ASIC or Application-specific integrated circuit is Chip used for specific application things and they cannot use for general purposes like microcontroller or microprocessor. For Design ASIC, at first use design logic gate for application on FPGA (Field Programmable Gate Array) After that then make ASIC chip. Designers of digital ASICs often use coding to describe the functionality of ASIC for hardware description languages (HDL), such as Verilog or VHDL.
Advantage of ASIC
Power consumption and efficiency are very good because of the design for a specific application.
Price of ASIC chip when productions are the same as MCU.
Disadvantage of ASIC
Feature not flexible.
Difficult to develop and cost too high.
Time to Market is very poor because difficult to develop and need to test confirm before releasing to ASIC chip.
As you can see, the ASIC has advanced on efficient performance but in the disadvantage are take time to develop and not flexible.
Example ASIC chip
SHA256 ASIC for Bitcoin mining
Google Cloud TPU (Tensor Processing unit) for Machine learning application
Tesla Full Self-Driving chip (FSD) for automatic Self-Driving Car