臺灣博碩士論文加值系統

摘要

當積體電路的尺寸一直微縮，二氧化矽的物理厚度必須快速遞減來符合高性能和低功率的互補式金屬氧化物半導體(CMOS)邏輯元件之應用，但由於直接穿隧的效應將會導致閘極漏電流的增加。將二氧化矽取代為高介電常數(high-K)的材料，做為閘極的介電層是解決此問題的方法之一，較厚的氧化層物理厚度可以得到相同的氧化層電性厚度(EOT)。因此，直接穿隧的載子能被有效地抑制。
在此研究中，為了進一步的提高目前最有希望的高介電常數閘極介電層，二氧化鉿的結晶溫度和介電常數。首次利用鉿鉭與鉿鈦二元靶材形成鉿鉭氧化物與鉿鈦氧化物薄膜，做為閘極介電層。利用不同的氣體，例如氮氣、氧氣和二氧化氮在不同溫度下對閘極介電層做後熱退火處理的電性與物性將被探討。鉿鉭氧化物與鉿鈦氧化物各自顯示出高的結晶溫度和介電常數。鉿鉭氧化物與鉿鈦氧化物經由後熱退火處理之後，在遲滯和頻率失真方面都能有效的改善。此外，頻率的失真可以藉由混和氮氣在閘極介電層而得到更進一步的改進。一個偶極結構的物理模型將被提出，以解釋氮結合的現象。

Abstract

As the dimensions of integrated circuits are being scaled down, the physical thickness of SiO2 has been aggressively scaled for high performance and low power complementary metal-oxide-semiconductor (CMOS) logic devices applications, but it will results in an increase of gate leakage current due to the direct tunneling effect. One solution for this issue is to replace SiO2 with high dielectric constant (high-K) materials as gate dielectrics, which provides a physically thicker film for the same electrically equivalent oxide thickness (EOT). Therefore, direct tunneling of carriers can be effectively suppressed.
In this study, in order to further increase the crystallization temperature and dielectric constant of the most promising high-k gate dielectric, HfO2. The HfTa and HfTi binary target was prepared to form the HfTaO and HfTiO thin films as the gate dielectrics, for the first time. The gate dielectrics with different gas sources post deposition annealing such as N2, O2 and N2O at different annealing temperature were discussed electrically and physically. The HfTaO and HfTiO gate dielectric shows the higher crystallization temperature and dielectric constant, respectively. The hysteresis voltage and frequency dispersion of HfTaO and HfTiO MOS capacitors were effectively improved by post deposition annealing treatments. Moreover, the frequency dispersion will be further improvement by incorporating nitrogen in the gate dielectrics. A physical model of dipole structures was proposed explaining the nitrogen incorporation phenomenon.

Contents

Acknowledgment i
Chinese Abstract ii
English Abstract iii
Contents iv
Figure Captions and Tables vii
Chapter 1 Introduction 1
1-1 CMOS Technology Scaling Trends………………………1
1-2 The Advantage of Thin Oxide……………………………1
1-3 Gate Oxide Scaling Limitation…………………………2
1-4 Dielectric Candidates…………………………………… 3
1-5 Issues for High-k Dielectric Layers…………………3
1-6 The Motivation in This Study……………………………4
1-7 Thesis Organization…………………………………………4

Chapter 2 Characteristics of HfTaO Thin Films with
Different Gas Sources Post Deposition Annealing 9
2-1 Introduction……………………………………………………9
2-2 Experiment………………………………………………………10
2-3 Results and Discussion……………………………………11
2-3-1 X-ray diffraction (XRD) physical analysis
of HfTaO films………………………………………11
2-3-2 Capacitor characteristics of HfTaO gate
dielectric……………………………………………11
2-3-3 The Hysteresis phenomenon of HfTaO gate
dielectric……………………………………………12
2-3-4 The negative current density-voltage (J-V)
characteristics of HfTaO gate dielectric.13
2-3-5 The frequency dispersion of HfTaO gate
dielectric……………………………………………14
2-4 Summary…………………………………………………………14

Chapter 3 Characteristics of HfTiO Thin Films with Different Gas Sources Post Deposition Annealing 33
3-1 Introduction……………………………………………………33
3-2 Experiment………………………………………………………33
3-3 Results and Discussion……………………………………34
3-3-1 X-ray diffraction (XRD) physical analysis
of HfTaO films………………………………………34
3-3-2 Capacitor characteristics of HfTaO gate
dielectric……………………………………………35
3-3-3 The Hysteresis phenomenon of HfTaO gate
dielectric……………………………………………35
3-3-4 The negative current density-voltage (J-V)
characteristics of HfTaO gate dielectric.36
3-3-5 The frequency dispersion of HfTaO gate
dielectric…………………………………………… 36
3-4 Summary……………………………………………………… …37

Chapter 4 Nitrogen Effect on Frequency Dispersion 56
4-1 Introduction……………………………………………………56
4-2 Experiment………………………………………………………57
4-3 Results and Discussion……………………………………57
4-3-1 The frequency dispersion of HfTaON gate
dielectric…………………………………………… 57
4-3-2 The frequency dispersion of HfTiON gate
dielectric………………………………………… …58
4-3-3 Physical model of dipole structures………58
4-4 Summary………………………………………………………… 59

Chapter 5 Conclusions and Future Works 68
5-1 Conclusions……………………………………………………68
5-1-1 HfTaO gate dielectric……………………………68
5-1-2 HfTiO gate dielectric……………………………68
5-1-3 Nitrogen Effect on Frequency Dispersion…69
5-2 Future works……………………………………………………69
References………………………………………………………………………70


Figure Captions and Tables

Table. 1-1 Requirement for High K Gate Dielectrics.
Table. 1-2 High-k dielectric candidate.
Table. 1-3 Challenges of high-k gate dielectric.
Fig. 1-1 The Device scaling over time.
Fig. 1-2 Major technology innovations required over the
next few years [7].
Table. 2-1 The detail process of HfTaO MOSCAP.
Fig. 2-1 The process flow of HfTaO high-k dielectric
MOSCAPs.
Fig. 2-2 XRD patterns of HfTaO films with N2 annealing
at different temperature.
Fig. 2-3 XRD patterns of HfTaO films with O2 annealing
at different temperature.
Fig. 2-4 XRD patterns of HfTaO films with N2O annealing
at different temperature.
Fig. 2-5 The high-frequency C-V curves of HfTaO MOS
capacitors with N2 annealing at different
temperature.
Fig. 2-6 The high-frequency C-V curves of HfTaO MOS
capacitors with O2 annealing at different
temperature.
Fig. 2-7 The high-frequency C-V curves of HfTaO MOS
capacitors with N2O annealing at different
temperature.
Fig. 2-8 CET versus annealing temperature for various
gas ambient.
Fig. 2-9 Hysteresis phenomenon of HfTaO MOS capacitor
before anneal.
Fig. 2-10 Hysteresis phenomenon of HfTaO MOS capacitor
after 700 oC anneal in N2 ambient.
Fig. 2-11 Hysteresis phenomenon of HfTaO MOS capacitor
after 800 oC anneal in N2 ambient.
Fig. 2-12 Hysteresis phenomenon of HfTaO MOS capacitor
after 900 oC anneal in N2 ambient.
Fig. 2-13 Hysteresis phenomenon of HfTaO MOS capacitor
after 700 oC anneal in O2 ambient.
Fig. 2-14 Hysteresis phenomenon of HfTaO MOS capacitor
after 800 oC anneal in O2 ambient.
Fig. 2-15 Hysteresis phenomenon of HfTaO MOS capacitor
after 900 oC anneal in O2 ambient.
Fig. 2-16 Hysteresis phenomenon of HfTaO MOS capacitor
after 700 oC anneal in N2O ambient.
Fig. 2-17 Hysteresis phenomenon of HfTaO MOS capacitor
after 800 oC anneal in N2O ambient.
Fig. 2-18 Hysteresis phenomenon of HfTaO MOS capacitor
after 900 oC anneal in N2O ambient.
Fig. 2-19 Hysteresis voltage versus annealing temperature
for various gas ambient.
Fig. 2-20 Negative current density versus gate voltage
characteristics of HfTaO MOS capacitors with N2
annealing at different temperature.
Fig. 2-21 Negative current density versus gate voltage
characteristics of HfTaO MOS capacitors with O2
annealing at different temperature.
Fig. 2-22 Negative current density versus gate voltage
characteristics of HfTaO MOS capacitors with
N2O annealing at different temperature.
Fig. 2-23 Normalize C-f curves of HfTaO MOS capacitors
with N2 annealing at different temperature.
Fig. 2-24 Normalize C-f curves of HfTaO MOS capacitors
with O2 annealing at different temperature.
Fig. 2-25 Normalize C-f curves of HfTaO MOS capacitors
with N2O annealing at different temperature.
Fig. 2-26 Frequency dispersion ( % ) of HfTaO MOS
capacitors with 900 oC annealing in various gas
ambient.
Table. 3-1 The detail process of HfTiO MOSCAP.
Fig. 3-1 The process flow of HfTiO high-k dielectric
MOSCAPs.
Fig. 3-2 XRD patterns of HfTiO films with N2 annealing
at different temperature.
Fig. 3-3 XRD patterns of HfTiO films with O2 annealing
at different temperature.
Fig. 3-4 XRD patterns of HfTiO films with N2O annealing
at different temperature.
Fig. 3-5 The high-frequency C-V curves of HfTiO MOS
capacitors with N2 annealing at different
temperature.
Fig. 3-6 The high-frequency C-V curves of HfTiO MOS
capacitors with O2 annealing at different
temperature.
Fig. 3-7 The high-frequency C-V curves of HfTiO MOS
capacitors with N2O annealing at different
temperature.
Fig. 3-8 CET versus annealing temperature for various
gas ambient.
Fig. 3-9 Hysteresis phenomenon of HfTiO MOS capacitor
before anneal.
Fig. 3-10 Hysteresis phenomenon of HfTiO MOS capacitor
after 700 oC anneal in N2 ambient.
Fig. 3-11 Hysteresis phenomenon of HfTiO MOS capacitor
after 800 oC anneal in N2 ambient.
Fig. 3-12 Hysteresis phenomenon of HfTiO MOS capacitor
after 900 oC anneal in N2 ambient.
Fig. 3-13 Hysteresis phenomenon of HfTiO MOS capacitor
after 700 oC anneal in O2 ambient.
Fig. 3-14 Hysteresis phenomenon of HfTiO MOS capacitor
after 800 oC anneal in O2 ambient.
Fig. 3-15 Hysteresis phenomenon of HfTiO MOS capacitor
after 900 oC anneal in O2 ambient.
Fig. 3-16 Hysteresis phenomenon of HfTiO MOS capacitor
after 700 oC anneal in N2O ambient.
Fig. 3-17 Hysteresis phenomenon of HfTiO MOS capacitor
after 800 oC anneal in N2O ambient.
Fig. 3-18 Hysteresis phenomenon of HfTiO MOS capacitor
after 900 oC anneal in N2O ambient.
Fig. 3-19 Hysteresis voltage versus annealing temperature
for various gas ambient.
Fig. 3-20 Negative current density versus gate voltage
characteristics of HfTiO MOS capacitors with N2
annealing at different temperature.
Fig. 3-21 Negative current density versus gate voltage
characteristics of HfTiO MOS capacitors with O2
annealing at different temperature.
Fig. 3-22 Negative current density versus gate voltage
characteristics of HfTiO MOS capacitors with
N2O annealing at different temperature.
Fig. 3-23 Negative current density versus gate voltage
characteristics of HfTiO MOS capacitors with
900 oC annealing in various gas ambient.
Fig. 3-24 Normalize C-f curves of HfTiO MOS capacitors
with N2 annealing at different temperature.
Fig. 3-25 Normalize C-f curves of HfTiO MOS capacitors
with O2 annealing at different temperature.
Fig. 3-26 Normalize C-f curves of HfTiO MOS capacitors
with N2O annealing at different temperature.
Fig. 3-27 Frequency dispersion ( % ) of HfTiO MOS
capacitors with 900 oC annealing in various gas
ambient.
Table. 4-1 The detail process of HfTaON and HfTiON MOSCAP.
Fig. 4-1 The process flow of HfTaON and HfTiON high-k
dielectrics MOSCAPs.
Fig. 4-2 Normalize C-f curves of HfTaON (Ar/O2/N2 =
20/4/1) MOS capacitors with N2O annealing at
different temperature.
Fig. 4-3 Normalize C-f curves of HfTaON (Ar/O2/N2 =
20/2/3) MOS capacitors with N2O annealing at
different temperature.
Fig. 4-4 Frequency dispersion ( % ) versus annealing
temperature of HfTaO(N) MOS capacitors for
different contain of N2.
Fig. 4-5 Normalize C-f curves of HfTiON (Ar/O2/N2 =
20/4/1) MOS capacitors with N2 annealing at
different temperature.
Fig. 4-6 Normalize C-f curves of HfTiON (Ar/O2/N2 =
20/2/3) MOS capacitors with N2 annealing at
different temperature.
Fig. 4-7 Frequency dispersion ( % ) versus annealing
temperature of HfTiO(N) MOS capacitors for
different contain of N2.
Fig. 4-8 Schematic model of oscillator dipoles.

Reference

[1] R. D. Isaac, “The future of CMOS technology”, IBM,
November 8, 1999.
[2] T. Hori, “Gate Dielectrics and MOS ULSIs”, Springer-
Verlag, New York, 1997.
[3] G. Baccarani, M.R. Wordeman, and R.H.
Dennard, “Generalized scaling theory and its
application to a ¼ micrometer MOSFET design”, IEEE
Trans. Electron Devices, 31, p. 452, 1984.
[4] Intel, “High-k and Metal Gate Research”.
[5] Robert M. Wallace and Glen Wilk, “High-k Gate
Dielectric Materials” MRS, 2002.
[6] J. C. Wang, S. H. Chiao and C. L. Lee, “A physical
model for the hysteresis phenomenon of the ultrathih
ZrO2 film” JAP, vol. 92, no. 7, October 2002.
[7] International Technology Roadmap for Semiconductors,
2007.
[8] M. Balog, M. Schieber, M. Michman, and S.
Patai, “Chemical vapor Deposition and characterization
of HfO2 films from organo-hafnium compounds,” Thin
Solid Films, vol. 41, no. 3, pp.247–259, Mar. 1977.
[9] J. Robertson, “Band offsets of wide-band-gap oxides
and implications for future electronic devices,” J.
Vac. Sci. Technol. B, Microelectron. Process. Phenom.,
vol. 18, no. 3, pp. 1785–1791, May 2000.
[10] K. J. Hubbard and D. G. Schlom, “Thermodynamic
stability of binary oxides in contact with silicon,”
J. Mater. Res., vol. 11, no. 11, pp. 2757–2776, Nov.
1996.
[11] L. Trojman, L.-A. Ragnarsson, L. Pantisano, G.S.
Lujan, M. Houssa, T. Schram, F. Cubaynes, M.
Schaekers, A.Van Ammel, G. Groeseneken, S. De Gendt,
M. Heyns, “Effect of the dielectric thickness and the
metal deposition technique on the mobility for
HfO2/TaN NMOS devices,” Mircoelec. Eng. 80, pp.86-
89, 2005.
[12] G. Lucovsky, “Band edge traps at spectroscopically-
detected O-atom vacancies in nanocrystalline ZrO2 and
HfO2: An engineering solution for elimination of O-
atom vacancy defects in non-crystalline ternary
silicate alloys,” ECS 208th, pp.381-392, October
2005.
[13] S. H. Bae, C. H. Lee, R. Clark, and D. L. Kwong, “MOS
characteristics of ultrathin CVD HfAlO gate
dielectrics,” IEEE Electron Device Lett. ,vol. 24,
pp. 556–558, Sep. 2003.
[14] W. Zhu, T. P. Ma, T. Tamagawa, Y. Di, J. Kim, R.
Carruthers, M. Gibson, “HfO2 and HfAlO for CMOS:
Thermal stability and current transport,” in IEDM.
Tech. Dig., pp. 463–466, 2001.
[15] G. D. Wilk, R. M. Wallace, and J. M.
Anthony, “Hafnium and zirconium silicates for
advanced gate dielectrics,” J. Appl. Phys., vol.87,
pp.484–492, 2000.
[16] A. L. P. Rotondaro, M. R. Visokay, J. J. Chambers, A.
Shanware, R. Khamankar, H. Bu, R. T. Laaksonen, L.
Tsung, M. Douglas, R. Kuan, M. J. Bevan, T. Grider, J.
McPherson, and L. Colombo, “Advanced CMOS transistors
with a novel HfSiON gate dielectric,” in Symp. VLSI
Tech. Dig., pp. 11–13, 2002.
[17] C. H. Choi, S. J. Rhee, T. S. Jeon, N. Lu, J. H. Sim,
R. Clark, M. Niwa, and D. L. Kwong, “Thermally stable
CVD HfOxNy advanced gate dielectrics with poly-Si gate
electrode,” in IEDM Tech. Dig., pp. 857–860, 2002.
[18] H. S. Jung, Y. S. Kim, J. P. Kim, J. H. Lee, J. H.
Lee, N. I. Lee, H. K. Kang, K. P. Suh, H. J. Ryu, C.
B. Oh, Y. W. Kim, K. H. Cho, H. S. Baik, Y. S. Chung,
H. S. Chang, and D. W. Moon, “Improved current
performance of CMOSFETs with nitrogen incorporated
HfO2-Al2O3 laminate gate dielectric,” in IEDM. Tech.
Dig., pp. 853–856, 2002.
[19] G. D. Wilk, R. M. Wallace, and J. M. Anthony, “High-κ
gate dielectrics: Current status and materials
properties considerations,” J. Appl. Phys., vol.89,
no.10, pp. 5243-5275, 2001.
[20] Xiongfei Yu, Chunxiang Zhu, and M.F.Li, “Electrical
characteristics and suppressed boron penetration
behavior Of thermally stable HfTaO gate dielectrics
with polycrystalline-silicon gate,” Appl. Phys. Lett,
Vol. 85, no. 14, 2004.
[21] F. Ji and J. P. Xu, “Electrical properties of HfTiON
gate-dielectric metal-oxide-semiconductor capacitors
with different Si-surface nitridations,” Appl. Phys.
Lett, 91, 2007.
[22] James A. Felix, Marty R. Shaneyfelt, and Daniel M.
Fleetwood, “Charge Trapping and Annealing in High-k
Gate Dielectrics,” Nuclear, Nuclear Science, IEEE
Transactions on, Volume 51, Issue 6, Page(s): 3143-
3149, Dec. 2004.
[23] G. Lucovsky, “Band edge traps at spectroscopically-
detected O-atom vacancies in nanocrystalline ZrO2 and
HfO2: An engineering solution for elimination of O-
atom vacancy defects in non-crystalline ternary
silicate alloys,” ECS 208th, pp.381-392, October
2005.
[24] Xiongfei Yu, “A Comparative Study of HfTaON/SiO2 and
HfON/SiO2 Gate Stacks With TaN Metal Gate for Advanced
CMOS Applications,” IEEE TED, VOL. 54, NO. 2,
FEBRUARY 2007.
[25] L. M. Lin, P. T. Lai, “Improved high-field
reliability for a SiC metal-oxide-semiconductor device
by the incorporation of nitrogen into its HfTiO gate
dielectric,” JOURNAL Appl. Phys, 102, 054515, 2007.
[26] Chao Sung Lai, Kung Ming Fan, “Fluorine effects on
the dipole structures of the Al2O3 thin films and
characterization by spectroscopic ellipsometry,”
Appl. Phys. Lett. 90, 172904, 2007.