, they used x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. They utilized specular x-ray reflectivity as a first principles method, followed by wavelength dispersive x-ray fluorescence to gain insight into cross-wafer variation on blanket wafers. The results were then fed into models developed for the x-ray photoelectron spectroscopy technique, which can be used as an inline method to characterize the composition and thickness of the patterned wafers for both as-deposited and postetching.

        随着半导体器件的尺寸变小,使用高k材料作为栅极氧化物已成为控制栅极漏电流的必要条件。此外,为了实现更高的性能,传统的多晶硅金属栅极已被具有工程功能的多层金属电极所取代。因此,可以使用具有不同性能和功率供给的一套设备。创建这种结构的集成方案涉及额外的沉积步骤和在复杂图案化设计中的选择性湿法蚀刻氮化钛(TiN),后者是在高k膜沉积之后进行的。氮化钽(TaN)是用作TaN / TiN双层方案中的蚀刻停止层的候选者之一。它防止了高k氧化铪 (HfO2) 栅极氧化物在图案化过程中暴露于湿蚀刻化学物质,否则可能导致损坏和/或缺失,从而造成对器件特性和可靠性的不良的影响。为了适应缩小了的沟槽宽度,这些双层叠层要保持尽可能的薄,因此, 在各种图案化步骤期间监测厚度非常具有挑战性。为了深入了解基本层生长和相互扩散特性,他们使用了X-射线光电子能谱和高分辨率透射电子显微镜。在这项研究中,作者提出了离线和在线计量设置的方法。作为第一原理方法, 他们利用了镜面X-射线反射率,然后使用波长色散X-射线荧光来深入了解覆盖晶片上的跨晶片变化。然后将结果输入到用于X-射线光电子能谱技术的模型中,该技术可以作为在线方法来表征用于沉积和后处理的图案化晶片的组分和厚度。


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