電感耦合電漿氮化製程與氟化製程對鉿系高介電常數材料薄膜之效果

The Effect of Inductively-Coupled Plasma Nitridation and Fluorination Process to Hf-based Dielectric Thin Films

陳柏寧(Bwo-Ning Chen)

指導教授 ： 張國明

國立交通大學/電機學院/電子工程系所/博士(2010年)

https://doi.org/10.6842/NCTU.2010.01001

摘要

在這篇論文中，我們致力於討論應用電感耦合電漿源對鉿系高介電常數材料作電漿氮化處理的應用，以期達到改善鉿系高介電常數材料之電特性，可靠度與熱穩定性之目的，然後再我們嘗試加入電感耦合電漿氟化處理的製程，以期進一步改善之前電漿氮化處理的效果，在我們的研究中，在調整到適合的實驗條件之下，電漿氮化與氟化製程的結合可以改善二氧化鉿（HfO2）與及氧化鉿鋁（HfAlOx）的電特性與可靠度。

首先，我們先專注於討論電感耦合電漿氮化製程對二氧化鉿高介電常數材料薄膜的效果，為了阻止雜質擴散，改善熱穩定度和增加鉿系閘極介電層介電常數之目的，利用氮化製程將氮摻雜入閘極介電質材料，這類的技術已被廣泛的研究，我們利用電感耦合電漿氮化製程以完成將氮摻雜進入二氧化鉿薄膜，實驗結果顯示二氧化鉿薄膜的電特性，可靠度與熱穩定度可以藉由電漿氮化製程而得到改善，在我們實驗步驟中，電漿製程之後整合了一個熱退火製程以減少由於電漿製程所帶給閘極介電層薄膜的傷害。
其次，因為二氧化鉿的熱穩定性不足以適應一般互補式金氧半導體元件製程，所以半導體元件製程中的熱製程，如源極/汲極的活化，將會使二氧化鉿作為閘極介電層材料時發生漏電流增加以及橫向不均勻等問題，為了增加二氧化鉿材料的熱穩定性，將鋁摻雜進入二氧化鉿形成氧化鉿鋁是一個有效的方法，因此我們嘗試應用相似的電感耦合電漿氮化技術於氧化鉿鋁薄膜上，實驗結果，氧化鉿鋁的薄膜可以因為氮化而進一步改善其電特性，可靠度與熱穩定度。

最後，摻雜氟進入二氧化鉿閘極介電層可以改善金屬氧化物半導體元件結構的種種特性，如臨界電壓不穩，閘極漏電流，崩潰電壓和電容-電壓曲線的磁滯現象，沈積後電漿處理技術已被研究用來摻雜氟進入二氧化鉿薄膜，在我們的研究中，我們結合了電感耦合電漿氮化技術和電感耦合電漿氟化技術兩者，以氟化製程進一步改善氮化製程對二氧化鉿和氧化鉿鋁的製程效果，增強其薄膜的電特性與可靠度。

關鍵字

高介電常數材料 ； 二氧化鉿 ； 氧化鉿鋁 ； 氮化 ； 氟化 ； 電感耦合電漿

並列摘要

In this dissertation, we concentrate our effect on applying plasma nitridation treatment in order to improve the electrical characteristics, the reliabilities and the thermal stability of Hf-based dielectric layers. Then we have tried to applied ICP fluorination process to enhance the improvement effect of the plasma treatment. The electrical characteristics and the reliabilities of HfO2 thin films and HfAlOx thin films could be modified in adequate process conditions.

First, we are focus on the effect of ICP plasma nitridation process to the HfO2 thin films. The incorporation of nitrogen into gate dielectrics by nitridation has been investigated with the aim of preventing dopant penetration, improving the thermal stability and enlarging the dielectric constant of Hf-based dielectrics. We use the plasma nitridation process to incorporate nitrogen into HfO2 thin films. The experimental result indicates that the electrical characteristic, the reliability and the thermal stability of HfO2 thin films could be improved by the plasma nitridation process. The post-nitridation annealing is integrated into the experimental steps for decreasing the plasma damage caused by the plasma treatment.

Secondly, since the thermal stability of the HfO2 dielectric layers is quite low, so the thermal process, such as Source/Drain activation, would cause the high leakage current and lateral nonuniformity associated with grain boundaries after the deposition of HfO2 thin films. In order to increase the crystallization temperature, Al could be added to HfO2 to form Hf aluminates. We use similar plasma nitridation process to HfAlOx dielectric layers in order to incorporate nitrogen. The electrical characteristic, the reliability and the thermal stability of HfAlOx thin films could be improved by the plasma nitridation process.

Finally, the incorporation of fluorine into the HfO2 gate dielectrics could improve the MOS structure characteristics including threshold voltage instability, gate leakage current, breakdown voltage and C-V hysteresis. The post-deposition plasma fluorination has been used to incorporate fluorine into the HfO2 gate dielectrics. In our research, we combine the ICP nitridation process and the ICP fluorination process to enhance the electrical characteristics and the reliability of HfO2 thin films and HfAlOx thin films.

並列關鍵字

high-k dielectric ； hafnium oxide ； hafnium aluminium oxide ； nitridation ； fluorination ； inductively-coupled plasma

參考文獻

[1] International Technology Roadmap for Semiconductors, presented at public.itrs.net (2009).

[2] G. D. Wilk, R. M. Wallace, and J. M. Anthony, “High-κ gate dielectrics: Current status and materials properties considerations”, J. Appl. Phys., 89, p. 5243 (2001).

[3] Y. Shimamoto, J. Yugami, M. Inoue, M. Mizutani, T. Hayashi, K. Shiga, F. Fujita, M. Yoneda, and H. Matsuoka, “Advantages of gate work-function engineering by incorporating sub-monolayer Hf at SiON/poly-Si interface in low-power CMOS”, Symposium on VLSI Technology Digest of Technical Papers, IEEE, p. 132, (2005).

[5] R. I. Hegde, “Film and Device Characteristics of Sputter-Deposited Hafnium Zirconate Gate Dielectric”, J. Electrochem. Soc., 155, 5, p. G121 (2008).

[6] K. J. Hubbard and D. G. Schlom, “Thermodynamic stability of binary oxides in contact with silicon”, J. Mater. Res., 11, p. 2757 (1996).