BCD stands for Bipolar-CMOS-DMOS, a semiconductor process that combines three device types on the same chip: bipolar for analog performance, CMOS for digital logic, and DMOS for higher voltages and power. That combination makes BCD the platform of choice for mixed-signal and power-management chips such as power management ICs, battery-management devices, and audio ICs.
These chips increasingly need embedded non-volatile memory, mostly to hold the firmware and code the device runs. As designers add more intelligence to power-management and mixed-signal parts, they are moving away from pairing the chip with a separate MCU and its own memory and instead integrating the controller and the NVM onto a single die. Embedded flash is a poor fit for that integration: it adds many mask steps, which translate to a significant cost adder. It is too power-hungry for these applications and provides limited endurance.
ReRAM (RRAM) suits BCD because unlike flash, ReRAM integrates in the back end of line (BEOL), above the transistor layers, with no major changes to the front-end process. A designer can add fast, low-power non-volatile memory to a BCD platform without disturbing the analog, power and logic characteristics that make BCD valuable. For BCD-based products where data has to survive for the life of the system, that is a simpler path to embedded NVM.