應用於電漿輔助原子層沉積製程之間接式電容耦合氫氣/氬氣電漿之研究

Study of an indirect capacitively coupled hydrogen/argon plasma discharge for atomic layer deposition process

張登彥(Chang, Teng Yen)

指導教授 ： 柳克強

國立清華大學/原子科學院/工程與系統科學系/碩士(2015年)

摘要

近年來，半導體元件尺寸越做越小，金屬氧化物製程中，尺寸小於22奈米後，半導體製程技術會面臨到很大的挑戰，所以原子層沉積技術在近年來倍感性趣，原因其ㄧ，原子層沉技術可以控制沉積的薄膜厚度是原子大小等級的尺寸，原因其二，可以藉由氣體可到達表面任何地方的特性，於非平面上也能沉積出厚度更均勻的薄膜。
本研究旨在探討氫氣/氬氣電漿環境下，參考儀科中心的儀器設計進行模擬。探討不同網層孔徑大小對於主要影響成膜的H粒子的通量密度的變化。內容包含模擬與實驗兩部分。從模擬結果在頻率為13.56 MHz的射頻電漿環境基本模擬條件下，電子密度、電子溫度、H粒子密度在0.2秒後都到達穩態。一個電壓周期內，電漿的電位分佈會隨著功率電極電位而改變，電漿與電極之間的電位差，會在靠近兩電極處產生強電場，可以加速電子來激發其餘重粒子，並使電漿中的正離子受電場加速往基板移動。
模擬結構有3個部分，分別是改變不同網層的孔徑(0.25 mm、0.5 mm、2 mm)大小隨著功率變化的模擬。隨著功率上升時，平均電位、電子密度、電子溫度隨之增加，H的通量密度到達基板數量也隨著功率而增加，代表有更多的活性粒子與前驅物反應，可以使得沉積均勻性提高，但是相對的其他離子的通量密度也隨著功率增加，意味著提高功率會帶來離子轟擊的影響也增加。
另外有做一組改變不同比例的氫氣與氬氣，隨著氫氣比例增加，可以知道H粒子的通量密度也加，可以知道氫氣比例增加會使得到達基板表面的通量更多，成膜的均勻性是否因此提升還需要考慮到離子轟擊的影響，其中H2+粒子Ar+粒子通量密度也會隨著氫氣比例而增加，離子轟擊的影響也會因此增加。
從光譜來看，Hα與Hβ特徵光譜強度隨著功率增加，強度上升；隨著壓力升高強度下降。Ar的特徵光譜也有相同趨勢。
根據本研究的模擬結果，想要讓薄膜沉積更均勻除了提高H粒子通量密度也必須同時考慮離子轟擊的影響，故需找到ㄧ個最佳的平衡點。

關鍵字

原子層沉積 ； 電容偶合電漿 ； 氫氣/氬氣電漿模擬

並列摘要

In the recent years, the semiconductor component size getting smaller and smaller. The metal oxide semiconductor field effect manufacturing process, after the size of less than 22 nm, the semiconductor process technology will face a big challenge. So Atomic Layer Deposition(ALD) process was interested and more popular in the recent years. There are some benefits of ALD process, one of this technology can be deposited the films at the atomic size, the other can be deposited films more uniform because of gas can be reached to anywhere of the surface, and it can also deposit on non-planar.
The purpose of this study is to investigate the argon/hydrogen plasma discharge for atomic layer deposition process. When using different size of the mesh size, the change of the H radical flux. There are two part of this study, simulation and experiment. In simulation studies, RF plasma was operated at 13.56 MHz. The electron density, electron temperature, and H number density were reached to steady state after 0.2 second. The plasma potential near two electrodes will accelerate electron and ions.
There are three parts of the simulation, changing different mesh size (0.25mm, 0.5mm, 2mm) of the structure. And then using different power to start the simulation. The simulation results, when the power increase, the electron density, electron temperature, average potential increase. H radicals flux are also increase when power increase. Representative more precursor reacted with the active radicals, so that the uniformity of the films can be improve. But relative to other ion flux increase, it means the ion bombardment effect increases.
There is another simulation which is changing input gas ratio of H2/Ar. The simulation result is that the ratio of H2/Ar increase the H radicals flux increase.
In spectrum analysis, the intensity of characteristic spectral lines of Hα and Hβ decrease when pressure increase. And argon intensity of characteristic spectral lines also the same trend.
In this simulation study, if we want to let the films more uniform, in addition to increasing H radicals flux but also need to consider the ion bombardment. So it should be find an optimum balance.

並列關鍵字

Atomic Layer Deposition ； capacitively coupled plasma ； hydrogen/argon simulation

參考文獻

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