Ho Justin, Ono Takahito, Tsai Ching-Hsiang, Esashi Masayoshi
Graduate School of Engineering, Tohoku University, 6-6-01 Aza Aoba Aramaki, Aoba-ku, Sendai 980-8579, Japan.
Nanotechnology. 2008 Sep 10;19(36):365601. doi: 10.1088/0957-4484/19/36/365601. Epub 2008 Jul 28.
In this paper we report on the development of a photolithographic process to fabricate a gated-emitter array with single-stranded carbon nanotubes (CNTs) self-aligned to the center of the emitter gate using plasma-enhanced chemical vapor deposition (PECVD). Si tips are formed on a silicon wafer by anisotropic etching of Si using SiO(2) as a mask. Deposition of a SiO(2) insulating layer and Cr-W electrode layers creates protrusions above the Si tips. This wafer is polished, and the Cr-W on the tips is removed. Etching of the SiO(2) using hydrofluoric acid is performed to expose the gated Si tip. Incorporation of a novel diffusion process produces single-stranded CNTs by depositing a thin Ni layer on the Si tips and thermally diffusing the Ni layer to yield a catalyst particle for single-stranded CNT growth. The large surface to volume ratio at the apex of the Si tip allows a Ni particle to remain to act as a catalyst to grow a single-stranded CNT for fabricating the CNT based emitter structure. Diffusion of the Ni is carried out in situ during the heating phase of the PECVD CNT growth process at 600 °C. The diameters of the observed CNTs are on the order of 20 nm. The field emission characteristics of the gated field emitters are evaluated. The measured turn-on voltage of the gated emitter is 5 V.
在本文中，我们报告了一种光刻工艺的进展，该工艺用于制造一种栅极发射极阵列，其中单链碳纳米管（CNT）通过等离子体增强化学气相沉积（PECVD）自对准到发射极栅极的中心。使用SiO₂作为掩膜，通过对硅进行各向异性蚀刻在硅片上形成硅尖。沉积SiO₂绝缘层和Cr-W电极层会在硅尖上方形成突起。对该晶圆进行抛光，并去除尖端上的Cr-W。使用氢氟酸蚀刻SiO₂以露出栅控硅尖。通过在硅尖上沉积一层薄镍层并对镍层进行热扩散以产生用于单链CNT生长的催化剂颗粒，采用一种新颖的扩散工艺来生成单链CNT。硅尖顶部较大的表面积与体积之比使得镍颗粒能够保留下来，作为生长单链CNT的催化剂，用于制造基于CNT的发射极结构。镍的扩散在PECVD CNT生长过程600 °C的加热阶段原位进行。观察到的CNT直径约为20纳米。对栅控场发射极的场发射特性进行了评估。测得的栅控发射极的开启电压为5伏。
