Converting a bulk radiation-hardened BiCMOS technology into a dielectrically-isolated process

RBCMOS (Radiation-hardened Bipolar CMOS) is a 10-volt, junction-isolated, radiation-hardened BiCMOS process developed at Analog Devices. It is a radiation-hardened version of Analog Devices' commercial Advanced Bipolar CMOS (ABCMOS) process. Both of these processes are designed for advanced mixed-signal circuits such as high-performance D/A and A/D converters. To improve the dose-rate performance of the process, the DI version is being developed. The isolation scheme employed is similar to that used on state-of-the-art commercial complementary-bipolar processes. The starting material is a bonded wafer SOI substrate. Full oxide isolation is achieved with deep trenches that are filled with a combination of oxide and polysilicon. Excellent transistor yield has been demonstrated. The DI process exhibits improved performance in high dose-rate environments, including higher upset thresholds, and improved recovery times. The addition of the oxide isolation did not introduce any radiation sensitivites