Attack ATmega MCU encryption system by using focus ion beam technique which one of the most commonly used Microcontroller unlocking methods to cut off the security fuse bit and readout Embeded Firmware from microprocessor memory;

Attack ATmega MCU encryption system by using focus ion beam technique which one of the most commonly used Microcontroller unlocking methods to cut off the security fuse bit and readout Embeded Firmware from microprocessor memory

The opposite process to chip fabrication is called deprocessing. A standard CMOS chip has many layers. The deepest doping layers inside the substrate form the transistors. The gate oxide layer isolates the gate from the active area of the transistors. The polysilicon layer on top of it forms the gates and interconnections. The interlayer oxide isolates conducting layers.

Metal layers, usually made of aluminium (Al), form the signal wires, and they are connected with other layers through ‘via’ plugs (Al, W, Ti). Finally, a passivation layer made out of silicon oxide SiO2 or nitride Si3N4 protects the whole structure from moisture and air which could harm the die. In plastic packages the passivation layer is covered with a polymer layer, usually polyimide, to protect against sharp grains in the compound during the package formation.

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