Semiconductor integrated circuit and ic card system

Abstract

A semiconductor integrated circuit capable of protection from card hacking, by which erroneous actions are actively induced by irradiation with light and protected secret information is illegitimately acquired, is to be provided. Photodetectors, configured by a standard logic process, hardly distinguishable from other circuits and consumes very little standby power, are mounted on a semiconductor integrated circuit, such as an IC card microcomputer. Each of the photodetectors, for instance, has a configuration in which a first state is held in a static latch by its initializing action and reversal to a second state takes place when semiconductor elements in a state of non-conduction, constituting the static latch of the first state, is irradiated with light. A plurality of photodetectors are arranged in a memory cell array. By incorporating the static latch type photodetector into the memory array, they can be arranged inconspicuously. Reverse engineering by irradiation with light can be effectively prevented.

1 - 3 . (canceled) 
     
     
         4 . A semiconductor integrated circuit comprising:
 photodetectors each including a semiconductor element and a photo-detecting semiconductor arranged in series on a current path and respectively placed in a state of conduction and in a state of non-conduction when they are operable,   wherein a potential of a connection point between the semiconductor element in the state of conduction and the photo-detecting semiconductor element in the state of non-conduction varies according to the ratio between a current driving force varying when the photo-detecting semiconductor element in the state of non-conduction is irradiated with light and a current driving force of the semiconductor element in the state of conduction, and photo-detection by said photodetectors is used for stopping internal actions.   
     
     
         5 . The semiconductor integrated circuit according to  claim 4 , wherein said photo-detecting semiconductor element in the state of non-conduction is a MOS transistor. 
     
     
         6 . The semiconductor integrated circuit according to  claim 4 , wherein said photo-detecting semiconductor element in the state of non-conduction is a diode element connected in a reverse bias on said current path. 
     
     
         7 - 16 . (canceled) 
     
     
         17 . The semiconductor integrated circuit according to  claim 4 , further including a logic circuit module operated in synchronism with a clock signal,
 wherein said photodetectors are arranged in said logic circuit module.   
     
     
         18 - 22 . (canceled) 
     
     
         23 . The semiconductor integrated circuit according to  claim 4 , further comprising a plurality of circuit modules, in each of which said photodetectors are arranged at random. 
     
     
         24 . (canceled) 
     
     
         25 . The semiconductor integrated circuit according to  claim 4 , wherein basic cells each comprising a pair of a basic element of a logic circuit and said photodetector are used. 
     
     
         26 . The semiconductor integrated circuit according to  claim 25 , wherein a plurality of said basic cells are distributively arranged. 
     
     
         27 - 37 . (canceled)