A contact hole test structure and a contact hole test method
By introducing a leakage current test structure and minimum design rules into the contact hole test structure, the problems of large layout area and long test time in the prior art are solved, realizing efficient resistance and leakage current testing, improving test efficiency and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GTA SEMICON CO LTD
- Filing Date
- 2023-03-31
- Publication Date
- 2026-07-21
AI Technical Summary
Existing active region contact hole test structures and polysilicon contact hole test structures with chain structures occupy a large layout area and have a long test time, which affects test efficiency.
A contact hole test structure is designed, including an active region contact hole test structure, a polysilicon contact hole test structure, a first leakage test structure, and a second leakage test structure. By setting a series of chains on a semiconductor substrate and inserting leakage test structures between the chains, the layout is optimized using the minimum design rule to achieve resistance and leakage test.
The layout area was reduced, the leakage current testing time was decreased, the testing efficiency was improved, and 60% of the layout area and leakage current testing time were saved, thus reducing the layout cost.
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Figure CN116314140B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor testing equipment technology, and in particular to a contact hole testing structure and a contact hole testing method. Background Technology
[0002] During the wafer development process, electrical testing is typically required to characterize the properties of wafer components, evaluate the performance of semiconductor devices, and determine whether the wafer product meets the electrical specifications of the process technology platform.
[0003] The CT (contact via) structure is the first crucial connection between the front-end device (front-end process) and the back-end metal (back-end process) interconnect. Its resistance is a very important electrical parameter, reflecting the connection status between the front-end device and the back-end metal interconnect. Furthermore, leakage current may exist between CT_AA (active area) and CT_Poly (polysilicon), which can affect the CT resistance, causing instability and directly impacting device functionality. For example... Figures 1-2 As shown, the currently used CT resistance measurement structures are two chain structures: the active region contact hole test structure and the polysilicon contact hole test structure. Their disadvantages are as follows: 1. Occupies a large area of land 2. The long testing time affects testing efficiency. Summary of the Invention
[0004] In view of this, embodiments of the present invention provide a contact hole testing structure and a contact hole testing method to at least solve the shortcomings of the existing chain structures of active region contact hole testing structure and polysilicon contact hole testing structure.
[0005] The embodiments of the present invention provide the following technical solutions: An embodiment of the present invention provides a contact hole testing structure, comprising an active region contact hole testing structure and a polysilicon contact hole testing structure disposed on a semiconductor substrate. The active region contact hole testing structure includes a plurality of first chains connected in series, and the polysilicon contact hole testing structure includes a plurality of second chains connected in series. The active region contact hole testing structure and the polysilicon contact hole testing structure extend in the same direction. The contact hole testing structure further includes: A first leakage current test structure is disposed on the semiconductor substrate and includes a plurality of third chains. Each third chain is inserted between two adjacent first chains. The first leakage current test structure is used to test whether there is leakage between two adjacent active regions within the active region contact hole test structure. The second leakage current test structure is disposed on the semiconductor substrate and connected to the active region contact hole test structure through a diode structure. The second leakage current test structure includes a plurality of fourth chains, each of which is inserted between two adjacent second chains. The second leakage current test structure is used in conjunction with the active region contact hole test structure to test whether there is leakage between two adjacent polysilicon cells in the polysilicon contact hole test structure and between the active region and the adjacent polysilicon cells.
[0006] Furthermore, at least one of the active region contact hole test structure, the polysilicon contact hole test structure, the first leakage test structure, the second leakage test structure, the distance between the active region contact hole test structure and the polysilicon contact hole test structure, the distance between the active region contact hole test structure and the first leakage test structure, and the distance between the polysilicon contact hole test structure and the second leakage test structure follows the minimum design rule.
[0007] Furthermore, the first chain and the third chain have the same structure and each includes several active regions arrayed on the semiconductor substrate. Each active region has an active region contact hole at both ends, and each pair of adjacent active region contact holes are connected by active region metal wiring.
[0008] Furthermore, the active regions within the first chain and the active regions within the third chain are alternately arranged.
[0009] Furthermore, the second chain and the fourth chain have the same structure and each includes several polysilicon layers arrayed on the semiconductor substrate. Each polysilicon layer has polysilicon contact holes at both ends, and each pair of adjacent polysilicon contact holes are connected by polysilicon layer metal wiring.
[0010] An embodiment of the present invention provides a contact hole testing method, applied to the above-mentioned contact hole testing structure, comprising: A voltage is applied to the second end of the active region contact hole test structure, and the second end of the polysilicon contact hole test structure and the metal wiring end of the first leakage test structure are connected to zero, wherein the metal wiring end of the first leakage test structure is connected in parallel with several third chains of the first leakage test structure. When there is a first current in the path of the contact hole test structure, at least one leakage current is determined between two adjacent active regions, between the active region and an adjacent polysilicon, and between two adjacent polysilicon.
[0011] Furthermore, after determining at least one leakage current between two adjacent active regions, between the active region and an adjacent polysilicon cell, and between two adjacent polysilicon cells, the method further includes: A voltage is applied to the metal wiring end of the first leakage current test structure, and the second end of the active area contact hole test structure is connected to zero. If there is a second current in the path, leakage current occurs between the two adjacent active areas.
[0012] Furthermore, after determining at least one leakage current between two adjacent active regions, between the active region and an adjacent polysilicon cell, and between two adjacent polysilicon cells, the method further includes: A voltage is applied to the second terminal of the polysilicon contact hole test structure, and the second terminal of the active region contact hole test structure is connected to zero. If there is a third current in the path, leakage occurs between the active region and the adjacent polysilicon.
[0013] Furthermore, if the first current is greater than the sum of the second current and the third current, it is determined that leakage has occurred between two adjacent polysilicon wafers.
[0014] Furthermore, when there is no first current in the path of the contact hole test structure, it also includes: A current signal is applied to the first end of the active region contact hole test structure and the first end of the polysilicon contact hole test structure, and the second end of the active region contact hole test structure and the second end of the polysilicon contact hole test structure are connected to zero to measure the resistance of the active region contact hole and the polysilicon contact hole.
[0015] Compared with the prior art, the contact hole testing method of the present invention applies a current signal to the first end of the active region contact hole testing structure and the first end of the polysilicon contact hole testing structure, and connects the second end of the active region contact hole testing structure and the second end of the polysilicon contact hole testing structure to zero to measure the resistance of the active region contact hole and the polysilicon contact hole. A voltage is applied to the second end of the active region contact hole testing structure, and the second end of the polysilicon contact hole testing structure and the metal wiring terminal of the first leakage current testing structure are connected to zero. The metal wiring terminal of the first leakage current testing structure is connected in parallel with several third chains of the first leakage current testing structure. When there is a first current in the path of the contact hole testing structure, at least one leakage current is determined between two adjacent active regions, between an active region and an adjacent polysilicon, and between two adjacent polysilicons. Thus, the resistance and leakage current tests of the contact hole area can be completed in the above two steps, reducing the original three leakage current tests to one test, thereby improving testing efficiency. Furthermore, by designing the contact hole test structure using minimum design rules, the layout area was also reduced. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of an active region contact hole test structure in the prior art. Figure 2 This is a schematic diagram of a polysilicon contact hole testing structure in the prior art; Figure 3 This is a schematic diagram of the contact hole test structure according to an embodiment of the present invention; Figure 4 This is a side view of the first chain according to an embodiment of the present invention; Figure 5 This is a side view of the second chain according to an embodiment of the present invention; The reference numerals in the drawings of this invention are as follows: 10. Active area contact hole test structure; 11. First chain; 111. Active area; 112. Active area contact hole; 113. Active area metal wiring; 20. Polysilicon contact hole test structure; 21. Second chain; 211. Polysilicon layer; 212. Polysilicon contact hole; 213. Polysilicon metal wiring; 30. First leakage current test structure; 31. Third chain; 40. Second leakage current test structure; 41. Fourth chain. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.
[0018] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.
[0019] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.
[0020] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. The terms "first," "second," and "third" used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.
[0021] Example 1 like Figures 3-5 As shown, this embodiment of the invention provides a contact hole test structure, including an active region contact hole test structure 10 and a polysilicon contact hole test structure 20 disposed on a semiconductor substrate. The active region contact hole test structure 10 includes a plurality of first chains 11 connected in series, and the polysilicon contact hole test structure 20 includes a plurality of second chains 21 connected in series, wherein the active region contact hole test structure 10 and the polysilicon contact hole test structure 20 extend in the same direction.
[0022] In the case where the active region contact hole test structure 10 and the polysilicon contact hole test structure 20 extend in the same direction, if both the first chain 11 and the second chain 21 are set as straight structures, then the first chain 11 and the second chain 21 are set in parallel.
[0023] In the case that the active region contact hole test structure 10 and the polysilicon contact hole test structure 20 extend in the same direction, the first end of the active region contact hole test structure 10 is close to the first end of the polysilicon contact hole test structure 20, and the last end of the active region contact hole test structure 10 is close to the last end of the polysilicon contact hole test structure 20.
[0024] The active region contact hole test structure 10 is used to test the resistance between the active region 111 and the active region contact hole 112 on the semiconductor substrate, and the polysilicon contact hole test structure 20 is used to test the resistance between the polysilicon layer 211 and the polysilicon contact hole 212 on the semiconductor substrate.
[0025] In some embodiments, both the first and second ends of the active region contact hole test structure 10 are connected to pin pads to facilitate the application of current or voltage to the active region contact hole test structure 10.
[0026] In some embodiments, both the first and second ends of the polysilicon contact hole test structure 20 are connected to pin pads to facilitate the application of current or voltage to the polysilicon contact hole test structure 20.
[0027] Furthermore, two adjacent first chains 11 or two adjacent second chains 21 are connected in series by metal wiring to form a chain structure.
[0028] Preferably, the first chains 11 and the second chains 21 are arranged in multiple rows and are all linear structures, in which case the first chains 11 and the corresponding second chains 21 are arranged in parallel.
[0029] Furthermore, the first chain 11 includes a plurality of active regions 111 arrayed on the semiconductor substrate, each active region 111 having an active region contact hole 112 at both ends, and each pair of adjacent active region contact holes 112 being connected by an active region metal wiring 113.
[0030] Furthermore, the second chain 21 includes a plurality of polysilicon layers 211 arrayed on a semiconductor substrate, each polysilicon layer 211 having polysilicon contact holes 212 at both ends, and each pair of adjacent polysilicon contact holes 212 being connected by polysilicon metal wiring 213.
[0031] The active region 111 of the first chain 11 and the polysilicon layer 211 of the second chain 21 are arranged in a corresponding manner.
[0032] The contact hole test structure also includes a first leakage test structure 30 and a second leakage test structure 40. The first leakage test structure 30 is disposed on a semiconductor substrate and includes several third chains 31, each third chain 31 being inserted between two adjacent first chains 11. The first leakage test structure 30 is used to test whether there is leakage between two adjacent active regions 111 within the active region contact hole test structure 10. The second leakage test structure 40 is disposed on a semiconductor substrate and connected to the active region contact hole test structure 10 via a diode structure. The second leakage test structure 40 includes several fourth chains 41, each fourth chain 41 being inserted between two adjacent second chains 21. The second leakage test structure 40 is used in conjunction with the active region contact hole test structure 10 to test whether there is leakage between two adjacent polysilicon layers 211 within the polysilicon contact hole test structure 20, and between an active region 111 and an adjacent polysilicon layer 211.
[0033] The first leakage current test structure 30 includes several third chains 31, and the several third chains 31 are connected in parallel to a metal wiring end.
[0034] The metal wiring end of the first leakage current test structure 30 is used to connect to the pin pad to facilitate the application of external voltage.
[0035] In this structure, several third chains 31 are interconnected at the same end by metal wiring to form a comb-like structure.
[0036] The structure of the third chain 31 is the same as that of the first chain 11, and will not be described again here.
[0037] The active region in the third chain 31 is alternately set with the active region 111 in the first chain 11.
[0038] The second leakage current test structure 40 includes several fourth chains 41 and has at least one metal wiring terminal connected in parallel. The metal wiring terminal of the second leakage current test structure 40 is used to connect to the N-terminal of the diode structure.
[0039] The second end of the active region contact hole test structure 10 is connected to the P-stage of the diode structure.
[0040] The fourth chain 41 has the same structure as the second chain 21, and will not be described in detail here.
[0041] Among them, the polysilicon layer of the fourth chain 41 is arranged in a corresponding manner to the polysilicon layer 211 of the second chain 21.
[0042] Furthermore, at least one of the following: active region contact hole test structure 10, polysilicon contact hole test structure 20, first leakage test structure 30, second leakage test structure 40, the distance between active region contact hole test structure 10 and polysilicon contact hole test structure 20, the distance between active region contact hole test structure 10 and first leakage test structure 30, and the distance between polysilicon contact hole test structure 20 and second leakage test structure 40, follows the minimum design rule to save layout area.
[0043] Specifically, at least one of the intervals between the first chain 11 and the second chain 21, the third chain 31, the second chain 21 and the fourth chain 41, and the third chain 31 and the fourth chain 41 follows the minimum design rule.
[0044] This invention is based on two existing test structure designs. It can measure the resistance values of the two structures and detect the leakage current between them. While achieving the structural function, it saves 60% of the layout area and reduces the leakage current test time to one-third of the original, effectively reducing layout costs and improving test efficiency.
[0045] Example 2 An embodiment of the present invention provides a contact hole testing method, applied to the above-mentioned contact hole testing structure, comprising: Step S102: Apply voltage to the second end of the active region contact hole test structure, and connect the second end of the polysilicon contact hole test structure and the metal wiring end of the first leakage test structure to zero, wherein the metal wiring end of the first leakage test structure is connected in parallel with several third chains of the first leakage test structure; Step S104: When there is a first current in the path of the contact hole test structure, determine at least one leakage current between two adjacent active regions, between an active region and an adjacent polysilicon, and between two adjacent polysilicon.
[0046] Furthermore, after determining at least one leakage current between two adjacent active regions, between an active region and an adjacent polysilicon cell, and between two adjacent polysilicon cells, the method further includes: A voltage is applied to the metal wiring end of the first leakage current test structure, and the second end of the active area contact hole test structure is connected to zero. If there is a second current in the path, then there is leakage between the two adjacent active areas.
[0047] Furthermore, after determining at least one leakage current between two adjacent active regions, between an active region and an adjacent polysilicon cell, and between two adjacent polysilicon cells, the method further includes: A voltage is applied to the second terminal of the polysilicon contact hole test structure, and the second terminal of the active region contact hole test structure is connected to zero. If there is a third current in the path, leakage occurs between the active region and the adjacent polysilicon.
[0048] Furthermore, if the first current is greater than the sum of the second and third currents, it is determined that leakage has occurred between two adjacent polysilicon cells.
[0049] In some embodiments, when there is no first current in the path of the contact hole test structure, it further includes: A current signal is applied to the first end of the active region contact hole test structure and the first end of the polysilicon contact hole test structure, and the second end of the active region contact hole test structure and the second end of the polysilicon contact hole test structure are connected to zero to measure the resistance of the active region contact hole and the polysilicon contact hole.
[0050] The following is a specific embodiment of a contact hole testing method according to an embodiment of the present invention: like Figure 3 As shown, the first end of the active region contact hole test structure is connected to pin pad PAD1, the second end of the active region contact hole test structure is connected to pin pad PAD3 and the P-terminal of the diode structure, the first end of the polysilicon contact hole test structure is connected to pin pad PAD2, the second end of the polysilicon contact hole test structure is connected to pin pad PAD4, the metal wiring end of the first leakage current test structure is connected to pin pad PAD5, and the metal wiring end of the second leakage current test structure is connected to the N-terminal of the diode structure.
[0051] When measuring the resistance between active regions and active region contact holes, and the resistance between polysilicon contact holes and polysilicon, a current signal is applied to pin pads PAD1 and PAD2, and pin pads PAD3 and PAD4 are connected to zero, thereby obtaining the resistance between active regions and active region contact holes, and the resistance between polysilicon contact holes and polysilicon.
[0052] When measuring whether there is leakage between two adjacent active regions, between an active region and an adjacent polysilicon, and between two adjacent polysilicons, a voltage is applied to pin pad PAD3, and pin pads PAD4 and PAD5 are connected to zero. If a first current flows through the path, it indicates that there is leakage at least once between two adjacent active regions, between an active region and an adjacent polysilicon, and between two adjacent polysilicons. If a first current flows through the path, it indicates that there is no leakage between two adjacent active regions, between an active region and an adjacent polysilicon, and between two adjacent polysilicons.
[0053] In the event of leakage at at least one of the following: between two adjacent active regions, between an active region and an adjacent polysilicon layer, and between two adjacent polysilicon layers, if a second current flows through the path when a voltage is applied to pin pad PAD5 and pin pad PAD3 is connected to zero, then leakage occurs between the two adjacent active regions. When a voltage is applied to pin pad PAD4 and pin pad PAD3 is connected to zero, the leakage current between the polysilicon layers will be cut off due to the unidirectional conduction characteristic of the diode structure connected to pin pad PAD3. If a third current flows through the path at this time, then leakage must occur between the active region and the polysilicon layer. If the first current is significantly higher than the sum of the second and third currents, then leakage occurs between the two adjacent polysilicon layers.
[0054] The CT Chain (Continuous Transmission Chain) of this invention is not limited in length or number of CTs, and the contact hole of this invention is representative of the through hole in the back-end metal interconnect line. It is not limited to CTs and can also be applied to the upper layer Via.
[0055] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0056] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A contact hole testing structure, comprising an active region contact hole testing structure and a polysilicon contact hole testing structure disposed on a semiconductor substrate, wherein the active region contact hole testing structure comprises a plurality of first chains connected in series, and the polysilicon contact hole testing structure comprises a plurality of second chains connected in series, characterized in that, The active region contact hole test structure and the polysilicon contact hole test structure extend in the same direction, and the contact hole test structure further includes: A first leakage current test structure is disposed on the semiconductor substrate and includes a plurality of third chains. Each third chain is inserted between two adjacent first chains. The first leakage current test structure is used to test whether there is leakage between two adjacent active regions within the active region contact hole test structure. The second leakage current test structure is disposed on the semiconductor substrate and connected to the active region contact hole test structure through a diode structure. The second leakage current test structure includes a plurality of fourth chains, each of which is inserted between two adjacent second chains. The second leakage current test structure is used in conjunction with the active region contact hole test structure to test whether there is leakage between two adjacent polysilicon cells in the polysilicon contact hole test structure and between the active region and the adjacent polysilicon cells.
2. The contact hole test structure according to claim 1, characterized in that, The spacing between each pair of the active region contact hole test structure, the polysilicon contact hole test structure, the first leakage test structure, and the second leakage test structure must follow at least one minimum design rule.
3. The contact hole test structure according to claim 1, characterized in that, The first chain and the third chain have the same structure and both include several active regions arrayed on the semiconductor substrate. Each active region has an active region contact hole at both ends, and each pair of adjacent active region contact holes are connected by active region metal wiring.
4. The contact hole test structure according to claim 3, characterized in that, The active regions in the first chain and the active regions in the third chain are alternately arranged.
5. The contact hole test structure according to claim 1, characterized in that, The second chain and the fourth chain have the same structure and both include several polysilicon layers arrayed on the semiconductor substrate. Each polysilicon layer has polysilicon contact holes at both ends, and each pair of adjacent polysilicon contact holes are connected by polysilicon layer metal wiring.
6. A method for testing contact holes, characterized in that, Applied to the contact hole test structure according to any one of claims 1 to 5, comprising: A voltage is applied to the second end of the active region contact hole test structure, and the second end of the polysilicon contact hole test structure and the metal wiring end of the first leakage test structure are connected to zero, wherein the metal wiring end of the first leakage test structure is connected in parallel with several third chains of the first leakage test structure. When there is a first current in the path of the contact hole test structure, at least one leakage current is determined between two adjacent active regions, between the active region and an adjacent polysilicon, and between two adjacent polysilicon.
7. The contact hole testing method according to claim 6, characterized in that, After determining at least one leakage current between two adjacent active regions, between the active region and an adjacent polysilicon cell, and between two adjacent polysilicon cells, the method further includes: A voltage is applied to the metal wiring end of the first leakage current test structure, and the second end of the active area contact hole test structure is connected to zero. If there is a second current in the path, leakage current occurs between the two adjacent active areas.
8. The contact hole testing method according to claim 7, characterized in that, After determining at least one leakage current between two adjacent active regions, between the active region and an adjacent polysilicon cell, and between two adjacent polysilicon cells, the method further includes: A voltage is applied to the second terminal of the polysilicon contact hole test structure, and the second terminal of the active region contact hole test structure is connected to zero. If there is a third current in the path, leakage occurs between the active region and the adjacent polysilicon.
9. The contact hole testing method according to claim 8, characterized in that, If the first current is greater than the sum of the second current and the third current, it is determined that leakage has occurred between two adjacent polysilicon cells.
10. The contact hole testing method according to claim 6, characterized in that, When there is no first current in the path of the contact hole test structure, it further includes: A current signal is applied to the first end of the active region contact hole test structure and the first end of the polysilicon contact hole test structure, and the second end of the active region contact hole test structure and the second end of the polysilicon contact hole test structure are connected to zero to measure the resistance of the active region contact hole and the polysilicon contact hole.