Test structure for filling process detection

Abstract

The utility model provides a test structure for filling process detection. The test structure comprises at least one test unit. The test unit comprises at least two second test lines, two sides of each second test line are respectively provided with at least one first test line, and the first test lines and the second test lines are patterns on the same layer; and after the second test lines are connected in series, the head and tail ends are respectively connected out through pins. The structure integration level is high, the area can be effectively saved, the structure sensitivity is high, the filling influence of the filling technology on the filling line can be effectively judged, and the device performance level and the product yield can be improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of semiconductor design and production, and in particular relates to a test structure for filling process detection. Background Art

[0002] With the rapid development of integrated circuit technology, semiconductor devices are becoming more and more integrated, and the size of semiconductor devices is gradually shrinking proportionally. In the advanced integrated circuit manufacturing process of 10nm and below nodes, copper interconnect technology is often implemented through SALELE (Selfaligned Litho-Etch Litho-Etch, self-aligned lithography and etching process) process, and metal line filling has always been a big challenge in advanced processes, mainly encountering the following two problems:

[0003] 1) Due to the shrinking of process nodes, the line width (CD) of metal lines is getting smaller and smaller, which poses an increasing challenge to metal filling;

[0004] 2) After OPC (optical proximity correction) correction and the influence of the actual complex environment, the graphics are deformed, the actual line width is reduced, and filling abnormalities occur.

[0005] Based on all or part of the above problems, some anomalies are often easily generated in the actual metal line filling process of the back-end metal filling process. Figure 1 These are some abnormalities that are easy to occur when metal lines are actually filled. The metal color A and metal color B in the figure refer to metal lines formed in the same layer but using different masks. The common defects include: metal filling holes ( Figure 1 The actual filling condition of 1 thin line), the metal lines on both sides cause the width of the end of the middle metal line to become smaller, making filling difficult ( Figure 1 The actual filling condition of 2 thin lines), and the overall width of the metal line leads to a smaller overall line width of the adjacent metal lines, making filling difficult ( Figure 1 The actual filling condition is shown in FIG3 (thin line). Similarly, the same problem will occur when the gate layer is formed.

[0006] In order to detect the above process problems, common detection methods include inline detection and electrical detection. Inline detection includes OCD detection (OCD, optical critical dimension), CD SEM detection (SEM, scanning electron microscope), etc. The inline detection method detects more comprehensive problems, but the efficiency is slightly lower. Electrical detection includes WAT testing, etc. Electrical detection is more efficient, but the current test structure (testkey) is not sensitive enough. The simple metal line chain (metal linechain) can no longer effectively monitor the actual process capability, so it is necessary to design a highly sensitive test structure for monitoring. Utility Model Content

[0007] In order to solve all or part of the problems of the above-mentioned prior art, the utility model provides a test structure for filling process detection to test the influence of the back-end metal filling process on the line width of the metal line end (or the gate layer formation process on the gate line end).

[0008] In order to achieve the above-mentioned purpose, the utility model provides a test structure for filling process detection, including at least one test unit; the test unit includes at least two second test lines, at least one first test line is arranged on both sides of the second test line, and the first test line and the second test line are graphics of the same layer; after the second test line is connected in series, the head and tail ends are connected through pins respectively.

[0009] The first test line and the second test line are polygonal structures of a metal layer or polygonal structures of a gate layer; the first test line and the second test line are structures manufactured using different masks, respectively.

[0010] In the test unit, the second test line is connected in series across layers using connection holes and connection lines of adjacent metal layers; the connection holes are arranged at the ends of the second test lines.

[0011] After the second test line is connected in series, the head and tail ends are connected through pins respectively, including: the head end and the tail end are connected by connecting holes and connecting wires of adjacent metal layers respectively, and pins are set at the connecting wires; the head end and the tail end are respectively provided with one pin or two pins, which are used to perform a two-terminal resistance test or a four-terminal Kelvin test on the test unit.

[0012] The test unit includes a first test unit and / or a second test unit, and the test structure includes at least one first test unit and / or a second test unit; in the first test unit, the second test line has the same line width as the first test lines on both sides; in the second test unit, the second test line has the same line width as the first test line on one side, and the line width of the first test line on the other side is greater than the line width of the second test line.

[0013] In the first test unit, the second test lines are arranged in multiple rows, and the multiple rows of second test lines are connected in series in a serpentine manner; in the second test unit, the second test lines are arranged in multiple rows, and the multiple rows of second test lines are connected in series in a serpentine manner.

[0014] The test structure includes at least one first test unit and a second test unit; at least one first test line is arranged on both sides of the second test line of the first test unit, and the second test line of the second test unit is arranged on the other side of the first test line of the first test unit, and the line width of the first test line on the other side of the second test line of the second test unit is greater than the line width of the second test line of the second test unit.

[0015] The first and second test lines in the first test unit are shorter than the second test line in the second test unit; the first and second test lines in the first test unit are shorter than the first test line on the other side of the second test line in the second test unit.

[0016] The line width of the second test line is 5-100 nm, and the line length is 50-10000 nm.

[0017] In order to adapt to different conditions, the length and width of the first test line and the second test line, the size of the connection hole, the distance between the connection hole and the end of the test line, the direction of the test line and the spacing of the test lines in the above test structure can be adjusted.

[0018] Compared with the prior art, the main beneficial effects of the utility model are: 1) The use of electrical testing methods to detect the filling effect of metal or gate layer materials has the advantages of convenient and fast testing; 2) Through the combined arrangement of line width and test line length, the defects of process and optical correction problems can be detected at the same time; 3) By integrating the test structure design of two test units, the structure has a high degree of integration and can effectively save area; 4) By expanding the setting of the test unit, that is, using the horizontal and vertical connections to connect more lines to be tested in series, the structural sensitivity can be improved, and the detection efficiency can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a schematic diagram of common anomalies in actual metal wire filling.

[0021] Figure 2 A schematic diagram of a test structure provided in Embodiment 1 of the present utility model.

[0022] Figure 3 A schematic diagram of a test structure provided for the second embodiment of the present utility model.

[0023] Figure 4 A schematic diagram of a test structure provided for the third embodiment of the present utility model.

[0024] Figure 5 A schematic diagram of a complex test structure provided in Embodiment 3 of the present utility model. DETAILED DESCRIPTION

[0025] The above and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention.

[0026] The test structure involved in the utility model includes a test unit, wherein the test structure can be composed of one test unit or a combination of multiple test units according to different test conditions. The following three embodiments are used to illustrate two test structures and a test structure composed of multiple and / or multiple test units in combination with the accompanying drawings.

[0027] Embodiment 1:

[0028] Embodiment 1 describes the first test structure.

[0029] like Figure 2 The figure shows a schematic diagram of a test structure provided by the first embodiment of the utility model. It should be noted that in this application, the diagrams and texts are illustrated using metal wires, but this patent does not exclude that the gate line can also use the test structure of this patent to test the influence of the filling problem on the line width of the line end. In this application, the metal wire filling process is used as an example to illustrate the test structure, so the test line is a metal wire, and when used for the test of the gate line, the test line is the gate line.

[0030] During the actual filling process of the metal wire, there may be problems such as metal filling holes or the width of the end of the middle metal wire becomes smaller due to the metal wires on both sides. In order to detect the above-mentioned abnormalities, the following test structure is provided. The test structure can be composed of one test unit or a combination of multiple test units. When there are multiple test units, each test unit is connected separately for testing.

[0031] When the test structure is composed of a test unit, refer to Figure 2 It can be seen that the test unit is composed of a plurality of first metal wires and second metal wires alternately arranged up and down, where the first metal wires and the second metal wires are polygonal structures of the metal layer (i.e., the first metal wires and the second metal wires are metal wires in the same metal layer, and each metal wire can be a different shape, such as a rectangular or angled polygonal structure, depending on the layout design), which are manufactured using different masks. In other embodiments, the same is true when used for testing gate lines, where the gate lines are in the same layer and the gate lines are polygonal structures of the gate layer.

[0032] like Figure 2 As shown, there are at least two second metal wires in the test unit, and the second metal wire to be tested is arranged between the two first metal wires (in other embodiments, at least one first metal wire is respectively arranged on both sides of the second metal wire). In this embodiment, multiple second metal wires are repeatedly arranged in the left-right direction and / or the up-down direction, and a first metal wire is arranged on both sides of each second metal wire and connecting holes are arranged at both ends of each second metal wire (the connecting holes can be through holes or contact holes). A series test link can be formed between the multiple second metal wires through the connection of the connecting wires of adjacent metal layers (i.e., the upper metal layer or the lower metal layer) and the connecting holes (in other embodiments, when testing the gate line, the connection can also be achieved through the connecting wires and connecting holes of the adjacent metal layers of the gate layer), and the second metal wires at both ends of the test link are connected through the connecting wires of the adjacent metal layers, and pins are set at the connecting wires.

[0033] One pin or two pins may be provided at the beginning and the end of the test link respectively. When one pin is provided at each end, a two-terminal resistance test of the test unit may be performed through the two pins; when two pins are provided at the beginning and the end respectively, a four-terminal Kelvin test may be performed through four pins.

[0034] In this embodiment, each test structure may include at least one test unit. When there are multiple (greater than one) test units in the test structure, each test unit may be individually connected for testing.

[0035] like Figure 2 As shown, in order to save the test area, when the second metal lines in the test unit are arranged in multiple rows in the vertical direction, two vertically adjacent second metal lines can share one first metal line.

[0036] To further improve the test sensitivity, in other embodiments, more second metal wires may be designed to be connected in series, that is, more second metal wires to be tested and corresponding first metal wires are arranged in the up-down direction and the left-right direction, and all the second metal wires are connected in series.

[0037] In order to adapt to different conditions, in other embodiments, the line length and line width of the first metal wire and the second metal wire in the above-mentioned test structure, the size of the connecting hole, the distance between the connecting hole and the end of the metal wire, the direction of the metal wire and the spacing of the metal wire can be adjusted and designed under the premise of satisfying the design rule.

[0038] For example, in this embodiment, the line width of the second metal line to be tested is 10 nm, and the line length is 100 nm. In other embodiments, the line width of the second metal line to be tested may be 5-100 nm, and the line length may be in the range of 50-10000 nm.

[0039] Through the connected pins, the resistance value of the test link formed by multiple second metal wires in series can be measured using the two-terminal method or the four-terminal Kelvin method to determine the impact of the first metal wires on the filling of the middle second metal wire.

[0040] The influence of the first metal line on the second metal line is judged based on the measured resistance value. Generally, an estimated value that is 5 times greater than the estimated value is used. That is, when the measured resistance value is 5 times the designed metal line width (that is, there are no defects such as holes and reduced line width), it is judged that the first metal line has an influence on the second metal line.

[0041] Embodiment 2:

[0042] like Figure 3 The figure shows a schematic diagram of a test structure provided by the second embodiment of the present utility model. The second embodiment is to illustrate the second test structure.

[0043] During the actual filling process of the metal wire, when the overall width of the metal wire filled on one or both sides of the metal wire is too large, the overall width of the metal wire may become smaller. In order to detect the above anomaly, the following test structure is provided.

[0044] The test structure provided in the second embodiment can be set up with reference to the test structure in the first embodiment. The difference between the two test structures lies in the difference in line widths of the first metal wire and the second metal wire, that is, the line widths of the first metal wire and the second metal wire in the first embodiment are the same, while in the second embodiment, the line width of the first metal wire on at least one side is greater than that of the second metal wire to be tested.

[0045] Reference Figure 3 It can be seen that the test structure of the second embodiment is also composed of multiple first metal wires and second metal wires, and the line width of the first metal wire on at least one side of the second metal wire to be tested is larger than the second metal wire, and the connection holes are set at the ends of both sides of the second metal wire.

[0046] like Figure 3As shown, in this embodiment, three second metal wires are arranged in the up and down directions (i.e., the second metal wires are arranged in multiple rows), a certain distance is left between the three second metal wires, a first metal wire with a larger line width is arranged on one side of each second metal wire, and the other side is a first metal wire with the same line width as the second metal wire. For the first metal wire with the same line width as the second metal wire, it can be a whole metal wire with a line length basically the same as the second metal wire, or it can be composed of multiple first metal wires with shorter line lengths, multiple short first metal wires are located on the same straight line, and the total length of the structure composed of multiple short first metal wires is also basically the same as the second metal wire to be tested; connection holes are provided at the ends of both sides of each second metal wire, and the connection wires of the upper / lower metal layers (i.e., the upper / lower metal) can be used to connect the connection holes on adjacent second metal wires, and then the multiple second metal wires can be connected in series into a test link by connecting the end to the end, and the second metal wires at both ends of the test link can be connected through the connection wires and set pins.

[0047] One pin or two pins may be provided at the beginning and the end of the test link respectively. When one pin is provided at each end, a two-terminal resistance test of the test unit may be performed through the two pins; when two pins are provided at the beginning and the end respectively, a four-terminal Kelvin test may be performed through four pins.

[0048] In order to further improve the test sensitivity, in other embodiments, more metal wires may be designed to be connected in series, that is, more second metal wires may be arranged in series in the up-down direction and the left-right direction.

[0049] In this embodiment, each test structure may include at least one test unit. When there are multiple (greater than 1) test units in the test structure, each test unit may be contacted individually for testing.

[0050] In order to adapt to different conditions, in other embodiments, the line length and line width of the first metal wire and the second metal wire in the above-mentioned test structure, the size of the connecting hole, the distance between the connecting hole and the end of the metal wire, the direction of the metal wire and the spacing of the metal wire can be adjusted and designed under the premise of satisfying the design rule.

[0051] For example, in this embodiment, the line width of the second metal line to be tested is 10 nm, and the line length is 500 nm. In other embodiments, the line width of the second metal line to be tested may be 5-100 nm, and the line length may be in the range of 50-10000 nm.

[0052] Through the pins at both ends, the resistance value of the test link formed by multiple second metal wires in series can be measured using the two-terminal method or the four-terminal method to determine the impact of the wider first metal wire on the filling of the second metal wire.

[0053] The influence of the first metal wire on the second metal wire is determined based on the measured resistance value. Generally, an estimated value that is 5 times greater than the estimated value is used to determine that the first metal wire has an influence on the second metal wire.

[0054] Embodiment three:

[0055] In order to simultaneously detect problems such as metal filling holes, metal lines on both sides causing the line width of the end of the middle metal line to become smaller, and the overall width of the metal line causing the overall line width of the adjacent metal line to become smaller, and to further save area, the two test structures in Example 1 and Example 2 can be integrated into a more integrated test structure, and the following test structure is provided.

[0056] like Figure 4 and Figure 5 Shown is a schematic diagram of a test structure provided in Embodiment 3 of the present utility model.

[0057] Reference Figure 4 As shown, in this embodiment, the two test units in the first and second embodiments are combined. Here, the relationship between the metal wires in different test units is briefly described, with the test unit in the first embodiment being the first test unit and the test unit in the second embodiment being the second test unit. In this embodiment, in the first test unit, the second metal wire has the same line width and substantially the same line length as the first metal wires on both sides thereof; in the second test unit, one side of the second metal wire is a plurality of shorter first metal wires (the plurality of shorter first metal wires are the first metal wires in the first test unit), and the other side of the second metal wire is a second metal wire having substantially the same line length as the first metal wires, and the line width of the second metal wire in the second test unit is the same as that of the second metal wire in the first test unit, but is smaller than the line width of the first metal wire on the other side of the second test unit.

[0058] like Figure 4 As shown, in this embodiment, the first test unit is composed of 6 second metal wires and 12 first metal wires on both sides thereof, which are distributed in two rows, upper and lower, and each row is provided with 3 second metal wires. The above 6 second metal wires are serpentinely connected in series through connecting holes and connecting wires of adjacent metal layers to form a test link; partial structures of the second test unit are arranged on the upper and lower sides of each row in the first test unit, that is, the other side of the first metal wire in the first test unit is the second metal wire of the second test unit, and the other side of the second metal wire of the second test unit is the first metal wire with a larger line width, and for the 4 second metal wires in the second test unit, they are also serpentinely connected in series through connecting holes and connecting wires of adjacent metal layers to form a test link; in this way, two test links are formed, which are respectively used to test the first test unit and the second test unit.

[0059] like Figure 5 As shown in , the second metal wires in the first test unit and the second test unit can be arranged in more rows, and more second metal wires in the first test unit in each row can be arranged, so as to realize the series connection of more second metal wires. Figure 5 The second metal wire in the first test unit is connected in series through adjacent metal layers to form a test link, and the first and last ends of the test link can be connected through pins; Figure 5 The second metal wires in all the second test units are connected in series through the metal layer to form another test link, and the first and last ends of the test link can be connected through pins.

[0060] One pin or two pins may be provided at the beginning and the end of the test link respectively. When one pin is provided at each end, a two-terminal resistance test of the test unit may be performed through the two pins; when two pins are provided at the beginning and the end respectively, a four-terminal Kelvin test may be performed through four pins.

[0061] In order to adapt to different conditions, in other embodiments, the line length and line width of the first metal wire and the second metal wire in the above-mentioned test structure, the size of the connecting hole, the distance between the connecting hole and the end of the metal wire, the direction of the metal wire and the spacing of the metal wire can be adjusted and designed under the premise of satisfying the design rule.

[0062] In this embodiment, the short second metal line to be tested has a line width of 10 nm and a line length of 100 nm, and the long second metal line has a line width of 10 nm and a line length of 500 nm. In other embodiments, the line width of the second metal line to be tested may be 5-100 nm, and the line length may be in the range of 50-10000 nm.

[0063] The resistance value of the test link in the first test unit can be tested by the two-terminal method or the four-terminal method through the pins, so as to determine the influence of the first metal line on the filling of the second metal line when the line width is the same; the resistance value of the test link in the second test unit can be tested by the two-terminal method or the four-terminal method through the pins, so as to determine the influence of the combined effect of the first metal line with a larger line width and the short first metal line on the filling of the middle second metal line.

[0064] The influence of the first metal wire on the second metal wire is determined based on the measured resistance value. Generally, an estimated value that is 5 times greater than the estimated value is used to determine that the first metal wire has an influence on the second metal wire.

[0065] It should be noted that the test structure in the present application is not limited to the test of metal lines. The gate lines can also use the test structure of this patent to test the impact of filling problems on the line width of the line ends.

Claims

1. A test structure for filling process detection, characterized in that: The test structure includes at least one test unit; The test unit includes at least two second test lines, at least one first test line is respectively arranged on both sides of the second test line, and the first test line and the second test line are graphics of the same layer; after the second test line is connected in series, the first and tail ends are respectively connected through pins.

2. A test structure for filling process detection according to claim 1, characterized in that: The first test line and the second test line are polygonal structures of a metal layer or polygonal structures of a gate layer; The first test line and the second test line are structures manufactured using different masks.

3. A test structure for filling process detection according to claim 1, characterized in that: In the test unit, the second test line is connected in series across layers using connection holes and connection lines of adjacent metal layers; The connection hole is provided at a terminal end of the second test line.

4. A test structure for filling process detection according to claim 1, characterized in that: After the second test line is connected in series, the first and last ends are connected through pins respectively, including: The head end and the tail end are connected through connection holes and connection lines of adjacent metal layers respectively, and pins are arranged at the connection lines; The head end and the tail end are respectively provided with one pin or two pins for performing a two-terminal resistance test or a four-terminal Kelvin test on the test unit.

5. A test structure for filling process detection according to claim 1, characterized in that: The test unit includes a first test unit and / or a second test unit, and the test structure includes at least one first test unit and / or a second test unit; In the first test unit, the second test line has the same line width as the first test lines on both sides; In the second test unit, the second test line has the same line width as the first test line on one side, and the line width of the first test line on the other side is greater than the line width of the second test line.

6. A test structure for filling process detection according to claim 5, characterized in that: In the first test unit, the second test lines are arranged in multiple rows, and the second test lines arranged in multiple rows are connected in series in a serpentine manner; In the second test unit, the second test lines are arranged in multiple rows, and the second test lines arranged in multiple rows are connected in series in a serpentine manner.

7. A test structure for filling process detection according to claim 6, characterized in that: The test structure includes at least one of the first test unit and the second test unit; At least one first test line is arranged on both sides of the second test line of the first test unit, the second test line of the second test unit is arranged on the other side of the first test line of the first test unit, and the line width of the first test line on the other side of the second test line of the second test unit is greater than the line width of the second test line of the second test unit.

8. A test structure for filling process detection according to claim 7, characterized in that: The lengths of the first test line and the second test line in the first test unit are shorter than the second test line in the second test unit; The line lengths of the first test line and the second test line in the first test unit are smaller than the first test line on the other side of the second test line in the second test unit.

9. A test structure for filling process detection according to claim 1, characterized in that: The line width of the second test line is 5-100 nm, and the line length is 50-10000 nm.

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