| 摘要: | 隨著科技的演進，電子產品相關應用大幅普及至各個產業，半導體元件材料利用電導率變化來處理資訊。三五族半導體是一種具有寬能隙且具有高導熱性之元件，為半導體材料發展重心之一。於薄膜製程中，金屬有機化學氣相沉積(Metal Organic Chemical Vapor deposition , MOCVD)隨著前驅物的更換，可生長均勻性良好的各種半導體金屬化合物。本研究以三甲基鋁(TMAl)與氨氣(NH3)作為前驅物進行AlN薄膜生長，為了達到元件電性的需求，須調整氮化鋁薄膜的電阻值，薄膜中碳濃度過高會導致電阻值提升，因此控制薄膜中碳含量至關重要。
當生長氮化鋁薄膜(AlN films)時，眾多文獻均探討實驗參數控制寄生反應(Parasitic reactions) 過程中產生的奈米微粒(Particles)，在過去文獻中較少有探討在生長AlN薄膜含碳相關研究，因此本研究建立包含TMAl、NH3、載氣H2反應式以及包含碳氣相反應的數值模型，探討在不同溫度、壓力、反應前驅物流量及載氣流量…等各項製程參數對於薄膜碳濃度的影響。
研究結果顯示，當提升溫度時，導致熱裂解反應速率加快，產生更多的MMAl及甲基，使薄膜碳濃度上升；當提高腔體壓力時，甲基解吸反應會加快，使得主要吸附物種從甲基變為乙烯，使得薄膜碳濃度上升；當增加氫氣流量時，氫氣可以抑制氨氣解離，並降低氣相反應中活性N前體的濃度，引起薄膜更多的N空位使得碳優先佔據；當增加NH3流量時，甲基會形成不吸附的甲烷，使腔體內部主要碳吸附物種減少，因此薄膜碳濃度下降；當提升TMAl流量時，有更多的反應氣體能夠熱裂解出甲基分子，使得含碳吸附物種有更高的濃度，因此薄膜碳濃度上升。
;With the evolution of technology, electronic product-related applications have spread to various industries. Semiconductor component materials utilize conductivity changes to process information. The tri-five semiconductor is an element with a wide energy gap and high thermal conductivity, and is one of the focuses of semiconductor materials. In the thin film process, Metal Organic Chemical Vapor Deposition (MOCVD) can grow various semiconductor metal compounds with good uniformity with the replacement of the precursor. In this study, TMAl and NH3 were used as precursors for AlN film growth. In order to meet the electrical requirements of the device, the resistance value of the aluminum nitride film must be adjusted. If the carbon concentration in the film is too high, the resistance value increases. It is vital that controlling the carbon content in the film.
When growing AlN films, many literatures have explored the use of experimental parameters to control the generation of nanoparticles in the parasitic reactions. In the past literature, there have been few studies on the carbon content of grown AlN films. In this study, a numerical model including Trimethyl Aluminum (TMAl), Ammonia (NH3), carrier gas Hydrogen (H2)reaction and carbon gas phase reaction was established to investigate the effects of various process parameters such as temperature, pressure, reaction precursor flow rate and carrier gas flow rate on the carbon concentration of the film.
The results show that when the temperature is raised, the rate of thermal cracking reaction is accelerated, and more MMAl and methane are generated. Thus, the carbon concentration of the film increases. When the pressure of the cavity is increased, the methane desorption reaction will be accelerated, causing the main adsorbed species to change from methane to ethene , causing the film carbon concentration to rise. When the Hydrogen flow rate, Hydrogen can inhibit the NH3 dissociation, and reduce the concentration of active N precursor in the gas phase reaction, causing more N vacancies in the film to make carbon preferentially occupy. When the NH3 flow rate is increased, the methyl group forms a non-adsorbed methane , the main carbon adsorption species inside the cavity is reduced, so the film carbon concentration decreases. When the TMAl flow rate is increased, more reaction gases can thermally crack the methyl molecules, making the carbon-containing adsorption species higher The concentration of the film thus increases the carbon concentration of the film. |
