改善砷化銦鎵金氧半場效電晶體及鰭式電晶體元件之源極與汲極特性研究

Abstract

在未來的先進互補式金屬氧化物半導體，將考慮三五族化合物半導體作為通道材料使摩爾定律繼續往前發展，由於其有較高的電子遷移率及在低電場下有較高的飄移速度，因此適合在高效能及低損耗之邏輯元件的應用上。然而，由於三五族材料的固態溶解度較矽基板材料低以及其高擴散率，因此在降低源/汲極阻值時是一大難題，也因為隨著技術節點持續微縮，源/汲極的阻值佔了大部分元件的總阻值，所以在這項研究中，我們將使用兩種實驗方法來做改善。第一種，利用自我對準金屬源/汲極(Self-Aligned Metal Source/Drain)技術來降低源/汲極片電阻值、接觸電阻以及電阻率，使元件特性獲得改善。第二種，引用微波熱退火(Microwave Annealing)來激化摻雜離子，由於微波熱退火是擁有較低熱預算的低溫製程，因此可以改善三五族材料高擴散率的特性，並在源/汲極形成淺接面（Shallow Junction）及降低源/汲極電阻率，進而使元件特性得到改善。本實驗首先會將這兩種方法應用在金氧半場效電晶體上，接著將第二種方法應用在鰭式場效電晶體(FinFET)，並使用良好的乾蝕刻和濕蝕刻技術來製造鰭式結構，最小鰭式寬度為20奈米，使元件有低次臨界擺幅(SS)、低汲極感應位障降低(DIBL)及減少臨界電壓下降(VTH roll-off)。另外，從我們元件的微縮指標(scaling metric)來看，證明本次實驗的鰭式場效電晶體有優秀抑制短通道效應的能力。

III–V compound semiconductors have been considered as the new channel materials for the future extremely scaled complementary metal oxide semiconductor (CMOS) devices due to their expected high injection velocity and electron mobility. However, one of the key challenges in realizing high performance III–V nMOSFETs is the reduction of source/drain (S/D) resistance (RSD). Due to nature low dopant solid solubility and high diffusivity of III-V based materials, a high RSD is disappointing the performance of III-V based MOSFET devices. In this study, we propose two methods to deal with source/drain engineering for In0.53Ga0.47 MOSFET devices. First is using a kind of self-aligned metal source/drain technique combined with Silicon implantation in reducing sheet resistance (RSHEET), contact resistance (RC) and resistivity to improve device performance. Second is using microwave annealing (MWA) to active implanted dopants. Due to its low thermal budget, MWA results in fewer dopants diffusion, being beneficial in the S/D formation with the shallow junction and low resistivity. In this study, these two methods are first demonstrated on In0.53Ga0.47As MOSFETs. In addition, utilizing MWA technique, the In0.53Ga0.47As FinFET devices with WFin down to 20 nm and Lch down to 80 nm have been fabricated and characterized. The scaling metrics for In0.53Ga0.47As FinFETs are also systematically studied with LCH from 200 nm to 80 nm and WFin from 60 nm to 20 nm which show an excellent immunity to short channel effects.