Plasma-enhanced chemical vapor deposition of thick silicon nitride films with low stress on InP

We have developed a low‐temperature plasma‐enhanced chemical vapor deposition process that facilitates the deposition of silicon nitride films with controlled stress by using periodically alternating high‐ and low‐frequency power sources. Very thick films of 3 μm with low stress were deposited on InP substrates. Suitable sidewall profiles for metallization are obtained at 250 °C deposition temperature. A 3‐μm‐thick low‐stress nitride film was successfully applied to reduce the capacitance of bond pad for an array of four InP based photodetectors, that were integrated with a four channel phased‐array wavelength demultiplexer. The capacitance of the detectors was below 0.5 pF at −5 V bias.