Evolution of Surface Morphology During Cu(TMVS)(hfac) Sourced Copper CVD
- PDF / 716,583 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 3 Downloads / 190 Views
Evolution of Surface Morphology During Cu(TMVS)(hfac) Sourced Copper CVD Daewon Yang, Jongwon Hong, and Timothy S. Cale Focus Center – New York, Rensselaer: Interconnections for Gigascale Integration, Rensselaer Polytechnic Institute, Troy, NY 12180 ABSTRACT In this paper, we describe an experimental study of the nucleation and growth stages during Cu(TMVS)(hfac) sourced Cu CVD on TaN substrates. In particular, we have investigated the effects of water vapor as a co-reactant on evolving surface morphology. The results of short (less than 10 s) depositions without/with water vapor indicate that water vapor helps to reduce the incubation time and to enhance the nuclei formation, uniformity, and adhesion (based on AFM analysis). Introducing water vapor during only the initial stage of deposition results in lower roughnesses, larger grain sizes, and lower short-range roughnesses as compared to the films deposited without water vapor. From this study, we conclude that water vapor enhances Cu nucleation and that a relatively small amount of water vapor before or during the initial stage of deposition improves surface morphology in terms of roughness and grain size. INTRODUCTION As the device densities of integrated circuits (ICs) increases, overall circuit performance becomes increasingly dependent on the properties of the metal films used to interconnect the devices [1,2]. Copper based metallization has been introduced into leading edge ICs because of its promising reliability performance, as well as the potential cost savings associated with damascene processing [3-5]. The cost savings and IC performance increases due to Cu introduction will be more fully realized if deep sub-quarter micron, high aspect ratio, features can be filled inexpensively with barrier material and copper. This is one of the most important issues for multilevel metallization (MLM) process flows today [1]. Over the last several years, chemical vapor deposition (CVD) of Cu has been heavily investigated as a way of depositing Cu into tight contact holes [4-7]. Cu(TMVS)(hfac) (TMVS is trimethylvinylsilane and hfac is 1,1,1,5,5,5-hexafluoroacetylacetonate) is the most widely used Cu(I) precursor. The overall reaction [3,6] has been proposed as: 2CuI(TMVS)(hfac)(g) → Cu0(s) + CuII(hfac)2 (g) + 2TMVS(g) (1) II Cu (hfac)2 and TMVS are thermally stable up to at least 523 K; and leave the surface without decomposing. Complete TMVS desorption from the surface occurs around 398 to 423 K. The addition of water vapor during CVD Cu deposition has been studied by several groups [4,5,7]. Kim et al. [7] reported that shorter incubation time and enhanced growth rate could be achieved using water vapor. Based on analyses of final thick film properties, the addition of water vapor into the reaction chamber enhanced nucleation [5,7] and increased deposition rate [4,5,7]. However, using excess water vapor resulted in higher resistivity [5,8]. Mermet et al. [5] reported that deposited film resistivity decreased upon annealing at 723 K for 30 min. Even though CVD of Cu ha
Data Loading...
