Structural and Micromechanical Assessment of Electrochemically Grown Metal Layers for Si Magnetic Microactuators
- PDF / 1,314,570 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 65 Downloads / 175 Views
Structural and micromechanical assessment of electrochemically grown metal layers for Si magnetic microactuators Susanna Martinez1, Nourdin Yaakoubi1,2, Christophe Serre1, Alejandro Pérez-Rodríguez1, Joan Ramon Morante1, Ismael Díez-Pérez3, Pau Gorostiza 3, Jaume Esteve2. 1 Lab. Enginyeria i Materials Electrònics (EME), Departament d’Electrònica, Unitat Associada CNM-CSIC, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain. 2 Centre Nacional de Microelectrònica CNM-CSIC, Campus UAB, 08193 Bellaterra, Spain 3 Departament de Química Física, Universitat de Barcelona, Martí i Franquès 1, 08028 Spain ABSTRACT The electrochemical deposition of Cu metal layers for Si based microactuator devices is investigated as a function of the substrate structure. For the direct deposition of Cu onto Si, a two step process involving pre-deposition of an intermediate layer under alkaline conditions has been developed. This has allowed the optimization of the process in terms of film adherence and thickness. On the other hand, for processes involving the use of dielectric sacrificial layers, the electrochemical growth of the Cu film requires a metallic seed layer. In this case, the growth of Cu onto Au coated surfaces has been investigated, and the process has been applied to the development of test microactuator structures based on the integration of Cu coils onto Si micromachined devices. The fabrication of these devices demonstrates the full compatibility of Electrochemical processes with Si standard micromachining technologies. INTRODUCTION Electrochemical (EC) deposition constitutes one of the most interesting technologies to deposit metal layers for Micro-Electro-Mechanical Systems (MEMS) [1]. EC has important advantages over alternative techniques. These are related to the higher rate of deposition, which allows the growth of thicker layers, the easy control of the thickness and composition of the layer, the possibility to process complex surfaces with non planar morphology and the low cost of the experimental set-up. Besides, EC is fully compatible with standard Si micromachining technology. The ability to selectively deposit metal layers on the window regions from a mask layout allows the post processing of CMOS processed wafers. This work deals with the study of EC deposition processes of metal layers for Si magnetic microactuators. These devices are based on the integration of a metallic coil onto micromachined Si wafers. Cu is very suited for these applications, because of its low resistivity, low cost and ease to grow electrochemically [2]. The EC deposition of Cu wafers has been investigated in two kinds of wafers: i) direct deposition onto the Si surface and ii) dielectric sacrificial layers (mainly SiO2) on Si. In the first case, a two step process has been designed to solve problems related to the film adherence to the surface. On the other hand, EC deposition onto dielectric layers needs the previous deposition of a thin seed film. The structural analysis of the layers has been performed by Atomic Forc
Data Loading...
