Effect of Initial Growth and Seeding Conditions on Boron Doped Hot Filament Diamond Films
- PDF / 226,495 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 77 Downloads / 218 Views
Effect of Initial Growth and Seeding Conditions on Boron Doped Hot Filament Diamond Films Jerry Zimmer1, Thomas Hantschel2, Gerry Chandler1, Andreas Schulze2, Wilfried Vandervorst2,3, Maria Peralta1 1 sp3 Diamond Technologies, 2220 Martin Ave., Santa Clara, CA 95050, U.S.A. 2 IMEC, Kapeldreef 75, B-3001, Leuven, Belgium 3 Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium ABSTRACT Boron doped CVD diamond has been extensively studied in bulk form but little has been published regarding the effects that the initial seeding and growth conditions can have on the characteristics of the initial layer of diamond. This can have a dramatic effect on the performance of the film in applications ranging from AFM probe tips to electrodes used for water purification and other applications. This paper will examine how initial growth conditions and seeding methods can affect the film interface characteristics of doped diamond grown in hot filament CVD reactors. INTRODUCTION Boron doped chemical vapor deposition (CVD) diamond is a very useful material in applications such as water purification electrodes [1], conductive atomic force microscopy (AFM) tips [2], and neural probes [3], and other applications where its electrical conductivity, mechanical characteristics and chemical durability can be combined to perform a function which cannot be replicated with other materials. The diamond must also have consistent properties at the interface with the substrate that it is grown on so that the electrical conductivity is not compromised in the case of electrodes and electrically conductive AFM probes. Hardness of the diamond at the interface must also be preserved for AFM probes. Both conductivity and hardness at the interface can be affected by initial growth conditions, seeding, and pretreatment of the substrate both before and after seeding but prior to growth. This paper examines how initial growth conditions and seeding methods can affect the film interface characteristics of doped diamond grown in hot filament CVD reactors. Most diamond growth begins with seeding of the substrate to promote growth by either polishing or sonication with micron sized diamond powder or exposure to 5-50 nm diamond particles in a suspension[4]. Both techniques leave a monolayer of 5nm or larger particles or agglomerates on the surface which act as nucleation sites for the subsequent diamond growth. Bias enhanced nucleation leads to a similar phenomenon. In all cases the relative density of nucleation sites will determine the initial characteristics of the film which is grown. In general the diamond nucleation sites consist of nonconductive particles of diamond. This creates a situation where increasing seeding density ultimately leads to a nonconductive interface which would block or retard current flow in the case of electrodes and would create a high resistance barrier in AFM probes until wear on the probe tip removed the nonconductive layer. In addition if large densities of agglomerates are present on
Data Loading...
