應用在金氧半電晶體之原子層沉積氧化鋁與砷化銦鎵、砷化銦介面之研究

Abstract

本論文集中研究減少InGaAs和InAs原生氧化層藉由使用數種表面處理和氣體退火條件去改善原子氣相沉積（ALD）Al2O3/InGaAs, Al2O3/InAs介面品質。三甲基鋁（TMA）製程及濕式化學溶液製程這兩種製程的結合與影響被提出。 使用乾式TMA來減少InGaAs, InAs表面的原生氧化層只有在第一次脈衝有效，接下來便無效。本研究中指出原生氧化層可以被顯著的移除，藉由使用濕式化學溶液製程，例如HCl或sulfide(硫化物)。然而，結合兩種方法（濕式化學溶液製程與TMA預先處理）對於InGaAs,InAs表面處理是最為有效的方式。 Al2O3/InAs MOSCAPs的電性指出對於改善Al2O3/InAs介面品質HCl加上TMA比起sulfide加上TMA是更有效果的。這個結果是由以下實驗觀察所得：ALD Al2O3 薄膜在200。C下沉積。300。C下沉積ALD Al2O3 薄膜再次驗證。同時本研究模擬Al2O3/InAs結構在低頻的C-V。結果顯示界面缺陷密度（Dit）分佈表現出 U 形在最小的Dit分佈位於InAs傳導帶最低處,i.e. 類施體陷阱在此能隙裡支配。這些類施體陷阱會顯著的減少藉由使用濕式化學溶液製程加上TMA預先處理。 藉由使用濕式化學溶液製程加上TMA預先處理和在純氫氣裡沉積後退火，對於Al2O3/In0.53Ga0.47As 界面品質有顯著提昇。使用ex-situ方法，強力的 C-V反轉行為第一次被觀察到在Al2O3/In0.53Ga0.47As MOSCAP。低Dit分佈可藉由模擬觀察到，同時模擬及電導法可確認最小Dit值 ~1011 eV-1cm-2。 Al2O3/InGaAs,InAs的電性表現不僅受與表面處理方法影響，同時也跟半導體本身性質有關。這些半導體參數例如：能隙、電子遷移率及Al2O3/InGaAs 結構的C-V、I-V本質濃度特性都被討論。

This dissertation concentrates on the study of the reduction of InGaAs and InAs native oxides by using several kinds of surface treatments and gas annealing conditions to improve the atomic layer deposition (ALD) Al2O3/InGaAs, Al2O3/InAs interfaces qualities. Effects of trimethyl aluminum (TMA) treatment, wet chemical surface treatments, and a combination of these two kinds of treatments are investigated. The use of dry TMA treatment for the reduction of InGaAs, InAs native oxides at surface was only effective in the first pulse and then it became effectless. The study shows that the native oxides could be significantly removed by using wet chemical solution treatments such as HCl or sulfide. However, the combination of wet chemical solution treatments plus TMA pretreatment is the most effective way for InGaAs, InAs surface treatment. Electrical characterization of Al2O3/InAs MOSCAPs showed that the HCl plus TMA treatment was more effective in the improvement of Al2O3/InAs interface quality than that of sulfide plus TMA treatment. This conclusion was observed for the samples which were deposited with ALD Al2O3 films at 200oC and was confirmed again for the samples deposited with ALD Al2O3 films at 300oC. Low-frequency C-V simulations were performed for the Al2O3/InAs structures and the extracted interface traps density Dit profiles present a U-shape with the minimum of the Dit profiles located around the InAs conduction band minimum, i.e. donor-like traps dominates inside the bandgap. These donor-like traps were significant reduced by using wet chemical plus TMA treatments. By using the chemical solution plus TMA treatment along with post deposition annealing in pure H2 gas, a significant improvement of Al2O3/In0.53Ga0.47As interface quality was obtained. A strong C-V inversion behavior was first time observed in Al2O3/In0.53Ga0.47As MOSCAP by using an ex-situ method. Low Dit profile extracted by simulation was observed and the minimum Dit value of ~1011 eV-1cm-2 was confirmed by both simulation and conductance method. The electrical characteristics of Al2O3/InGaAs, InAs not only depend on the surface treatment methods but also depend on the properties of semiconductors themselves. The effect of semiconductor parameters such as bandgap, electron mobility, and intrinsic concentration on the C-V, I-V characteristics of Al2O3/InGaAs structures are discussed.