Comparative analysis of the nucleation and growth of copper on different low-k polymers
- PDF / 546,234 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 102 Downloads / 229 Views
Comparative analysis of the nucleation and growth of copper on different low-k polymers V. Zaporojtchenko1, J. Erichsen1, T. Strunskus1, K. Behnke1, F. Faupel1, M. Baklanov2 and K. Maex2 1 Lehrstuhl für Materialverbunde, , Faculty of Engineering, University of Kiel, Kaiserstr. 2, 24143 Kiel, Germany 2 IMEC, Leuven, Belgium
Abstract In this work we present investigations of the nucleation and growth of evaporated copper on several low-k polymers. The evolving interfaces were characterized using transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results were compared between the PMDA/ODA polyimide, Teflon AF 1601 and Silk. A diffusion coefficient for copper atoms in Silk determined by low energy ion-beam depth profiling in conjunction with XPS is reported.
1. Introduction In view of the great need for further miniaturization and reduction of propagation delay in future device generation Al will increasingly be replaced by the lower resistivity Cu. Polymers are seen as potential low-k dielectrics even for on-chip interconnects. Therefore, the investigation of the growth of Cu on low-k polymers is of considerable technological interest. In the past decades, different metal-polymer interfaces have been studied. Various metallization schemes available to prepare metal/polymer interfaces and the physical and chemical properties of the interface will depend strongly on the particular deposition process used as well as the pre-treatment procedure of the polymer surface. It was shown that metals have a strong tendency to be immobilized by aggregation at the polymer surface and inside the polymer [1-3]. Here we only consider metal/polymer interfaces prepared by evaporation of Cu onto fully cured polymer films. The degree of intermixing increases markedly at low deposition rates and elevated temperatures, where an appreciable fraction of isolated metal atoms is able to diffuse into the polymer. Here condensation coefficients may deviate markedly from unity, particularly for polymers with a low surface energy [4,5]. The microstructure of the metal films as well as the extent of diffusion into the polymer is mainly determined by the early stage of the deposition process, i.e., the nucleation and early growth regime [1-4]. In this study we consider the nucleation and growth of Cu onto low-k polymer with different composition. The effect of metal-polymer interaction as well as of the deposition parameters on the nucleation process are analyzed in order to understand its role in copper/polymer interface formation.
L8.1.1
2. Experimental Three low-k polymers of different chemical composition were used. PMDA/ODA (pyromellitic dianhydride/oxydianiline) (DuPont, PI 2545) polyimide contains carbonyl groups, nitrogen and substituted aromatic ring systems. Teflon AF 1601 (DuPont) has no carbonyl groups and no aromatic systems, but a large fluorine content. SiLK (Dow Chemical) semiconductor dielectric [6] is one of the low-k organic polymer, which has an aromatic hyd
Data Loading...
