Studies on selective productions of radicals using electron temperature controlled plasmas

我们通过原料气和各种等离子体源的结合，实现了自由基的选择性产生，方法如下：通过控制电子束激发N_2等离子体的电子束能量和电流，可以控制氮自由基密度，这是一种在超低工作压力下很有前途的高密度氮自由基源。此外，我们开发了一种新型紧凑型EBEP源，不仅适用于高密度自由基源，还适用于类金刚石碳沉积和玻璃基板表面清洁工艺。在类金刚石碳的沉积过程中，我们成功地在电浮基底上合成了类金刚石碳薄膜。我们首次在1.3Pa的低工作压力下，通过选择性地产生CH_3、H和OH自由基而不是C原子，并通过控制中性自由基与离子自由基的比例，成功地合成了纳米晶体金刚石。利用超高频（UHF, 500MHz）电源实现了极低电子温度为0.5 eV的硅烷/氢等离子体，并发现可以通过脉冲调制等离子体来控制硅原子与氢原子的比例。此外，我们还发现可以通过控制Si/H原子比和SiH_3/H自由基比来控制沉积的微晶硅膜的结晶度和取向。我们发现，与RF (13.56MHz) N_2/H_2/NH_3等离子体相比，UHF N_2/H_2/NH_3等离子体中的氮原子密度可以选择性地增强，实现了低介电有机膜的极细各向异性刻蚀。

We have achieved selective productions of radicals by combining feed gases and various plasma sources as follows ;1. We have clarified that nitrogen radical density can be controlled through controlling the electron beam energy and current of electron-beam excited N_2 plasma, which is a promising high-density nitrogen radical source under ultra low operating pressures. Moreover, we have developed a novel compact EBEP source and applied to not only high-density radical sources but also to processes of diamond-like carbon deposition and surface cleaning of glass substrates. In the deposition process of diamond-like carbon, we have successfully synthesized the diamond-like carbon films on electrically floating substrates.2. We have successfully synthesized nano-crystalline diamond at the low operating pressure of 1.3Pa for the first time by producing CH_3, H, and OH radicals selectively rather than C atoms and by controlling the ratio of neutral radicals to ionic radicals.3. We have realized silane/hydrogen plasmas with very low electron temperature of 0.5 eV by using ultra-high frequency (UHF, 500MHz) power supply and found that the ratio of Si atom to H atom can be controlled by using pulse modulation of the plasma. Moreover, we have found that the crystallinity and orientation of deposited microcrystallin silicon film can be controlled by controlling Si/H atom ratio and SiH_3/H radical ratio.4. We have found that the nitrogen atom density in UHF N_2/H_2/NH_3 plasma can be selectively enhanced compared to that in RF (13.56MHz) N_2/H_2/NH_3 plasma and realized the very fine anisotropic etching of low dielectric organic films.