We demonstrate a new doping technique for chemical vapor deposition (CVD) growth of diamond. The method involves immersing a solid-state dopant source into the plasma during microwave plasma-assisted CVD. We applied this simple and versatile technique to the growth of boron-doped diamond. The grown films were characterized by X-ray diffraction (XRD), Raman microscopy, glow discharge optical emission spectroscopy (GDOES), and electrical conductivity measurements. The average concentration of boron was 0.5 atom % and the conductivity was 1.5 x 10(-2) Omega cm, which showed irregular behavior at low temperature.