Test structure for detecting size of connection structure

Abstract

The utility model provides a test structure for detecting the size of a connection structure. The test structure comprises a plurality of test units. The test unit comprises a first metal wire, a through hole and a second metal wire; the first metal wire and the second metal wire belong to different metal layers, and the first metal wire and the second metal wire are connected through a through hole; the test unit is set based on a preset offset value; wherein the offset value comprises an offset distance generated by movement of the through hole and / or the first metal wire along a preset direction based on a reference point on the second metal wire; the plurality of test units of the test structure comprise test units set based on different offset values. According to the invention, the size of the connection structure is detected by performing the electrical test on the test structure, the detection is easy to realize, the pattern damage is not caused, and the semiconductor process can be adjusted in time and the yield is improved.

Description

A test structure for detecting the dimensions of a connection structure. Technical Field

[0001] This utility model belongs to the field of semiconductor design and manufacturing, and in particular relates to a test structure for detecting the dimensions of a connection structure. Background Technology

[0002] In semiconductor process development, monitoring various critical dimensions is crucial; in back-end processes, monitoring the critical dimensions (size) of vias is particularly important. Vias that are too large or too small can cause process problems, leading to short circuits or bridging failures. Common methods for monitoring via dimensions include in-line measurement using critical size scanning electron microscopy (CD-SEM) or OCD equipment. However, this method is prone to pattern damage, causing distortion of the measured pattern, and is also time-consuming.

[0003] Therefore, monitoring critical dimensions in back-end processes such as vias without causing pattern damage is crucial for semiconductor process development and improving product yield. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing a test structure for detecting the dimensions of a connection structure, enabling the detection of the dimensions of the connection structure through electrical testing.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] A test structure for detecting the dimensions of a connection structure, comprising multiple test units;

[0007] The test unit includes a first metal wire, a through hole, and a second metal wire;

[0008] The first metal wire and the second metal wire belong to different metal layers, and the first metal wire and the second metal wire are connected through the through hole;

[0009] The test unit is set based on a preset offset value;

[0010] The offset value includes the offset distance generated by moving the through hole and / or the first metal line along a preset direction based on a reference point on the second metal line.

[0011] The test structure includes multiple test units with different offset values.

[0012] In some embodiments, the dimensions of the connection structure include the dimensions of the second metal wire and / or the through-hole in the first direction and / or the dimensions in the second direction;

[0013] The first and second directions are orthogonal to each other.

[0014] In some embodiments, the preset direction includes a first direction and the opposite direction of the first direction, and / or a second direction and the opposite direction of the second direction.

[0015] In some embodiments, the test units in the test structure are set based on different offset values, and the offset values ​​are set to increase or decrease sequentially based on a preset offset step size.

[0016] In some embodiments, the test unit has at least one first test pin on the first metal line and at least one second test pin on the second metal line;

[0017] The at least one first test pin and the at least one second test pin are used to perform resistance testing on the test unit.

[0018] In some embodiments, the test structure includes multiple first test units and / or multiple second test units among its multiple test units;

[0019] In the first test unit, the first metal wire is a metal wire that runs along a first direction, and the second metal wire is a metal wire that runs along a second direction;

[0020] In the second test unit, both the first metal wire and the second metal wire are metal wires that run along the second direction.

[0021] In some embodiments, the test structure includes a plurality of first test units;

[0022] In the first test unit, the first metal wire is a metal wire that runs along a first direction, and the second metal wire is a metal wire that runs along a second direction; the first direction and the second direction are orthogonal to each other;

[0023] The plurality of first test units include test units set based on different offset values; and the offset values ​​of the first test units are set to increase or decrease sequentially based on a preset offset step size;

[0024] The offset value includes the offset distance generated by the movement of the through hole along a first direction or the opposite direction, based on a reference point on the second metal line.

[0025] In some embodiments, the reference point on the second metal line is the center point of the overlapping area of ​​the first and second metal lines.

[0026] In some embodiments, the test structure includes a plurality of second test units;

[0027] In the second test unit, both the first metal wire and the second metal wire are metal wires that run along the second direction;

[0028] The plurality of second test units include test units set based on different offset values; and the offset values ​​of the second test units are set to increase or decrease sequentially based on a preset offset step size;

[0029] The offset value includes the first metal line and the through hole, and the offset distance generated by moving along the first direction or the opposite direction based on the reference point on the second metal line.

[0030] In some embodiments, the test unit further includes virtual graphics, which serve as an environment graphic and are not connected to the test unit for testing.

[0031] The virtual graphic includes at least one of a virtual first metal line, a virtual through hole, and a virtual second metal line;

[0032] Wherein, the virtual first metal line and the first metal line belong to the same metal layer; the virtual via and the via belong to the same via layer; and the virtual second metal line and the second metal line belong to the same metal layer.

[0033] The beneficial effects of this utility model are:

[0034] This application discloses a test structure for detecting the dimensions of a connection structure. The dimensions of the connection structure can be detected by performing electrical tests on the test structure. This method is easy to implement and will not cause damage to the pattern. It is beneficial for timely adjustment of semiconductor processes and yield improvement.

[0035] To make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0036] 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.

[0037] Figure 1 is a schematic diagram of a test structure for detecting the dimensions of a connection structure provided in Embodiment 1 of this application.

[0038] Figure 2 is a schematic diagram of a test structure for detecting the dimensions of a connection structure provided in Embodiment 1 of this application.

[0039] Figure 3 is a schematic diagram of a test structure for detecting the dimensions of a connection structure provided in Embodiment 2 of this application.

[0040] Figure 4 is a schematic diagram of a test structure for detecting the dimensions of a connection structure provided in Embodiment 2 of this application.

[0041] Figure 5 is a schematic diagram of the test unit setup provided in Embodiment 2 of this application.

[0042] Figure 6 is a fitting curve of the actual measured resistance value and the corresponding offset value of the test unit provided in Embodiment 2 of this application. Detailed Implementation

[0043] 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.

[0044] By performing electrical tests on the test structure, the key dimensions of the connection structure can be detected. The specific design and application of this utility model are described in detail below with reference to the accompanying drawings and two preferred embodiments.

[0045] Example 1:

[0046] As shown in Figures 1 and 2, a test structure for detecting the dimensions of a connection structure includes multiple test units.

[0047] The test unit includes: a first metal line (upper metal layer), a via, and a second metal line (lower metal layer); the first metal line and the second metal line belong to different metal layers and are connected by the via; the test structure includes multiple test units set based on different preset offset values, the offset values ​​including the via and / or the first metal line, and the offset distance generated by moving along a preset direction based on a reference point on the second metal line.

[0048] Using the test structure of this embodiment to detect the dimensions of the connection structure is easy to implement and will not damage the pattern. This is beneficial for timely adjustment of the production process and continuous improvement of product yield. Moreover, the detection efficiency is higher, and more patterns can be measured in a short time, which helps to obtain more comprehensive connection structure dimension information and facilitates better tracing of process problems.

[0049] In this embodiment, the dimensions of the connection structure include the dimensions of the second metal wire and / or the through hole in the first direction (lateral) and / or the second direction (longitudinal); the first direction and the second direction are orthogonal to each other.

[0050] By setting test units with different offset values ​​in the test structure, a test structure for detecting the critical dimensions of the required connection structure can be formed; these offset values ​​can be set for the dimensional data (width) of the second metal wire in the first direction, or for the dimensional data of the through hole in the second direction, and this application does not make specific limitations.

[0051] In this embodiment, the preset direction includes a first direction and the opposite direction of the first direction, and / or a second direction and the opposite direction of the second direction.

[0052] Specifically, for example, in Figure 1, the center point of the overlapping area between the via and the second metal line (lower metal) in the first test unit (Shift=0) is used as the reference point, and the offset values ​​of the other test units are set with a preset direction of horizontal to the right; for example, in Figure 2, the center point of the overlapping area between the via and the second metal line (lower metal) in the first test unit (Shift=0) is used as the reference point, and the offset values ​​of the other test units are set with a preset direction of horizontal to the left. In this application, a test structure can have only one preset direction or more than one preset direction; for example, the test units in Figure 1 can constitute a test structure set for the horizontal width of the via; for example, the test units in Figure 1 and Figure 2 can also jointly constitute a test structure set for the horizontal line width of the second metal line (lower metal); this application does not limit the number of preset directions in a test structure, and can set them according to the specific application scenario.

[0053] In this embodiment, the test units in the test structure are set based on different offset values, and the offset values ​​are set to increase or decrease sequentially based on a preset offset step size.

[0054] Specifically, as shown in Figure 1, the first test unit (shift = 0) indicates an offset value of zero; the second test unit (shift = +1 step) indicates that the via is offset 1 step to the right from the reference point; the third test unit (shift = +2 step) indicates that the via is offset 2 steps to the right from the reference point; and subsequent test units follow the same pattern. The preset offset step size is 'step', and a positive offset value indicates that the preset offset direction is to the right, with 'step' > 0. Similarly, as shown in Figure 2, the first test unit (shift = 0) indicates an offset value of zero; the second test unit (shift = -1 step) indicates that the via is offset 1 step to the left from the reference point; the third test unit (shift = -2 step) indicates that the via is offset 2 steps to the left from the reference point; and subsequent test units follow the same pattern. The preset offset step size is 'step', and a negative offset value indicates that the preset offset direction is to the left.

[0055] In the test unit of this embodiment, at least one first test pin is provided on the first metal line, and at least one second test pin is provided on the second metal line; resistance testing is performed on the test unit based on at least one first test pin and at least one second test pin.

[0056] Specifically, in the test unit shown in Figure 1, two first test pins, pin2 and pin4, are provided on the first metal line (upper metal layer), and two second test pins, pin1 and pin3, are provided on the second metal line (lower metal layer). The resistance of the test unit can be measured using the Kelvin four-terminal method through these four test pins. Alternatively, in some other embodiments, only one first test pin, pin2, can be provided on the first metal line (upper metal layer), and one second test pin, pin1, can be provided on the second metal line (lower metal layer). The resistance of the test unit can be measured using the two-terminal method through these two test pins. This application does not impose a specific limit on the number of test pins on the first and second metal lines in the test unit; at least one test pin on each line is sufficient for measuring resistance using the two-terminal method. The specific configuration can be adjusted according to the needs of different application scenarios.

[0057] In this embodiment, the test structure includes multiple first test units; in the first test unit, the first metal line is a metal line running along a first direction, and the second metal line is a metal line running along a second direction; the first direction and the second direction are orthogonal to each other; the multiple first test units include test units set based on different offset values; and the offset values ​​of the first test units are set to increase or decrease sequentially based on a preset offset step size.

[0058] Specifically, the test structure of this embodiment includes test units as shown in Figures 1 and 2. The first metal line (upper metal) is a metal line running along a first direction (horizontal), and the second metal line (lower metal) is a metal line running along a second direction (vertical). The horizontal and vertical directions are orthogonal to each other, meaning these test units are all first test units. The multiple test units in this test structure include test units set based on different offset values, and the offset values ​​between the test units are set to increase or decrease sequentially based on a preset offset step size. For example, in Figure 1, the offset values ​​of the test units drawn from left to right sequentially increase to 0, 1 step, 2 step, ..., N step, where N > 0, and positive offset values ​​indicate a preset offset direction to the right; similarly, in Figure 2, the offset values ​​of the test units drawn from left to right sequentially increase to 0, -1 step, -2 step, ..., -N step, and negative offset values ​​indicate a preset offset direction to the left.

[0059] In this embodiment, the test unit also includes a virtual graphic, which serves as an environment graphic and is not connected to the test unit for testing. The virtual graphic includes at least one of a virtual first metal line, a virtual via, and a virtual second metal line. The virtual first metal line and the first metal line belong to the same metal layer; the virtual via and the via belong to the same via layer; and the virtual second metal line and the second metal line belong to the same metal layer.

[0060] Specifically, in the first test unit (shift0) shown in Figure 1, the first metal line is the upper metal layer with test pins 2 and 4. All other upper metal layers surrounding it are virtual first metal lines. The second metal line is the lower metal layer with test pins 1 and 3. All other lower metal layers surrounding it are virtual second metal lines. The via is the point where the first and second metal lines overlap; all other surrounding vias are virtual vias. The virtual first metal line, virtual vias, and virtual second metal line are not connected to the test unit for testing. By setting the environmental graphics, it can be used to blur the actual product layout scenario, or to compare the impact of different environmental graphics densities and other variable settings on key dimensions in the test unit.

[0061] Based on the test structure of this embodiment, the dimensions of vias, metal, etc. can be monitored through electrical testing methods without damaging the pattern. Furthermore, the test is fast, allowing for the measurement of more patterns in a short time and obtaining more comprehensive dimensional information.

[0062] Example 2:

[0063] As shown in Figures 3 and 4, a test structure for detecting the dimensions of a connection structure includes multiple test units.

[0064] The test unit includes: a first metal wire (upper metal layer), a via, and a second metal wire (lower metal layer); the first and second metal wires belong to different metal layers and are connected by the via; the test structure includes multiple test units set based on different preset offset values, the offset values ​​including the offset distance generated by moving the via and / or the first metal wire along a preset direction based on a reference point on the second metal wire. The dimensions of the connection structure include the dimensional data of the second metal wire and / or the via in a first direction (lateral) and / or the dimensional data in a second direction (vertical); the first and second directions are orthogonal to each other.

[0065] In this embodiment, the preset direction includes a first direction and the opposite direction of the first direction, and / or a second direction and the opposite direction of the second direction.

[0066] Specifically, for example, in Figure 3, the center point of the overlapping area between the via and the second metal line (lower metal) in the first test unit (Shift=0) is used as the reference point, and the offset values ​​of the other test units are set with the preset direction of vertical to the right; for example, in Figure 4, the center point of the overlapping area between the via and the second metal line (lower metal) in the first test unit (Shift=0) is used as the reference point, and the offset values ​​of the other test units are set with the preset direction of vertical to the left. In this application, a test structure can have only one preset direction or more than one preset direction; for example, the test units in Figure 3 can constitute a test structure set for the horizontal width of the via; for example, the test units in Figures 3 and 4 can also jointly constitute a test structure set for the horizontal line width of the second metal line (lower metal); this application does not limit the number of preset directions in a test structure, and can set them according to the specific application scenario.

[0067] In this embodiment, the test units in the test structure are set based on different offset values, and the offset values ​​are set to increase or decrease sequentially based on a preset offset step size.

[0068] Specifically, as shown in Figure 3, the first test unit (shift = 0) indicates that the offset value is zero, the second test unit (shift = +1 step) indicates that the first metal wire (upload metal) and the via together are offset to the right by 1 step based on the reference point, the third test unit (shift = +2 step) indicates that the first metal wire (upload metal) and the via together are offset to the right by 2 steps based on the reference point, and subsequent test units follow the same pattern. The preset offset step size is step, and the offset value is a positive number to indicate that the preset offset direction is to the right, and step > 0.

[0069] For example, in Figure 4, the first test unit (shift = 0) indicates that the offset value is zero, the second test unit (shift = -1 step) indicates that the first metal wire (upload metal) and the via together are offset to the left by 1 step based on the reference point, the third test unit (shift = -2 step) indicates that the first metal wire (upload metal) and the via together are offset to the left by 2 steps based on the reference point, and subsequent test units follow the same pattern. The preset offset step size is step, and the offset value is a negative number to indicate that the preset offset direction is to the left.

[0070] In the test unit of this embodiment, at least one first test pin is provided on the first metal line, and at least one second test pin is provided on the second metal line; resistance testing is performed on the test unit based on at least one first test pin and at least one second test pin.

[0071] Specifically, in the test unit shown in Figure 3, two first test pins, pin2 and pin4, are provided on the first metal line (upper metal layer), and two second test pins, pin1 and pin3, are provided on the second metal line (lower metal layer). The resistance of the test unit can be measured using the Kelvin four-terminal method through these four test pins. Alternatively, in some other embodiments, only one first test pin, pin2, can be provided on the first metal line (upper metal layer), and one second test pin, pin1, can be provided on the second metal line (lower metal layer). The resistance of the test unit can be measured using the two-terminal method through these two test pins. This application does not impose a specific limit on the number of test pins on the first and second metal lines in the test unit; at least one test pin on each line is sufficient for two-terminal resistance measurement, and the specific configuration can be adjusted according to the needs of different application scenarios.

[0072] In this embodiment, the test structure includes multiple second test units; in the second test units, the first metal wire and the second metal wire are both metal wires that run along the second direction; the multiple second test units include test units set based on different offset values; and the offset values ​​between the second test units are set to increase or decrease sequentially based on a preset offset step size; the offset value includes the first metal wire and the through hole, and the offset distance generated by moving along the first direction or the opposite direction based on the reference point on the second metal wire.

[0073] Specifically, the test structure of this embodiment includes test units as shown in Figures 3 and 4. The first metal line (upper metal) and the second metal line (lower metal) are both metal lines running along the second direction (vertical direction), meaning these test units are all second test units. The multiple test units in this test structure include test units set based on different offset values, and the offset values ​​between the test units are set to increase or decrease sequentially based on a preset offset step size. For example, in Figure 3, the offset values ​​of the test units drawn from left to right sequentially increase to 0, 1 step, 2 step, ..., N step, where N > 0, and positive offset values ​​indicate a preset offset direction to the right; similarly, in Figure 4, the offset values ​​of the test units drawn from left to right sequentially increase to 0, -1 step, -2 step, ..., -N step, and negative offset values ​​indicate a preset offset direction to the left.

[0074] It should be noted that, in other embodiments, the test structure may simultaneously include multiple first test units and multiple second test units; in the first test unit, the first metal line is a metal line running along a first direction, and the second metal line is a metal line running along a second direction; in the second test unit, both the first metal line and the second metal line are metal lines running along a second direction. This application does not impose specific limitations on the number of different types of test units in the test structure, and can set them according to different application scenarios.

[0075] In this embodiment, the test unit also includes a virtual graphic, which serves as an environment graphic and is not connected to the test unit for testing. The virtual graphic includes at least one of a virtual first metal line, a virtual via, and a virtual second metal line. The virtual first metal line and the first metal line belong to the same metal layer; the virtual via and the via belong to the same via layer; and the virtual second metal line and the second metal line belong to the same metal layer.

[0076] Based on the test structure of this embodiment, the dimensions of via, metal, etc. can be monitored by electrical testing methods. The following is a detailed explanation in conjunction with the multiple test units shown in Figure 5 and the corresponding test results shown in Figure 6.

[0077] Figure 5 shows the six test units in the test structure of this embodiment. Because the first metal wire (upper metal layer) and the via move together, the upper metal layer is omitted from Figure 5 for ease of illustration. The first three test units from left to right are similar to those shown in Figure 3. The solid-lined via indicates the via position of the current test unit. The direction from the solid-lined via to the dashed-lined via indicates the preset direction for the offset value of subsequent test units. It can be seen that the last three test units from left to right in Figure 5 also include test units similar to those shown in Figure 4, but with the preset direction set in the opposite direction. Shift4 represents the offset value of this test unit, and the marking of offset values ​​in the test units is similar.

[0078] The resistance of each test unit in Figure 5 was measured using the four-terminal method, and the corresponding test results are shown in Figure 6. In Figure 6, each point represents the test result of one test unit; the horizontal axis represents the shift value of that test unit, and the vertical axis represents the measured resistance value. As shown in Figure 6:

[0079] 1) The test structure on the left side of shift4 has no overlap between its via and the underlying metal, so the test structure is equivalent to an open circuit, and the measured resistance is very large.

[0080] 2) From shift4 to shift2, the via moves from initial overlap with the lower metal layer to complete overlap. The distance the via moves can be used to calculate the width Wvia of the via. Similarly, from shift1 to shift3, it is the opposite process.

[0081] 3) From shift2 to shift1, during the movement of the via, the via always completely overlaps with the lower metal. The distance the via moves can be used to calculate the metal line width Wmetal of the lower metal.

[0082] The following specific calculations can then be performed:

[0083] Wmetal=|shift1|+|shift2|+Wvia;

[0084] Wvia=(|shift3-shift1|+|shift4-shift2|) / 2;

[0085] The technical solution in this embodiment has higher testing efficiency, can measure more patterns in a short time, helps to obtain more comprehensive connection structure size information, and is conducive to better tracing the source of process problems.

[0086] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0087] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this utility model, and are not intended to limit the scope of protection of this utility model. All equivalent implementation methods or modifications made without departing from the spirit of this utility model should be included within the scope of protection of this utility model.

Claims

1. A test structure for detecting the dimensions of a connection structure, characterized in that, The test structure includes multiple test units; each test unit includes a first metal wire, a through-hole, and a second metal wire; the first metal wire and the second metal wire belong to different metal layers and are connected through the through-hole; the test units are set based on a preset offset value; wherein, the offset value includes the offset distance generated by moving the through-hole and / or the first metal wire along a preset direction based on a reference point on the second metal wire; the multiple test units of the test structure include test units set based on different offset values.

2. The test structure for detecting the dimensions of a connection structure according to claim 1, characterized in that, The dimensions of the connection structure include the dimensions of the second metal wire and / or the through hole in the first direction and / or the second direction; the first and second directions are orthogonal to each other.

3. The test structure for detecting the dimensions of a connection structure according to claim 2, characterized in that, The preset direction includes a first direction and the opposite direction of the first direction, and / or a second direction and the opposite direction of the second direction.

4. The test structure for detecting the dimensions of a connection structure according to claim 1, characterized in that, The test units in the test structure are set based on different offset values, and the offset values ​​are set to increase or decrease sequentially based on a preset offset step size.

5. A test structure for detecting the dimensions of a connection structure according to claim 1, characterized in that, In the test unit, at least one first test pin is provided on the first metal line, and at least one second test pin is provided on the second metal line; the at least one first test pin and the at least one second test pin are used to perform resistance testing on the test unit.

6. A test structure for detecting the dimensions of a connection structure according to claim 2, characterized in that, The test structure includes multiple test units, including multiple first test units and / or multiple second test units; in the first test unit, the first metal wire is a metal wire that runs along a first direction, and the second metal wire is a metal wire that runs along a second direction; in the second test unit, both the first metal wire and the second metal wire are metal wires that run along a second direction.

7. A test structure for detecting the dimensions of a connection structure according to claim 1, characterized in that, The test structure includes multiple first test units; in each first test unit, the first metal line is a metal line running along a first direction, and the second metal line is a metal line running along a second direction; the first direction and the second direction are orthogonal to each other; the multiple first test units include test units set based on different offset values; and the offset values ​​between the first test units are set to increase or decrease sequentially based on a preset offset step size; the offset value includes the offset distance generated by the through hole moving along the first direction or the opposite direction based on a reference point on the second metal line.

8. A test structure for detecting the dimensions of a connection structure according to claim 7, characterized in that, The reference point on the second metal line is the center point of the overlapping area of ​​the first metal line and the second metal line.

9. A test structure for detecting the dimensions of a connection structure according to claim 1, characterized in that, The test structure includes multiple second test units; in each second test unit, the first metal wire and the second metal wire are both metal wires that run along a second direction; the multiple second test units include test units set based on different offset values; and the offset values ​​between the second test units are set to increase or decrease sequentially based on a preset offset step size; the offset value includes the offset distance generated by moving the first metal wire and the through hole along the first direction or the opposite direction based on a reference point on the second metal wire.

10. A test structure for detecting the dimensions of a connection structure according to claim 1, characterized in that, The test unit also includes a virtual graphic, which serves as an environment graphic and is not connected to the test unit for testing. The virtual graphic includes at least one of a virtual first metal line, a virtual via, and a virtual second metal line. The virtual first metal line and the first metal line belong to the same metal layer. The virtual via and the via belong to the same via layer. The virtual second metal line and the second metal line belong to the same metal layer.

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