- 學位論文
高介電閘場效電晶體之可靠度與輻射效應研究
Reliability and Radiation Effects in High-k Gated FET
摘要
可靠度與輻射效應對積體電路(IC)元件是很重要的研究課題。因為在IC元件製造中的電漿製程及EUV微影技術，或是元件應用於航太科技、或衛星通訊都可能處在高能輻射的環境中。高介電係數材料(high-k)閘極已為先進IC元件所使用，因此閘介層的可靠度與輻射傷害值得探討研究。 本論文第一部份，透過不同通道結構來改善電晶體電特性，可以克服短通道效應所造成的問題。對平面式、鰭式以及全環繞式電晶體，經不同輻射傷害後，對元件之電性與可靠度分析。由電晶體電特性的比較，全環繞式電晶體相較於平面式電晶體與鰭式電晶體，有較佳的抗輻射能力。 為了將摩爾定律進一步擴展到5nm以下的技術節點，將鍺材料用於取代矽被視為一種前瞻的解決方案。其不僅擁有比矽更高的載子遷移律，製程技術更與傳統矽製程相容。然而，鍺電晶體的界面品質較差將是其發展的瓶頸。本論文第二部份，探討金屬閘極與high-K閘介電層之界面製程對鍺電晶體電性之影響。High-K氧化層與金屬閘之間以原子層沉積(ALD)成長TiN，來減少界面缺陷、抑制漏電流，可以獲得較佳的元件及抗輻射特性。 第三部份，應用超臨界流體處理來鈍化原子層沉積的閘極介電層，通過SC CO2將H2O分子帶入氧化物薄膜中，並且添加乙醇來增強反應。SC CO2+H2O+乙醇的處理可減少閘極介電層中的缺陷，提升電晶體之電特性。 最後，透過電荷汲引技術(Charge Pumping technique)，探討超臨界流體製程處理的鍺電晶體在經NBTI stress及輻射照射後，對於界面態陷阱(Nit, interface trap)與氧化層陷阱(Not, oxide traps)之影響。因SC CO2+H2O+乙醇的處理可以減少閘極介電層中的缺陷，使元件經輻射照射後有較少的界面陷阱產生，可以獲得較佳的元件及抗輻射特性。
並列摘要
Reliability and radiation effects are very important research topics for integrated circuit (IC) devices, because the IC devices may be in a high-energy radiation environment when a plasma process or EUV lithography are used in IC production, or IC devices are applied in aerospace or satellite communications. Since high-k gate dielectrics are widely implemented in modern IC, the reliability and radiation damage on them are worthy of study. In the first part of this thesis, the short channel effects of field effect transistor (FET) are reduced and electrical characteristics can be improved by modifying channel structure. The effects of radiation damages on electrical characteristics and reliability of MOSFET, FinFET, and GAAFET were studied. Based on the comparison of electrical characteristics, GAAFET shows better radiation hardness than FinFET and planar MOSFET. In order to further extend Moore’s law beyond sub-5nm node, Ge is regarded as a promising channel material to replace Si because of not only its much higher carrier mobility but also the compatibility with Si manufacturing technology. However, the poor interface quality of Ge MOSFET is the bottleneck for its development. In the second part of this thesis, the process integration of metal gate/high-k gate dielectric for improving radiation hardness of Ge MOSFET was investigated. The electrical characteristics and radiation hardness of Ge MOSFET can be clearly improved by using an atomic layer deposition (ALD)-formed TiN between high-k gate dielectric and metal gate to decrease the border trap and reduce the leakage. In the third part of this thesis, a supercritical fluid (SCF) treatment was applied to passivate the ALD formed-gate oxide. The H2O molecules are carried into the oxide film by SC CO2, and the reaction can be enhanced by adding ethanol. The defects in gate dielectric can be reduced and the electrical characteristics of Ge MOSFET can be clearly improved by a SC CO2+H2O+ethanol treatment. Finally, a charge pumping technique was used to assess the negative bias temperature instability stress and radiation exposure induced oxide and interface traps in Ge MOSFET with SCF treatment. The electrical characteristics and radiation hardness of Ge MOSFET can be clearly improved by a SCF treatment with SC CO2+H2O+ethanol, because the defects in gate dielectric may be reduced.