Electromigration test structure and test method

Abstract

This invention provides an electromigration test structure and method. The test structure includes a target structure, a first connection structure, a second connection structure, and a third connection structure. The target structure includes a first end and a second end, with the second end positioned opposite to the first end. The first connection structure connects to the first end from a first side of the target structure. The second connection structure connects to the first end from a second side of the target structure, with the second side positioned opposite to the first side. The third connection structure connects to the second end from the second side of the target structure. This electromigration test structure, by simultaneously electrically connecting two connection structures to at least one end of the target structure, allows the test current to enter the target structure through these two connection structures. This reduces the current density in a single connection structure while allowing a relatively large current to be applied to the target structure, avoiding changes to the failure mode of the target structure and saving test time.

Description

Technical Field

[0001] This invention relates primarily to the field of semiconductor manufacturing, and more specifically to an electromigration testing structure and method. Background Technology

[0002] As semiconductor technology nodes shrink further, the electromigration reliability of metal interconnects becomes increasingly important and challenging. Electromigration (EM) is one of the major failure modes in microelectronic devices, causing open and short circuits in the metallization and increasing leakage current. With the advancement of devices towards submicron and deep submicron dimensions, current density continues to increase, making them more susceptible to failure due to electromigration. Therefore, with the advancement of process technology, the electromigration reliability of metal interconnects has become a major concern.

[0003] The direct cause of electromigration is the movement of metal atoms. When a large current flows through an interconnect, the electrostatic force drives electrons from the cathode to the anode. These high-speed electrons exchange energy with the metal atoms, subjecting the atoms to a powerful electron impact force—this is known as electron wind. The metal atoms also experience an electrostatic force in the opposite direction. When the current density in the interconnect is high, a large number of electrons moving towards the anode collide with the atoms, making the electron wind force on the metal atoms greater than the electrostatic force. Therefore, driven by this electron wind, the metal atoms diffuse directionally from the cathode to the anode, resulting in electromigration. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an electromigration test structure and test method, which can quickly and accurately measure the lifetime of metal interconnects.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is an electromigration test structure, comprising: a target structure, a first connection structure, a second connection structure, and a third connection structure, wherein the target structure includes a first end and a second end, the second end being disposed opposite to the first end; the first connection structure is connected to the first end from a first side of the target structure; the second connection structure is connected to the first end from a second side of the target structure, the second side being disposed opposite to the first side; and the third connection structure is connected to the second end from a second side of the target structure.

[0006] In one embodiment of the present invention, the first connection structure includes a first sub-connection structure, the first sub-connection structure having a first sub-end and a second sub-end, the first sub-end being in contact with a first end of the target structure, and the critical dimension of the first sub-end being smaller than the critical dimension of the second sub-end.

[0007] In one embodiment of the present invention, a fourth connection structure is further included, the fourth connection structure being connected from a second side of the target structure to the second end.

[0008] In one embodiment of the present invention, the material of the target structure includes metal or alloy.

[0009] In one embodiment of the present invention, it further includes: a cathode structure, the cathode structure being connected to the first end via the first connecting structure and the second connecting structure; and an anode structure, the anode structure being connected to the second end via the third connecting structure.

[0010] In one embodiment of the present invention, the anode structure is further connected to the second end via the fourth connection structure.

[0011] In one embodiment of the present invention, the cathode structure includes a first cathode lead and a second cathode lead, wherein the first cathode lead is connected to the first connecting structure, and the second cathode lead is connected to the second connecting structure.

[0012] In one embodiment of the present invention, the first connection structure further includes a second sub-connection structure, the second sub-connection structure having a third sub-end and a fourth sub-end, the third sub-end being in contact with the second sub-end of the first sub-connection structure, the fourth sub-end being in contact with the first cathode lead, and the critical dimension of the fourth sub-end being smaller than the critical dimension of the third sub-end.

[0013] In one embodiment of the present invention, the critical dimension of the third sub-end of the second sub-connection structure is smaller than the critical dimension of the second sub-end of the first sub-connection structure.

[0014] In one embodiment of the present invention, the anode structure includes a first anode lead and a second anode lead, wherein the first anode lead is connected to the third connection structure and the second anode lead is connected to the fourth connection structure.

[0015] In one embodiment of the present invention, the first cathode lead is electrically connected to the applied voltage node and the sensing voltage node, and the second cathode lead is electrically connected to the applied voltage node and the sensing voltage node; the applied voltage node is used to contact the first probe of the testing machine, and the testing machine applies current to the target structure through the applied voltage node; the sensing voltage node is in contact with the second probe of the testing machine, and the testing machine obtains the resistance of the target structure through the sensing voltage node.

[0016] In one embodiment of the present invention, the first anode lead is electrically connected to the applied voltage node and the sensing voltage node, and the second anode lead is electrically connected to the applied voltage node and the sensing voltage node; the applied voltage node is used to contact the first probe of the test machine, and the test machine applies current to the target structure through the applied voltage node; the sensing voltage node is in contact with the second probe of the test machine, and the test machine obtains the resistance of the target structure through the sensing voltage node.

[0017] In one embodiment of the present invention, the target structure includes metal interconnects located in a semiconductor structure.

[0018] To address the aforementioned technical problems, this invention also proposes an electromigration testing method based on the electromigration test structure described above, characterized by comprising: applying a current to the target structure, the current entering the target structure through the first connection structure and the second connection structure; and real-time monitoring of the resistance change of the target structure.

[0019] In one embodiment of the present invention, the method further includes: when the change in resistance reaches a predetermined value, recording the duration of current applied to the target structure and ending the test.

[0020] The electromigration test structure of the present invention connects two connection structures to at least one end of the target structure simultaneously, allowing the test current to enter the target structure through the two connection structures. This reduces the current density in a single connection structure while applying a relatively large current to the target structure, avoiding changes to the failure mode of the target structure and saving test time. Attached Figure Description

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0022] Figure 1 This is a schematic diagram of an electromigration test structure.

[0023] Figure 2 This is a schematic diagram of another electromigration test structure;

[0024] Figure 3 This is a schematic diagram of an electromigration test structure according to an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of an electromigration test structure according to another embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of an electromigration test structure according to an embodiment of the present invention;

[0027] Figure 6 This is an exemplary flowchart of an electromigration testing method according to an embodiment of the present invention. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the invention is not limited to the specific embodiments disclosed below.

[0030] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0031] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0032] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, various steps can be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0033] To perform electromigration testing on the target structure, an electromigration test structure can be used. Figure 1 This is a schematic diagram of an electromigration test structure. (Reference) Figure 1 As shown, the electromigration test structure includes a cathode structure 104 and an anode structure 105 connected to the target structure 101, wherein the target structure 101 is the structure to be subjected to the electromigration test. Figure 1As shown, the target structure 101 is located above the cathode structure 104 and the anode structure 105. This can be represented as, in a product with a three-dimensional structure such as 3D NAND, the target structure 101 is on the upper layer, and the cathode structure 104 and anode structure 105 are on the lower layer. The cathode structure 104 is connected to one end of the target structure 101 through a through-hole structure 102, and the anode structure 105 is connected to the other end of the target structure 101 through a through-hole structure 103. During electromigration testing of the target structure 101, a certain current is applied through the cathode structure 104 and the anode structure 105, causing the current to flow upward from the anode structure 105 through the through-hole structure 103 into the target structure 101, and then downward through the through-hole structure 102 into the cathode structure, forming an electron wind within the target structure 101. Figure 1 The electrons e- shown enter one end of the target structure 101 from the cathode structure 104 and then flow to the other end connected to the anode structure 105. Figure 1 In the electromigration test structure shown, electrons e- flow upward from the cathode structure 104 into the target structure 101. This structure is called the upstream structure.

[0034] Figure 2 This is a schematic diagram of another electromigration test structure. (Reference) Figure 2 As shown, the electromigration test structure includes the target structure 101, cathode structure 104, anode structure 105, and... Figure 1 As shown, they are the same, therefore the same labels are used. However, with Figure 1 Compared to what is shown, in Figure 2 In the electromigration test structure shown, the cathode structure 104 is located above the target structure 101 and is connected to one end of the target structure 101 through a through-hole structure 106. The anode structure 105 is located above the target structure 101 and is connected to the other end of the target structure 101 through a through-hole structure 107. In this electromigration test structure, electrons e- flow downwards from the cathode structure 104 into the target structure 101; therefore, this structure is called a downstream structure.

[0035] according to Figure 1 and Figure 2 The electromigration test structure shown involves applying a constant current to the target structure 101. Under the influence of an electron wind, metal atoms in the target structure 101 migrate, forming voids. By monitoring the resistance of the target structure 101, the size of the voids is determined, thereby determining whether the target structure 101 has failed and further obtaining the lifetime of the target structure 101.

[0036] During electromigration testing, the current density is typically calculated based on the cross-sectional area of ​​the target structure 101. Assuming the cross-sectional area is S1, the corresponding current density is ρ1. In semiconductor manufacturing, depending on project requirements, some projects require reducing the resistance of metal wires. This is achieved by increasing the thickness of the metal wire, thus increasing its cross-sectional area to S2, thereby reducing resistance. When such a metal wire is used as… Figure 1 and 2 When testing a target structure with a cross-sectional area of ​​S2, since the cross-sectional area of ​​the through-hole remains unchanged, the difference between the cross-sectional area of ​​the target structure and the cross-sectional area of ​​the connected through-hole increases accordingly. In this case, for a target structure with a cross-sectional area of ​​S2, if the target structure is tested using the original current density ρ1, the current density in the through-hole will be much higher than the current density when the target structure has a cross-sectional area of ​​S1, thus causing a change in the failure mode of the target structure. If the current density used for testing is reduced to ensure that the failure mode of the target structure does not change, the testing time will increase significantly, reducing testing efficiency.

[0037] Furthermore, measuring the electromigration of the target structure via upstream and downstream structures requires a large number of loading voltage nodes and sensing voltage nodes, leading to increased testing costs. For example... Figure 1 and Figure 2 As shown, the cathode structure 104 and the anode structure 105 are respectively connected to the applied voltage node 106 and the sensing voltage node 107. A total of 8 nodes are required for a pair of upstream and downstream structures.

[0038] The electromigration test structure of this invention can be used to test the electromigration reliability of a target structure, offering advantages such as accurate test results, short test time, and reduced node count. The test structure will now be described through specific embodiments.

[0039] Figure 3 This is a schematic diagram of an electromigration test structure according to an embodiment of the present invention. (Reference) Figure 3 As shown, in this embodiment, the test structure 100 includes a target structure 110, a first connection structure 120, a second connection structure 130, and a third connection structure 140. Specifically, the target structure 110 has a first end 111 and a second end 112, with the second end 112 disposed opposite to the first end 111; the first connection structure 120 is electrically connected to its first end 111 via a first side 110a of the target structure 110; the second connection structure 130 is electrically connected to its first end 111 via a second side 110b of the target structure 110, with the second side 110b disposed opposite to the first side 110a; and the third connection structure 140 is connected from the second side 110b of the target structure 110 to the second end 112.

[0040] Figure 3The image shown is a front view of the test structure 100. In some embodiments, the target structure 110 may have a strip-shaped structure with its length direction being... Figure 3 As shown in the diagram, the target structure 110 has a certain length along the first direction D1, and a certain cross-sectional area S along the second direction D2 perpendicular to the first direction D1. Assuming the target structure 110 is located in a layer of a three-dimensional structure, there is a height difference between the position of its first side 110a and the position of its second side 110b in the three-dimensional structure. This height difference is equal to the height of the target structure 110 along the second direction D2. When the cross-section of the target structure 110 is rectangular, the target structure 110 is a cuboid, with the first side 110a being the upper surface of the cuboid and the second side 110b being the lower surface.

[0041] In some embodiments of the present invention, the target structure 110 is a metal interconnect located in a semiconductor device, including a memory chip such as 3D NAND. In other embodiments, the target structure 110 can be a metal interconnect in any semiconductor device. The material of the target structure 110 includes metals or alloys, for example, it can be copper (Cu), aluminum (Al), or an alloy of both. Figure 3 The first connection structure 120, the second connection structure 130, and the third connection structure 140 can be vias connected to the target structure 110. The second side 110b is positioned opposite to the first side 110a, indicating that they are in different layers within the semiconductor structure. The vias are filled with conductive materials, such as metallic materials, including copper, tungsten, etc.

[0042] according to Figure 3 The electromigration test structure shown has a first connection structure 120 connected upwards and a second connection structure 130 connected downwards at the first end 111 of the target structure 110. This reduces the current density in a single connection structure while allowing a relatively large current to be applied to the target structure, thus avoiding changes to the failure mode of the target structure and saving test time.

[0043] refer to Figure 3 As shown, in one embodiment of the present invention, the test structure 100 further includes a third connection structure 140, and the target structure 110 further includes a second end 112 disposed opposite to the first end 111. The third connection structure 140 is electrically connected to the second end 112 of the target structure 110 via a second side 110b. In other embodiments of the present invention, the third connection structure 140 may also be electrically connected to the second end 112 of the target structure 110 via a first side 110a.

[0044] It is understood that the opposite arrangement of the first end 111 and the second end 112 indicates that they are located at the two ends of the elongated structure, respectively. In some other embodiments of the present invention, the first end 111 of the target structure 110 is not limited to... Figure 3 The right end of the target structure 110 shown can be swapped with the position of the second end 112, that is, the first end 111 is located at the left end of the target structure 110, and the second end 112 is located at the right end of the target structure 110. In this way, the positions of the first connecting structure 120, the second connecting structure 130 and the third connecting structure 140 are also changed accordingly.

[0045] refer to Figure 3 As shown, the first connection structure 120 includes a first sub-connection structure 120a, which has a first sub-end 120a1 and a second sub-end 120a2. The first sub-end 120a1 contacts the first end 111 of the target structure 110, and the critical dimension of the first sub-end 120a1 is smaller than the critical dimension of the second sub-end 120a2. When the first connection structure 120 is a through-hole, the critical dimension here can refer to the diameter of the through-hole. According to this embodiment, the first sub-connection structure 120a is a structure that is larger at the top and smaller at the bottom, with the first sub-end 120a1 being the smaller end and the second sub-end 120a2 being the larger end. This structure is formed during the etching of a multi-layer structure, such as 3D NAND.

[0046] Further reference Figure 3 In some embodiments of the present invention, the test structure 100 further includes a cathode structure 150 and an anode structure 160. Specifically, the cathode structure 150 includes a first cathode lead 151 and a second cathode lead 152, wherein the first cathode lead 151 is electrically connected to the first end 111 of the target structure 110 through a first connecting structure 120, the second cathode lead 152 is electrically connected to the first end 111 of the target structure 110 through a second connecting structure 130, and the anode structure 160 is electrically connected to the second end 112 of the target structure 110 through a third connecting structure 140.

[0047] To further illustrate the anode and cathode structures of this invention, a more specific embodiment is provided here. (See reference...) Figure 3 As shown, when the test structure 100 of this invention is specifically implemented in a semiconductor device (e.g., 3D NAND), the target structure 110 is a metal interconnect located in a certain layer of the semiconductor device, the first cathode lead 151 is a metal interconnect located on the upper layer, and the second cathode lead 152 and the anode structure 160 are metal interconnects located on the lower layer. The cathode structure 150 and the anode structure 160 are electrically connected to the target structure 110 through vias connecting metal interconnects in different layers. The second cathode lead 152 and the anode structure 160 may be located in the same layer or in different layers; this invention does not impose any limitations on this.

[0048] When current is applied to the target structure 110 through the first cathode lead 151, the second cathode lead 152, and the anode structure 160, a structure such as... will be formed in the target structure 110. Figure 3 The electron flow indicated by the middle arrow is used to perform electromigration tests on the target structure 110.

[0049] like Figure 3 As shown, the first connection structure 120 further includes a second sub-connection structure 120b, wherein the first sub-connection structure 120a is located below the second sub-connection structure 120b. In this embodiment, the second sub-connection structure 120b has a third sub-end 120b1 and a fourth sub-end 120b2. The third sub-end 120b1 contacts the second sub-end 120a2 of the first sub-connection structure 120a, and the fourth sub-end 120b2 contacts the first cathode lead 151. The critical dimension of the fourth sub-end 120b2 is smaller than the critical dimension of the third sub-end 120b1. The critical dimension may refer to the diameter of the through-hole.

[0050] like Figure 3 As shown, the second sub-connection structure 120b has a structure that is smaller at the top and larger at the bottom. The third sub-end 120b1 is the larger end, and the fourth sub-end 120b2 is the smaller end.

[0051] In some embodiments, the first sub-connection structure 120a and the second sub-connection structure 120b are connected by bonding, wherein the first sub-connection structure 120a and the second sub-connection structure 120b are connected by bonding between the second sub-end 120a2 and the third sub-end 120b1. In some embodiments, the target structure 10 is located in one die, and the first cathode lead 151 and the second sub-connection structure 120b are formed in another die. During the bonding process, the two dies form a bonding structure of the first sub-connection structure 120a and the second sub-connection structure 120b through the second sub-end 120a2 and the third sub-end 120b1.

[0052] like Figure 3 As shown, in some embodiments, the critical dimension of the third sub-end 120b1 of the second sub-connection structure 120b is smaller than the critical dimension of the second sub-end 120a2 of the first sub-connection structure 120a. According to this embodiment, it is beneficial to align and fully contact the second sub-connection structure 120b with the first sub-connection structure 120a during the bonding process.

[0053] like Figure 3 As shown, the third connecting structure 140 has a structure that is larger at the top and smaller at the bottom. Its larger upper end is in contact with the second end 112 of the target structure 110, and its smaller lower end is in contact with the anode structure 160. The third connecting structure 140 and the second connecting structure 130 can be formed in the same process step.

[0054] The structural features of the aforementioned sub-connection structures 120a, 120b and the third connection structure 140 are related to the formation process. In the manufacturing process of 3DNAND, the formation processes of other structures can be combined to simplify the process steps and form the first sub-connection structure 120a, the second sub-connection structure 120b and the third connection structure 140 in the test structure.

[0055] In some embodiments, the cross-sectional area ratio of the target structure 110 and the third connecting structure 140 is approximately 5. For example, the target structure 110 has a layer thickness of 5500 Å and a width of 0.2 μm perpendicular to the paper; the third connecting structure 140 has a aperture of 0.15 μm, and the cross-sectional area ratio of the two is: (0.55*0.2) / (0.15*0.15)=4.88.

[0056] Figure 4 This is a schematic diagram of the electromigration test structure according to another embodiment of the present invention, with reference to... Figure 4 As shown, the test structure 200 in this embodiment is... Figure 3 Based on the illustrated embodiment, a fourth connection structure 170 is also included. This fourth connection structure 170 is electrically connected from the first side 110a of the target structure 110 to its second end 112. It is understood that the above embodiments are merely illustrative examples of considering the top surface of the target structure 100 as the first side 110a and the bottom surface as the second side 110b. In other embodiments of the present invention, the first side 110a and the second side 110b may also be other opposing sides of the target structure 110.

[0057] In one embodiment of the present invention, reference is made to... Figure 4 As shown, the anode structure 160 includes a first anode lead 161 and a second anode lead 162. The first anode lead 161 is electrically connected to the second end 112 of the target structure 110 via a fourth connecting structure 170, and the second anode lead 162 is electrically connected to the second end 112 of the target structure 110 via a third connecting structure 140. It can be understood that although in the above embodiment the anode structure 160 is located on the second end 112 side of the target structure 110 and the cathode structure 150 is located on the first end 111 side of the target structure 110, in other embodiments of the present invention, the first end 111 and the second end 112 can be interchanged, and the positions of the anode structure 160 and the cathode structure 150 can be interchanged accordingly.

[0058] By simultaneously connecting two connection structures to at least one end of the target structure, the test current enters the target structure through these two connection structures. This reduces the current density in a single connection structure while allowing a relatively large current to be applied to the target structure, thus avoiding changes to the failure mode of the target structure and saving test time.

[0059] Figure 5 This is a schematic diagram of an electromigration test structure according to an embodiment of the present invention, with reference to... Figure 5 As shown, in one embodiment of the present invention, an applied voltage node and a sensing voltage node are provided on the anode structure 160 and the cathode structure 150. The applied voltage node is used to contact the first probe of the testing machine, and the testing machine applies current to the target structure through the applied voltage node; the sensing voltage node is in contact with the second probe of the testing machine, and the testing machine obtains the resistance of the target structure through the sensing voltage node.

[0060] When performing electromigration testing, the target structure is connected to the applied voltage node and the sense voltage node via leads. Specifically, the applied voltage node and the sense voltage node can be, for example, pads. The testing machine is an instrument with the function of applying current and measuring resistance. For example... Figure 5 As shown, the testing machine includes multiple probes. During testing, multiple probes are simultaneously placed on each pad. Current is applied through the voltage loading node, and the sensed voltage is received through the voltage sensing node, thereby allowing the resistance change of the target structure to be calculated.

[0061] refer to Figure 5 Specifically, the first cathode lead 151 is electrically connected to the applied voltage node 171 and the sensing voltage node 181, and the second cathode lead 152 is electrically connected to the applied voltage node 172 and the sensing voltage node 182; the anode structure 160 is electrically connected to the applied voltage node 173 and the sensing voltage node 183. The applied voltage node is used to apply voltage to the cathode structure 150 and the anode structure 160, and the sensing voltage node is used to measure the voltage of the cathode structure 150 and the anode structure 160. If the voltage value measured through the sensing voltage node 180 differs from the voltage value applied through the applied voltage node 170, or if the difference is greater than the value required for the test, it indicates a problem with the circuit connection of the target structure 110, and this problem should be eliminated before testing.

[0062] By setting connecting structures on both sides of one end of the target structure, current can be simultaneously generated flowing into the target structure from two directions. For example, as Figure 5 As shown, the current flowing in from the top from the first side 110a of the first end 111 of the target structure 110 and the current flowing in from the bottom from the second side 110b of the second end 112 of the target structure 110 eliminate the need to manufacture separate downstream and upstream structures to form currents with different flow directions. Figure 5 The embodiment shown includes a total of 6 nodes, which reduces the number of voltage loading nodes and voltage sensing nodes.

[0063] exist Figure 4In the embodiment shown, since the anode structure 160 includes a first anode lead 161 and a second anode lead 162, when setting the applied voltage node and the sensing voltage node, the first anode lead 161 can be electrically connected to the applied voltage node and the sensing voltage node, and the second anode lead 162 can be electrically connected to the applied voltage node and the sensing voltage node.

[0064] The present invention also provides an electromigration testing method based on the electromigration test structure described above. Figure 6 This is an exemplary flowchart of an electromigration testing method according to an embodiment of the present invention, with reference to... Figure 6 As shown, the testing method in this embodiment includes the following steps:

[0065] Step S410: Apply current to the target structure so that the current enters the target structure through the first connection structure and the second connection structure.

[0066] Step S420: Monitor the resistance change of the target structure in real time.

[0067] In some embodiments, the method further includes:

[0068] Step S430: When the resistance change reaches the predetermined value, record the duration of current applied to the target structure and end the test.

[0069] The following details steps S410, S420, and S430.

[0070] Combination Figure 5 As shown, in step S410, a testing machine can apply a voltage to the target structure 110 through a voltage loading node connected to the cathode structure 150, and simultaneously apply another voltage to the target structure 110 through a voltage loading node connected to the anode structure 160. The voltage applied to the cathode structure 150 is less than the voltage applied to the anode structure 160, thereby forming a voltage in the target structure 110. Figure 5 The electron flow indicated by the middle arrow is used to test the electromigration reliability of the target structure 110 by forming a continuous electron flow in the target structure 110.

[0071] In step S420, the resistance change of the target structure 110 is detected in real time by a testing machine. Due to the continuous electron flow in the target structure 110, the metal atoms therein will migrate, thereby causing the resistance of the target structure 110 to change.

[0072] In one embodiment of the present invention, the testing method further includes step S430, which can be performed by a testing machine. When the resistance change of the target structure 110 reaches a predetermined value, the duration of current applied to the target structure is recorded, and the test ends. For example, the predetermined value can be set to 10%. When the tissue change of the target structure 110 reaches 10%, the duration of current applied to the target structure 110 is recorded, and the target structure is determined to have failed; this duration is its lifespan. It is understood that in other embodiments of the present invention, the predetermined value can be set to 5%, 15%, or other values.

[0073] By simultaneously electrically connecting two connection structures to at least one end of the target structure, current is applied to the target structure, allowing the test current to enter the target structure through these two connection structures. This reduces the current density in a single connection structure while allowing a relatively large current to be applied to the target structure, avoiding changes to the failure mode of the target structure and saving test time.

[0074] The basic concepts have been described above. Obviously, for those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0075] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0076] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

Claims

1. An electromigration test structure, characterized in that, include: The target structure includes a first connection structure, a second connection structure, and a third connection structure, wherein the target structure includes a first end and a second end, and the second end is disposed opposite to the first end; The first connection structure is connected to the first end from a first side of the target structure; The second connection structure is connected to the first end from the second side of the target structure, and the second side is disposed opposite to the first side; The third connection structure is connected from the second side of the target structure to the second end; The electromigration test structure is configured such that, during electromigration testing, the test current enters the target structure through the first connection structure and the second connection structure, thereby reducing the current density in the first connection structure and the second connection structure while applying a relatively large current to the target structure.

2. The electromigration test structure as described in claim 1, characterized in that, The first connection structure includes a first sub-connection structure, which has a first sub-end and a second sub-end. The first sub-end is in contact with a first end of the target structure, and the critical dimension of the first sub-end is smaller than the critical dimension of the second sub-end.

3. The electromigration test structure as described in claim 2, characterized in that, Also includes: A fourth connection structure is provided, wherein the fourth connection structure is connected to the second end from the second side of the target structure.

4. The electromigration test structure as described in claim 1, characterized in that, The material of the target structure includes metals or alloys.

5. The electromigration test structure as described in claim 3, characterized in that, Also includes: A cathode structure, wherein the cathode structure is connected to the first end via the first connecting structure and the second connecting structure; An anode structure, wherein the anode structure is connected to the second end via the third connection structure.

6. The electromigration test structure as described in claim 5, characterized in that, The anode structure is also connected to the second end via the fourth connection structure.

7. The electromigration test structure as described in claim 5, characterized in that, The cathode structure includes a first cathode lead and a second cathode lead, wherein the first cathode lead is connected to the first connecting structure, and the second cathode lead is connected to the second connecting structure.

8. The electromigration test structure as described in claim 7, characterized in that, The first connection structure further includes a second sub-connection structure, which has a third sub-end and a fourth sub-end. The third sub-end is in contact with the second sub-end of the first sub-connection structure, and the fourth sub-end is in contact with the first cathode lead. The critical dimension of the fourth sub-end is smaller than the critical dimension of the third sub-end.

9. The electromigration test structure as described in claim 8, characterized in that, The critical dimension of the third sub-end of the second sub-connection structure is smaller than the critical dimension of the second sub-end of the first sub-connection structure.

10. The electromigration test structure as described in claim 6, characterized in that, The anode structure includes a first anode lead and a second anode lead, wherein the first anode lead is connected to the third connection structure and the second anode lead is connected to the fourth connection structure.

11. The electromigration test structure as described in claim 7, characterized in that, The first cathode lead is electrically connected to the applied voltage node and the sensing voltage node, and the second cathode lead is electrically connected to the applied voltage node and the sensing voltage node; the applied voltage node is used to contact the first probe of the test machine, and the test machine applies current to the target structure through the applied voltage node; the sensing voltage node is in contact with the second probe of the test machine, and the test machine obtains the resistance of the target structure through the sensing voltage node.

12. The electromigration test structure as described in claim 10, characterized in that, The first anode lead is electrically connected to the applied voltage node and the sensing voltage node, and the second anode lead is electrically connected to the applied voltage node and the sensing voltage node; the applied voltage node is used to contact the first probe of the test machine, and the test machine applies current to the target structure through the applied voltage node; the sensing voltage node is in contact with the second probe of the test machine, and the test machine obtains the resistance of the target structure through the sensing voltage node.

13. The electromigration test structure as described in claim 1, characterized in that, The target structure includes metal interconnects located in a semiconductor structure.

14. An electromigration testing method based on the electromigration test structure as described in any one of claims 1-13, characterized in that, include: A current is applied to the target structure, and the current enters the target structure through the first connection structure and the second connection structure, thereby reducing the current density in the first connection structure and the second connection structure while applying a relatively large current to the target structure; Real-time monitoring of the resistance changes of the target structure.

15. The electromigration testing method as described in claim 14, characterized in that, Also includes: When the change in resistance reaches a predetermined value, the duration of current applied to the target structure is recorded, and the test ends.

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