Characterization and Integration in Cu Damascene Structures of AURORA, an Inorganic Low-k Dielectric
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Characterization and integration in Cu damascene structures of AURORA, an inorganic low-k dielectric R. A. Donaton, B. Coenegrachts, E. Sleeckx, M. Schaekers, G. Sophie1, N. Matsuki1, M. R. Baklanov, H. Struyf, M. Lepage, S. Vanhaelemeersch, G. Beyer, M. Stucchi, D. De Roest, K. Maex2 IMEC, Kapeldreef 75, B-3001 Leuven, Belgium 1 ASM Japan, 6-23-1, Nagayama, Tama, Tokyo, Japan 2 IMEC and E.E. Department, K. U. Leuven, Belgium
ABSTRACT AURORA films, which have a Si-O-Si network with –CH3 terminations, were characterized and integrated into Cu single damascene structures. The relatively low carbon concentration (~ 20%) and the very small pore size (~ 0.6 nm) found could be advantageous during integration of AURORA. Integration of AURORA into Cu single damascene structures was successfully achieved. Suitable resist strip processes, which are critical for Si-O-C type materials, were developed, resulting in trenches with satisfactory profiles. After a complete single damascene process, a interline dielectric constant value of 2.7 was found for line spacing down to 0.25 µm. INTRODUCTION The replacement of silicon dioxide by materials with lower dielectric constant in metallization schemes becomes mandatory as the technologies migrate towards the 130 nm (and below) technology nodes. As the dimensions decrease, the line to line capacitance dominates the parasitic capacitance of the interconnects and, in long parallel lines, cross talk becomes an issue due to coupling capacitance [1]. Even though a long list of candidates, deposited either by spinon or vapor deposition techniques, has been investigated over the last years [2,3], it is not clear at this moment which material will be the selected one. Among them, there is a myriad of materials with dielectric constant between 2.6 and 3.0, including diamond-like carbon films, organic polymers, hybrid organic siloxane polymers and organosilicate glasses (OSG), the later also known as carbon-doped SiO2 or simply Si-O-C films. A long residence plasma CVD (LR-CVD) method to deposit inorganic low-k materials has been shown recently by Matsuki et al. [4]. The key feature of this process is the enhanced dissociation and polymerization of source gas molecules in the vapor phase, followed by a completion of the reaction on the substrate after deposition. As the residence time increases, the dielectric constant is reduced from 3.6 to 2.6 and the deposition rate is increased. AURORA, a material with Si-O-Si network with –CH3 terminations, is therefore formed by optimizing the LR-CVD technique and using dimethyldimethoxysilane (CH3)2Si(OCH3)2 as precursor. In this paper we discuss the basic characteristics of AURORA films deposited at IMEC and the integration of this material in Cu single damascene structures. RESULTS AND DISCUSSION
D5.14.1
S i-O
0.1 4 0.1 2
Absorbance
0.1 0 0.0 8 0.0 6
C H 3 -S i 0.0 4 0.0 2
S i-C S i-C H n
CH3
0.0 0 35 00
30 0 0
25 0 0
20 0 0
1 50 0
1 00 0
5 00
-1
W a v en u m b e r (c m )
Fig. 1 – FTIR spectrum measured from a 500nm thick AURORA layer
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