We have constructed a chemical vapor deposition/etching system consisting of a 2.45 GHz microwave generator (ASTeX S-1000) and two movable coaxial magnetic coils. A unique rotatable planar Langmuir probe was designed to characterize the plasma. The Langmuir probe measurements showed an anisotropic character of the plasma which was mainly a result of the magnetic field gradient and propagation direction of the microwaves. By placing the coils at certain distances from the microwave window and adjusting the current through the coils, a critical condition was established, known as "high mode plasma." In this high mode, the plasma ion density was more than four times that in the normal mode. The physical basis of the high mode invoked placing the electron cyclotron resonance critical field (875 G) just in front of the microwave window with a positive magnetic field gradient toward the direction of microwave propagation. This condition produced a high absorption of microwave power and also prevented charged particles from escaping from the plasma.