Interfacial Electrical Properties of In-situ ALD-HfAlO/GaAs MOS Capacitor

原位原子層沉積成長氧化鉿鋁/砷化鎵之介面及其電性研究

許嘉倫(Chia-Lun Hsu)

指導教授 ： 洪銘輝 ； 郭瑞年

國立清華大學/工學院/材料科學工程學系/碩士(2011年)

https://doi.org/10.6843/NTHU.2011.00325

摘要

The scaling of Si-based metal-oxide-semiconductor field-effect transistors (MOSFETs) is approaching to the physical limitations when scaling down. One potential solution is to replace to the traditional SiO2/Si MOS structure with high k oxide/GaAs.
In this work, in-situ ALD-HfAlO on n-GaAs and p-GaAs without using interfacial passivation layers and chemical treatments between oxide/III-V interfaces were performed in a multi-chamber UHV MBE/ALD system.
The C-V frequency dispersions were 59% and 23% on n- and p- GaAs, respectively. After RTA at 850oC in He for 10 sec, the frequency dispersion were decreased to 30% for n-type and 13% for p-type. The electrical property shows the structure has high thermal stability. The ALD-HfAlO/GaAs stack has a high dielectric constant ranged from 13.8 to 15, and the CET was decreased to 1.18nm.
The study shows that in-situ ALD-HfAlO is a suitable dielectric oxide for MOSFETs design due to its effective passivation of GaAs surface and excellent thermodynamic stability after RTA to 850oC for S/D activation.

關鍵字

原位原子層沉積 ； 氧化鉿鋁 ； 砷化鎵 ； 電晶體

並列摘要

隨著互補式金氧半場效電晶體(MOSFETs)電子元件尺寸的縮小，現有的矽半導體相關的電子元件已面臨本質材料特性與技術上前所未有的挑戰，如此一來，我們必須要具備有高載子遷移率之半導體材料，像是三五族半導體砷化鎵，再搭配高介電常數氧化物成為未來發展的趨勢。
　　本實驗藉著原子層沉積法成長高介電常數氧化鉿鋁於乾淨的砷化鎵半導體通道上，過程中全部都在超高真空系統中進行。
　　在經過850oC快速高溫氦氣退火10秒後，由MOSCAP的電容電壓曲線量測結果顯示在聚積層和空乏層中電容的分散趨勢有明顯的縮小，n型半導體砷化鎵由59%降低到30%，p型半導體砷化鎵由23%降低到13%，這說明了我們實驗室利用超高真空系統原子層沉積方式成長氧化鉿鋁在砷化鎵半導體上有良好的熱定性，並且有相當高的介電常數接近13.8到15，同時可降低電容等效氧化厚度(CET)到達1.18奈米左右。
　　為了要活化場效電晶體的源極與汲極區，電晶體必須要能夠耐熱到850oC以上快速高溫退火，因此，原子層沉積氧化鉿鋁在砷化鎵半導體上，具有高發展潛力做為未來場效電晶體的設計。

並列關鍵字

ALD ； HfAlO ； GaAs ； MOS

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