Fine Grain CVD W Film Produced by Modulating Reactor Gasses
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
A dynamic chemical vapor deposition (CVD) process is reported for VLSI semiconductor fabrication, allowing film properties to be controlled by process parameters including the deposition duty cycle, gas ratio, temperature and pressure. By modulating the gas flow in a CVD reactor, a fine grained tungsten film is formed with an average surface roughness of 4% which eliminates lithographic imaging problems. The new process reduces void formation for better hole fill. Moreover, the deposition rate is significantly increased. Dynamic deposition is carried out utilizing one of the methods shown in Fig. 1. The first method shown in Fig. 1a starts with the introduction of a constant flow of hydrogen (H2) and silane mixture (SiH4). Tungsten hexaflouride (WF6) is modulated to create a certain duty cycle.