Reliability test structure and test method
By designing nested stress migration and medium time breakdown test structures in the chip storage unit, the problem of difficulty in performing these two tests at the same time in the prior art is solved, and the savings of the test structure and the improvement of the test efficiency are achieved.
Patent Information
- Application Number
- CN202510238423.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-06-03
AI Technical Summary
The prior art is difficult to perform reliability testing of stress migration and medium breakdown in a limited chip storage unit simultaneously, resulting in wasted area of the test structure.
A reliability test structure is designed, in which the stress migration test structure is set as a serpentine structure, and metal wire segments are set in the recess opening of the serpentine structure and lead out to the welding pad to form a time-breaking test structure for the medium, thereby achieving nesting and coexistence of the two tests.
The test of stress migration and medium breakdown in a limited chip storage unit is realized, saving the test structure area and improving the test efficiency.
Smart Images
Figure CN120089662A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor integrated circuit manufacturing, and particularly to a reliability test structure. The present invention also relates to a reliability test method. Background Art
[0002] Reliability testing has become increasingly challenging with the continuous update of technology and the shrinking of technology nodes, and wafer-level monitoring has also become very important.
[0003] Currently, in the back-end testing of process reliability, isothermal electro migration (EM), inter metal dielectrics time dependent dielectric breakdown (IMD TDDB), and stress migration (SM) are commonly used process reliability monitoring methods.
[0004] Stress migration is a diffusion process caused by mechanical stress. Large stresses in metals during high-temperature processes can cause metal voids. General stress migrations can be divided into pure metal wire structures (Metal Serp.), Kelvin via structures, and via chain structures.
[0005] As Figure 1A shown, it is a schematic diagram of the existing first stress migration test structure; the existing first stress migration test structure is a pure metal wire structure, including a serpentine structure formed by connecting multiple metal line segments 101a. The pads at both ends of the serpentine structure can form the signal terminals of F1, F2, S1, and S2 for the Kelvin test. The metal line segments 101a are all composed of the same metal layer M1.
[0006] As Figure 1B shown, it is a schematic diagram of the existing second stress migration test structure; the existing second stress migration test structure is a Kelvin via structure, mainly composed of a via 102a. Figure 1B In
[0007] As Figure 1CAs shown, it is a schematic diagram of the existing third stress migration test structure; the existing third stress migration test structure is a via chain structure, which is mainly formed by connecting the metal line segments 101c composed of multiple metal layers M1 and the metal line segments 103a composed of multiple metal layers M2 end to end through vias 102b.
[0008] Time-dependent dielectric breakdown is the phenomenon that the dielectric loses its electrical insulation ability under the action of a constant strong electric field. General time-dependent dielectric breakdown can be divided into metal line-to-metal line structure (MxMx), metal line-to-via structure (VxMx+1), and via-to-via structure (VxVx).
[0009] As Figure 2A shown, it is a schematic diagram of the existing first time-dependent dielectric breakdown test structure; the existing first time-dependent dielectric breakdown test structure is a metal line-to-metal line structure, including a comb structure formed by connecting the metal line segments 201a1 and 202a1 and another comb structure formed by connecting the metal line segments 201b1 and 202b1. The metal line segments 201a1 and 201b1 are alternately arranged to form a finger-like structure. The metal line segments 201a1, 202a1, 201b1, and 202b1 are all composed of the same metal layer. The two comb structures are respectively provided with corresponding pads 203a1 and 203b1.
[0010] As Figure 2B shown, it is a schematic diagram of the existing second time-dependent dielectric breakdown test structure; the existing second time-dependent dielectric breakdown test structure is a metal line-to-via structure, including a comb structure formed by connecting the metal line segments 201a2 and 202a2 and another comb structure formed by connecting the metal line segments 201b2 and 202b2. Multiple vias 204 are provided at the tops of the metal line segments 201a2. The metal layers of the metal line segments 201a1 and 202a1 are one layer lower than those of the metal line segments 201b1 and 202b1. For example, if the metal line segments 201a1 and 202a1 are composed of the metal layer M1, then the metal line segments 201b1 and 202b1 are composed of the metal layer M2. The two comb structures are respectively provided with corresponding pads 203a2 and 203b2.
[0011] As Figure 2CAs shown in the figure, it is a schematic diagram of the existing time-dependent dielectric breakdown test structure for the third medium; the existing time-dependent dielectric breakdown test structure for the third medium is a via-to-via structure, including a comb structure formed by connecting metal line segments 201a3 and 202a3 and another comb structure formed by connecting metal line segments 201b3 and 202b3. The metal line segments 201a3 and 201b3 are alternately arranged to form a finger-like structure. The metal line segments 201a3, 202a3, 201b3, and 202b3 are all composed of the same metal layer. Corresponding pads 203a3 and 203b3 are provided for the two comb structures respectively. In addition, a plurality of vias 204 are provided at the tops of the metal line segments 201a3 and 201b3 respectively.
[0012] As the number of chip memory cells increases and the number of scribe lines decreases, there is not enough space to place the test structure. The test structure has always been required to be streamlined, and there is an urgent need to integrate multi-purpose reliability test structures to save the area of the test structure. Summary of the Invention
[0013] The technical problem to be solved by the present invention is to provide a reliability test structure that can be used to test stress migration and time-dependent dielectric breakdown simultaneously, thereby saving the area of the test structure. To this end, the present invention also provides a reliability test method.
[0014] To solve the above technical problem, the reliability test structure provided by the present invention includes:
[0015] A stress migration test structure, including a first pad and a second pad and a plurality of first metal line segments connected between the first pad and the second pad. Each of the first metal line segments is connected end to end to form a serpentine structure, and the serpentine structure has a first concave opening facing the first side and a second concave opening facing the second side.
[0016] A time-dependent dielectric breakdown test structure, at least including: a first comb structure.
[0017] The first comb structure includes a plurality of second metal line segments. Each of the second metal line segments is disposed in the corresponding first concave opening, and each of the second metal line segments is connected to a third pad through a third metal line segment located outside the first concave opening; the third pad serves as the first test end of the time-dependent dielectric breakdown test structure, and the second test end of the time-dependent dielectric breakdown test structure is composed of any one or two of the first pad and the second pad.
[0018] A further improvement is that the time-dependent dielectric breakdown test structure further includes: a second comb structure.
[0019] The second sparse structure includes a plurality of fourth metal line segments, each of the fourth metal line segments is disposed in the corresponding opening of the second recess, and each of the fourth metal line segments is connected to the third bonding pad through a fifth metal line segment located outside the opening of the second recess.
[0020] A further improvement is that the first metal line segments are all line segments of the same metal layer, and the stress migration test structure is a pure metal line structure.
[0021] A further improvement is that the second metal line segments, the third metal line segments, the fourth metal line segments, and the fifth metal line segments are all line segments of the same metal layer; the metal layer of the second metal line segments is the same as that of the first metal line segments.
[0022] The time-dependent dielectric breakdown test structure is a metal line-to-metal line structure.
[0023] A further improvement is that a plurality of through holes are formed on the top of the corresponding first metal line segments.
[0024] The second metal line segments, the third metal line segments, the fourth metal line segments, and the fifth metal line segments are all line segments of the same metal layer, and the metal layer of the second metal line segments is the layer above the metal layer of the first metal line segments.
[0025] The time-dependent dielectric breakdown test structure is a metal line-to-through hole structure.
[0026] A further improvement is that a plurality of through holes are formed on the top of the corresponding first metal line segments.
[0027] The second metal line segments, the third metal line segments, the fourth metal line segments, and the fifth metal line segments are all line segments of the same metal layer, and the metal layer of the second metal line segments is the same as that of the first metal line segments.
[0028] A plurality of through holes are also formed on the top of each of the second metal line segments and the fourth metal line segments.
[0029] The time-dependent dielectric breakdown test structure is a through hole-to-through hole structure.
[0030] A further improvement is that the first metal line segments include line segments of two metal layers, the first metal line segments with different metal layers are arranged alternately, and adjacent first metal line segments are connected through through holes.
[0031] The stress migration test structure is a through hole chain structure.
[0032] A further improvement is that the second metal line segment, the third metal line segment, the fourth metal line segment, and the fifth metal line segment are all line segments of the same metal layer, and the metal layer of the second metal line segment is the same as one of the two metal layers corresponding to the first metal line segment.
[0033] To solve the above technical problems, the reliability test method provided by the present invention includes the following steps:
[0034] Step 1: Perform a stress migration test using the stress migration test structure, including:
[0035] Step 11: Measure the initial resistance of the stress migration test structure by performing a resistance test at room temperature.
[0036] Step 12: Bake the reliability test structure.
[0037] Step 13: Measure the second resistance by performing a resistance test on the stress migration test structure after the baking.
[0038] Step 14: Calculate the resistance change value between the second resistance and the initial resistance and evaluate the stress migration condition based on the resistance change value.
[0039] A further improvement is that in Step 2, a voltage is applied between the first test terminal and the second test terminal to perform a time-dependent dielectric breakdown test.
[0040] A further improvement is that in the resistance tests of Step 11 and Step 13, a voltage is applied to one of the first pad and the second pad, and the other is grounded.
[0041] A further improvement is that the order of Step 1 and Step 2 can be interchanged.
[0042] A further improvement is that the time-dependent dielectric breakdown test structure further includes: a second sparse structure.
[0043] The second sparse structure includes a plurality of fourth metal line segments, each of the fourth metal line segments is disposed in the corresponding opening of the second recess, and each of the fourth metal line segments is connected to the third pad through a fifth metal line segment located outside the opening of the second recess.
[0044] A further improvement is that the first metal line segments are all line segments of the same metal layer, and the stress migration test structure is a pure metal wire structure.
[0045] A further improvement is that the second metal line segment, the third metal line segment, the fourth metal line segment, and the fifth metal line segment are all line segments of the same metal layer; the metal layer of the second metal line segment is the same as that of the first metal line segment;
[0046] The time-dependent dielectric breakdown test structure of the medium is a metal wire-to-metal wire structure.
[0047] In the present invention, by setting the stress migration test structure as a serpentine structure, arranging metal line segments in the concave openings of the serpentine structure and leading them out to the third pad, a time-dependent dielectric breakdown test structure of the medium can be obtained. Therefore, the present invention can realize the mutual nesting of the stress migration test structure and the time-dependent dielectric breakdown test structure of the medium, and can be used for testing stress migration and time-dependent dielectric breakdown simultaneously, thereby saving the area of the test structure. BRIEF DESCRIPTION OF THE DRAWINGS
[0048] The present invention will be further described in detail below with reference to the drawings and specific embodiments:
[0049] Figure 1A is a schematic diagram of the first conventional stress migration test structure;
[0050] Figure 1B is a schematic diagram of the second conventional stress migration test structure;
[0051] Figure 1C is a schematic diagram of the third conventional stress migration test structure;
[0052] Figure 2A is a schematic diagram of the first conventional time-dependent dielectric breakdown test structure of the medium;
[0053] Figure 2B is a schematic diagram of the second conventional time-dependent dielectric breakdown test structure of the medium;
[0054] Figure 2C is a schematic diagram of the third conventional time-dependent dielectric breakdown test structure of the medium;
[0055] Figure 3 is a schematic diagram of the reliability test structure of the embodiment of the present invention;
[0056] Figure 4A is a circuit connection diagram when the reliability test structure of the embodiment of the present invention performs a stress migration test;
[0057] Figure 4B is a circuit connection diagram when the reliability test structure of the embodiment of the present invention performs a time-dependent dielectric breakdown test of the medium. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0058] As Figure 3 shown, it is a schematic diagram of the reliability test structure of the embodiment of the present invention; the reliability test structure of the embodiment of the present invention includes:
[0059] The stress migration test structure includes a first pad 302a and a second pad 302b, and multiple first metal line segments 301 connected between the first pad 302a and the second pad 302b. Each of the first metal line segments 301 is connected end to end to form a serpentine structure. Figure 3 In Figure 3 , the serpentine structure is also represented by Serp. The serpentine structure has a first recess opening facing the first side and a second recess opening facing the second side.
[0060] The time-dependent dielectric breakdown test structure includes at least: a first comb structure.
[0061] The first comb structure includes multiple second metal line segments 303. Each of the second metal line segments 303 is disposed in a corresponding first recess opening. Each of the second metal line segments 303 is connected to a third pad 302c through a third metal line segment 304 located outside the first recess opening. The third pad 302c serves as the first test end of the time-dependent dielectric breakdown test structure, and the second test end of the time-dependent dielectric breakdown test structure is composed of any one or two of the first pad 302a and the second pad 302b.
[0062] In an embodiment of the present invention, the time-dependent dielectric breakdown test structure further includes: a second comb structure.
[0063] The second comb structure includes multiple fourth metal line segments 305. Each of the fourth metal line segments 305 is disposed in a corresponding second recess opening. Each of the fourth metal line segments 305 is connected to the third pad 302c through a fifth metal line segment 306 located outside the second recess opening. Figure 3 In Figure 3 , the first comb structure and the second comb structure are also represented by Comb.
[0064] Figure 3 In Figure 3 , the first pad 302a, the second pad 302b, and the third pad 302c are also represented by PAD1, PAD2, and PAD3 respectively.
[0065] In an embodiment of the present invention, all the first metal line segments 301 are line segments of the same metal layer, and the stress migration test structure is a pure metal wire structure.
[0066] The second metal line segments 303, the third metal line segments 304, the fourth metal line segments 305, and the fifth metal line segments 306 are all line segments of the same metal layer; the metal layer of the second metal line segments 303 is the same as that of the first metal line segments 301.
[0067] The time-dependent dielectric breakdown test structure is a metal wire to metal wire structure.
[0068] In some other embodiments, it can also be that a plurality of through holes (not shown) are formed on the top of each corresponding first metal line segment 301.
[0069] The second metal line segment 303, the third metal line segment 304, the fourth metal line segment 305, and the fifth metal line segment 306 are all line segments of the same metal layer, and the metal layer of the second metal line segment 303 is the upper layer of the metal layer of the first metal line segment 301.
[0070] The time-dependent dielectric breakdown test structure is a structure of a metal line to a through hole.
[0071] In some other embodiments, it can also be that a plurality of through holes are formed on the top of each corresponding first metal line segment 301.
[0072] The second metal line segment 303, the third metal line segment 304, the fourth metal line segment 305, and the fifth metal line segment 306 are all line segments of the same metal layer, and the metal layers of the second metal line segment 303 and the first metal line segment 301 are the same.
[0073] A plurality of through holes are also formed on the top of each of the second metal line segment 303 and the fourth metal line segment 305.
[0074] The time-dependent dielectric breakdown test structure is a structure of a through hole to a through hole.
[0075] In some other embodiments, it can also be that the first metal line segment 301 includes line segments of two metal layers, the first metal line segments 301 with different metal layers are arranged alternately, and adjacent first metal line segments 301 are connected through through holes.
[0076] The stress migration test structure is a through hole chain structure.
[0077] The second metal line segment 303, the third metal line segment 304, the fourth metal line segment 305, and the fifth metal line segment 306 are all line segments of the same metal layer, and the metal layer of the second metal line segment 303 is the same as one of the corresponding two side metal layers of the first metal line segment 301.
[0078] In the embodiment of the present invention, by setting the stress migration test structure as a serpentine structure and arranging a metal line segment in the concave opening of the serpentine structure and leading it out to the third pad 302c, a time-dependent dielectric breakdown test structure can be obtained. Therefore, the embodiment of the present invention can realize the mutual nesting of the stress migration test structure and the time-dependent dielectric breakdown test structure, and can be used for testing stress migration and time-dependent dielectric breakdown simultaneously, thereby saving the area of the test structure.
[0079] The reliability test method of the embodiment of the present invention adopts Figure 3Perform the reliability test structure as shown, including the following steps:
[0080] Step 1: Perform a stress migration test using the stress migration test structure, including:
[0081] Step 11: Measure the initial resistance of the stress migration test structure by performing a resistance test at room temperature.
[0082] In the method of the embodiment of the present invention, during the resistance test, apply a voltage to one of the first pad 302a and the second pad 302b, and ground the other. As Figure 4A shown, it is the circuit connection diagram when the stress migration test is performed on the reliability test structure of the embodiment of the present invention; it can be seen that the first pad 302a is connected to the first probe Pin1, and the second pad 302b is connected to the second probe Pin2.
[0083] Step 12: Bake the reliability test structure. In some embodiments of the method, the baking time is 500 hours or more.
[0084] Step 13: Measure the resistance of the stress migration test structure after the baking to obtain a second resistance.
[0085] Step 14: Calculate the resistance change value between the second resistance and the initial resistance and evaluate the stress migration condition based on the resistance change value.
[0086] Step 2: Apply a voltage between the first test terminal and the second test terminal to perform a time-dependent dielectric breakdown test. As Figure 4B shown, it is the circuit connection diagram when the stress migration test is performed on the reliability test structure of the embodiment of the present invention. It can be seen that the first pad 302a is connected to the first probe Pin1, and the third pad 302c is connected to the second probe Pin2.
[0087] In other embodiments of the method, it can also be: both the first pad 302a and the second pad 302b are connected to the first probe Pin1, and the third pad 302c is connected to the second probe Pin2; or, the second pad 302b is connected to the first probe Pin1, and the third pad 302c is connected to the second probe Pin2.
[0088] In the method of the embodiment of the present invention, complete Step 1 first, and then perform Step 2. In other embodiments of the method, it can also be: complete Step 2 first, and then perform Step 1.
[0089] The present invention has been described in detail through specific embodiments, but these do not constitute a limitation to the present invention. Without departing from the principle of the present invention, those skilled in the art can also make many modifications and improvements, which should also be regarded as the protection scope of the present invention.
Claims
1. A reliability test structure, characterized in that: include: A stress migration test structure, comprising a first pad, a second pad, and a plurality of first metal wire segments connected between the first pad and the second pad, wherein each of the first metal wire segments is connected end to end to form a serpentine structure, wherein the serpentine structure has a first recess opening toward a first side and a second recess opening toward a second side; The dielectric time-dependent breakdown test structure comprises at least: a first sparse structure; The first sparse structure includes multiple second metal wire segments, each of which is arranged in the corresponding first recess opening, and each of the second metal wire segments is connected to the third welding pad through a third metal wire segment located outside the first recess opening; the third welding pad serves as the first test end of the dielectric time breakdown test structure, and the second test end of the dielectric time breakdown test structure is composed of any one or two of the first welding pad and the second welding pad.
2. The reliability test structure according to claim 1, characterized in that: The dielectric time-dependent breakdown test structure further includes: a second sparse structure; The second sparse structure includes a plurality of fourth metal wire segments, each of which is disposed in a corresponding second recess opening, and each of which is connected to the third pad via a fifth metal wire segment located outside the second recess opening.
3. The reliability test structure according to claim 2, characterized in that: The first metal line segments are all line segments of the same metal layer, and the stress migration test structure is a pure metal line structure.
4. The reliability test structure according to claim 3, characterized in that: The second metal line segment, the third metal line segment, the fourth metal line segment, and the fifth metal line segment are all line segments of the same metal layer; the second metal line segment and the first metal line segment have the same metal layer; The dielectric time-dependent breakdown test structure is a metal line-to-metal line structure.
5. The reliability test structure according to claim 3, characterized in that: A plurality of through holes are formed on the top of each corresponding first metal line segment; The second metal line segment, the third metal line segment, the fourth metal line segment, and the fifth metal line segment are all line segments of the same metal layer, and the metal layer of the second metal line segment is an upper layer of the metal layer of the first metal line segment; The dielectric time-dependent breakdown test structure is a metal line-to-through-hole structure.
6. The reliability test structure according to claim 3, characterized in that: A plurality of through holes are formed on the top of each corresponding first metal line segment; The second metal line segment, the third metal line segment, the fourth metal line segment, and the fifth metal line segment are all line segments of the same metal layer, and the second metal line segment and the first metal line segment have the same metal layer; A plurality of through holes are also formed on the top of each of the second metal line segment and the fourth metal line segment; The dielectric time-dependent breakdown test structure is a through-hole to through-hole structure.
7. The reliability test structure according to claim 2, characterized in that: The first metal line segments include line segments of two metal layers, the first metal line segments of different metal layers are arranged alternately, and adjacent first metal line segments are connected through through holes; The stress migration test structure is a through-hole chain structure.
8. The reliability test structure according to claim 7, characterized in that: The second metal line segment, the third metal line segment, the fourth metal line segment, and the fifth metal line segment are all line segments of the same metal layer, and the metal layer of the second metal line segment is the same as one of the metal layers on both sides corresponding to the first metal line segment.
9. A reliability testing method using the reliability testing structure as claimed in claim 1, characterized in that: The steps include: Step 1: using the stress migration test structure to perform a stress migration test, including: Step 11, performing a resistance test at room temperature to measure the initial resistance of the stress migration test structure; Step 12, baking the reliability test structure; Step 13, performing a resistance test on the stress migration test structure after the baking to obtain a second resistance; Step 14: Calculate the resistance change value between the second resistor and the initial resistor and evaluate the stress migration status based on the resistance change value.
10. The reliability testing method according to claim 9, characterized in that: Also includes: Step 2: Apply voltage between the first test terminal and the second test terminal to perform a dielectric breakdown test.
11. The reliability testing method according to claim 9, characterized in that: In the resistance test of step 11 and step 13, a voltage is applied to one of the first bonding pad and the second bonding pad, and the other is grounded.
12. The reliability testing method according to claim 10, characterized in that: The order of steps 1 and 2 can be interchanged.
13. The reliability testing method according to claim 10, characterized in that: The dielectric time-dependent breakdown test structure further includes: a second sparse structure; The second sparse structure includes a plurality of fourth metal wire segments, each of which is disposed in a corresponding second recess opening, and each of which is connected to the third pad via a fifth metal wire segment located outside the second recess opening.
14. The reliability testing method according to claim 13, characterized in that: The first metal line segments are all line segments of the same metal layer, and the stress migration test structure is a pure metal line structure.
15. The reliability testing method according to claim 14, characterized in that: The second metal line segment, the third metal line segment, the fourth metal line segment, and the fifth metal line segment are all line segments of the same metal layer; the second metal line segment and the first metal line segment have the same metal layer; The dielectric time-dependent breakdown test structure is a metal line-to-metal line structure.