- #1
austinuni
- 57
- 24
I have gotten access to a large bare silicon die (almost 1" across, 14nm process) that my company gets from a fab. I've been monkeying around with an ohmmeter placed at the top of the die, with the test leads placed at various points around the die, and I almost always measure the same value (0.2 ohm) as when the leads are touching together directly. At one point I measured 18 ohms with the leads about 1/8" away from each other on the die. On the back side of the die, I always get a reading consistent with non-conduction.
I understand that the top layer of the die is a passivity layer designed to protect the die, and I assume this top layer is non-conductive, but perhaps it is not present in the silicon die that I have. (I think this die may have been a test reject, otherwise I probably would not have it).
I measured the resistance of the top layer of a completed silicon wafer from a different device (much smaller die), and between the test points on the same die, I either get a non-conductive reading or a very small reading like around 20 ohms.
I think below the passivity layer of the die would be the metal layers, and I assume that's what the test leads are touching. But why is it always close to 0 ohms? Wouldn't I get a non-zero conductive reading or inconsistent reading between non-zero conductive and non-conductive, reflecting the various paths through the transistor circuit that is conducting the meter's current?
I understand that the top layer of the die is a passivity layer designed to protect the die, and I assume this top layer is non-conductive, but perhaps it is not present in the silicon die that I have. (I think this die may have been a test reject, otherwise I probably would not have it).
I measured the resistance of the top layer of a completed silicon wafer from a different device (much smaller die), and between the test points on the same die, I either get a non-conductive reading or a very small reading like around 20 ohms.
I think below the passivity layer of the die would be the metal layers, and I assume that's what the test leads are touching. But why is it always close to 0 ohms? Wouldn't I get a non-zero conductive reading or inconsistent reading between non-zero conductive and non-conductive, reflecting the various paths through the transistor circuit that is conducting the meter's current?