Method and apparatus for detecting exposure of a semiconductor circuit to ultra-violet light
View Patent ↗A method and apparatus are disclosed for detecting if a semiconductor circuit has been exposed to ultra-violet light. An ultra-violet light detection circuit detects exposure to ultra-violet light and will automatically activate a security violation signal. The security violation signal may optionally initiate a routine to clear sensitive data from memory or prevent the semiconductor circuit from further operation. The ultra-violet light detection circuit detects whether a semiconductor circuit has been exposed to ultra-violet light, for example, by employing a dedicated mini-array of non-volatile memory cells. At least two active bit lines, blprg and bler, are employed corresponding to program and erase, respectively. One of the bit lines is only programmable and the other bit line is only eraseable. Generally, all of the bits in the dedicated non-volatile memory array are initially in approximately the same state, which could be erased, programmed or somewhere in between. An offset current is added to one bit line and a change in the resulting current difference is used to detect an exposure to ultra-violet light.
1. A semiconductor circuit, comprising:
a processor for executing one or more instructions;
a memory; and
a circuit for detecting whether said semiconductor circuit is exposed to ultra-violet light, said circuit comprising a mini-array of non-volatile memory cells dedicated to detecting whether said semiconductor circuit is exposed to ultra-violet light.
2. The semiconductor circuit of claim 1 , wherein said circuit initiates a clearing of said memory of said semiconductor circuit in response to said detection of said exposure to ultra-violet light.
3. The semiconductor circuit of claim 1 , wherein said circuit initiates a disabling of said semiconductor circuit in response to said detection of said exposure to ultra-violet light.
4. The semiconductor circuit of claim 1 , wherein said circuit uses a state of the non-volatile memory cells to detect whether said semiconductor circuit is exposed to ultra-violet light.
5. A semiconductor circuit comprising:
a processor for executing one or more instructions;
a memory; and
a circuit for detecting whether said semiconductor circuit is exposed to ultra-violet light, said circuit comprises a dedicated mini-array of non-volatile memory cells,
wherein said dedicated mini-array of non-volatile memory cells includes at least two active bit lines, corresponding to program and erase, and wherein said first bit line, is only programmable and said second bit line, is only erasable.
6. The semiconductor circuit of claim 5 , wherein said cells in said dedicated mini-array of non-volatile memory are initially in approximately a same state and wherein said exposed state is detected by sensing said at least two active bit lines.
7. The semiconductor circuit of claim 5 , wherein an offset current is added to one of said at least two active bit lines, to detect when said semiconductor circuit is exposed to ultra-violet light.
8. The semiconductor circuit of claim 1 , wherein said memory is a non-volatile memory array.
9. The semiconductor circuit of claim 5 , wherein cells in said dedicated mini-array of non-volatile memory are in a neutral state when said semiconductor circuit is unexposed and wherein an exposed state of said semiconductor circuit is detected by evaluating a current generated by said cells.
10. The semiconductor circuit of claim 1 , further comprising a plurality of other circuits for detecting whether said semiconductor circuit is exposed to ultra-violet light.
11. A semiconductor circuit comprising:
a processor for executing one or more instructions:
a memory; and
a circuit for detecting whether said semiconductor circuit is exposed to ultra-violet light, said circuit comprises a dedicated mini-array of non-volatile memory cells,
wherein said circuit for detecting whether said semiconductor circuit is exposed to ultra-violet light can detect a previous exposure to ultra-violet light that occurred without power being applied to said semiconductor circuit.
12. A method for detecting a security violation in a semiconductor circuit, said method comprising the steps of:
employing an array of dedicated non-volatile memory cells to detect whether said semiconductor circuit is exposed to ultra-violet light; and
initiating a security procedure if said semiconductor circuit is exposed to ultra-violet light.
13. The method of claim 12 , wherein said security procedure clears a memory of said semiconductor circuit in response to said detection of said exposure to ultra-violet light.
14. The method of claim 12 , wherein said security procedure initiates a disabling of said semiconductor circuit in response to said detection of said exposure to ultra-violet light.
15. The method of claim 12 , wherein said employing step further comprises the step of evaluating a circuit indicating whether said semiconductor circuit is exposed to ultra-violet light.
16. The method of claim 12 , wherein said array of non-volatile memory cells is embedded on said semiconductor circuit.
17. The method of claim 12 , further comprising the step of evaluating a plurality of other circuits for detecting whether said semiconductor circuit is exposed to ultra-violet light.
18. A method for detecting a security violation in a semiconductor circuit, said method comprising the steps of:
employing an array of non-volatile memory cells to detect whether said semiconductor circuit is exposed to ultra-violet light;
initiating a security procedure if said semiconductor circuit is exposed to ultra-violet light; and
detecting a previous exposure to ultra-violet light that occurred without power being applied to said semiconductor circuit.