MEMORY AUTO REPAIRING CIRCUIT AND ASSOCIATED METHOD
a memory auto repairing circuit including: a decoding circuit, a latch enable circuit and a first latch circuit, wherein the decoding circuit is arranged to compare a first input address with a plurality of fail addresses to generate a control signal; the latch enable circuit is arranged to selectively generate a first enable signal at least according to the control signal; and the first latch circuit is arranged to receive the first input address, and store the first input address when the first enable signal is received by the first latch circuit; wherein when the control signal indicates that the first input address is identical to one of the plurality of fail addresses, the enable signal is prevented from being transmitted from the latch enable circuit to the first latch circuit.
The present invention relates to a memory auto repairing circuit and an associated method.
2. Description of the Prior ArtConventional memory requires two testing stages before leaving the factory; for example, a Chip Probing (CP) mode and a Final Test (FT) mode are executed to test memories. During a typical testing process, when a word line corresponding to an input address is found defective, a redundancy word line is accessed to repair the defective word line. When a word line corresponding to a specific address is found defective, there is a good chance that two different redundancy word lines will be used for the specific address during the CP mode and the Final mode, causing a multi-selection problem. In addition, certain problems need to be fixed during the FT mode. Therefore, a novel memory auto repairing circuit design is desired.
SUMMARY OF THE INVENTIONOne of the objectives of the present invention is to provide a memory auto repairing circuit and an associated method to solve the abovementioned problems.
According to an embodiment of the present invention, a memory auto repairing circuit is disclosed, comprising: a decoding circuit, a latch enable circuit and a first latch circuit, wherein the decoding circuit is arranged to compare a first input address with a plurality of fail addresses to generate a control signal; the latch enable circuit is arranged to selectively generate a first enable signal at least according to the control signal; and the first latch circuit is arranged to receive the first input address, and store the first input address when the first enable signal is received by the first latch circuit; wherein when the control signal indicates that the first input address is identical to one of the plurality of fail addresses, the enable signal is prevented from being transmitted from the latch enable circuit to the first latch circuit.
According to an embodiment of the present invention, a memory auto repairing method is disclosed, comprising: comparing a first input address with a plurality of fail addresses to generate a control signal; selectively generating a first enable signal at least according to the control signal; and utilizing a first latch circuit to receive the first input address, and store the first input address when the first enable signal is received by the first latch circuit; wherein when the control signal indicates that the first input address is identical to one of the plurality of fail addresses, the enable signal is prevented from being transmitted to the first latch circuit.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should not be interpreted as a close-ended term such as “consist of”. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.
Three different conditions should be considered with respect to the embodiment of
Four different conditions should be considered with respect to the embodiment of
When the memory auto repairing circuit 300 is powered off and then powered on again, the latch circuits 304_1 and 304_2 are notified if the E-fuse circuits 305_1 and 305_2 store the fail addresses FA1 and FA2 by the burned signals B1 and B2. Other fail addresses will not be written to the E-fuse circuits 305_1 and 305_2, thereby preventing the multi-selection problem.
In the above description, an example in which the address input to the latch circuit is a row address, corresponding to a word line has been described. However, the address input to the latch circuit may be a column address, corresponding to a bit line. In the latter case, the operation of the memory auto repairing circuit is the same as that described above, and a description thereof is omitted.
It should be noted that the numbers of the latch circuits and the E-fuse circuits installed in the memory auto repairing circuits 100-400 are only for illustrative purposes. In other embodiments, the memory auto repairing circuit can comprise more than two latch circuits. These alternative designs also fall within the scope of the present invention.
Briefly Summarized, by using the control signal CS from the decoding circuits 101-401, the comparing result COM from the comparing circuits 206-406, and the burned signals from the E-fuse circuit 305_1, 305_2, 405_1 and 405_2, the multi-selection problem can be effectively solved.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A memory auto repairing circuit, comprising:
- a decoding circuit, arranged to compare a first input address with a plurality of fail addresses to generate a control signal;
- a latch enable circuit, arranged to selectively generate a first enable signal at least according to the control signal; and
- a first latch circuit, arranged to receive the first input address, and store the first input address when the first enable signal is received by the first latch circuit;
- wherein when the control signal indicates that the first input address is identical to one of the plurality of fail addresses, the enable signal is prevented from being transmitted from the latch enable circuit to the first latch circuit.
2. The memory auto repairing circuit of claim 1, further comprising:
- a comparing circuit, arranged to compare the first input address and a second input address to generate a comparing signal to the latch enable circuit;
- wherein when the comparing signal indicates that the first input address is not identical to the second input address, the latch enable circuit generates a second enable signal.
3. The memory auto repairing circuit of claim 2, further comprising:
- a second latch circuit, arranged to receive the second input address after the first input address is stored by the first latch circuit, and store the second input address when the second enable signal is received by the second latch circuit.
4. The memory auto repairing circuit of claim 3, further comprising:
- a first E-fuse circuit, wherein the first latch circuit stores the first input address into the first E-fuse circuit as a first fail address when the first enable signal is received by the first latch circuit; and
- a second E-fuse circuit, wherein the second latch circuit stores the second input address into the second E-fuse circuit as a second fail address when the second enable signal is received by the second latch circuit.
5. The memory auto repairing circuit of claim 4, wherein the first E-fuse circuit generates a first burned signal to the first latch circuit when the first E-fuse circuit stores the first input address as the first fail address, and the second E-fuse circuit generates a second burned signal to the second latch circuit when the second E-fuse circuit stores the second input address as the second fail address.
6. The memory auto repairing circuit of claim 5, wherein the first latch circuit no longer receives any input address after receiving the first burned signal from the first E-fuse circuit, and the second latch circuit no longer receives any input address after receiving the second burned signal from the second E-fuse circuit.
7. The memory auto repairing circuit of claim 2, wherein the latch enable circuit ignores the comparing signal and generates the first enable signal when an active command and a test mode commands are received by the latch enable circuit, and when the first enable signal is activated, the first latch circuit stores a specific address which is designated when the active command is issued.
8. The memory auto repairing circuit of claim 1, wherein when the control signal indicates that the first input address is identical to one of the plurality of fail addresses, the memory auto repairing circuit accesses a redundancy line according to the first input address.
9. The memory auto repairing circuit of claim 1, wherein when the control signal indicates that the first input address is not identical to any fail address, the memory auto repairing circuit accesses a normal line according to the first input address.
10. The memory auto repairing circuit of claim 1, further comprising:
- an inspecting circuit, arranged to check a normal line corresponding to the first input address, and generate an inspecting signal to the latch enable circuit;
- wherein the latch enable circuit generates the first enable signal when the inspecting signal indicates that the normal line corresponding to the first input address is defective.
11. A memory auto repairing method, comprising:
- comparing a first input address with a plurality of fail addresses to generate a control signal;
- selectively generating a first enable signal at least according to the control signal; and
- utilizing a first latch circuit to receive the first input address, and store the first input address when the first enable signal is received by the first latch circuit;
- wherein when the control signal indicates that the first input address is identical to one of the plurality of fail addresses, the enable signal is prevented from being transmitted to the first latch circuit.
12. The memory auto repairing method of claim 11, further comprising:
- comparing the first input address and a second input address to generate a comparing signal;
- wherein when the comparing signal indicates that the first input address is not identical to the second input address, a second enable signal is generated.
13. The memory auto repairing method of claim 12, further comprising:
- utilizing a second latch circuit to receive the second input address after the first input address is stored by the first latch circuit, and store the second input address when the second enable signal is received by the second latch circuit.
14. The memory auto repairing method of claim 13, further comprising:
- utilizing a first E-fuse circuit to store the first input address as a first fail address when the first enable signal is received; and
- utilizing a second E-fuse circuit to store the second input address as a second fail address when the second enable signal is received.
15. The memory auto repairing method of claim 14, wherein the first E-fuse circuit generates a first burned signal to the first latch circuit when the first E-fuse circuit stores the first input address as the first fail address, and the second E-fuse circuit generates a second burned signal to the second latch circuit when the second E-fuse circuit stores the second input address as the second fail address.
16. The memory auto repairing method of claim 15, wherein the first latch circuit no longer receives any input address after receiving the first burned signal from the first E-fuse circuit, and the second latch circuit no longer receives any input address after receiving the second burned signal from the second E-fuse circuit.
17. The memory auto repairing method of claim 11, further comprising:
- ignoring the comparing signal and generating the first enable signal when an active command and a test mode commands are received by the latch enable circuit, and when the first enable signal is activated, the first latch circuit stores a specific address which is designated when the active command is issued.
18. The memory auto repairing method of claim 11, wherein when the control signal indicates that the first input address is identical to one of the plurality of fail addresses, a redundancy line is accessed according to the first input address.
19. The memory auto repairing method of claim 11, wherein when the control signal indicates that the first input address is not identical to any fail address, a normal line is accessed according to the first input address.
20. The memory auto repairing method of claim 11, further comprising:
- checking a normal line corresponding to the first input address and generating an inspecting signal; and
- generating the first enable signal when the inspecting signal indicates that the normal line corresponding to the first input address is defective.
Type: Application
Filed: Dec 14, 2016
Publication Date: Jun 14, 2018
Inventors: Tse-Hua Yao (Hsinchu County), Yi-Fan Chen (Hsinchu City)
Application Number: 15/378,073