Nanometer lithography on silicon and hydrogenated amorphous silicon with low energy electrons
Nanometer lithography on silicon and hydrogenated amorphous silicon with low energy electrons
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低能电子硅和氢化非晶硅上的纳米光刻
DOI：
10.1116/1.587858
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发表时间：
1995
影响因子：
1.4
通讯作者：
C. Schönenberger
中科院分区：
文献类型：
--
作者：
N. Kramer;J. Jorritsma;H. Birk;C. Schönenberger
氢终止的Si表面的氧化可以用在空气中操作的扫描隧道显微镜（STM）或用在受控氧环境中的自由电子束局部诱导。对两种工艺的氧化机理进行了研究和比较。STM在空气中的氧化强烈依赖于所施加的尖端衬底电压和写入速度，但与隧穿电流不成比例。这与自由电子束的过程相反。电子束诱导氧化层的厚度作为电子能量，电子剂量和氧气压力的函数进行了研究。使用俄歇光谱测量0.5-3 nm的氧化物厚度。氧化过程的初始步骤是电子束诱导从表面去除氢。该步骤的电子剂量要求被确定为电子能量的函数。发现对于100 eV的电子，剂量是最小的，并且是104 mC/cm 2。利用STM在Si（110）上形成的氧化物线用作掩模以将图案湿法蚀刻到Si（110）中。用四甲基氢氧化铵（一种选择性各向异性蚀刻液）制作了宽度为35 nm、深度为300 nm的沟槽。我们表明，也可以局部氧化氢化非晶硅（a-Si：H），并使用氧化物作为蚀刻掩模。氢化非晶硅的优点是它可以在几乎任何衬底上以非常薄的层沉积，因此具有作为STM和电子束抗蚀剂的巨大潜力。
The oxidation of a hydrogen terminated Si surface can locally be induced with a scanning tunnelling microscope (STM) operating in air or with a beam of free electrons in a controlled oxygen environment. The oxidation mechanism of both processes was studied and compared. The oxidation with the STM in air depends strongly on the applied tip‐substrate voltage and writing speed, but is not proportional to the tunnelling current. This is in contrast to the process with a beam of free electrons. The thickness of the electron beam induced oxide is studied as a function of electron energy, electron dose, and oxygen pressure. Oxide thicknesses of 0.5–3 nm are measured using Auger spectroscopy. The initial step of the oxidation process is the electron beam induced removal of hydrogen from the surface. The electron dose requirement for this step was determined as a function of electron energy. The dose is found to be minimal for 100 eV electrons, and is ≊4 mC/cm2. Oxide lines made with the STM on Si(110) were used as a mask to wet etch the pattern into the Si(110). With tetramethyl ammonium hydroxide, a selective anisotropic etch liquid, trenches with a width of 35 nm and a depth of 300 nm were made. We show that it is also possible to locally oxidize hydrogenated amorphous silicon (a‐Si:H) and use the oxide as an etching mask. Hydrogenated amorphous silicon has the advantage that it can be deposited in very thin layers on almost any substrate and therefore has great potential as STM and electron‐beam resist.