Leakage measurement systems

• US 9,269,410 B2
• Filed: 12/29/2014
• Issued: 02/23/2016
• Est. Priority Date: 02/28/2011
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Yamada, Shigekazu
• Primary Examiner(s): Nguyen, Tuan T
• Application Number:
  US14/584,584
• Publication Number:
  US 20150109867A1
• Time in Patent Office: 421 Days
• US Class Current: 1/1
• CPC Class Codes: G11C 16/00 Erasable programmable read-only memories G11C14/00 takes precedence
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 2029/1202 Word line control
• CPC Class Codes: G11C 2029/5006 Current
• CPC Class Codes: G11C 29/025 in signal lines
• CPC Class Codes: G11C 29/50008 of impedance
• CPC Class Codes: G11C 7/06 Sense amplifiers; Associated circuits , e.g. timing or triggering circuits

Abstract

Described examples include leakage measurement systems and methods for measuring leakage current between a word line at a boosted voltage and a word line at a supply voltage. The boosted voltage may be generated by charge pump circuitry. Examples of leakage measurement systems described herein may be included in memory devices.

Claims

1. An apparatus, comprising:

a current source configured to be coupled between a supply voltage and a reference voltage, wherein the current source is configured to provide a reference current to a first word line; and

a comparator having a first input configured to receive the supply voltage and a second input coupled to the first word line, wherein the comparator is configured to generate a signal indicative of a comparison between the supply voltage and a voltage on the first word line.

2. The apparatus of claim 1, wherein the signal is indicative of a leakage current between the first word line and a second word line.

3. The apparatus of claim 2, wherein the second word line is charged to a boosted voltage, wherein the boosted voltage is greater than the supply voltage.

4. The apparatus of claim 3, wherein boosted voltage is provided by charge pump circuitry.

5. The apparatus of claim 1, further comprising logic coupled to the comparator, the logic configured to generate a logic signal based at least in part on the comparison between the supply voltage and the voltage on the first word line, wherein the logic signal indicates whether a leakage current at the first word line is an acceptable amount.

6. The apparatus of claim 1, wherein the current source is configured to provide a plurality of reference currents to a plurality of word lines.

7. The apparatus of claim 6, further comprising a measurement enable circuit, wherein the measurement enable circuit is configured to provide a reference current of the plurality of reference currents to a word line of the plurality of word lines.

8. The apparatus of claim 6, wherein the apparatus is configured to automatically run a series of leakage tests on the plurality of word lines, wherein each of the leakage tests uses a different reference current of the plurality of reference currents.

9. The apparatus of claim 6, further comprising an input pad coupled to the current source, wherein the input pad is configured to receive a current setting signal that is provided to the current source to select a reference current of the plurality of reference currents.

10. The apparatus of claim 1, further comprising an output pad configured to receive the signal from the comparator.

11. A method, comprising:

providing a reference current to a word line;

comparing a voltage on the word line to a supply voltage; and

generating a signal based, at least in part, on a comparison of the voltage on the word line and the supply voltage indicative of a leakage current the word line.

12. The method of claim 11, further comprising precharging a second word line to a boosted voltage, wherein the boosted voltage is greater than the supply voltage.

13. The method of claim 12, further comprising precharging the word line before precharging the second word line to the boosted voltage.

14. The method of claim 11, further comprising determining whether the leakage current is acceptable responsive to the signal.

15. The method of claim 11, further comprising repeating the method of claim 11 for a plurality of word lines.

16. An apparatus, comprising:

a plurality of current sources configured to be coupled to a respective one of a plurality of word lines;

a plurality of comparators, each having a first input coupled to receive a supply voltage and a second input coupled to the respective one of the plurality of word lines, wherein each of the plurality of comparators is configured to generate a respective signal indicative of a comparison between the supply voltage and a voltage on the respective one of the plurality of word lines; and

a logic circuit coupled to the plurality of comparators and configured to combine the signals from the plurality of comparators and provide a signal indicative of pass or fail.

17. The apparatus of claim 16, wherein a current source of the plurality of current sources comprises a current mirror.

18. The apparatus of claim 16, further comprising a plurality of transistors, each of the plurality of transistors coupled to a respective one of the plurality of word lines and to the respective one of the plurality of comparators.

19. The apparatus of claim 16, wherein the voltage on the respective one of the plurality of word lines is based, at least in part, on a leakage current between the respective one of the plurality of word lines and another word line of the plurality of word lines.

20. The apparatus of claim 19, wherein the another word line of the plurality of word lines is at a voltage higher than the supply voltage.