Preparation, characterization and application of RF sputter deposited boron doped silicon dioxide thin films

We report the preparation of thin film boron doped silicon dioxide (also called borosilicate-glass or BSG) by RF magnetron and its use as a boron diffusion source, especially for shallow junctions. For this purpose, a sputtering target of BSG was prepared through conventional solid state reaction route. Deposition rates of sputter deposited BSG film at different sputtering parameters were studied. The presence of boron in the deposited film was confirmed by hot probe and sheet resistance techniques on silicon wafer following a diffusion step. The structural evaluation of BSG thin film was performed using Fourier Transform Infrared Spectroscopy (FTIR). Secondary Ion Mass Spectroscopy (SIMS) was used to measure the concentration profile of boron in the BSG film. The effect of sputtering parameters on boron concentration in the deposited BSG film was also studied. A p-n junction diode was fabricated using BSG thin film as diffusion source of boron. The junction depth was measured to be in the range of 0.06-1.0 µm for different sputtering and diffusion parameters.