Using a time invariant statistical process variable of a semiconductor chip as the chip identifier

• US 20060063286A1
• Filed: 09/23/2004
• Published: 03/23/2006
• Est. Priority Date: 09/23/2004
• Status: Active Grant

• Current Assignee: Pixim, Inc. (Sony Group Corp.)
• Original Assignee: Pixim, Inc. (Sony Group Corp.)
• Inventors: Frank, Michael, Bidermann, William R.
• Granted Patent: US 7,291,507 B2
• Time in Patent Office: Days
• US Class Current: 438/17
• CPC Class Codes: H01L 2223/54413 comprising digital information, e.g. bar codes, data matrix
• CPC Class Codes: H01L 2223/5444 for electrical read out
• CPC Class Codes: H01L 2223/5448 Located on chip prior to dicing and remaining on chip after dicing
• CPC Class Codes: H01L 23/544 Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps test patterns for characterising or monitoring manufacturing processes H01L22/00
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/148 Charge coupled imagers individual charge coupled devices H01L29/765
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method for providing an identifier for a semiconductor chip after the manufacture of the semiconductor chip using a fabrication process includes selecting one or more circuit elements formed on the semiconductor chip where each of the circuit elements having an electrical parameter that has a time-invariant statistical process variation, measuring data values of the electrical parameter of the one or more circuit elements, processing the data values, and deriving the identifier for the semiconductor chip using the processed data values. The identifier identifies the semiconductor chip from other semiconductor chips manufactured using the fabrication process. The circuit elements can be selected from the group of bipolar transistors, MOS transistors, light detecting pixel elements, and memory cells. The chip identification method is particularly useful for identifying image sensor chips where the dark current values or the defective pixel locations can be used as the chip identifier.

Claims

1. A method for providing an identifier for a semiconductor chip after the manufacture of the semiconductor chip using a fabrication process, the method comprising:

selecting one or more circuit elements formed on the semiconductor chip, each of the circuit elements having an electrical parameter that has a time-invariant statistical process variation;

measuring data values of the electrical parameter of the one or more circuit elements;

processing the data values; and

deriving the identifier for the semiconductor chip using the processed data values, wherein the identifier identifies the semiconductor chip from other semiconductor chips manufactured using the fabrication process.

2. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises:

selecting one or more circuit elements from the group of bipolar transistors, MOS transistors, light detecting pixel elements, memory cells, resistors, capacitors and inductors.

3. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more resistors, the resistors having resistance values as the electrical parameter that has a time-invariant statistical process variation;

and wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises measuring the resistance values of the one or more resistors.

4. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more capacitors, the capacitors having capacitance values as the electrical parameter that has a time-invariant statistical process variation;

and wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises measuring the capacitance values of the one or more capacitors.

5. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more inductors, the inductors having inductance values as the electrical parameter that has a time-invariant statistical process variation;

and wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises measuring the inductance values of the one or more inductors.

6. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more oscillators, the oscillators having center frequency values as the electrical parameter that has a time-invariant statistical process variation;

and wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises measuring the center frequency values of the one or more oscillators.

7. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more amplifiers, the amplifiers having gain values as the electrical parameter that has a time-invariant statistical process variation;

and wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises measuring the gain values of the one or more amplifiers.

8. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more bipolar transistors, the bipolar transistors having base-to-emitter voltage values, β

gain values and collector current values as the electrical parameters that have time-invariant statistical process variations; and

wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises measuring the base-to-emitter voltage values or the β

gain values or the collector current values of the one or more bipolar transistors.

9. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more MOS transistors, the MOS transistors having threshold voltage values and drain current values as the electrical parameters that have time-invariant statistical process variations;

and wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises measuring the threshold voltage values or the drain current values of the one or more MOS transistors.

10. The method of claim 1, wherein processing the data values comprises:

comparing the data value associated with each circuit element to a reference value;

assigning a first logical value when the data value is greater than the reference value;

assigning a second logical value when the data value is less than the reference value; and

providing a set of logical values associated with the one or more circuit elements as processed data values.

11. The method of claim 10, wherein deriving the identifier for the semiconductor chip using the processed data values comprises:

serializing the set of logical values associated with the one or more circuit elements; and

providing the serial logical values as the identifier.

12. The method of claim 1, wherein processing the data values comprises:

digitizing each of the data values to a k-bit digital value; and

providing a set of k-bit digital values associated with the one or more circuit elements as processed data values.

13. The method of claim 12, wherein deriving the identifier for the semiconductor chip using the processed data values comprises:

serializing the set of k-bit digital values associated with the one or more circuit elements; and

providing the serial digital values as the identifier.

14. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more light detecting pixel elements from an array of light detecting pixel elements, the light detecting pixel elements having dark current values as the electrical parameter that has time-invariant statistical process variations;

and wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises measuring the dark current values of the one or more light detecting pixel elements.

15. The method of claim 14, wherein processing the data values comprises digitizing the measured dark current values of the one or more light detecting pixel elements into a set of k-bit digital values;

and wherein deriving the identifier for the semiconductor chip using the processed data values comprises serializing the set of k-bit digital values associated with the one or more circuit elements and providing the serial digital values as the identifier.

16. The method of claim 14, wherein processing the data values comprises selecting P light detecting pixel elements having the P highest dark current values and digitizing the measured dark current values of the P light detecting pixel elements into a set of k-bit digital values;

and wherein deriving the identifier for the semiconductor chip using the processed data values comprises serializing the set of k-bit digital values associated with the one or more circuit elements and providing the serial digital values as the identifier.

17. The method of claim 14, wherein processing the data values comprises selecting P light detecting pixel elements having the P highest dark current values and obtaining the locations of the P light detecting pixel elements in the array of light detecting pixel elements;

and wherein deriving the identifier for the semiconductor chip using the processed data values comprises serializing the locations of the P light detecting pixel elements and providing the serial location values as the identifier.

18. The method of claim 14, wherein processing the data values comprises selecting and ordering P light detecting pixel elements, comparing the dark current value of each light detecting pixel element with the dark current value of the next light detecting pixel element;

and wherein deriving the identifier for the semiconductor chip using the processed data values comprises serializing the comparison result of the P light detecting pixel elements and providing the serial digital values as the identifier.

19. The method of claim 1, wherein selecting one or more circuit elements formed on the semiconductor chip comprises selecting one or more balanced memory cells of a memory array, the balanced memory cells having intrinsic logical values upon power-up as the electrical parameters that have time-invariant statistical process variations;

and wherein measuring data values associated with the electrical parameter of the one or more circuit elements comprises reading the intrinsic logical values of the one or more balanced memory cells.

20. The method of claim 19, wherein processing the data values comprises providing the intrinsic logical values of the one or more memory cells read out of the memory array as processed data values;

and wherein deriving the identifier for the semiconductor chip using the processed data values comprises serializing the intrinsic logical values associated with the one or more memory cells and providing the-serial intrinsic logical values as the identifier.

21. A method for providing an identifier for an image sensor semiconductor chip including an array of pixels after the manufacture of the image sensor semiconductor chip using a fabrication process, the method comprising:

measuring dark current values of each pixel in the array of pixels;

selecting N pixels from the array of pixels having the N highest dark current values;

obtaining the locations of the N pixels in the array of pixels;

serializing the location values of the N pixels into a bit string; and

providing the bit string as the identifier for the image sensor semiconductor chip.

22. The method of claim 21, wherein measuring dark current values of each pixel in the array of pixels comprises measuring dark current values of M pixels in the array of pixels, wherein M is greater than N.

23. A method for providing an identifier for an image sensor semiconductor chip including an array of pixels after the manufacture of the image sensor semiconductor chip using a fabrication process, the method comprising:

measuring dark current values of each pixel in the array of pixels;

selecting N pixels from the array of pixels having the N highest dark current values;

digitizing the dark current values of the N pixels into a set of k-bit digital values;

serializing the k-bit digital values of the N pixels into a bit string; and

providing the bit string as the identifier for the image sensor semiconductor chip.

24. The method of claim 23, wherein measuring dark current values of each pixel in the array of pixels comprises measuring dark current values of M pixels in the array of pixels, wherein M is greater than N.

25. A method for providing an identifier for an image sensor semiconductor chip including an array of pixels after the manufacture of the image sensor semiconductor chip using a fabrication process, the method comprising:

determining pixels that are defective in the array of pixels;

selecting N pixels from the defective pixels;

obtaining the locations of the N pixels in the array of pixels;

serializing the location values of the N pixels into a bit string; and

providing the bit string as the identifier for the image sensor semiconductor chip.

26. A method for providing an identifier for a semiconductor chip including an array of balanced memory cells after the manufacture of the semiconductor chip using a fabrication process, the method comprising:

powering up the semiconductor chip;

reading logical values from N balanced memory cells in the array of memory cells, the logical values being the intrinsic logical values of the array of balanced memory cells;

serializing the logical values read from the N balanced memory cells into a bit string; and

providing the bit string as the identifier for the semiconductor chip.