Method and apparatus for measuring transfer characteristics of a semiconductor device

• US 20060044004A1
• Filed: 08/31/2004
• Published: 03/02/2006
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ketchen, Mark B., Bhushan, Manjul
• Granted Patent: US 7,145,347 B2
• Time in Patent Office: Days
• US Class Current: 324/762.90
• CPC Class Codes: G01R 31/3004 Current or voltage test

Abstract

A method and apparatus for measuring alternating current (AC) and direct current (DC) characteristics of a plurality of semiconductor devices. A ring oscillator generates pulses to drive the plurality of semiconductor devices under test. Current/Voltage (IV) and transfer characteristics of the plurality of semiconductor devices are measured using only DC input/output.

Claims

1. A method of testing a plurality of semiconductor devices, comprising:

sequentially generating a continuous sequence of non-overlapping pulses;

using the pulses to drive the plurality of semiconductor devices; and

measuring transfer characteristics of the plurality of semiconductor devices using only direct current inputs and direct current outputs.

2. The method of claim 1, further comprising obtaining alternating current characteristics of the plurality of semiconductor devices.

3. The method of claim 1, further comprising obtaining direct current characteristics of the plurality of semiconductor devices.

4. The method of claim 1, wherein the plurality of semiconductor devices, comprise n-channel field effect transistors (NFETs), p-channel field effect transistors (PFETs), or both.

5. The method of claim 1, wherein said measuring step further comprises providing a direct comparison of alternating current and direct current transfer characteristics for said plurality of semiconductor devices.

6. The method of claim 1, wherein the measuring step further comprises obtaining direct current transfer characteristics by measuring a constant amplitude output from the plurality of semiconductor devices in response to a constant amplitude input to the plurality of semiconductor devices.

7. The method of claims 6, wherein the pulses for measuring alternating current transfer characteristics are obtained by alternating an on/off status of the constant amplitude input for each of the plurality of semiconductor devices such that at any given time the constant amplitude input pulse is applied to only one of the plurality of semiconductor devices.

8. The method of claim 7, wherein a time required to alternate the on/off status of the constant amplitude input to each of the semiconductor devices is negligible compared to a width in time of the input pulses.

9. The method of claim 1, wherein pulses for measuring alternating current transfer characteristics are obtained by alternating an on/off status of an input for each of the plurality of semiconductor devices such that at any given time a constant amplitude input pulse is applied to only one of the plurality of semiconductor devices.

10. The method of claim 1, wherein the plurality of semiconductor devices comprises a set of M nominally identical semiconductor devices.

11. The method of claim 1, wherein circuitry used to create the pulses, and the plurality of semiconductor devices are part of an integrated circuit.

12. The method of claim 1, wherein the pulses are generated using a ring oscillator comprising M equal segments.

13. The method of claim 12, further comprising generating a pulse across each ring oscillator segment as a circulating ring signal passes through each segment.

14. The method of claim 12, wherein a frequency of the ring oscillator is adjustable.

15. The method of claim 1, wherein each of the nonoverlapping pulses is applied for 1/M of the time, where M equals a number of nominally identical semiconductor devices

16. The method of claim 1, wherein an output from an alternating current transfer curve measurement comprises a direct current quantity comprised of a sum of the outputs from the plurality of semiconductor devices, each of said plurality of semiconductor devices being driven by its respective pulsed input.

17. The method of claim 15, wherein alternating current and direct current transfer characteristics are compared by comparing 1/M times a direct current measurement output with an alternating current measurement output for a same input amplitude.

18. The method of claim 1, wherein the semiconductor devices comprise transistors.

19. The method of claim 1, wherein the semiconductor devices comprise logic gates.

20. The method of claim 1, wherein the plurality of semiconductor devices are powered in parallel.

21. The method of claim 10, wherein the continuous sequence of non-overlapping pulses is provided by a ring oscillator.

22. The method of claim 1, wherein said measuring step further comprises:

obtaining alternating current characteristics of the plurality of semiconductor devices by first measuring a direct current transfer response corresponding to a direct current input of zero amplitude; and

obtaining an off current of the plurality of semiconductor devices, where an alternating current measurement of each of the plurality of semiconductor devices equals on current minus off current.

23. An apparatus for testing a plurality of semiconductor devices, comprising:

means for sequentially generating a continuous sequence of non-overlapping pulses;

means for using the pulses to drive the plurality of semiconductor devices; and

means for measuring transfer characteristics of the plurality of semiconductor devices using only direct current inputs and direct current outputs.

24. An apparatus, comprising:

a plurality of semiconductor devices under test; and

a ring oscillator for sequentially generating a continuous sequence of non-overlapping pulses to drive the plurality of semiconductor devices in order to measure transfer characteristics of the plurality of semiconductor devices using only direct current inputs and direct current outputs.

25. The apparatus of claim 24, wherein the ring oscillator further comprises a plurality of segments.

26. The apparatus of claim 25, further comprising a plurality of exclusive nors (XNORs) where each XNOR is connected across one of the plurality of segments.

27. The apparatus of claim 26, further comprising a plurality of inverters, each inverter being driven by one of the plurality of XNORs.

28. The apparatus of claim 27, wherein the plurality of inverters are utilized to drive the plurality of semiconductor devices under test.

29. The apparatus of claim 25, further comprising a plurality of “

not ANDs”

(NANDs) and “

not ORs”

(NORs), wherein each NAND or NOR is connected across one of the plurality of segments.

30. The apparatus of claim 26, further comprising a plurality of inverters, each inverter being driven by one of the plurality of “

not ANDs”

(NANDs) or “

not ORs”

(NORs).

31. The apparatus of claim 27, wherein the plurality of inverters are utilized to drive the plurality of semiconductor devices under test.

32. The apparatus of claim 24, wherein the ring oscillator comprises stages comprising current starved inverters that allow a frequency of the ring oscillator to be varied.