A test structure for monitoring gate metal connection layer opens

Abstract

The utility model provides a kind of test structure for monitoring gate metal connection layer open circuit, including at least one test unit, wherein, the test unit includes the metal connection line of several gates and several active regions that are arranged in turn, and at least one gate metal connection line across adjacent the gate and the active region metal connection line;Along predetermined extension direction, adjacent the gate, the active region metal connection line is formed in order by the gate metal connection line ladder series connection one snakelike test chain between, and the both ends of the snakelike test chain are respectively connected by the gate metal connection line of head and tail end. By the utility model, the connection stability of gate metal connection layer M0GT can be effectively monitored.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor design and manufacturing technology, and particularly relates to a test structure for monitoring open circuits in the gate metal interconnect layer. Background Technology

[0002] In more mature manufacturing processes, a single contact via (CT) is typically used to connect the active area (AA) and gate of a MOSFET to the interconnects in subsequent processes. However, as manufacturing technologies shrink to more advanced nodes, a single CT is no longer sufficient to achieve this connection. To address the challenges of size reduction, a metal layer 0 (M0) is often used to more effectively connect the AA and gate to subsequent metal interconnect layers. This separate design not only improves wiring flexibility and density but also optimizes circuit performance.

[0003] In more advanced manufacturing processes, the role of the contact hole connecting both the AA (Analog Array) and the Gate is fulfilled by the M0 layer metal connecting the gate. As the minimum design rule requires increasingly smaller dimensions, the overlay between the M0 layer metal connecting the Gate and the M0 layer metal connecting the AA or the Gate becomes very small, making connection reliability a critical issue. Factors such as the size of the M0 layer metal connecting the Gate, the overlay between the M0 layer metal connecting the Gate and the M0 layer metal connecting the AA or the Gate, and the size of the M0 layer metal connecting the AA or the Gate itself, can cause the connection between the M0 layer metal connecting the Gate and the M0 layer metal connecting the AA or the Gate to break. Therefore, structural monitoring is necessary to ensure connection integrity and electrical performance. Utility Model Content

[0004] To address the problems of the prior art, this invention provides a test structure for monitoring open circuits in the gate metal interconnect layer, thereby solving the problem of monitoring the connection stability of the gate metal interconnect layer.

[0005] To achieve the above objectives, this utility model provides a test structure for monitoring open circuits in the gate metal interconnect layer. The test structure includes at least one test unit, wherein the test unit includes a plurality of gates and a plurality of active region metal interconnects arranged sequentially and alternately, and a gate metal interconnect across adjacent gates and active region metal interconnects.

[0006] Along a predetermined extension direction, adjacent gates and active region metal connection lines are connected in a stepped manner through the gate metal connection lines to form a serpentine test chain, and the two ends of the serpentine test chain are respectively connected through the gate metal connection lines at the beginning and end.

[0007] In some embodiments, the predetermined extension direction is along the gate length direction or perpendicular to the gate length direction.

[0008] In some embodiments, a gate metal connection line is provided between adjacent gates and active region metal connection lines. Along the direction perpendicular to the length of the gate, adjacent gates and active region metal connection lines are connected in a step-like manner through the gate metal connection line to form a first serpentine test chain.

[0009] In some embodiments, at least two gate metal connection lines are provided on adjacent gate and active region metal connection lines. Along the length direction of the gate, adjacent gates and active region metal connection lines are connected in a stepped manner through the gate metal connection lines to form a second serpentine test chain. The second serpentine test chain includes multiple inflection points and connection segments on both sides of the inflection points. Two gate metal connection lines are provided on the inflection points of the second serpentine test chain.

[0010] A first cutting layer is provided between two gate metal connection lines at the same inflection point of the second serpentine test chain. The first cutting layer is used to cut off one of the gate or the active region metal connection line. At least one second cutting layer is provided on the connection segment on both sides of the same inflection point. The second cutting layer is used to cut off the other of the gate or the active region metal connection line.

[0011] The first cut-off layer and the second cut-off layer extend through all gate and active region metal interconnects.

[0012] In some embodiments, the inflection point of the second serpentine test chain includes a gate, and two gate metal connection lines are disposed on the inflection point;

[0013] A first cutting layer is provided between two gate metal connection lines at the same inflection point. The first cutting layer is used to cut off the active region metal connection lines. At least one second cutting layer is provided on the connection segments on both sides of the same inflection point. The second cutting layer is used to cut off the gate between adjacent connection segments.

[0014] In some embodiments, the inflection point of the second serpentine test chain includes an active region metal connection line, and two gate metal connection lines are disposed on the inflection point;

[0015] A first cutting layer is provided between two gate metal connection lines at the same inflection point, and the first cutting layer is used to cut off the gate; at least one second cutting layer is provided on the connection segments on both sides of the same inflection point, and the second cutting layer is used to cut off the active region metal connection lines between adjacent connection segments.

[0016] In some embodiments, the test structure for monitoring the open circuit of the gate metal interconnect layer includes at least two test units, and a third cutting layer is provided between different test units. The third cutting layer is used to cut off the active region metal interconnect line and the gate between different test units.

[0017] The serpentine test chains of different test units are connected in series through the rear wiring and then connected through the gate metal connection lines in the first and last test units.

[0018] In some embodiments, the distance between the gate metal interconnect and the first cut-off layer, the second cut-off layer and the third cut-off layer is -10nm to 100nm.

[0019] In some embodiments, the width of the gate is 12nm-300nm, the width of the active region metal interconnect is 20nm-100nm, the width of the gate metal interconnect is 20nm-80nm, and the length is 50nm-150nm.

[0020] The above-mentioned test structure for monitoring open circuits in the gate metal interconnect layer includes at least one test unit. The test unit includes a plurality of gates and a plurality of active region metal interconnects arranged alternately, as well as gate metal interconnects spanning adjacent gates and active region metal interconnects. Along a predetermined extension direction, adjacent gates and active region metal interconnects are connected in a stepped manner through the gate metal interconnects to form a serpentine test chain.

[0021] By simultaneously connecting the gate metal interconnect layer MOGT to both the gate and the active area metal interconnect line MOAA, and forming a serpentine test chain through a sequential stepped chain, a large area of ​​the gate metal interconnect layer can be covered. This allows for the detection of short circuits or poor contact between the gate metal interconnect layer MOGT and the gate or active area metal interconnect line MOAA, comprehensively detecting the connection status at different locations. This effectively monitors the connection stability of the gate metal interconnect layer MOGT, providing an effective monitoring method for gate metal interconnect layer processes in advanced manufacturing processes.

[0022] The arrangement of several gates and several active area metal interconnects in alternating phases conforms to the actual process pattern shape and pattern density, is compatible with existing process flows and testing equipment, facilitates practical applications, and can provide feedback parameters to the manufacturing process to help optimize parameters such as alignment accuracy. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the specific embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a test structure for monitoring open circuits in the gate metal interconnect layer, provided as an embodiment, along the direction perpendicular to the gate length.

[0025] Figure 2 This is a schematic diagram of a test structure for monitoring open circuits in the gate metal interconnect layer along the gate length direction, as provided in one embodiment.

[0026] Figure 3 A schematic diagram of a test structure for monitoring open circuits in the gate metal interconnect layer along the gate length direction, provided for another embodiment.

[0027] Figure 4 This is a schematic diagram showing the dimensions of the gate, gate metal interconnect, and active region metal interconnect in a test structure for monitoring open circuits in the gate metal interconnect layer, provided as an embodiment.

[0028] Figure 5 A schematic diagram of a test structure for monitoring open circuits in the gate metal interconnect layer, including at least two test units, is provided for one embodiment. Detailed Implementation

[0029] The foregoing and other technical contents, features, and effects of this utility model will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, or back, are only for reference to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the scope of this utility model.

[0030] With the development of semiconductor technology, node sizes are gradually shrinking. Due to further reduction in size and increase in device density, traditional MOSFET interconnection methods face challenges, such as insufficient alignment accuracy, limited electrical performance, and complex design rules. This severely restricts the size and spacing of contact holes (CTs), and traditional single-layer contact holes (CTs) are no longer sufficient to meet the requirements for connection reliability and efficiency. Therefore, the introduction of a metal layer 0 (M0) becomes necessary. In the M0 metal layer, M0AA and M0GT are defined to connect the active region (AA) and the gate (GT), respectively. The use of these M0AA and M0GT metal layers can more effectively connect the active region AA and the gate to the subsequent metal interconnect layers.

[0031] To optimize device performance and meet specific application requirements, the gate metal interconnect layer (MOGT) needs to be connected to the MOAA and the gate. For example, in some circuit modules, signal transmission between the gate and the active region requires higher integration and lower latency. Direct connection between the MOGT and MOAA can reduce signal path length and complexity, improving signal integrity. Furthermore, direct connection between the MOGT and MOAA enables more compact, flexible, and efficient circuit layouts, enhancing overall circuit performance.

[0032] As the minimum design rule requires increasingly smaller dimensions, the alignment (overlay) between the MOGT and MOAA / Gate becomes very limited, making connection reliability a critical issue. Factors such as the size of the MOGT, the alignment (overlay) between the MOGT and MOAA / Gate, and the dimensions of the MOAA and Gate can all lead to a break in the connection between the MOGT and MOAA / Gate. Therefore, structural monitoring is essential to ensure connection integrity and electrical performance.

[0033] In advanced manufacturing processes, due to the complexity of the manufacturing process and the high requirements for electrical performance, there are strict requirements on the density pattern and design rules of Gates and MOAAs. A relatively regular arrangement is required, and in some specific design requirements and application scenarios, MOAAs must be present between adjacent Gates. Please refer to [link / reference]. Figure 1 Based on this, this embodiment provides a test structure for monitoring open circuits in the gate metal interconnect layer MOGT. The test structure includes a test unit comprising several gates and several active area metal interconnects MOAAs. The gates and active area metal interconnects MOAAs are arranged alternately to maintain uniform pattern density. The test unit also includes gate metal interconnects MOGTs spanning adjacent gates and active area metal interconnects MOAAs, which connect adjacent gates and active area metal interconnects MOAAs. Along a predetermined extension direction, adjacent gates and active area metal interconnects MOAAs are connected in a stepped manner via the gate metal interconnects MOGTs to form a serpentine test chain. The two ends of the serpentine test chain are connected via the gate metal interconnects MOGTs at their respective ends. The predetermined extension direction can be along the length of the gate or perpendicular to the length of the gate.

[0034] By simultaneously connecting the gate metal interconnect layer MOGT to both the gate and active area metal interconnect lines MOAA, and forming a serpentine test chain through a stepped chain, a large area of ​​the gate metal interconnect layer can be covered. This allows for the detection of short circuits or poor contact between the gate metal interconnect layer MOGT and the gate or active area metal interconnect lines MOAA, comprehensively detecting the connection status at different locations. This effectively monitors the connection stability of the gate metal interconnect layer MOGT, providing an effective monitoring method for gate metal interconnect layer processes in advanced manufacturing processes. The alternating arrangement of several gates and active area metal interconnect lines MOAA conforms to the actual process pattern shape and density, ensuring compatibility with existing process flows and testing equipment, facilitating practical applications. Simultaneously, it provides feedback parameters to the manufacturing process, helping to optimize parameters such as alignment accuracy.

[0035] Depending on the testing conditions, the test structure can consist of a single test unit or a combination of multiple test units. The following descriptions, using multiple embodiments, illustrate test structures consisting of a single test unit and test structures composed of multiple test units, respectively, with reference to the accompanying drawings.

[0036] like Figure 1 As shown, in some embodiments, the gate and active region metal connection lines MOAA are arranged alternately to form an alternating pattern. A gate metal connection line MOGT is provided on adjacent gates and active region metal connection lines MOAA to ensure that the gate metal connection line MOGT can form a continuous connection with the gate and active region metal connection lines MOAA. Along a direction perpendicular to the gate length, adjacent gates and active region metal connection lines MOAA are connected in a stepped manner via the gate metal connection lines MOGT to form a first serpentine test chain. The two ends of the first serpentine test chain are respectively connected through the gate metal connection lines MOGT at the beginning and end, forming a continuous test path.

[0037] like Figure 5 As shown, in some embodiments, the width (W) of the gate Gate The active region metal interconnect width (W) is 12nm-300nm. M0AA The width of the gate metal interconnect is 20nm-100nm, and the width (W) of the gate metal interconnect is... M0GT The wavelength range is 20nm-80nm, and the length (L) is... M0GT The wavelength range is 50nm-150nm.

[0038] The above test structure allows for the determination of whether there is an open circuit in the gate metal interconnect layer MOGT by detecting the electrical continuity of the first serpentine test chain.

[0039] During testing, pins HPin and LPin are connected through the gate metal interconnect M0GT at both ends. The resistance value of the first serpentine test chain formed by the gate and active region metal interconnect M0AA connected in series through the gate metal interconnect M0GT can be measured using the two-end method. This allows for monitoring the connection stability of the gate metal interconnect layer M0GT and provides an effective monitoring method for the gate metal interconnect layer process in advanced processes.

[0040] Generally, a high voltage is applied to pin HPin and a low voltage to pin Lpin. The current between the two pins is measured, and the resistance between them is calculated. The resistance value R of the first serpentine test chain varies under different connection stability conditions. When the resistance value R is greater than 1×e... 10 Ω indicates an open circuit in the test link, and the alignment accuracy between M0GT and M0AA / Gate in the first serpentine test link is poor. When the resistance value R is between 1×e 7 Ω~1×e 8 Ω indicates that the test link has good connection stability and the alignment accuracy of M0GT and M0AA / Gate in the first serpentine test link is high.

[0041] In some embodiments, the gate and active region metal interconnects MOAA are arranged alternately to form an alternating pattern. Along the length of the gate, adjacent gates and active region metal interconnects MOAA are connected in a stepped manner through gate metal interconnects MOGT to form a second serpentine test chain. The two ends of the second serpentine test chain are respectively connected through the gate metal interconnects MOGT at the beginning and end to form a continuous test path.

[0042] Please see Figures 2-3In this embodiment, along the length of the gate, to form a second serpentine test chain by sequentially connecting adjacent gates and active region metal interconnects MOAA via gate metal interconnects MOGT, at least two gate metal interconnects MOGT are provided on adjacent gates and active region metal interconnects MOAA to form multiple inflection points. Specifically, the second serpentine test chain includes multiple inflection points and connecting segments on both sides of the inflection points. Two gate metal interconnects MOGT are provided on the inflection points of the second serpentine test chain, and any connecting segment on both sides of the inflection point includes a stepped test chain between adjacent inflection points. It can be understood that the inflection point of the second serpentine test chain can be a gate, and the gate inflection point can be provided with two gate metal interconnects MOGT; the inflection point of the second serpentine test chain can also be an active region metal interconnect MOAA, and the active region metal interconnect MOAA inflection point can be provided with two gate metal interconnects MOGT. In the actual test structure, the inflection point object and position can be flexibly selected according to the actual design requirements, and this application is not limited thereto.

[0043] A first severing layer is provided between the two gate metal connection lines MOGT at the same inflection point of the second serpentine test chain. This first severing layer is used to sever either the gate or the active area metal connection line MOAA, and it extends through all gate and active area metal connection lines MOAA. With this configuration, after the first severing layer severs either the gate or the active area metal connection line MOAA between the two gate metal connection lines MOGT at the same inflection point of the second serpentine test chain, the other gate or active area metal connection line MOAA forms a unique continuous signal path.

[0044] At least one second cutting layer is provided on the connecting segments on both sides of the same inflection point. The second cutting layer is used to cut off the other of the gate or the active area metal connection line MOAA. The second cutting layer runs through all gates and active area metal connection lines MOAA. With this configuration, the gate metal connection lines MOGT on the connecting segments on both sides of the same inflection point cannot be directly connected through the gate or the active area metal connection line MOAA, so that the signal is transmitted sequentially between the inflection point and the connecting segment to form a unique ladder-type series test chain.

[0045] For example, the inflection point of the second serpentine test chain includes a gate, and two gate metal connection lines MOGT are disposed on the inflection point. A first cutting layer MOCut (Metal 0 Cut) is disposed between the two gate metal connection lines MOGT at the same inflection point. MOCut refers to a cutting or isolation operation performed on the Metal 0 layer (MO) to cut off unnecessary electrical connections and ensure electrical isolation between different circuit nodes. In this embodiment, the first cutting layer MOCut is used to cut off the active area metal connection line MOAA at the inflection point; at least one second cutting layer GateCut is disposed on the connection segment on both sides of the same inflection point. The second cutting layer GateCut is used to cut off the gate between adjacent connection segments, and the gate metal connection lines MOGT on the connection segment on both sides of the same inflection point cannot be directly connected through the gate. With the above settings, the signal is transmitted sequentially between the gate and the connection segments on both sides to form a unique ladder-type series test chain. The resistance values ​​of the stepped series test chain are measured by connecting the HPin and LPin pins through the gate metal interconnect M0GT at the beginning and end of the chain, thereby monitoring the connection stability of the gate metal interconnect layer M0GT.

[0046] For example, the inflection point of the second serpentine test chain includes an active region metal interconnect line MOAA, and two gate metal interconnect lines MOGT are disposed at the inflection point. A first cut-out layer GateCut is disposed between the two gate metal interconnect lines MOGT at the same inflection point. GateCut refers to a cutting or isolation operation performed on the gate layer. The first cut-out layer is used to cut off the gate at the inflection point. At least one second cut-out layer MOCut is disposed on the connection segment on both sides of the same inflection point. The second cut-out layer MOCut is used to cut off the active region metal interconnect line MOAA between adjacent connection segments. The gate metal interconnect lines MOGT on the connection segment on both sides of the same inflection point cannot be directly connected through the active region metal interconnect line MOAA. With the above settings, the signal is sequentially transmitted between the active region metal interconnect line MOCut and the connection segments on both sides to form a unique stepped series test chain. The resistance value of the stepped series test chain is measured by connecting the pins HPin and Lpin of the gate metal interconnect lines MOGT at the beginning and end, respectively, thereby monitoring the connection stability of the gate metal interconnect layer MOGT.

[0047] It should be noted that adjacent inflection points on the second serpentine test chain can be the same or different. The first cleaving layer between two gate metal interconnects at the same inflection point can be used to cut the active region metal interconnects or to cut the gate. Correspondingly, the second cleaving layer on the connecting segments on both sides of the same inflection point can be used to cut the gate or to cut the active region metal interconnects, as long as it is different from the cutting object of the first cleaving layer. This application does not limit this.

[0048] The second cut-off layer is disposed between any two gate metal interconnect layers MOGT on the connection segment. One or more second cut-off layers may be disposed. Optionally, one second cut-off layer may be disposed on either connection segment on both sides of the same inflection point, or one or more second cut-off layers may be disposed on each of the connection segments on both sides. This application does not limit this.

[0049] like Figure 4 As shown, in some embodiments, the test structure for monitoring open circuits in the gate metal interconnect layer includes at least two test units. A third severing layer, MOCut+GateCut, is provided between different test units. The third severing layer, MOCut+GateCut, is used to sever the active region metal interconnect line MOAA and the gate between different test units. The serpentine test chain of different test units is connected in series through the rear trace and then exited through the gate metal interconnect line MOGT in the first and last test units.

[0050] By setting up at least two test units, and severing the active area metal connection line MOAA and the gate gate between different test units through the third cutting layer MOCut+GateCut, signal transmission lines between different test units are isolated. A serpentine test chain of different test units is then connected in series via the rear trace and exited through the gate metal connection line MOGT in the first and last test units, linking each test unit into a continuous test path for testing. This setup allows for flexible configuration of multiple test units with different extension directions, coverage areas, and serpentine patterns to cover more test scenarios, ensuring that the connection status of the gate metal connection layer at each critical location can be detected. In subsequent fault analysis such as EFA (Electrical Failure Analysis), only one sample preparation is needed to locate the problem, improving testing efficiency.

[0051] Please see Figure 5 In this embodiment, the distance (D) between the gate metal interconnect line MOGT and the first cut-off layer, the second cut-off layer and the third cut-off layer is -10nm to 100nm, which can be adaptively designed according to the overlay error and process window.

[0052] 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.

[0053] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A test structure for monitoring open circuits in the gate metal interconnect layer, characterized in that: The test structure includes at least one test unit, wherein the test unit includes a plurality of gates and a plurality of active region metal interconnects arranged sequentially and alternately, and a gate metal interconnect across adjacent gates and active region metal interconnects. Along a predetermined extension direction, adjacent gates and active region metal connection lines are connected in a stepped manner through the gate metal connection lines to form a serpentine test chain, and the two ends of the serpentine test chain are respectively connected through the gate metal connection lines at the beginning and end.

2. The test structure for monitoring open circuits in the gate metal interconnect layer according to claim 1, characterized in that, The predetermined extension direction is along the gate length direction or perpendicular to the gate length direction.

3. The test structure for monitoring open circuits in the gate metal interconnect layer according to claim 1, characterized in that, A gate metal connection line is provided on the adjacent gate and active region metal connection lines. Along the direction perpendicular to the length of the gate, the adjacent gates and active region metal connection lines are connected in a step-like manner through the gate metal connection line to form a first serpentine test chain.

4. The test structure for monitoring open circuits in the gate metal interconnect layer according to claim 1, characterized in that, At least two gate metal connection lines are provided on the adjacent gate and active region metal connection lines. Along the length direction of the gate, the adjacent gate and active region metal connection lines are connected in a step-like manner through the gate metal connection lines to form a second serpentine test chain. The second serpentine test chain includes multiple inflection points and connection segments on both sides of the inflection points. Two gate metal connection lines are provided on the inflection points of the second serpentine test chain. A first cutting layer is provided between two gate metal connection lines at the same inflection point of the second serpentine test chain. The first cutting layer is used to cut off one of the gate or the active region metal connection line. At least one second cutting layer is provided on the connection segment on both sides of the same inflection point. The second cutting layer is used to cut off the other of the gate or the active region metal connection line. The first cut-off layer and the second cut-off layer extend through all gate and active region metal interconnects.

5. The test structure for monitoring open circuits in the gate metal interconnect layer according to claim 4, characterized in that, The inflection point of the second serpentine test chain includes a gate, and two gate metal connection lines are provided on the inflection point; A first cutting layer is provided between two gate metal connection lines at the same inflection point. The first cutting layer is used to cut off the active region metal connection lines. At least one second cutting layer is provided on the connection segments on both sides of the same inflection point. The second cutting layer is used to cut off the gate between adjacent connection segments.

6. The test structure for monitoring open circuits in the gate metal interconnect layer according to claim 4, characterized in that, The inflection point of the second serpentine test chain includes an active region metal connection line, and two gate metal connection lines are provided on the inflection point; A first cutting layer is provided between two gate metal connection lines at the same inflection point, and the first cutting layer is used to cut off the gate; at least one second cutting layer is provided on the connection segments on both sides of the same inflection point, and the second cutting layer is used to cut off the active region metal connection lines between adjacent connection segments.

7. The test structure for monitoring open circuits in the gate metal interconnect layer according to claim 1, characterized in that, It includes at least two test units, and a third cutting layer is provided between different test units. The third cutting layer is used to cut off the active area metal connection line and gate between different test units. The serpentine test chains of different test units are connected in series through the rear wiring and then connected through the gate metal connection lines in the first and last test units.

8. The test structure for monitoring open circuits in the gate metal interconnect layer according to any one of claims 5-7, characterized in that, The distance between the gate metal connection line and the first, second, and third cut-off layers is -10nm to 100nm.

9. The test structure for monitoring open circuits in the gate metal interconnect layer according to claim 1, characterized in that, The gate width is 12nm-300nm, the active region metal interconnect width is 20nm-100nm, the gate metal interconnect width is 20nm-80nm, and the length is 50nm-150nm.

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