本文選題：HVPE反應(yīng)器　切入點：GaN　出處：《江蘇大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：GaN是重要的寬禁帶半導(dǎo)體材料,氫化物氣相外延(Hydride Vapor Phase Epitaxy,HVPE)是制備GaN同質(zhì)襯底的主要方法。在GaN的HVPE生長中,存在嚴重的氣相寄生反應(yīng),使反應(yīng)腔壁面產(chǎn)生大量的寄生沉積,嚴重影響薄膜生長速率及質(zhì)量。本文針對自制的大尺寸垂直式HVPE反應(yīng)器,通過數(shù)值模擬與實驗對比,研究了反應(yīng)腔壁面寄生沉積以及GaN生長速率的分布規(guī)律,特別是寄生沉積分布與載氣流量的關(guān)系。通過改變反應(yīng)腔幾何模型,討論了原始模型與新模型之間的差異,以及在不同操作參數(shù)下對寄生沉積和生長速率的影響。論文的主要結(jié)論如下:1.在基準條件下,頂壁寄生沉積速率由中心向邊緣逐漸降低,與實驗結(jié)果吻合;側(cè)壁出現(xiàn)8個高寄生沉積區(qū)域,對應(yīng)噴頭邊緣處排布的GaCl管,說明沉積主要取決于GaCl的濃度輸運。模擬得出的石墨托表面生長速率低于實驗速率,但趨勢一致。2.保持其他條件不變,增大NH_3管載氣N_2流量,頂壁和側(cè)壁的寄生沉積速率及分布區(qū)域均隨之增大,石墨托表面生長速率隨之減小而均勻性隨之提高;增大GaCl管載氣N_2流量,頂壁和側(cè)壁的寄生沉積速率及分布區(qū)域均隨之減小,石墨托表面生長速率隨之增大,而均勻性隨之降低。增大托盤轉(zhuǎn)速后,對頂壁寄生沉積分布影響不大,對側(cè)壁影響較大,能顯著提高生長速率。3.針對目前反應(yīng)腔結(jié)構(gòu)的參數(shù)調(diào)整,不能明顯抑制寄生沉積。為進一步減少寄生沉積,改變原頂壁處改為隔離N_2入口后,繼續(xù)調(diào)整氣體流量、改變重力矢量方向、改變?nèi)肟跍囟鹊?再次進行模擬,尋求減少寄生沉積的最佳方法。模擬結(jié)果表明:(1)改進反應(yīng)腔幾何模型以后,GaCl與NH_3之間引入額外的隔離N_2,能夠有效減少寄生沉積;(2)增大隔離N_2流量,側(cè)壁寄生沉積速率及分布區(qū)域均隨之減少,生長速率降低,但均勻性提高;(3)增大GaCl管載氣N_2流量,側(cè)壁寄生沉積速率及分布區(qū)域隨之減少,生長速率增大,均勻性提高;(4)增大NH_3管載氣N_2流量,側(cè)壁寄生沉積及分布區(qū)域隨之增大,生長速率降低,均勻性提高;(5)改變重力矢量方向后,對寄生沉積的影響。發(fā)現(xiàn)側(cè)壁寄生沉積速率及分布區(qū)域增大,生長速率降低,均勻性提高;(6)結(jié)合實際情況,當入口溫度低于理論溫度時,對寄生沉積的影響。發(fā)現(xiàn)側(cè)壁寄生沉積隨之降低,生長速率隨之降低,生長均勻性不變。
[Abstract]:GaN is an important wide band gap semiconductor material, and hydride vapor phase epitaxy (Vapor Phase EpitaxyHVPE) is the main method for the preparation of homogeneous GaN substrates. In the HVPE growth of GaN, there is a serious vapor phase parasitic reaction, which results in a large amount of parasitic deposition on the wall of the reaction chamber. The film growth rate and quality are seriously affected. In this paper, the parasitic deposition on the wall of the reaction chamber and the distribution of the GaN growth rate are studied by numerical simulation and experimental comparison for the large scale vertical HVPE reactor. In particular, the relationship between parasitic deposition distribution and carrier gas flow is discussed. The difference between the original model and the new model is discussed by changing the geometric model of the reaction chamber. The main conclusions of this paper are as follows: 1. Under the reference condition, the parasitic deposition rate of the top wall decreases from the center to the edge, which is consistent with the experimental results. There are 8 high parasitic deposition areas on the lateral wall, corresponding to the GaCl tube arranged at the edge of the nozzle, which indicates that the deposition mainly depends on the concentration transport of GaCl. The simulated surface growth rate of graphite bracket is lower than the experimental rate. However, the trend is the same. 2. Keeping the other conditions unchanged, increasing the flow rate of NH_3 tube carrier gas, the parasitic deposition rate and distribution area of the top wall and side wall increase, the growth rate of graphite substrate surface decreases and the uniformity increases. The parasitic deposition rate and distribution area of the top wall and the side wall decrease with the increase of the flow rate of GaCl tube carrier gas N _ 2, and the growth rate of graphite bracket surface increases, and the uniformity decreases with the increase of the rotating speed of the tray. It has little effect on the distribution of parasitic deposition in the apical wall, but a great influence on the lateral wall, which can significantly increase the growth rate .3.To further reduce the parasitic deposition, the parasitic deposition can not be significantly inhibited by adjusting the parameters of the current reaction cavity structure. After changing the original top wall to isolate the entrance of Nflesh 2, continue to adjust the gas flow, change the direction of the gravity vector, change the inlet temperature, and conduct the simulation again. The simulation results show that the introduction of extra isolation between GaCl and NH_3 can effectively reduce parasitic deposition and increase the flow of isolated N2. The parasitic deposition rate and distribution area of lateral wall decreased, but the growth rate decreased, but the homogeneity increased) the flow rate of GaCl pipe carrier gas N2 increased, the deposition rate and distribution region of lateral wall parasitic deposition decreased, and the growth rate increased. After increasing the flow rate of NH_3 tube carrier gas N2, the parasitic deposition and distribution area of the lateral wall increases, the growth rate decreases, and the homogeneity increases after changing the direction of gravity vector. It is found that the parasitic deposition rate and distribution area of the lateral wall increase, the growth rate decreases, and the homogeneity increases in combination with the actual situation, when the inlet temperature is lower than the theoretical temperature, It is found that the lateral parasitic deposition decreases, the growth rate decreases and the growth uniformity remains unchanged.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN304.05

【參考文獻】

相關(guān)碩士學(xué)位論文 前1條

1 左朝朝;MOVPE生長GaN的表面反應(yīng)研究[D];江蘇大學(xué);2016年

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本文編號：1559343