臺灣博碩士論文加值系統

現今Ta-N阻障層為積體電路之內連接導線系統之主流，但由於Ta-N薄膜中其晶界為銅原子高溫擴散之途徑，因此本實驗採用非晶質態薄膜Ta-Si-N作為擴散阻障層應用於銅內連接導線系統中，期待利用其非晶質態的特性能有效阻礙銅原子的擴散。
本研究第一部分藉由控制鉭靶及矽靶的功率，搭配不同流量的氮氣氣氛進行反應性濺鍍，濺鍍出不同成分的鉭-矽-氮( Ta-Si-N )薄膜。之後以掃描式電子顯微鏡( SEM )觀察表面、以X射線光電子能譜儀( XPS )分析化學鍵結、以低掠角X光繞射(GIAXRD)分析結晶相、使用拉塞福背向散射技術( RBS )作成份分析及密度測量，並做片電阻及膜厚量測計算薄膜電阻率，探討濺鍍製程與鉭-矽-氮薄膜微結構間之關聯性。
第二部分則將銅濺鍍於不同成分之Ta-Si-N/SiO2/Si結構上，經500 ~ 900 ℃真空爐管退火。並以掃描式電子顯微鏡(SEM)觀察表面、以低掠角繞射(GIAXRD)分析結晶相，並做片電阻量測探討銅在氮化鉭矽薄膜上的熱穩定性，最後採用RBS及歐傑電子能譜儀(AES)探討銅擴散之情形以及不同成份之Ta-Si-N薄膜對於銅於高溫擴散情形之比較。
實驗結果第一部分顯示，本實驗可利用控制鉭靶及矽靶功率來製作出9種不同成分的Ta-Si-N非晶質薄膜，分別命名為A1~A3、B1~B3、C1~C3。其中Ta/Si的比例為A > B > C 而N含量為3 > 2 > 1。所有薄膜之電阻率及化學鍵結皆具有高溫之熱穩定性。Ta-Si-N中各元素之作用分別為增加Si原子將會增進其非晶質態的程度、增加Ta原子將有助於降低電阻率及增加密度值，而增加N原子則可提高其結晶溫度。
從實驗結果第二部分中我們可以看出當Cu在Ta53Si3N44 (A2)、Ta53Si11N36 (B2)這兩組系統上時，幾乎沒有擴散的情形產生且片電阻在900℃退火後只上升些許。而Ta57Si5N38 (A1), Ta56Si12N32 (B1)這兩組系統中Ta的含量過高，因此可能有部分的Ta沒有和Si或是N鍵結住而容易擴散出Cu，導致Cu因此擴散進入Ta-Si-N。相反的在C組中Ta的含量非常低，當Ta量過少且N含量很高時，Ta-Si-N會是一個比較鬆散的結構進而造成Cu容易擴散進去。因此Ta-Si-N的成份會是影響當作阻障層好壞的因素且也會影響結晶的溫度。但是Ta-Si-N是否結晶並不是造成Cu和Ta-Si-N間是否會交互擴散的主因。

Ta-N based diffusion barrier has been used widely in copper interconnection system in IC. However, Ta-N films are mostly polycrystalline and the grain boundaries will serve as expedient diffusion paths. To overcome this problem, amorphous thin films of Ta-Si-N alloys were developed. We expect these alloys be a good structure to resist copper diffusion since their microstructures are free of grain boundaries.
In the first experiment, Ta-Si-N thin films were prepared by co-sputtering from Ta and Si targets, in an Ar+N2 atmosphere. The composition, resistivity, crystallographic structure and chemical bonding configuration were investigated by using Rutherford backscattering spectrometry(RBS), four-point probe, glancing incident angle X-ray diffraction(GIAXRD) and X-ray photoelectron spectroscopy(XPS).
In the second experiment, Ta-Si-N films of various compositions were applied as the diffusion barriers in Cu-SiO2 metallization system. Cu/Ta-Si-N/Ta/SiO2 samples were annealed in vacuum (2×10-5 Torr) at temperature ranging from 500 to 900oC for 30 min. The sheet resistance of Cu/Ta-Si-N/Ta/SiO2 samples, before and after annealing, was measured with a four-point probe. Compositional depth profiles of Cu/Ta-Si-N/Ta/SiO2 structures were analyzed with RBS and Auger electron spectroscopy(AES). Surface morphology of the samples was characterized using scanning electron microscopy (SEM). The characteristic phases were identified using glancing incident angle x-ray diffraction (GIAXRD).
From the first experiment, nine Ta-Si-N films of different compositions were fabricated. They are named as A1~A3, B1~B3, and C1~C3. Where the Ta/Si ratio is A > B > C, and the N content is 3 > 2 > 1. It is found that all Ta-Si-N films exhibit amorphous structures, and the degree of amorphism is enhanced when the Si ratio increases. All Ta-Si-N films show good thermal stability in their resistivity and chemical bonding configuration. Since Ta is a metallic element, high Ta content shall promote the conductivity and higher N content will increase the crystallization temperature of Ta-Si-N.
From the second experimet, the system with the Ta53Si3N44 (A2), Ta53Si11N36 (B2) barriers exhibits almost no intermixing between Cu and Ta-Si-N and it shows a minimum increase of sheet resistance after annealing at 900 oC. The system of the Ta57Si5N38 (A1), Ta56Si12N32 (B1) barriers with high Ta content and low N content, some of the Ta atoms may not bond with Si and N atoms so that they are free to diffuse across the Cu layer and some Cu atoms consequently diffuse into Ta-Si-N. On the contrary, group C barriers has a rather low Ta concentration. If the Ta content is too low and the N content is too high, the atomic arrangement of Ta-Si-N will become less closely packed and Cu atoms may penetrate into Ta-Si-N easily. Therefore, an adequate composition is critical for the barrier behavior of Ta-Si-N. Composition of Ta-Si-N may also determine the crystallization temperature. However, crystallization of Ta-Si-N does not directly relate with the interdiffusion between Cu and Ta-Si-N.

第一章 前言與研究目的 …………………………………1
1-1 前言……………………………………………………1
1-2 研究目的………………………………………………4
第二章 理論基礎 …………………………………………7
2-1 電阻電容延遲(RCdelay )……………………………7
2-2 銅金屬導線與其後段連線製程發展…………………8
2-3 擴散阻障層……………………………………………9
2-4 Ta-Si-N之文獻回顧…………………………………13
第三章 實驗方法與步驟…………………………………23
3-1 實驗材料 ……………………………………………23
3-2 實驗設備 ……………………………………………24
3-2.1 濺鍍系統 …………………………………………24
3-2.2 真空退火系統 ……………………………………24
3-2.3 乾式熱氧化系統 …………………………………24
3-3 實驗流程 ……………………………………………28
3-3.1 熱氧化 ……………………………………………28
3-3.2 Ta-Si-N鍍膜實驗…………………………………28
3-3.3 Cu/Ta-Si-N鍍膜實驗 ……………………………29
3-3.4 真空退火實驗 ……………………………………29
3-4 分析儀器 ……………………………………………33
3.4.1 薄膜厚度分析 ……………………………………33
3-4.2 薄膜電性分析 ……………………………………34
3-4.3 拉塞福回向散射分析儀 …………………………35
3-4.4 多功能X光薄膜繞射儀……………………………36
3-4.5 化學分析電子分析 ………………………………37
3-4.6 掃描式電子顯微鏡 ………………………………37
3-4.7 歐結電子能譜儀 …………………………………38
第四章 結果與討論………………………………………39
4-1 初鍍Ta-Si-N薄膜基本性質…………………………39
4-1.1 晶體結構分析 ……………………………………45
4-1.2 化學鍵結分析 ……………………………………49
4-1.3 表面型態分析 ……………………………………58
4-1.4 表面粗糙度分析 …………………………………58
4-2 退火後Ta-Si-N………………………………………65
4-2.1 電性及晶體結構分析 ……………………………65
4-2.2 表面型態分析 ……………………………………72
4-2.3 化學鍵結分析 ……………………………………76
4-3 Cu/Ta-Si-N/Ta/SiO2/Si之熱穩定性………………81
4-3.1 電性量測結果 ……………………………………81
4-3.2 表面型態探討 ……………………………………86
4-3.3 Cu/TaSiN結晶相探討 ……………………………96
4-3.4 Cu/TaSiN之RBS縱深分析 ………………………101
4-4 實驗結果討論………………………………………111
4-4.1 Ta-Si-N結晶相之探討 …………………………111
4-4.2 Ta-Si-N密度與Cu/Ta-Si-N界面擴散之關 ……118
第五章 結論 ……………………………………………122
參考文獻…………………………………………………123

1.International technology roadmap for
semiconductor 2002.
2.曾偉志, 矽半導體元件中之金屬導線製程簡介, 金屬工
業, Vol. 33, No.3 ,96 (1999).
3.S. P. Murarka, “Low Dielectric Constant
Materials for Interlayer Dielectric
Applications”, Solid State Technology, 39(3), 83
(1996).
4.吳文發, 秦玉龍, 電遷移效應對銅導線可靠度之影響,
毫微米通訊, Vol.6,No.117(1999).
5.R.J. Gutmann, T. P. Chow, A. E. Kaloyeros, W. A.
Lanford, and S. P. Murarka, “Thermal Stability
of On-chip Copper Interconnect Structures”, Thin
Solid Films, 262(1-2), 177 (1995).
6.N. Awaya., H. Inokawa, E. Yamamoto, Y. Okazaki,
M. Miyake, Y. Arita ,and T. Kobayashi, “Evaluation of a Copper Metallization Process and
the Electric characteristics of
Copper-interconnected Quarter-micron CMOS”, IEEE
Trans. Electron Devices, 43(8), 1206 (1996).
7.J. Tao, N. W. Cheung, and C. M. Hu, “Metal
electromigration damage healing under
bidirectional current stress”, IEEE Electron
Device Letters, 14(12), 554(1993).
8.T. Nitta, T. Ohmi, T. Hoshi, S. Sakai, K.
Sakaibara, S. Imai, and T. Shibata,
“Evaluating the Electromigration Resistance of
Copper Interconnects Employing a Newly Developed
Accelerated Life-Test Method”, J. Electrochem.
Soc., 140 (4), 1131 (1993).
9.吳文發, 黃麒峰, 銅製程之擴散阻障層, 毫微米通訊,
Vol. 6, No. 4, 30 (1999).
10.J.-C. Chiou, H.-I. Wang, and M.-C. Chen,
“Dielectric Degradation of Cu/SiO2/Si Structure
During Thermal Annealing”, J. Electrochem.
Soc., 143(3), 990(1996).
11.K. Abe, Y. Harada, and H. Onoda, “ Study of
crystal orientation in Cu film on TiN layered
structures”, J. Vac. Sci & Technol., B17(4) ,
1464 (1999).
12.A. E. Kaloyeros, and E. Eisenbraun,
“Ultrathin/Liners for Gigascale Copper
Metallization ”, Anuu. Rev. Mater. Sci., 30,
363(2000).
13.J.O. Olowolafe, I. Rau, K.M. Unruh, C.P. Swann,
Z. Jawad, and T. Alford, “The Effect of Ta to
Si Ratio on Magnetron Sputtered Ta-Si-N Thin
Films”,J. Electronic Materials, 28(12),
1399(1999).
14.Y.J. Lee, B.-S. Suh, M.S. Kwon, and C.-O. Park,
“Barrier properties and failure mechanism of
Ta-Si-N thin films for Cu interconnection”, J.
Appl.Phys. 85(3), 1927(1999).
15.Q.-T. Jaing, R. Faust, H. Lam, and J. Micha,
“Investigation of Ta, TaN and TaSiN Barriers for
Copper Interconnects”, 1999 IEEE IITC 99.
16.S.R. Willson, C.J. Tracy, “Handbook of
Multilevel Matallization for Intergrated
Circuits”, (Noyes Publications, Park Ridge, New
Jersey, USA, 1993), Chap 1.
17.劉偉志, 陳文章, “IC製程之低介電常數高分子材
料”, 塑膠資訊, 43,16 (2000).
18.劉富臺, “銅製程及低介電係數材料技術”,電子月刊,
卷5(12), 100(1999).
19.M.-A. Nicolet, “Diffusion barriers in thin
films”, Thin Solid Films 52,415(1978).
20.K. Holloway and P. M. Fryer, “Tantalum as
diffusion barrier between copper and silicon”,
Appl. Phys. Lett. 57 (17), 1736 (1990).
21.T. Laurila, K. Zeng, J. K. Kivilahti, J.
Molarius and I. Suni, “Failure mechanism of Ta
diffusion barrier between Cu and Si”, J. Appl.
Phys, 88 (6), 3377 (2000).
22.H. Ono, T. Nakano, and T. Ohta, “Diffusion
barrier effects of transition metals for Cu/M/Si
multilayers (M=Cr, Ti, Nb, Mo, Ta, W)”, Appl.
Phys. Lett. 64 (12), 1511 (1994).
23.Y. Ezer, J. Harkonen, V. Sokolov, J. Saarilahti,
J. Kaitila, and P. Kuivalainen, “Diffusion
barrier performance of thin Cr films in the
Cu/Cr/Si structure”, Materials Research
Bulletin, 33 (9), 1331 (1998)
24.F. Braud, J. Torres, J. Palleau, J. L. Mermet,
and M. J. Mouche, “Ti-diffusion barrier in
Cu-based metallization”, Appl. Surf. Sci., 91
(1-4), 251 (1995).
25.J. Y. Lee, S. R. Jeon, and J. W. Park, “Effect
of deposition conditions on the physical and
electrical properties of reactive sputtered
molybdenum nitride film”, J. Mater. Sci. Lett.,
15 (17), 1495 (1996).
26.K. Sakaki, H. Miyake, S. Shinkai, Y. Abe and H.
Yanagisawa, “Realization of Cu(111)
single-oriented state on SiO2 by annealing Cu-Zr
film and the thermal stability of
Cu-Zr/ZrN/Zr/Si contact system”, Jpn. J. Appl.
Phys., part1, 40 (7), 4661 (2001).
27.T. Nitta, T. Ohmi, M. Otsuki, T. Takewaki and T.
Shibata, “Electrical Properties of Giant-Grain
Copper Thin Films Formed by a Low Kinetic Energy
Particle Process”, J. Electrochem. Soc., 139
(3), 922 (1992).
28.J.-Y. Lee and J.-W. Park, “Diffusion barrier
property of Molybdenum nitride films for copper
metallization”, Jpn, J. Appl. Phys., part1, 35
(8), 4280 (1996).
29.K. Holloway, P. M. Fryer, C. Cabral, Jr., J. M.
E. Harper, P. J. Bailey and K. H. Kelleher,
“Tantalum as a diffusion barrier between copper
and silicon : Failure mechanism and effect of
nitrogen additions”, J. Appl. Phys., 71 (11),
5433 (1992).
30.W. L. Yang, W.-F. Wu, D.-G. Liu, C.-C. Wu, and
K. L. Ou, “Barrier capability of TaNx films
deposited by different nitrogen flow rate
against Cu diffusion in Cu/TaNx/n+-p junction
diodes”, Solid-State Electronics, 45(1), 149
(2001).
31.J.-C. Chuang, S.-L. Tu, and M.-C. Chen,
“Sputtered Cr and reactively sputtered CrNx
serving as barrier layers against copper
diffusion”, J. Electrochem. Soc., 145 (12),
4290 (1998).
32.S.-Q. Wang, I. J. Raaijmarkers, B. J. Burrow, S.
Suthar, S. Redkar and K.-B. Kim, “Reactively
sputtered TiN as a diffusion barrier between Cu
and Si“, J. Appl. Phys., 68 (10), 5176 (1990).
33.M. Y. Kwak, D. H. Shin, T. W. Kang, and K. N.
Kim, “Characteristics of WN diffusion barrier
layer for copper metallization”, Physica Status
SolidI A - Applied Research, 174 (1), R5-R6
(1999).
34.J. Li, J. W. Strane, S. W. Russell, S. Q. Hong,
J. W. Mayer, T. K. Marais, C. C. Theron, and R.
Pretorius, “Observation and prediction of first
phase formation in binary Cu-metal thin films”,
J. Appl. Phys., 72 (7), 2810 (1992).
35.E. Kolawa, P. J. Pokala, J. S. Chen, R. P. Ruiz,
and M.A. Nicolet, “Sputtered Ta-Si-N diffusion
barriers in Cu metallizations for Si”, IEEE
Electron Device Letters, 12 (6), 321 (1991).
36.J.-T. No, J.-H. O, and C. Lee, “Evaluation of
Ti-Si-N as a diffusion barrier between copper
and silicon”, Materials Chemistry and Physics,
63 (1), 44 (2000).
37.G. S. Chen, and S. C. Huang, “Intrinsic
properties and barrier behaviors of thin films
of sputter-deposited single-layered and
alternately layered tantalum nitrides
(Ta2N/TaN)”, J. Electrochem. Soc., 148 (8),
G424 (2001).
38.C. Lee, Y.S. Gong, and J.-C. Lin,
“Interdiffusion and reactions in the
Cu/TiN/Si thin film system”, Applied Surface
Science 92(not difined), 335(1996).
39.T. Oku, E. Kawakami, M. Uekubo, M. Murakami, K.
Takahiro, and S. Yamaguchi, “Diffusion barrier
property of TaN between Si and Cu”, Applied
Surface Science 99(4), 265 (1996).
40.C. Lee, and Y.-H. Shin.,”Ta-Si-N as a diffusion
barrier between Cu and Si”, Materials Chemistry
and Physics 57(1), 17(1998).
41.P. Rogl and J. C. Schuster, “Phase Diagrams of
Ternary Boron Nitride and Silicon Nitride
Systems”, ASM International, Ohio, 1992.
42.E. Kolawa, J.M. Molarius, C.W. Nieh, and M-A
Nicolet, “Amousphous Ta-Si-N thin film alloy as
diffusion barrier in Al/Si interconnections”,
J. Vac. Sci.Technol. A 8(3), 3006(1990).
43.E. Kolawa, P.J. Pokela, J.S. Reid, J.S. Chen and
M-A Nicolet, “Amorphous Ta-Si-N diffusion
barriers in Si/Al and Si/Cu metallizations”,
Applied Surface Science 53 ,373(1991).
44.E. Kolawa, J.S. Chen, J. S. Reid, P.J. Pokela,
and M.-A. Nicolet, “Tantalum-Based diffusion
barrier in Si/Cu VLSI metallizations”, J. Appl.
Phys. 70(3), 1369(1991).
45.J.S. Reid , E. Kolawa, R.P. Ruiz, and M.-A.
Nicolet, “Evaluation of amorphous (Mo, Ta,
W)-Si-N diffusion barriers for |Cu
metallizations”, Thin Solid Films 236,
319(1993).
46.J.S. Reid, E. Kolawa, C.M. Garland, and M.-A
Nicolaet, “Amorphous (Mo, Ta, or W)-Si-N
diffusion barrier for Al metallizations”, J.
Appl. Phys. 79(2), 1109(1996).
47.T. Hara, M. Tanaka, K. Sakiyama, and S. Omishi,
“Barrier Properties for Oxygen Diffusion in a
TaSiN Layer”, Jap. J. Appl. Phys. 36(7B),
L893(1997).
48.D. J. Kim, and Y. T. Kim, “Nanostructured
Ta-Si-N barrier for Cu metallization”, J. Appl.
Phys. 82(10),4847(1997).
49.Y.-J. Lee, B.-S. Suh, S.-K. Rha, and C.-O. Park,
“Structure and chemical stability of Ta-Si-N
thin film between Si and Cu”, Thin Solid Films
320(1), 141(1998).
50.E. Ivanov, “Evaluation of tantalum silicide
sputtering target materials for amorphous
Ta-Si-N diffusion barrier for Cumetallization",
Thin Solid Films 332(1-2), 325 (1998).
51.C. Cabral. Jr., K.L. Saenger, D.E. Kotecki, and
J.M.E. Harper, “Optimization of Ta-Si-N thin
films for use as oxidation-resistant diffusion
barriers”, J. Mater. Res. 15,194(2000).
52.J.W. Nah, S.K. Hwang, and C.M. Lee,
“Development of a complex heat resistant
hard coating based on (Ta, Si)N by reactive
sputtering”, Materials Chemistry and Physics
62(2), 115(2000).
53.J.W. Nah, E.S. Choi, S.K. Hwang, and C.M. Lee,
“Chemical state of (Ta, Si)-N reactively
sputtered coating on a high-speed steel
substrate”, Surface and
Coatings Technology 123(1), 1( 2000).
54.D. Fischer, T. Scherg, J.G. Bauer, H-J. Schulze,
C. Wenzel, “Study of Ta-Si-N thin films for
use as barrier layer in copper metallizations”,
Microelectrnic Engineering 50(1-4), 459(2000)
55.J.O. Olowolafe, I. Rau, K.M. Unruh, C.P. Swann,
Z.S. Jawad, and T. Alford,“Effect of
composition on thermal stability and electrical
resistivity of Ta-Si-N films”, Thin Solid Films
365(1), 19(2000).
56.M. Oizumi, K. Aoki, S. Hashimoto, S. Nemoto, and
Y. Fukuda, “Control of Crystalline Structure
and Electrical Properties of TaSiN Thin Film
Formed by Reactive RF-Sputtering”, Jap. J.
Appl. Phys. 39(3A), 1291(2000).
57.T. Hara, H. Toida, and Y. Yoshida, “Control of
the (111) Orientation in Copper Interconnection
Layer” Electrochemical and Solid-State Letters
5(3) ,C41(2002).
58.T. Hara, Y. Yoshida, and H. Toida, “ Improved
Barrier and Adhesion Properties in Sputtered
TaSiN Layer for Copper Interconnects”,
Electrochemical and Solid-State Letters 5(5)
,G36(2002).
59.Y.-S.Suh, G.P.Heuss, and V.Misra, “Electrical
characteristics of TaSixNy/SiO2/Si structures by
Fowler—Nordheim current analysis”, Applied
Physics Letters 80(8), 1403 (2002).
60.Ch. Wengera, M. Alberta, B. Adolphia, H. Heuera,
J.W. Barthaa, and F. Schlenkrich, “ Integration
of high dielectric Ba0.5Sr0.5TiO3 .lms into
amorphous TaSiN barrier layer structures”,
Materials Science in Semiconductor
Processing 5(2-3), 233(2003).
61.H. Lee, and S.S.Wong, “Correlation of stress
and texture evolution during self- and thermal
annealing of electroplated Cu films” J. Appl.
Phys. 93(7), 3796(2003).
62.材料分析 汪建民主編，中國材料科學學會(1998).
63. T. Hara, T. Kitamura, M. Tanaka, T. Kobayashi,
K. Sakiyama, S. Onishi, K. Ishihara, J. Kudo, Y.
Kino, and. N. Yamashita,“Barrier Effect of
TaSiN Layer for Oxygen Diffusion”, J.
Electrochem. Soc. 143(11), L264 (1996).
64. B. D. Cullity and S. R. Stock, Elements of
X-ray Diffraction, 3rd ed. (Prentice Hall, New
Jersey, 2001), p. 170.
65. J. Emsley, “The Elements” (Oxford University
Press, Oxford, 1989).