US 12,352,801 B2
Wafer testing for current property of a power transistor
Iman Abdali Mashhadi, Kanata (CA); Thomas William MacElwee, Nepean (CA); Mohammad Bozorgi, Kanata (CA); Ting-Hsiang Hsu, Hsinchu (TW); Meng-ta You, Hsinchu (TW); Regina Inyangat Akudo, Kanata (CA); and Yueh Lin Chiang, Ottawa (CA)
Assigned to Infineon Technologies Canada Inc., Ottawa (CA)
Filed by Infineon Technologies Canada Inc., Ottawa (CA)
Filed on Jul. 10, 2023, as Appl. No. 18/349,780.
Prior Publication US 2025/0020712 A1, Jan. 16, 2025
Int. Cl. G01R 31/26 (2020.01)
CPC G01R 31/2621 (2013.01) [G01R 31/2601 (2013.01); G01R 31/2644 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A method for determining a current property of a power transistor while the power transistor is still on a wafer, the method comprising:
applying a first probe, a drain probe, to a drain terminal of a sense transistor that shares a drain node with the power terminal, the sense transistor being constructed using at least part of a same epitaxial stack as was used to construct which the power transistor, the sense transistor having a lower current flow area than the power transistor;
applying a second probe, a source probe, to a source terminal of the sense transistor;
applying a third probe, a gate probe, to a gate terminal of the sense transistor;
pre-conditioning the sense transistor by alternate turning on and off the sense transistor multiple cycles while allowing a source terminal of the power transistor to float,
wherein turning on the sense transistor comprises 1) applying an on gate voltage via the gate probe to the gate terminal of the sense transistor, 2) applying an on drain voltage via the drain probe to the drain terminal of the sense transistor, and 3) applying an on source voltage via the second probe to the source terminal of the sense transistor;
wherein turning off the sense transistor comprises 1) applying an off gate voltage via the gate probe to the gate terminal of the sense transistor, 2) applying an off drain voltage via the drain probe to the drain terminal of the sense transistor, the off drain voltage greater than the on drain voltage, and 3) applying an off source voltage via the second probe to the source terminal of the sense transistor;
after pre-conditioning the sense transistor, turning on the sense transistor and measuring at least one of 1) the current passing through the sense transistor from the drain terminal of the sense transistor to the source terminal of the sense transistor as the current increases, and 2) a drain-source voltage between the drain terminal of the sense transistor and the source terminal of the sense transistor as the drain-source voltage increases; and
determining a current property of the power transistor based on the measurement.