The effects of low-energy (<15 eV) high-flux O₂⁺ ion bombardment on the properties of Al₂O₃ films deposited on 3D nanostructures by plasma-enhanced atomic layer deposition (PE-ALD) were investigated. High-dose O₂⁺ ion bombardment (>10¹⁷ cm⁻² cycle⁻¹) during the oxidation steps caused interfacial mixing, and AlSiO_x films with abrupt interfaces were formed on Si surfaces. Interfacially mixed AlSiO_x films were selectively formed on single-crystal Si, amorphous Si, and degraded SiO₂ surfaces, whereas normal ALD Al₂O₃ films were formed on thermally grown SiO₂ surfaces. At the same time, the interfacially mixed AlSiO_x films were selectively formed on the horizontal top and bottom faces of the 3D nanostructures, whereas normal ALD Al₂O₃ films were formed on the vertical sidewalls. The morphology and thickness of the film deposited on the amorphous Si surface were the same as those on the single-crystal Si surface. The interfacially mixed AlSiO_x film possessed rough surface morphology and a layered structure of Al-/Si-/Al-rich AlSiO_x layers. The low-energy high-flux O₂⁺ ion bombardment condition required for the interfacial-mixing ALD was realized in a direct inductively coupled plasma (ICP) reactor with a self-resonant planar coil, in which high-density plasma was excited near the substrate. The O₂⁺ ion flux was found to be controllable over a wide range through variation in the O₂ pressure. The ratio of O₂⁺ ion flux at 0.01 Torr to that at 1 Torr was 289. The steep decrease of the ion flux with increasing pressure was attributed to the decrease of electron density in the upstream plasma for intensifying electron energy loss and the decrease of the ambipolar diffusion coefficient in the downstream plasma. A comparison of electron densities near the substrate and those at the presheath edge calculated from measured positive ion fluxes using the Bohm criterion revealed that negative ions, which significantly affect the positive ion flux, scarcely exist near the substrate. The interfacial-mixing PE-ALD has the potential to realize area-selective and topographically selective depositions, which are key technologies for fabricating next-generation electronic devices with 3D nanostructures. The direct ICP reactor is suitable for realizing selective deposition using the interfacial-mixing ALD.

中文翻译：

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界面混合等离子体增强原子层沉积的直接感应耦合等离子体反应器中离子流和离子能量的控制

研究了低能（<15 eV）高通量O ₂ ⁺离子轰击对通过等离子体增强原子层沉积（PE-ALD）沉积在3D纳米结构上的Al ₂ O ₃膜的性能的影响。氧化步骤中的大剂量O ₂ ⁺离子轰击（> 10 ¹⁷  cm ^-2 循环^-1）引起界面混合，并在Si表面形成具有突变界面的AlSiO _x膜。在单晶硅，非晶硅和降解的SiO ₂表面上选择性地形成界面混合的AlSiO _x膜，而普通的ALD Al ₂ O ₃在热生长的SiO ₂表面上形成膜。同时，在3D纳米结构的水平顶面和底面上选择性地形成界面混合的AlSiO _x膜，而在垂直侧壁上形成普通的ALD Al ₂ O ₃膜。沉积在非晶硅表面上的膜的形态和厚度与单晶硅表面上的相同。界面混合的AlSiO _x膜具有粗糙的表面形态和Al- / Si- /富含Al的AlSiO _x层的层状结构。低能量高通量O ₂ ⁺在具有自谐振平面线圈的直接感应耦合等离子体（ICP）反应器中实现了界面混合ALD所需的离子轰击条件，其中高密度等离子体在基板附近被激发。通过O ₂压力的变化，发现O ₂ ⁺离子通量可在很宽的范围内控制。O ₂ ⁺的比例离子流量在0.01托时的离子通量比在1托时的离子通量大，为289。随着压力的增加，离子通量的急剧下降归因于上游等离子体中电子密度的降低，从而加剧了电子能量的损失，并且双极扩散系数的降低。下游血浆。使用Bohm准则对基材附近的电子密度和由测得的正离子通量计算出的鞘前边缘电子密度进行比较，发现显着影响正离子通量的负离子几乎不存在于基材附近。界面混合PE-ALD具有实现区域选择沉积和地形选择沉积的潜力，这是制造具有3D纳米结构的下一代电子设备的关键技术。