Crack IC Code other Improvement will make it become more expensive involve using a top metal sensor mesh. All paths in this mesh are continuously monitored for interruptions and short circuits, and cause reset or zeroing of the EEPROM memory if alarmed.
Normally such protection is not used in ordinary microcontrollers because, firstly, it increases the design cost and, secondly, it can be triggered unintentionally in abnormal working conditions such as high electromagnetic noise, low or high temperatures, irregular clock signal or power supply interruptions.
Instead, ordinary microcontrollers adopt the less expensive approach of placing a fake top layer mesh, but this still remains a very effective annoyance for optical analysis and microprobing IC code extraction. In smartcards such meshes are implemented properly with the sensor wires going between the power supply and ground wires.
Some design flaws were found in such implementations making microprobing program reading possible. Also such meshes do not protect against non-invasive mcu break, and some semi-invasive microcontroller crack are still possible because the mesh has gaps between the wires and light can pass through it down to the active areas of the circuit.