Method, circuit and system for determining burn-in reliability from wafer level burn-in
A method, circuit and system for determining burn-in reliability from wafer level burn-in are disclosed. The method according to the present invention includes recording the number of failures in each IC die in nonvolatile elements on-chip at points in time over the duration of wafer level burn-in testing. The number of failures in each IC die, along with their associated points in time, may be used to create burn-in reliability curves which are conventionally derived using other processes that may be less cost effective or not possible to effect with unpackaged IC dice. Circuits and system associated with the method of the present invention are also disclosed.
1. Wafer level burn-in circuitry comprising:
nonvolatile elements configured for storing defect information detected during wafer level burn-in testing;
signal detection circuitry for detecting a signal indicating initiation of a cycle of wafer level burn-in testing; and
comprising burn-in control circuitry coupled to the nonvolatile elements, the signal detection circuitry built-in self-stress (BISS) and built-in self-test (BIST) circuitry for controlling wafer level burn-in.
2. The wafer level burn-in circuitry according to claim 1 , further comprising address compression circuitry coupled to the BISS and BIST circuitry for compressing cells of a memory array into redundancy space.
3. The wafer level burn-in circuitry according to claim 2 , wherein the nonvolatile elements, the signal detection circuitry, the burn-in control circuitry and the address compression circuitry comprise circuitry on a single integrated circuit (IC) die.
4. The wafer level burn-in circuitry according to claim 1 , wherein the nonvolatile elements comprise a bank of antifuse registers.
5. The wafer level burn-in circuitry according to claim 4 , wherein each of the antifuse registers includes a time stamp bit.
6. The wafer level burn-in circuitry according to claim 1 , wherein the signal detection circuitry comprises supervoltage detection circuitry.
7. The wafer level burn-in circuitry according to claim 2 , wherein the redundancy space comprises row-repair space.
8. The wafer level burn-in circuitry according to claim 2 , wherein the redundancy space comprises column-repair space.
9. The wafer level burn-in circuitry according to claim 1 , wherein the burn-in control circuitry comprises a state machine for logging failure data into the nonvolatile elements during cycles of the wafer level burn-in testing.
10. The wafer level burn-in circuitry according to claim 1 , wherein the burn-in control circuitry is configured to facilitate reading of wafer level burn-in data from the nonvolatile elements for generating a burn-in reliability curve.
11. A system for wafer level burn-in, comprising high current power supplies for providing power and control signals to individual integrated circuit (IC) dice on a wafer during the wafer level burn-in, wherein wafer level burn-in data is stored in nonvolatile elements in each IC die on the wafer.
12. The system according to claim 11 , further comprising a wafer probe tester for reading the wafer level burn-in data stored in the nonvolatile elements of each IC die on the wafer to generate at least one wafer level burn-in reliability curve.
13. The system according to claim 11 , wherein the high current power supplies comprise:
a high current power supply for VCC and VSS; and
a high current power supply for CMN.
14. A bulk substrate including at least one integrated circuit (IC) die, wherein the at least one IC die comprises:
a memory array;
address compression circuitry in communication with the memory array for compressing memory array addresses into redundancy space;
nonvolatile elements for storing wafer level burn-in data; and
burn-in control circuitry in communication with the memory array and the nonvolatile elements for controlling wafer level burn-in and storing wafer level burn-in data in the nonvolatile elements.
15. The bulk substrate according to claim 14 , further comprising supervoltage detect circuitry in communication with the burn-in control circuitry for detecting a signal indicating a transition between wafer level burn-in self-stress (BISS) and built-in self-test (BIST) modes.
16. The bulk substrate according to claim 14 , wherein the at least one IC die further comprises built-in self-stress (BISS) and built-in self-test (BIST) circuitry in communication with the address compression circuitry, the nonvolatile elements, the burn-in control circuitry and the memory array for controlling the wafer level burn-in.
17. The bulk substrate according to claim 14 , wherein the nonvolatile elements comprise antifuse registers.
18. The bulk substrate according to claim 17 , wherein the antifuse registers comprise a number m+1 of n-bit antifuse registers for storing failures detected before and after m cycles of wafer level burn-in, wherein m and n each comprise positive integers.
19. The bulk substrate according to claim 18 , wherein each of the n-bit antifuse registers comprises one bit for a time stamp and n−1 bits for storing a binary number of failures detected.
20. The bulk substrate according to claim 14 , wherein the redundancy space comprises row redundancy space or column redundancy space.
21. The bulk substrate according to claim 14 , wherein a wafer level burn-in reliability curve may be generated from the wafer level burn-in data.
22. The bulk substrate according to claim 14 , wherein the bulk substrate comprises a silicon wafer.