在本論文中，我們先嘗試在鈦、鉭、氮化鈦以及氮化鉭四種材料中，選擇一種材料做為擴散阻障層。經過300℃兩個小時的回火之後，我們由AES發現四種材料皆可以阻擋銅之擴散。在經由XRD圖發現，當銅沉積在鈦上面之時，其在(111)面的結晶性最好，以及配合目前砷化鎵之製成，因此我們先以鈦做為擴散阻障層。
但是我們發現鈦在氮氣環境下，經過320℃2.5分鐘的回火之後，並不能成功的防止銅氧化，而鉭能夠防止銅氧化，因此我們選擇鉭做為保護層。另外銅在經過回火之後，因為(111)面的結晶性變好，造成電阻值有明顯的下降。
再來便是分別用銅和金做為AlGaAs/GaAs HBT的導線，我們發現當使用銅做為導線之時，HBT的寄生電阻Rc、Rb、Re較小，電流增益也比較大。高頻方面，使用銅當導線的HBT其截止頻率也比用金導線來的大。因此不論直流或高頻特性，銅導線之特性皆比金導線來的好。

In this thesis, we try to find the diffusion barrier material from Ti, Ta, TiN and TaN. After 300℃ 2hours annealing, we find that all of them can stop the diffusion of copper from the AES diagrams. We also find as copper deposited on the Ti, the (111) face of copper is the best. And according to the process of GaAs, we select Ti to be the diffusion barrier first.
But we find Ti can not prevent copper oxidized successfully after 320℃ 2.5 mins annealing in nitrogen environment. Ta can prevent copper oxidized and we select Ta to be the protection layer. Besides, the resistivity of copper gets smaller after 320℃ 2.5 mins annealing. We find that is because the (111) face of copper becomes better to make the resistivity gets smaller obviously.
Next we use copper and gold to be the interconnections of AlGaAs/GaAs HBT separately. As using copper to be the interconnections, the parasitic resistance Rc, Rb and Re of HBT are smaller and the current gain is also larger. About RF characteristic, the cut-off frequency of HBT using copper as interconnections is also larger than that using gold. Therefore no matter DC or RF characteristics, copper interconnections are better than gold ones.

[1] SIA Nation Technology Roadmap for Semiconductors 1997
[2] M. Otuki, T. Takewaki, T. Shibata, T. T. Ohmi and T. Nitta, Extended
Abstracts 23rd Conf. Solid State Devices and Materials, pp.186, (1991).
[3] Chang-You Chen, Edward Yi Chang, Member, IEEE, Li Chang, and Szu-Hung Chen, “Backside Copper Metallization of GaAs MESFETs Using TaN as the Diffusion Barrier” IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 48, NO.6, JUNE 2001.
[4] T. Fukada, Y. Toyoda, M. Hasegawa, H. Kurokawa, K. K. Sato and M. Nunoshita, 9th Conf. Materials Research Society, pp. 109~115, (1994).
[5] Room-Temperature oxidation of Silicon in the Presence of Cu3Si, C. S. Liu and L. J. Chen, Thin Solid Films, 262, 187(1995).
[6] Interfacial Reactions of Ultrahigh-Vacuum-Deposited Cu Thin Films on Atomically Cleaned (111) Si. I. Phase Formation and Interface Structure, C. S. Liu and L. J. Chen, J. Appl. Phys., 74, 5001 (1993).
[7] J.D. McBrayer, RM. Swanson and T.W. Sigmon, J. Electrochem. Soc. Solid-State Science and Technology, Vol. 133, No.6, pp.1242, (1986).
[8]Dielectric Degradation of Cu/SiO2/Si Structure During Thermal Annealing, J. C. Chiou, H. I. Wang and M. C. Chen, J. Electrochem. Soc., 143, 990 (1996).
[9] R. S. Muller and T. I. Kamins, Device Electronics for Integrated Circuits, 2nd ed., John Wiley and Sons, New York, pp. 1-56(1986).
[10] E. R. Weber, “Transition metals in silicon,” Appl. Phys. A, Solids Surf., vol. 1, pp. 1–22, 1983.
[11] A. Cros, M. O. Aboelfofotoh, and K. N. Tu, “Formation, oxidation, electronic, and electrical properties of copper silicides,” J. Appl. Phys., vol. 67, no. 7, pp. 3328–3336, Apr. 1, 1990.
[12] C. A. Chang, “Formation of copper silicides from Cu(100)/Si(100) and Cu(111) / Si(111) structures,” J. Appl. Phys., vol. 67, no. 1, pp. 556–569, Jan. 1, 1990.
[13] P. H.Wohlbier, Diffusion and Defect Data. Zürich, Switzerland: Trans Tech, 1975, vol. 10, pp. 89–91.
[14] Study of crystal orientation in Cu film on TiN layered structures, K. Abe, Y. Harada and H. Onoda: J. Vac. Sci and Technol. B17, 1464 (1999).
[15] Thermal Stability of A Cu/Ta Multilayer: An Intriguing Interfacial Reaction, H. Jeong; Kwon and K. Won, Acta Material., Vol. 47, 3965 (1999).
[16] H. Ono, T. Nakano, and T. Ohta, Appl. Phys. Lett., 64(12), pp. 1511-1513(1994).
[17] K. Holloway, P.M. Fryer, C. Cabral Jr, J.M.E. Harper, P.J. Bailey, K.H. Kelleher, J. Appl. Phys. 71 (1992) 5433.
[18] M. Takeyama, A. Noya, T. Sase, A. Ohta, J. Vac. Sci. Technol. B 14 (1996) 674.
[19] K.H. Min, K.C. Chun, K.B. Kim, J. Vac. Sci. Technol. B 14 (1996) 3263.
[20] J.O. Olowolafe, C.J. Mogab, R.B. Gregory, M. Kottke, J. Appl. Phys. 72 (1992) 4099.
[21]銅製程之擴散阻障層，吳文發、黃麒峰，豪微米通訊，VOL.6, NO.4, 30(1999).
[22] Q. T. Jiang, Rick Faust, Hieu Robbie Lam, and Jay Muchda, Proceedings of the International Interconnect Technology Conference, pp. 125-127 (1999).
[23] VLSI製造技術，莊達人
[24] Silicon processing for the VLSI ERA ,VOL 1: process technology
[25] Pieter L.D. Abrie, “Design of RF and Microwave Amplifier and Oscillators” Artech House, Inc. 1999.
[26] George D. Vendelin, Anthony M. Pavio, Ulrich L. Rohde, “Microwave Circuit Design Using Linear and Nonlinear Techniques” John Wilely & Sons, Inc. 1990.
[27]W. R. Runyan and T. J. Shaffer, Semiconductor Measurements and Instrumentation, The McGraw-Hill Companies, Inc, pp. 357~377
[28] W. R. Runyan and T. J. Shaffer, Semiconductor Measurements and Instrumentation, The McGraw-Hill Companies, Inc, pp. 386~389
[29] W. R. Runyan and T. J. Shaffer, Semiconductor Measurements and Instrumentation, The McGraw-Hill Companies, Inc, pp. 279~307
[30] Reactive sputter deposition and characterization of tantalum nitride thin films, K. Radhakrishnan, Ng Geok Ing, R. Gopalakrishnan, Materials Science and Engineering B57(1999) 224-227.
[31] The Evaluation of the Diffusion Barrier Performance of Reactively Sputtered TaNx Layers for Copper Metallization, J.C. Lin, C.S, Liu, S.L. Shue, C.H. Yu, and M.S. Liang, 2000 IEEE.