Isolation circuit

• US 8,624,615 B2
• Filed: 08/16/2011
• Issued: 01/07/2014
• Est. Priority Date: 09/28/2006
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Attalla, Hani S., Cram, Daniel P.
• Primary Examiner(s): Nguyen, Tung X
• Application Number:
  US13/211,022
• Publication Number:
  US 20120001680A1
• Time in Patent Office: 875 Days
• Field of Search: 32476201-7621, 32475001-7503, 257/48, 438 14- 18
• US Class Current: 324/750.3
• CPC Class Codes: G01R 31/2884 using dedicated test connectors, test elements or test circuits on the IC under test G01R31/2855 takes precedence
• CPC Class Codes: G01R 31/31721 Power aspects, e.g. power supplies for test circuits, power saving during test for scan test G01R31/318575
• CPC Class Codes: G01R 31/31723 Hardware for routing the test signal within the device under test to the circuits to be tested, e.g. multiplexer for multiple core testing, accessing internal nodes routing the test signal to or from the device under test G01R31/31926
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

The present disclosure includes various method, device, and system embodiments for isolation circuits. One such isolation circuit embodiment includes: a first transistor configured for connection to a supply voltage via a first terminal; a register connected to the first transistor; a second transistor in parallel with a resistor, wherein the second transistor is configured for connection to the first terminal, with a gate of the second transistor configured for connection to an output of the register; and wherein the second transistor is configured for connection to a second terminal, the second transistor having a state that depends on a status of the register.

Claims

1. A semiconductor die, comprising:

a first terminal; and

an on-die isolation circuit coupled to the first terminal, wherein the isolation circuit is configured to;

allow a first amount of current to be drawn by the die in response to a particular potential at a second terminal when the die is defective; and

allow a second amount of current to be drawn by the die in response to the particular potential at the second terminal when the die is not defective, wherein the first and second amounts of current are different.

2. The die of claim 1, wherein the isolation circuit comprises a current limiting resistance coupled between the first terminal and the second terminal.

3. The die of claim 2, further comprising a transistor coupled in series between the current limiting resistance and the first terminal.

4. The die of claim 2, wherein the current limiting resistance comprises a resistance stack including at least two resistors coupled in parallel.

5. The die of claim 2, further comprising a transistor coupled in parallel with the current limiting resistance.

6. The die of claim 1, wherein the isolation circuit is configured to:

allow the first amount of current to be drawn by the die in response to the second terminal being shorted; and

allow the second amount of current to be drawn by the die in response to the second terminal not being shorted.

7. The die of claim 1, wherein the first terminal is an external voltage supply terminal and the second terminal is an internal voltage supply terminal.

8. The die of claim 7, wherein the second terminal is coupled to testing circuitry.

9. A semiconductor die, comprising:

an input terminal coupled to an external voltage supply; and

an on-die isolation circuit coupled to the input terminal, wherein the isolation circuit includes a current limiting resistance coupled between the input terminal and a supply terminal and is configured to;

allow a first amount of current to be drawn by the die in response to a particular potential at the supply terminal of the die if the die is defective; and

allow a second amount of current to be drawn by the die in response to the particular potential at the supply terminal if the die is not defective, wherein the first and second amounts of current are different.

10. The die of claim 9, wherein the isolation circuit includes a first transistor connected between the input terminal and a register having an output provided to a gate of a second transistor in parallel with a resistor of the current limiting resistance.

11. The die of claim 10, wherein the output of the register is configured to place the second transistor in a conducting state in response to a short at the supply terminal.

12. The die of claim 11, wherein the output of the register is configured to place the second transistor in a non-conducting state if the supply terminal is not shorted.

13. The die of claim 10, wherein the input terminal is connected to a source of the first transistor and the register is connected to a drain of the first transistor.

14. The die of claim 10, wherein the input terminal is connected to a source of the first transistor and to a source of the second transistor.

15. The die of claim 9, wherein the current limiting resistance includes a resistor stack.

16. The die of claim 15, wherein the resistor stack includes:

a first level having a first resistor connected to a first transistor, a gate of the first transistor being connected to a first enable input; and

a second level having a second resistor connected to a second transistor, a gate of the second transistor being connected to a second enable input.

17. The die of claim 16, wherein the first and second enable inputs are controlled to set a resistance value of the resistor stack.

18. A semiconductor die, comprising:

a first terminal coupled to an external voltage supply; and

an on-die isolation circuit coupled to the first terminal, wherein the isolation circuit includes;

a current limiting resistor coupled between the first terminal and a second terminal; and

a transistor coupled to the current limiting resistor, wherein the isolation circuit is configured to;

allow a first amount of current to be drawn by the die responsive to a particular potential at the second terminal of the die when the die is defective; and

allow a second amount of current to be drawn by the die responsive to the particular potential at the second terminal when the die is not defective, wherein the first and second amounts of current are different.

19. The die of claim 18, wherein the second terminal is coupled to a particular device under test (DUT).

20. The die of claim 18, wherein the isolation circuit is configured to provide at least one of:

I/O (input/output) isolation;

control line isolation; and

power isolation.