A test circuit and test method for E-fuse fusing characteristics

Abstract

The present invention provides a test circuit for E-fuse fusing characteristics, comprising a switch controller, a voltage source, at least one E-fuse to be tested and a switch module; the output end of the switch control module is connected to the switch module; one end of the E-fuse to be tested is connected to a fixed potential end, and the other end is connected to the voltage source, and each E-fuse to be tested is connected to a switch module for controlling the on-off of a test circuit where the E-fuse to be tested is located through the switch module; the test circuit greatly increases the number of testable DUTs, saves the area of ​​a test chip, and adopts a fusing voltage and a non-fusing voltage for testing, so as to judge whether the fusing of the E-fuse is caused by the test; when a pulse voltage test signal is adopted, it not only avoids the hidden danger of current accumulation caused by testing the E-fuse in a traditional addressable test structure, but also can further reduce the area occupied by the peripheral test circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of chip testing, and in particular to a testing circuit and a testing method for E-fuse fusing characteristics. Background Art

[0002] Fuse has always been used to guide electronic signals in chips and is a key element in realizing repair technology. The difference in resistance before and after the fuse is blown is used to change the connection relationship of the original circuit, so that the failed storage unit is replaced by the Redundancy Cells, so as to repair the failed storage unit array and improve the chip yield. Traditionally, most chip manufacturers use Laser-fuse technology, which is to blow the fuse by emitting a laser of a certain energy and time. However, with the miniaturization of manufacturing processes, Laser-fuse occupies a large amount of chip area, and its size cannot be reduced with the improvement of the process. At the same time, Laser-fuse requires special laser and testing processes, resulting in low production capacity and limiting the use of Laser-fuse.

[0003] The birth of E-fuse stems from a discovery made by IBM engineers a few years ago: Electron migration (EM) can be used to generate much smaller fuse structures compared to older Laser-fuser technology. EM fuses can be programmed on chip, either at the wafer probing stage or in the package. Using the on-chip voltage of the I / O circuit (typically 2.5V), a 10 mA DC pulse lasting 200 microseconds is sufficient to program a single fuse.

[0004] E-fuse is a two-terminal structure, one end is the Poly end, and the other end is the Active end. A certain fuse voltage is applied to both ends, and the current value of the E-fuse is measured to determine whether it is blown. The current test method for E-fuse is very simple, and generally one E-fuse port is directly connected for testing. This test method can only test a few DUTs, and the test chip area is seriously consumed. Summary of the invention

[0005] The purpose of the present invention is to provide a test circuit and a test method for E-fuse fusing characteristics, which increases the number of testable DUTs through test circuit design and solves the area problem of the test chip.

[0006] Another object of the present invention is to provide a test circuit and test method for E-fuse blowing characteristics, by designing a simplified test circuit and a pulse test signal of a single-channel transmission gate, while further reducing the area occupied by the peripheral test circuit and improving the area utilization.

[0007] Another object of the present invention is to provide a test circuit and test method for the E-fuse blowing characteristics. By using a pulse test signal, the current before the E-fuse blows before the pulse is applied can be measured to determine whether the E-fuse blowing is caused by the test.

[0008] Another object of the present invention is to provide a test circuit and test method for the E-fuse blowing characteristics. By using two switch controls and two tests, the current under two voltage signals of the E-fuse can be measured to determine whether the E-fuse blows normally. At the same time, it can also be determined whether the E-fuse blowing is caused by the test.

[0009] In order to meet the above objectives and other objectives and advantages of the present invention, the present invention provides a test circuit for the melting characteristics of an E-fuse, comprising: a switch controller, a voltage source, at least one E-fuse to be tested and a switch module; the output end of the switch control module is connected to the switch module; one end of the E-fuse to be tested is connected to a fixed potential end, and the other end is connected to the voltage source, and each E-fuse to be tested is connected to a switch module for controlling the on and off of the test circuit where the E-fuse to be tested is located through the switch module.

[0010] The potential value of the fixed potential terminal may be provided by a voltage source or by an external circuit.

[0011] The voltage source provides a test voltage signal, which forms a voltage difference with the fixed potential terminal to test the E-fuse.

[0012] As a further improvement, the switch module includes a switch, and the voltage source can generate a pulse test signal. The frequency of the pulse test signal is consistent with the switching frequency of the switch control module. The current before the E-fuse blows before the pulse is applied can be measured to determine whether the E-fuse blowing is caused by the test.

[0013] As a further improvement, the switch is a transmission gate.

[0014] As a further improvement, the switch control module includes a decoder, and the decoder outputs a signal to select the E-fuse to be tested to form a test path.

[0015] As a further improvement, the test circuit further includes a current acquisition unit for acquiring the current flowing through the selected E-fuse to be tested.

[0016] As a further improvement, the test circuit also includes at least (Y+4) pads, the number of E-fuses to be tested is X≤M×N, which are divided into M blocks, each block has N E-fuses, then at least two pads are connected to the switch control module and the switch module to provide a voltage source; at least two pads are connected to both ends of all E-fuses to be tested; at least Y=m+n pads are connected to the switch control module to provide an address signal, when log2M and log2N are integers, then m=log2M, n=log2N, when log2M and log2N are not integers, then m is an integer greater than log2M and the difference is less than 1, and n is an integer greater than log2N and the difference is less than 1.

[0017] In order to meet the above objectives and other objectives and advantages of the present invention, the present invention also provides an E-fuse fusing characteristic testing method, which specifically includes the following steps:

[0018] Step 1: The fixed potential end applies voltage Vdd to one end of all E-fuses, and the switch control module selects the E-fuse to be tested;

[0019] Step 2: The voltage source applies a pulse test signal to the other end of the E-fuse. When the pulse test signal outputs a high potential, an unfused voltage is formed at both ends of the E-fuse, and the current value I1 is measured at the voltage source. When the pulse test signal outputs a low potential, a fused voltage is formed at both ends of the E-fuse, and the current value I2 is measured at the voltage source.

[0020] Step 3: Use the current values ​​I1 and I2 to determine whether the E-fuse is blown normally;

[0021] Step 4: Select the next E-fuse to be tested through the switch control module, and repeat the above steps 2 and 3 until all the E-fuses to be tested are judged.

[0022] As a further improvement, the switch module includes two switches, namely switch A and switch B; the voltage source is provided with two, namely voltage source A and voltage source B, voltage source A is used to provide a blown test voltage, and voltage source B is used to provide an unblown test voltage; each E-fuse to be tested is connected to power source A through its own switch A, and each E-fuse to be tested is connected to power source B through its own switch B. During the test, only one switch connected to the designated E-fuse to be tested is kept open.

[0023] In combination with the above test circuit, the E-fuse fusing characteristic test method specifically comprises the following steps:

[0024] Step 1: The fixed potential end applies voltage Vdd to one end of all E-fuses, and the switch control module selects the E-fuse to be tested;

[0025] Step 2: The switch control module selects switch A to be disconnected and switch B to be connected. The voltage source B applies a voltage signal Vdd1 to the other end of the E-fuse. An un-fused voltage is formed at both ends of the E-fuse. The current value I1 is measured at the voltage source B.

[0026] Step 3: The switch control module selects switch A to be connected and switch B to be disconnected, and the voltage source A applies a voltage signal of Vdd2 to the other end of the E-fuse, a fuse voltage is formed at both ends of the E-fuse, and the current I2 is measured at the voltage source A;

[0027] Step 4: Use the current values ​​I1 and I2 to determine whether the E-fuse is blown normally;

[0028] Step 5: Select the next E-fuse to be tested through the switch control module, and repeat the above steps 2, 3, and 4 until all the E-fuses to be tested are judged.

[0029] The present invention also provides a testing system, comprising the testing circuit for the E-fuse fusing characteristic.

[0030] The beneficial effect of the present invention is to provide a test circuit and test method for E-fuse fusing characteristics, which greatly increases the number of testable DUTs, saves the test chip area, and uses a fusing voltage and a non-fusing voltage for testing, so as to determine whether the E-fuse fusing is caused by the test. When a pulse voltage test signal is used, it not only avoids the hidden danger of current accumulation caused by the traditional addressable test structure testing E-fuse, but also can further reduce the area occupied by the peripheral test circuit and improve the area utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of an E-fuse fusing characteristic test circuit according to a preferred embodiment of the present invention;

[0032] Figure 2 A schematic diagram of an E-fuse fusing characteristic test circuit according to another preferred embodiment of the present invention;

[0033] Figure 3 Schematic diagram of PAD allocation under 1×24PAD conditions. DETAILED DESCRIPTION

[0034] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0035] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0036] Referring to the accompanying drawings of the present invention Figure 1 , a test circuit and a test method for the E-fuse fusing characteristics according to a preferred embodiment of the present invention are explained. The E-fuse fusing characteristics test circuit comprises a switch control module, a voltage source, at least one E-fuse to be tested and a switch module; the output end of the switch control module is connected to the switch module; one end of the E-fuse to be tested is connected to a 6V fixed potential end, and the other end is connected to the voltage source, and each E-fuse to be tested is connected to a switch module, which is connected to the voltage source through the switch module and controls the on and off of the test circuit where the E-fuse to be tested is located.

[0037] In some embodiments, the switch module includes a switch, which is a transmission gate. The voltage source can generate a 0-3V pulse test signal, and the frequency of the pulse test signal is consistent with the switching frequency of the switch control module. The current before the E-fuse is blown before the pulse is applied can be measured, so that it can be determined whether the E-fuse is blown due to the test.

[0038] In some embodiments, the switch control module includes a decoder. The switch control module selects a switch connected to a specified E-fuse to be tested according to a decoder signal. At the same time, a voltage source provides a pulse voltage signal. By providing two high and low voltage signals, an unblown voltage and a blown voltage are formed at both ends of the E-fuse, respectively. The current information is measured at the voltage source, and the blowing condition of the E-fuse is judged according to the measured current value.

[0039] In some embodiments, the number of decoders is at least one. When the number of decoders is one, the designated E-fuse to be tested can be directly selected. When there are multiple decoders, the E-fuse area to be tested can be locally selected, and then the corresponding designated E-fuse to be tested is selected.

[0040] In some embodiments, an E-fuse fusing characteristic test circuit further includes a pad. Figure 3 As shown, in this embodiment, the switch control module is a decoder and the switch module is a transmission gate. Under the conditions of 1×24PAD, 240 E-fuse DUTs and two decoders, a total of 20 PADs are used, and the specific allocation is as follows:

[0041] Two VDD pads and two GND pads are connected to the decoder and the transmission gate, and the power supply is supplied to them through the group of pads; in some embodiments, only one VDD pad and one GND pad may be connected to the switch control module and the switch module;

[0042] The four S-terminal pads are connected to the Poly end of the E-fuse, and the three D-terminal pads are selectively connected to the Active end of the E-fuse through a transmission gate; in some embodiments, only two pads may be connected to the E-fuse to be tested, of which one S-terminal pad is connected to the Poly end of the E-fuse, and one D-terminal pad is selectively connected to the Active end of the E-fuse through a transmission gate;

[0043] The 240 E-fuse DUTs are divided into 20 blocks, each block has 12 DUTs, 5 pads Drow1 to Drow5 are connected to the decoder address of the control selection block in the switch control module, and 4 pads Dcol1 to Dcol4 are connected to the decoder address of the control selection DUT in the switch control module.

[0044] In combination with the above test circuit, the E-fuse fusing characteristic test method specifically comprises the following steps:

[0045] Step 1: A fixed voltage source applies a 6V voltage Vdd to one end of all E-fuses, and the switch control module selects the E-fuse to be tested;

[0046] Step 2: The voltage source applies a pulse test signal to the other end of the E-fuse through the switch module. When the pulse test signal outputs a high-level signal, the voltage source applies a voltage value of 3V, and an unfused voltage is formed at both ends of the E-fuse. The current value I1 is measured at the voltage source; when the pulse test signal outputs a low level, the voltage value at this time is 0V, a fused voltage is formed at both ends of the E-fuse, and the current value I2 is measured at the voltage source;

[0047] Step 3: Use the current values ​​I1 and I2 to determine whether the E-fuse is blown normally. The specific judgment basis is as follows:

[0048] If I1≈1e-8A, I2≈6mA, it means that the E-fuse is blown normally during the test;

[0049] If I1≈6mA, I2≈6mA, it means that the E-fuse has been blown before the test;

[0050] If I1≈1e-8A, I2≈1e-8A, it means that the E-fuse did not blow during the test.

[0051] Step 4: Select the next E-fuse to be tested through the switch control module, and repeat the above steps 2 and 3 until all the E-fuses to be tested are judged.

[0052] Referring to the accompanying drawings of the present invention Figure 2 According to another preferred embodiment of the present invention, a test circuit and a test method for the E-fuse fusing characteristics are explained. The test circuit of this embodiment includes a switch control module, a voltage source, at least one E-fuse to be tested and a switch module; wherein the output end of the switch control module is connected to the switch module; one end of the E-fuse to be tested is connected to a fixed potential end, and the other end is connected to the voltage source, and each E-fuse to be tested is connected to a switch module, through which it is connected to the voltage source and controls the on and off of the test circuit where the E-fuse to be tested is located. The switch module includes at least two switches, set as switch A and switch B; the voltage source is provided with two, namely, voltage source A and voltage source B, voltage source A is used to provide a fusing test voltage, and voltage source B is used to provide an unfusing test voltage; each E-fuse to be tested is connected to power source A through its own switch A, and each E-fuse to be tested is connected to power source B through its own switch B. During the test process, only one switch connected to the designated E-fuse to be tested is kept open.

[0053] In combination with the above test circuit, the E-fuse fusing characteristic test method specifically comprises the following steps:

[0054] Step 1: A fixed potential terminal applies a voltage Vdd of 6V to one end of all E-fuses, and the switch control module selects the E-fuse to be tested;

[0055] Step 2: The switch control module selects switch A to be disconnected and switch B to be connected. The voltage source B applies a 3V voltage signal to the other end of the E-fuse. An unfused voltage is formed at both ends of the E-fuse. The current value I1 is measured at the voltage source B.

[0056] Step 3: The switch control module selects switch A to be connected and switch B to be disconnected, and the voltage source A applies a 0V voltage signal to the other end of the E-fuse, forming a fuse voltage at both ends of the E-fuse, and the current I2 is measured at the voltage source A;

[0057] Step 4: Use the current values ​​I1 and I2 to determine whether the E-fuse is blown normally. The specific judgment basis is as follows:

[0058] If I1≈1e-8A, I2≈6mA, it means that the E-fuse is blown normally during the test;

[0059] If I1≈6mA, I2≈6mA, it means that the E-fuse has been blown before the test;

[0060] If I1≈1e-8A, I2≈1e-8A, it means that the E-fuse did not blow during the test.

[0061] Step 5: Select the next E-fuse to be tested through the switch control module, and repeat the above steps 2, 3, and 4 until all the E-fuses to be tested are judged.

[0062] The test circuit and test method provided by the present invention greatly increase the number of testable DUTs, save the test chip area, and use a fuse voltage and a non-fuse voltage for testing, so as to determine whether the E-fuse is blown due to the test. When a pulse voltage test signal is used, it not only avoids the hidden danger of current accumulation caused by the traditional addressable test structure testing E-fuse, but also further reduces the area occupied by the peripheral test circuit and improves the area utilization rate.

[0063] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A test circuit for E-fuse fusing characteristics, characterized in that: The test circuit includes a switch control module, a voltage source, a plurality of pads, at least one E-fuse to be tested and a switch module; the output end of the switch control module is connected to the switch module; one end of the E-fuse to be tested is connected to a fixed potential end, and the other end is connected to the voltage source, and each E-fuse to be tested is connected to a switch module for controlling the on and off of the test circuit where the E-fuse to be tested is located through the switch module; The switch control module includes a decoder, and the decoder outputs a signal to select the E-fuse to be tested to form a test path; The voltage source is used to provide a test voltage signal, and forms a voltage difference with the fixed potential end to test the E-fuse to be tested; the voltage difference includes a blown voltage and an unblown voltage.

2. The E-fuse fusing characteristic test circuit according to claim 1, characterized in that: The switch module includes a switch, and the voltage source can generate a pulse test signal, and the frequency of the pulse test signal is consistent with the switching frequency of the switch control module.

3. The E-fuse fusing characteristic test circuit according to claim 1, characterized in that: The switch module includes two switches, namely switch A and switch B; the voltage source is provided with two, namely voltage source A and voltage source B, voltage source A is used to provide a fuse test voltage, and voltage source B is used to provide an un-fused test voltage; each E-fuse to be tested is connected to power supply A through its own switch A, and each E-fuse to be tested is connected to power supply B through its own switch B.

4. A test circuit for E-fuse fusing characteristics according to claim 2 or 3, characterized in that: The switch is a transmission gate.

5. The E-fuse fusing characteristic test circuit according to claim 1, characterized in that: It also includes at least Y+4 pads; the number of E-fuses to be tested is X≤M×N, which is divided into M blocks, each block has N E-fuses, then at least two pads are connected to the switch control module and the switch module, for providing a voltage source; at least two pads are connected to both ends of all E-fuses to be tested; at least Y=m+n pads are connected to the switch control module, for providing an address signal, m=log2M, n=log2N, when m and n are not integers, m is an integer greater than log2M and the difference is less than 1, and n is an integer greater than log2N and the difference is less than 1.

6. The E-fuse fusing characteristic test circuit according to claim 1, characterized in that: The test circuit also includes a current collection unit for collecting the current flowing through the selected E-fuse to be tested.

7. A method for testing the fusing characteristics of an E-fuse, based on the test circuit of claim 2, characterized in that: The method comprises: Step 1: Apply voltage Vdd to one end of all E-fuses at a fixed potential end, and select the E-fuse to be tested through the switch control module; Step 2: The voltage source applies a pulse test signal to the other end of the E-fuse. When the pulse test signal outputs a high potential, an unfused voltage is formed at both ends of the E-fuse, and the current value I1 is measured at the voltage source. When the pulse test signal outputs a low potential, a fused voltage is formed at both ends of the E-fuse, and the current value I2 is measured at the voltage source. Step 3: Use the current values ​​I1 and I2 to determine whether the E-fuse is blown normally; Step 4: Select the next E-fuse to be tested through the switch control module, and repeat the above steps 2 and 3 until all the E-fuses to be tested are judged.

8. A method for testing the fusing characteristics of an E-fuse, based on the test circuit of claim 3, characterized in that: The method comprises: Step 1: The fixed potential end applies voltage Vdd to one end of all E-fuses, and the switch control module selects the E-fuse to be tested; Step 2: The switch control module selects switch A to be disconnected and switch B to be connected. The voltage source B applies a voltage signal to the other end of the E-fuse. An un-fused voltage is formed at both ends of the E-fuse. The current value I1 is measured at the voltage source B. Step 3: The switch control module selects switch A to be connected and switch B to be disconnected, and the voltage source A applies a voltage signal to the other end of the E-fuse, a fuse voltage is formed at both ends of the E-fuse, and the current I2 is measured at the voltage source A; Step 4: Use the current values ​​I1 and I2 to determine whether the E-fuse is blown normally; Step 5: Select the next E-fuse to be tested through the switch control module, and repeat the above steps 2, 3, and 4 until all the E-fuses to be tested are judged.

9. A testing system, characterized in that: A test circuit for E-fuse fusing characteristics comprising the test circuit described in any one of claims 1 to 6.

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