Test structure and test method

Abstract

The invention discloses a test structure and a test method, and the structure comprises a substrate which comprises a chip region and a to-be-tested region; the to-be-tested device is positioned above the substrate of the to-be-tested area; the heating device is located above the substrate of the to-be-tested area and surrounds the to-be-tested device, and the heating device and the to-be-tested device are exposed out of the top of the chip area. By arranging the heating device surrounding the device to be tested, the reliability of the test structure is improved, and the flexibility of the electromigration reliability test is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and more particularly to a test structure and test method. Background Technology

[0002] Electromigration testing (EM) is an important method for evaluating the reliability of integrated circuits. This test focuses on the forces exerted on metal atoms by electron flow under high current density, which may cause voids or mounds to form in metal wires, ultimately leading to open circuits or short circuits and affecting the normal operation of the chip.

[0003] EM testing is a destructive experiment, meaning the testing process may damage the sample, making it impossible to perform other types of testing afterward. EM testing is typically performed after wafer die sawing. Wafer dicing is the process of dividing a wafer into individual dies, a step in the semiconductor packaging process. After dicing, these smaller dies are placed into specialized test cassettes.

[0004] To accelerate the testing process and obtain reliability data in a short time, EM testing is typically conducted under harsh conditions, including applying high current and high temperature to accelerate electron migration, thereby simulating chip failure under prolonged use.

[0005] However, due to the destructive nature of EM testing, its reliability and flexibility still need to be improved. Summary of the Invention

[0006] The problem solved by the embodiments of the present invention is to provide a test structure and test method that is beneficial to improving the reliability of the test structure and the test flexibility.

[0007] To address the aforementioned issues, this invention provides a test structure comprising: a substrate including a chip region and a region under test; a device under test (DUT) located above the substrate in the DUT area; and a heating device located above the substrate in the DUT area and surrounding the DUT, with the heating device and the DUT exposed above the top of the chip region.

[0008] Optionally, the heating device includes multiple metal layers stacked longitudinally, and the multiple metal layers surround the device under test.

[0009] Optionally, the metal layer includes sub-metal lines extending along a first direction and spaced parallel to each other along a second direction, wherein the first direction is perpendicular to the second direction.

[0010] Optionally, the sub-metal lines in the same layer are spaced apart by a distance of 36 nanometers to 540 nanometers in the second direction.

[0011] Optionally, the length of the sub-metal wire in the first direction is the same as the length of the device under test in the first direction.

[0012] Optionally, the metal layer located on the side of the device under test is in the same layer as the device under test.

[0013] Optionally, the metal layer on the same layer as the device under test extends in the same direction as the device under test.

[0014] Optionally, the distance between the metal layer on the same layer as the device under test and the device under test is 20 nanometers to 500 nanometers.

[0015] Optionally, the test structure further includes: a first interconnect via structure located at both ends of the device under test, and the first interconnect via structure being electrically connected to the device under test; and a second interconnect via structure located at both ends of the heating device, and the second interconnect via structure being electrically connected to the heating device.

[0016] Optionally, the heating device may be made of one or more of copper, aluminum, tungsten, and cobalt.

[0017] Optionally, the device under test includes a metal wire under test.

[0018] Optionally, the test structure further includes an active device located above the substrate of the chip region.

[0019] Accordingly, embodiments of the present invention also provide a testing method, comprising: providing the test structure provided by the present invention; heating the device under test using the heating device; and obtaining the electromigration reliability of the device under test after heating the device under test.

[0020] Optionally, the test structure further includes: a second interconnect via structure located at both ends of the heating device, and the second interconnect via structure being electrically connected to the heating device; the step of heating the device under test through the heating device includes: setting a first voltage loading line electrically connected to the second interconnect via structure; and continuously applying voltage to the heating device through the first voltage loading line.

[0021] Optionally, the test structure further includes: a first interconnect via structure located at both ends of the device under test (DUT), and the first interconnect via structure being electrically connected to the DUT; the step of obtaining the electromigration reliability of the DUT includes: setting a first current loading line electrically connected to the first interconnect via structure; setting a second voltage loading line electrically connected to the first interconnect via structure; applying a fixed current value to the DUT through the first current loading line; after applying current to the DUT, obtaining the voltage value across the DUT through the second voltage loading line; obtaining the resistance value of the DUT based on the voltage value and the fixed current value, and using the change in the resistance value to characterize the electromigration reliability of the DUT.

[0022] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages:

[0023] This invention provides a test structure with a substrate including a chip area and a test area. A device under test (DUT) is located above the substrate in the DUT area, and a heating device is located above the substrate in the DUT area and surrounds the DUT. Both the heating device and the DUT are exposed above the top of the chip area. Compared to existing solutions that require separating the chip area and the DUT area of ​​the test structure and placing the DUT separately in a test chamber with a simulated heating environment, this invention, by setting a heating device surrounding the DUT, can heat the DUT during subsequent testing, thereby obtaining the electromigration reliability of the DUT under a heating environment. In other words, the embodiments of the present invention can obtain the electromigration reliability of the device under test without dividing the test structure, reducing the probability of the test structure being damaged. Correspondingly, this also reduces the probability of damage to the devices in the chip area, thereby improving the reliability of the test structure. At the same time, since the electromigration reliability of the device under test can be obtained without dividing the test structure, the electromigration reliability of the device under test can be tested at any stage during the formation of the test structure, thereby increasing the flexibility of electromigration reliability testing. In summary, by setting a heating device around the device under test, the reliability of the test structure is improved, and the flexibility of electromigration reliability testing is increased. Attached Figure Description

[0024] Figures 1 to 2 This is a schematic diagram of an embodiment of the test structure of the present invention;

[0025] Figure 3 This is a flowchart of the steps of an embodiment of the testing method of the present invention. Detailed Implementation

[0026] As the background technology indicates, EM testing is a destructive experiment and is typically performed after wafer dicing. Wafer dicing is the process of dividing a wafer into individual dies, a step in the semiconductor packaging process. After dicing, these small dies are placed in a specialized test chamber, where high-temperature and high-current conditions are simulated. However, EM testing requires wafer dicing, increasing the destructiveness to the wafer and the probability that the usable dies may be damaged during the dicing process.

[0027] To address the technical problem, embodiments of the present invention provide a test structure, comprising: a substrate, the substrate including a chip region and a region under test; a device under test, located above the substrate of the region under test; and a heating device, located above the substrate of the region under test and surrounding the device under test, wherein the heating device and the device under test are exposed above the top of the chip region.

[0028] In the test structure provided by this invention, the substrate includes a chip area and a test area. The device under test (DUT) is located above the substrate of the DUT, and a heating device is located above the substrate of the DUT and surrounds the DUT. Both the heating device and the DUT are exposed above the top of the chip area. Compared to existing solutions that require separating the chip area and the DUT of the test structure and placing the DUT separately in a test box with a simulated heating environment, this invention, by setting a heating device surrounding the DUT, can heat the DUT in subsequent testing methods, thereby obtaining the electromigration reliability of the DUT under a heating environment. In other words, the embodiments of the present invention can obtain the electromigration reliability of the device under test without dividing the test structure, reducing the probability of the test structure being damaged. Correspondingly, this also reduces the probability of damage to the devices in the chip area, thereby improving the reliability of the test structure. At the same time, since the electromigration reliability of the device under test can be obtained without dividing the test structure, the electromigration reliability of the device under test can be tested at any stage during the formation of the test structure, thereby increasing the flexibility of electromigration reliability testing. In summary, by setting a heating device around the device under test, the reliability of the test structure is improved, and the flexibility of electromigration reliability testing is increased.

[0029] To make the above-mentioned objects, features and advantages of the embodiments 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.

[0030] Figures 1 to 2 This is a schematic diagram of an embodiment of the test structure of the present invention.

[0031] The test structure includes: a substrate 110, which includes a chip region 100B and a region under test 100A; a device under test 150, located above the substrate 110 of the region under test 100A; and a heating device (not shown), located above the substrate 110 of the region under test 100A and surrounding the device under test 150, with the heating device and the device under test 150 exposed above the top of the chip region 100B.

[0032] It should be noted that by setting a heating device surrounding the device under test 150, the device under test 150 can be heated in subsequent testing methods, thereby obtaining the electromigration reliability of the device under test 150 under a heated environment. In other words, this embodiment of the invention can obtain the electromigration reliability of the device under test 150 without dividing the test structure, reducing the probability of the test structure being damaged. Correspondingly, it also reduces the probability of the device in the chip area 100B being damaged, thereby improving the reliability of the test structure. At the same time, since the electromigration reliability of the device under test 150 can be obtained without dividing the test structure, the electromigration reliability of the device under test 150 can be tested at any stage during the formation of the test structure, thereby increasing the flexibility of electromigration reliability testing. In summary, by setting a heating device surrounding the device under test 150, the reliability of the test structure is improved, and the flexibility of electromigration reliability testing is increased.

[0033] The substrate 110 is used to provide a process platform for the formation of the test structure.

[0034] In this embodiment, the substrate 110 is a silicon substrate. In other embodiments, the substrate material may also be germanium, silicon germanide, silicon carbide, gallium arsenide, or indium gallium ionide, or other materials. The substrate may also be a silicon-on-insulator substrate or a germanium-on-insulator substrate, or other types of substrates.

[0035] Chip area 100B is the area for setting up active devices, and test area 100A is the area for setting up the device under test 150 and the heating device.

[0036] In this embodiment, the test structure further includes an active device (not shown) located above the substrate 110 of the chip region 100B.

[0037] As an example, an effective device includes a device structure layer (not shown) and a back-end interconnect layer (not shown) located on and electrically connected to the device structure layer.

[0038] The device structure layer is formed through front-end device fabrication processes. In specific implementations, the device structure layer may include a substrate and a device structure located on the substrate. The device structure may include MOS transistors, such as NMOS transistors and PMOS transistors.

[0039] It should be noted that the back-end interconnect layer is formed through back-end manufacturing processes.

[0040] As an example, the back-end interconnect layer includes a dielectric layer and one or more back-end metal lines located within the dielectric layer.

[0041] Specifically, the dielectric layer is used to achieve isolation between the subsequent metal lines. As an example, the dielectric layer is an inter-metal dielectric (IMD) layer between metal layers 122.

[0042] It should be noted that in the subsequent testing method, the device under test 150 is used as the device under test, and the electromigration reliability of the effective device in the chip area 100B is obtained by acquiring the electromigration reliability of the device under test 150.

[0043] As an example, the device under test 150 includes a metal wire under test.

[0044] Specifically, by obtaining the electromigration reliability of the metal lines, the electromigration reliability of the later metal lines in the chip region 100B can be determined, thereby judging the product reliability of the effective devices in the chip region 100B.

[0045] It should be noted that by setting a heating device surrounding the device under test 150, the device under test 150 can be heated in subsequent testing methods, thereby obtaining the electromigration reliability of the device under test 150 under a heated environment. In other words, this embodiment of the invention can obtain the electromigration reliability of the device under test 150 without dividing the test structure, reducing the probability of the test structure being damaged. Correspondingly, it also reduces the probability of the device in the chip area 100B being damaged, thereby improving the reliability of the test structure. At the same time, since the electromigration reliability of the device under test 150 can be obtained without dividing the test structure, the electromigration reliability of the device under test 150 can be tested at any stage during the formation of the test structure, thereby increasing the flexibility of electromigration reliability testing. In summary, by setting a heating device surrounding the device under test 150, the reliability of the test structure is improved, and the flexibility of electromigration reliability testing is increased.

[0046] It should also be noted that the heating device surrounds the device under test 150. In the subsequent test method, the heating circuit can quickly raise the temperature of the device under test 150, thereby obtaining the electromigration reliability of the device under test 150 in a high-temperature environment.

[0047] In this embodiment, the heating device includes multiple metal layers 122 stacked vertically, and the multiple metal layers 122 surround the device under test 150.

[0048] It should be noted that by stacking multiple metal layers 122 in the longitudinal direction and surrounding the device under test 150, the top, bottom and sides of the device under test 150 can be heated, thereby making the device under test 150 heated evenly and thus accurately obtaining the electromigration reliability of the device under test 150 in a high-temperature environment.

[0049] Specifically, the multilayer metal layer 122 is located on the top, bottom and side of the device under test 150, which means that the multilayer metal layer 122 can surround the device under test 150.

[0050] In this embodiment, the metal layer 122 includes a first direction (e.g., Figure 2 Extending along the X direction (as shown) and along the second direction (as shown) Figure 2 Sub-metal lines 120 are arranged in parallel at intervals (as shown in the Y direction), and the first direction is perpendicular to the second direction.

[0051] It should be noted that the metal layer 122 includes sub-metal lines 120 extending along the first direction and arranged in parallel at intervals along the second direction. The chip region 100B also has one or more back-end metal lines, so that the pattern distribution density of the back-end metal lines in the chip region 100B is not much different from the pattern distribution density of the sub-metal lines 120 in the test region. This can improve the problem of pattern loading effect in the chip region 100B and thus improve the formation quality of the back-end metal lines in the chip region 100B.

[0052] It should also be noted that the spacing between the sub-metal lines 120 in the same layer in the second direction should not be too large or too small. If the spacing between the sub-metal lines 120 in the same layer in the second direction is too large, after the device under test 150 is heated by the heating device, the temperature generated by the heating device is likely to diffuse out through the area between adjacent sub-metal lines 120, thus preventing the heating device from providing a heating environment for the device under test 150. This affects the test results of obtaining the electromigration reliability of the device under test 150 under high temperature conditions, and thus affects the reliability of the test structure. If the spacing between the sub-metal lines 120 in the same layer in the second direction is too small, it increases the difficulty of forming the sub-metal lines 120. Therefore, in this embodiment, the spacing between the sub-metal lines 120 in the same layer in the second direction is 36 nanometers to 540 nanometers.

[0053] In this embodiment, the length of the sub-metal wire 120 in the first direction is the same as the length of the device under test 150 in the first direction.

[0054] Specifically, the length of the sub-metal line 120 in the first direction is the same as the length of the device under test 150 in the first direction, which enables all parts of the device under test 150 to be heated, thereby improving the reliability of obtaining the electromigration of the device under test 150 in a high-temperature environment.

[0055] In this embodiment, the metal layer 122 located on the side of the device under test 150 is on the same layer as the device under test 150.

[0056] Specifically, the metal layer 122 located on the side of the device under test 150 is in the same layer as the device under test 150, which enables the entire side of the device under test 150 to be heated, and the same metal layer 122 enables the device under test 150 to be heated more evenly.

[0057] In this embodiment, the metal layer 122, which is on the same layer as the device under test 150, extends in the same direction as the device under test 150.

[0058] Specifically, the metal layer 122, which is on the same layer as the device under test 150, extends in the same direction as the device under test 150. This reduces the probability of the metal layer 122 coming into contact with the device under test 150, thereby reducing the risk of a short circuit between the device under test 150 and the metal layer 122, and thus avoiding the impact on the electromigration reliability test of the device under test 150.

[0059] It should be noted that the distance between the metal layer 122, which is on the same layer as the device under test (DUT) 150, and the DUT 150 should not be too large or too small. If the distance between the metal layer 122 and the DUT 150 is too large, after the DUT 150 is heated by a heating device, the temperature generated by the heating device may easily diffuse out through the area between adjacent sub-metal lines 120, thus preventing the heating device from providing a heating environment for the DUT 150. This affects the test results of obtaining the electromigration reliability of the DUT 150 under high-temperature conditions, and consequently affects the reliability of the test structure. If the distance between the metal layer 122 and the DUT 150 is too small, it increases the difficulty of forming the sub-metal lines 120. Therefore, in this embodiment, the distance between the metal layer 122 and the DUT 150 is 20 nanometers to 500 nanometers.

[0060] In this embodiment, the heating device is made of one or more of copper, aluminum, tungsten, and cobalt.

[0061] Specifically, copper, aluminum, tungsten, and cobalt are all commonly used conductive materials. In the subsequent heating process of the device under test 150 by the heating device, a voltage is continuously applied to both ends of the heating device, so that the conductive material is gradually heated and the heat is gradually diffused to the surroundings, thereby increasing the temperature of the device under test 150 itself.

[0062] As an example, the test structure further includes: a first interconnect via structure (not shown) located at both ends of the device under test 150, and the first interconnect via structure is electrically connected to the device under test 150.

[0063] It should be noted that a first interconnect via structure is provided at both ends of the device under test 150. In the subsequent process of obtaining the electromigration reliability of the device under test 150, a fixed current can be applied to the device under test 150 through the first interconnect via structure, and the voltage across the device under test 150 can be obtained.

[0064] In this embodiment, the material of the first interconnect via structure includes ruthenium.

[0065] In this embodiment, the test structure further includes a second interconnect via structure (not shown), located at both ends of the heating device, and the second interconnect via structure is electrically connected to the heating device.

[0066] It should be noted that a second interconnecting via structure is provided at both ends of the heating device. In the subsequent process of obtaining the electromigration reliability of the device under test 150, a voltage can be continuously applied to the heating device through the second interconnecting via structure, so that the heating device is gradually heated and the heat is gradually diffused to the surroundings, thereby increasing the temperature of the device under test 150 itself.

[0067] Accordingly, embodiments of the present invention also provide a testing method. Wherein, Figure 3 This is a flowchart of the steps corresponding to one embodiment of the testing method of the present invention. The following is in conjunction with the appendix. Figure 1 and Figure 2 The testing methods of this implementation will be described in detail.

[0068] Reference Figures 1 to 2 Step S1: Provide the test structure provided by the present invention.

[0069] It should be noted that for a detailed description of the test structure, please refer to the corresponding description in the foregoing embodiments, which will not be repeated here.

[0070] In this embodiment, the test structure further includes: a first interconnect via structure located at both ends of the device under test 150, and the first interconnect via structure is electrically connected to the device under test 150.

[0071] It should be noted that a first interconnect via structure is provided at both ends of the device under test 150. In the subsequent process of obtaining the electromigration reliability of the device under test 150, a fixed current can be applied to the device under test 150 through the first interconnect via structure, and the voltage across the device under test 150 can be obtained.

[0072] In this embodiment, the test structure further includes a second interconnect via structure located at both ends of the heating device, and the second interconnect via structure is electrically connected to the heating device.

[0073] Specifically, a second interconnecting via structure is provided at both ends of the heating device. During the subsequent heating of the device under test 150 through the heating device, a voltage can be continuously applied to the heating device through the second interconnecting via structure, so that the heating device is gradually heated and the heat is gradually diffused to the surroundings, thereby increasing the temperature of the device under test 150 itself.

[0074] Reference Figures 1 to 2 Step S2: Heating the device under test 150 using the heating device.

[0075] It should be noted that by setting a heating device surrounding the device under test 150, the device under test 150 can be heated during the subsequent acquisition of its electromigration reliability, thereby obtaining the electromigration reliability of the device under test 150 under a heated environment. In other words, this embodiment of the invention can obtain the electromigration reliability of the device under test 150 without dividing the test structure, reducing the probability of the test structure being damaged. Correspondingly, it also reduces the probability of damage to the devices in the chip area 100B, thereby improving the reliability of the test structure. At the same time, since the electromigration reliability of the device under test 150 can be obtained without dividing the test structure, the electromigration reliability of the device under test 150 can be measured at any stage during the formation of the test structure, thereby increasing the flexibility of electromigration reliability testing. In summary, by setting a heating device surrounding the device under test 150, the reliability of the test structure is improved, and the flexibility of electromigration reliability testing is increased.

[0076] It should also be noted that the heating device surrounds the device under test 150. In the subsequent test method, the heating circuit can quickly raise the temperature of the device under test 150, thereby obtaining the electromigration reliability of the device under test 150 in a high-temperature environment.

[0077] In this embodiment, the step of heating the device under test 150 through the heating device includes: setting a first voltage loading line electrically connected to the second interconnect via structure; and continuously applying voltage to the heating device through the first voltage loading line.

[0078] Specifically, a voltage is continuously applied to the heating device through the first voltage loading line, thereby gradually heating the heating device and gradually spreading the heat to the surroundings, thereby increasing the temperature of the device under test 150 itself.

[0079] Reference Figures 1 to 2 Step S3: After heating the device under test 150, obtain the electromigration reliability of the device under test 150.

[0080] Specifically, by obtaining the electromigration reliability of the device under test 150, the product quality and reliability of the effective devices in the chip region 100B can be determined.

[0081] In this embodiment, the step of obtaining the electromigration reliability of the device under test 150 includes: setting a first current loading line electrically connected to the first interconnect via structure; setting a second voltage loading line electrically connected to the first interconnect via structure; applying a fixed current value to the device under test 150 through the first current loading line; after applying current to the device under test 150, obtaining the voltage value across the device under test 150 through the second voltage loading line; obtaining the resistance value of the device under test 150 based on the voltage value and the fixed current value, and using the change in the resistance value to characterize the electromigration reliability of the device under test 150.

[0082] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A test structure, characterized in that, include: A substrate, the substrate comprising a chip region and a region to be tested; The device under test is located above the substrate of the area under test; A heating device is located above the substrate of the area under test and surrounds the device under test, with the heating device and the device under test exposed on the top of the chip area.

2. The test structure as described in claim 1, characterized in that, The heating device includes multiple metal layers stacked longitudinally, and the multiple metal layers surround the device under test.

3. The test structure as described in claim 2, characterized in that, The metal layer includes sub-metal lines extending along a first direction and spaced parallel to each other along a second direction, wherein the first direction is perpendicular to the second direction.

4. The test structure as described in claim 3, characterized in that, The sub-metal lines in the same layer are spaced apart by a distance of 36 nanometers to 540 nanometers in the second direction.

5. The test structure as described in claim 3, characterized in that, The length of the sub-metal wire in the first direction is the same as the length of the device under test in the first direction.

6. The test structure as described in claim 2, characterized in that, The metal layer located on the side of the device under test is in the same layer as the device under test.

7. The test structure as described in claim 6, characterized in that, The metal layer that is in the same layer as the device under test extends in the same direction as the device under test.

8. The test structure as described in claim 6, characterized in that, The distance between the metal layer on the same layer as the device under test and the device under test is 20 nanometers to 500 nanometers.

9. The test structure as described in claim 1, characterized in that, The test structure further includes: a first interconnect via structure located at both ends of the device under test, and the first interconnect via structure is electrically connected to the device under test; The second interconnecting via structure is located at both ends of the heating device, and the second interconnecting via structure is electrically connected to the heating device.

10. The test structure as described in claim 1, characterized in that, The heating device is made of one or more of copper, aluminum, tungsten, and cobalt.

11. The test structure as described in claim 1, characterized in that, The device under test includes a metal wire under test.

12. The test structure as described in claim 1, characterized in that, The test structure also includes an active device located above the substrate of the chip region.

13. A testing method, characterized in that, include: Provide a test structure as described in any one of claims 1 to 12; The device under test is heated by the heating device. After heating the device under test, the electromigration reliability of the device under test is obtained.

14. The test method as described in claim 13, characterized in that, The test structure further includes: a second interconnecting via structure located at both ends of the heating device, and the second interconnecting via structure being electrically connected to the heating device; The step of heating the device under test using the heating device includes: setting a first voltage loading line electrically connected to the second interconnect via structure; and continuously applying voltage to the heating device through the first voltage loading line.

15. The test method as described in claim 13, characterized in that, The test structure further includes: a first interconnect via structure located at both ends of the device under test, and the first interconnect via structure is electrically connected to the device under test; The steps for obtaining the electromigration reliability of the device under test include: setting a first current loading line electrically connected to the first interconnect via structure; setting a second voltage loading line electrically connected to the first interconnect via structure; applying a fixed current value to the device under test through the first current loading line; after applying current to the device under test, obtaining the voltage value across the device under test through the second voltage loading line; obtaining the resistance value of the device under test based on the voltage value and the fixed current value, and using the change in the resistance value to characterize the electromigration reliability of the device under test.

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