具HfLaO與HfZrLaO介電層MOS電容器的TDDB

TDDB of MOS Capacitors with HfLaO and HfZrLaO Dielectrics

廖育緯(Yu-Wei Liao)

指導教授 ： 陳雙源 ； 黃恆盛

國立臺北科技大學/機電學院/機電整合研究所/碩士(2009年)

https://doi.org/10.6841/NTUT.2009.00592

摘要

45 nm 及以下的CMOS 技術，為了避免短通道效應，閘極介電層的等效厚度勢必將縮減的更薄，但為防止漏電流，必定要使用高介電係數(High-κ)的材料，不過，與SiO2 或SiON 相比，其崩潰特性可能會變差，TDDB(Time Dependent Dielectric Breakdown)會變小。這些High-κ 材料中，因HfLaO及HfZrLaO薄膜有高介電常數、低漏電流密度及高穩定性等優點，在未來應用上具有相當潛力，故本研究以它們的MOS電容為研究對象。
因為HfLaO及HfZrLaO是新的High-κ材料，過去的文獻較少有崩潰特性相關的研究，且崩潰特性會因不同的成分，而有不同的結果，其間差異之比較與分析，是本論文的重點。實驗考慮的參數，包括改變電場、溫度等，再依據所得資料，進行統計(如韋伯斜率(Weibull slope))，分析實驗結果與電場、溫度及面積的關係，了解製程的穩定度及兩種High-κ材料的差異。
研究結果顯示，在溫度85℃下，預估HfLaO閘極介電層有TDDB十年壽命的安全電壓為Vg=1.9V，它是優於HfZrLaO閘極介電層的1.69V。因此，由本研究的實驗發現， HfLaO的堆疊結構有出色的特性，在未來high-κ閘極材料的應用中，非常具有潛力。

關鍵字

韋伯分佈 ； 依時性介質崩潰 ； 高介電材料 ； 溫度 ； 氧化鑭

並列摘要

For the 45 nm and beyond CMOS technologies, the equivalent thickness of gate dielectrics must become thinner to avoid short channel effect. Thus using high-κ materials are unavoidable in achieving both high permittivity and enough physical thickness to reduce gate leakage. But comparing with SiO2 and SiON, the high-κ dielectrics may be not as qualified and their TDDB may reveal relatively smaller. To concentrate our efforts, the paper is aimed to study the breakdown behaviors of HfLaO and HfZrLaO for they possess high dielectric constants, low leakage current density, high stability and thus very promising in the current and future applications.
Because HfLaO and HfZrLaO is less mentioned in the previous literatures, we then propose to study its breakdown characteristics thoroughly. The different breakdown characteristics of the composition have different results. Compare and analyze the difference is the focus of this paper.
The considered variables include process differences, electrical fields, and temperatures. By analyzing the test results (for example Weibull slope) with the experimental data, we can figure out the stability of the processes and the difference of two high-κ dielectrics.
At 85℃, the maximum voltage projected to have 10-year TDDB lifetime is Vg=1.9V for HfLaO dielectric. It is better than HfZrLaO dielectric, Vg is 1.69V. The excellent electrical properties and TDDB characteristics indicate that ALD HfLaO stacked gate dielectric has outstanding scalability for future high-κ gate-dielectric applications.

並列關鍵字

Weibull distribution ； Time-Dependent Dielectric Breakdown (TDDB) ； High-k dielectric ； Temperature ； LaO

參考文獻

[1] H. W. Chen et al., “Interface Characterization and Current Conduction in HfO2-Gated MOS Capacitors,” Applied Surface Science, 2008, pp. 6112-6115.

[2] E. P. Gusev et al., “Ultrathin high-K gate stacks for advanced CMOS devices,” IEDM 2001, pp. 451-454.

[3] J. K. Schaeffer et al., “Challenges for the integration of metal gate electrodes,” IEDM Tech. Dig., 2004, p. 287.

[4] H.-H. Tseng et al., “Improved short channel device characteristics with stress relieved pre-oxide (SRPO) and a novel tantalum carbon alloy metal gate/HfO2 stack,” IEDM Tech. Dig., 2004, p. 821.

[5] C. H. Wu et al., “High work function IrxSi gates on HfAlON p-MOSFETs,” IEEE Electron Device Lett., 27 (2006), p. 90.