Fabrication of MIM capacitors with 1000Â Ã silicon nitride layer deposited by PECVD for InGaP/GaAs HBT applications

For InGaP/GaAs HBT applications, we have developed and characterized MIM capacitors with thin 1000 Å PECVD silicon nitride which were deposited with SiH4/NH3 gas mixing rate, working pressure, and RF power of PECVD at 300 °C. These MIM capacitors had the capacitance density of 600 pF/mm2 with the breakdown electric fields of 3.0∼7.3 MV/cm. Three PECVD process parameters were designed to lower the refractive index and then lower the deposition rate of silicon nitride films for the high breakdown electric field. At the PECVD process condition of gas mixing rate (0.92), working pressure (1.3 Torr), RF power (53 W), the AFM Rms value of about 1000 Å silicon nitride on the bottom metal was the lowest of 0.662 nm and breakdown electric field was the highest of about 7.3 MV/cm.