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在Spindt场发射阴极制作工艺流程中,剥离层对于形成良好的发射尖锥形状至关重要,同时它也是实现阴极阵列中尖锥均匀性的关键因素。本文研究了几种常用的剥离层材料包括金属铜,Al2O3以及水溶性的NaCl和Na2CO3。实验表明NaCl和Na2CO3用作剥离层,可以被去离子水迅速、容易地去除,并同时实现很好的腐蚀选择性。但用这些水溶性材料得到的发射尖锥形状不很规则且表面粗糙,由此也会带来整个阴极阵列上尖锥的不均匀性。使用Al2O3作为剥离层则较为理想,可以得到光滑的栅极收口和很好的尖锥阵列。但传统用来腐蚀Al2O3的热H3PO4,对于加热制作的Al2O3剥离层腐蚀较为困难。尝试了使用基于NaOH的腐蚀液来剥离加热Al2O3层,通过严格的工艺参数控制,如腐蚀液浓度和刻蚀时间,可以制作出质量较好尖锥发射体阵列。
In the Spindt field emission cathode fabrication process, the peel-off layer is crucial for forming a good launch cone shape and is also a key factor in achieving cone uniformity in a cathode array. This article studies several commonly used release layer materials including copper, Al2O3, and water-soluble NaCl and Na2CO3. Experiments show that NaCl and Na2CO3 are used as peel layer, which can be quickly and easily removed by deionized water and at the same time have good corrosion selectivity. However, the echogenic cone shapes obtained with these water-soluble materials are not very regular and have a rough surface, thereby resulting in non-uniformities in the pyramids over the entire cathode array. Using Al2O3 as a release layer is ideal for smooth gate closures and very sharp-edged arrays. However, the conventional thermal H3PO4 used to etch Al2O3 is more difficult to etch the Al2O3 peeling layer made by heating. Attempts have been made to strip the Al2O3 layer by using NaOH-based etching solution, and through the strict process parameters control such as etching solution concentration and etching time, a better quality cone emitter array can be fabricated.