低温碳纳米管垂直互连的制作兼容半导体技术
Summary
A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.
Abstract
We demonstrate a method for the low temperature growth (350 °C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-κ dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.
Introduction
铜和钨，这是目前用于国家的最先进的非常大规模集成电路（VLSI）技术的互连金属，正在接近的可靠性和电导率1项自己的体能极限。而向下缩放晶体管通常可以提高它们的性能，但实际上增加了电阻和互连的电流密度。这导致互连支配在延迟和功耗2方面的集成电路（IC）的性能。
碳纳米管（CNT）被建议作为替代的Cu和W的金属化，特别是对垂直互连（通孔），为的CNT可以很容易地被生长垂直3。碳纳米管已被证明具有优良的电可靠性，允许高达1000倍更高的电流密度比铜4。此外，CNT不会从表面和晶界散射受到影响，这是增加第r铜esistivity在纳米尺度5。最后，碳纳米管已经被证明是优良的热导体 6，其中所用的热管理在VLSI芯片帮助。
对于碳纳米管在VLSI技术成功的集成是很重要的，对于碳纳米管的生长过程是用半导体制造兼容。这要求使用的材料和这被认为是兼容和可扩展的，以大规模的制造设备的CNT（<400℃）的低温生长。虽然CNT测试过孔许多实例已被证明在文献中7,8,9,10,11,12,13,14，大多数这些使用铁作为催化剂，它被认为是在集成电路中的污染物的制造15。此外，在许多这些作品中使用的生长温度高于400℃的上限要高得多。优选的CNT甚至应种植在350℃以下，为了让拥有现代化的低κ电介质或灵活的集成基材。
在这里，我们提出了一个可扩展的方法生长碳纳米管在温度低至350℃下使用钴作为催化剂 16。该方法是用于制造不同电结构由垂直对准的CNT的集成电路，从互连和电极，以超级电容器和场致发射装置的兴趣。钴催化剂金属通常用在集成电路制造为硅化物的17的制造中，而氮化钛是一种经常用于阻挡材料7。此外，我们证明了制造CNT的测试孔，而只能使用从标准的半导体制造技术的过程。由此，CNT测试过孔被制造，检查通过扫描电子显微镜（SEM）和拉曼光谱，并且电特征。
Protocol
Representative Results
Discussion
图1显示制造在这项工作中的结构的示意图，并且其被用于4点探针测量。作为电位通过探针携带没有电流测量，准确的电位降（Vħ-V L），在中央CNT束及其触点的金属可以被测量。更大直径的CNT束被用于接触从接触垫的底TiN层，以减少用于当前迫使探头的总电阻并最大化在中央CNT束中的电势降。
如从图2可以看出，在CNT被成功地生…
Divulgations
The authors have nothing to disclose.
Acknowledgements
Part of the work has been performed in the project JEMSiP_3D, which is funded by the Public Authorities in France, Germany, Hungary, The Netherlands, Norway and Sweden, as well as by the ENIAC Joint Undertaking. The authors would like to thank the Dimes Technology Centre staff for processing support.
Materials
| Materials | Company | Catalog Number | Comments/Description |
| Si (100) wafer 4" | International Wafer Service | Resisitivity: 2-5 mΩ-cm, thickness: 525 µm | |
| Ti-sputtertarget (99.995 % purity) | Praxair | ||
| Al (1% Si)-sputtertarget (99.999 % purity) | Praxair | ||
| Co (99.95 % purity) | Kurt J. Lesker | ||
| Chemicals | Company | Catalog Number | Comments/Description |
| SPR3012 positive photoresist | Dow Electronic Materials | ||
| MF-322 developer | Dow Electronic Materials | ||
| HNO3 (99.9 %) | KMG Ultra Pure Chemicals | ||
| HNO3 (69.5%) | KMG Ultra Pure Chemicals | ||
| HF 0.55% | Honeywell | ||
| Tetrahydrofuran | JT Baker | ||
| Acetone | Sigma-Aldrich | ||
| ECI3027 positive photoresist | AZ | ||
| Tetraethyl orthosilicate (TEOS) | Praxair | ||
| Gasses | Company | Catalog Number | Comments/Description |
| N2 (99.9990%) | Praxair | ||
| O2 (99.9999%) | Praxair | ||
| CF4 (99.9970%) | Praxair | ||
| CL2 (99.9900%) | Praxair | ||
| HBr (99.9950%) | Praxair | ||
| Ar (99.9990%) | Praxair | ||
| C2F6 (99.9990%) | Praxair | ||
| CHF3 (99.9950%) | Praxair | ||
| H2 (99.9950%) | Praxair | ||
| C2H2 (99.6000%) | Praxair | ||
| Equipment | Company | Catalog Number | Comments/Description |
| EVG 120 coater/developer | EVG | ||
| ASML PAS5500/80 waferstepper | ASML | ||
| SPTS Ωmega 201 plasma etcher | SPTS | Used for Si and metal etching | |
| SPTS Σigma sputter coater | SPTS | ||
| Novellus Concept One PECVD | LAM | ||
| Drytek 384T plasma etcher | LAM | Used for oxide etching | |
| CHA Solution e-beam evaporator | CHA | ||
| AIXTRON BlackMagic Pro CVD tool | AIXTRON | Carbon nanotube growth | |
| Philips XL50 scanning electron microscope | FEI | ||
| Tepla 300 | PVA TePla | Resist plasma stripper | |
| Avenger rinser dryer | Microporcess Technologies | ||
| Leitz MPV-SP reflecometer | Leitz | ||
| Renishaw inVia Raman spectroscope | Renishaw | ||
| Agilent 4156C parameter spectrum analyzer | Agilent | ||
| Cascade Microtech probe station | Cascade Microtech |
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