locates fails, identifies repairable die and generates repair solutions
blows antifuses to enable redundant elements base on repair solutions generated by pre-repair
verifies repair success and produces a final map for assembly and the Fabs.
Extra rows and column that are build at the edge of the array
Fall out bin
A die will fall out to a specific bin when the number of fails exceeds the number of available redundant element.
To replace a dysfunctional row or column with a redundant element, selected antifuses are “blown”. A blown antifuse has a short circuit between the gate and the substrate. Post repair ensures if the repair was a success.
Prefuse Probe (RPP)
Prefuse Probe tests the die for functionality after all fabrication steps are completed. No repairs are made at Prefuse Probe. Usually the Probe program is being dialed in for a new part. Parts can be re-probed (though there may be some yield loss in re-probe.)
Final Probe (FPP)
Final Probe tests the die for functionality after all fabrication steps are completed and then repairs the non-functional addresses with available redundant elements. Prior to repair, the wafers are tested and a repair solution is generated. The repairs are then made (antifuses are blown) and the die is re-tested while still in contact with the probe card.
An ESDA (enhanced software defect analysis)
ESDA Color Code:
Gray areas indicate low numbers of failing bits
White areas indicate high numbers of failing bits (each white dot represents a failing memory cell)
Black die are massively failing. They failed even before ESDA data could be collected.
Major Bin Categories
1) Parametric Tests
2) Functional Tests
3) Margin Tests
4) Post Repair Tests
Bin - Parametric Tests
Parametric Tests check for shorts, opens, pin leakage and current problems under normal operating conditions. These tests measure current (or voltage) produced by the part to ensure the circuits are functioning within specified parameters. These tests can be found at the beginning and end of the Probe test flow. Parametric tests do not test the memory array, so they are non-repairable. If the die passes the Parametric tests, it moves on to the Functional tests. (Bins H, I, X, and x are the first Parametric Tests)
Bin - Functional Test
Functional Tests evaluate the basic overall functionality of the part under normal operating conditions. They identify specific memory cells in the array that fail to function properly. ESDA data is produced on functional fails. Functional fails are repairable provided enough redundancy is available. If the die passes the Functional tests, it moves on to the Margin tests. (Bins V and B are the Functional Tests)
Bin - Margin Test
Margin Tests After the part passes tests under normal operating conditions, it is put through a series of stress tests to aggravate certain fails. By stressing the part, Probe identifies additional failing memory cells that would have probably failed the Backend* tests. Margin fails are repairable, provided sufficient redundancy is available. (There are approximately 20 Margin Tests)
Bin - Post-Repair
Post-Repair Tests Following the above tests, if there is enough redundancy available, the tester will generate a repair algorithm and then blow the necessary fuses to make the repair. Once this is complete, the die will be re-tested to ensure they are still functional.