WAT test structure and WAT test method
By designing a WAT test structure with different area test components, and using test resistance monitoring to determine the offset state of the first metal layer, the problem of accurate judgment caused by the offset of the alignment mark in the prior art is solved, and a more accurate judgment of the offset state is achieved.
Patent Information
- Application Number
- CN202411751417.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-03-18
AI Technical Summary
It is difficult to accurately determine the offset state of the first metal layer under process conditions in the existing WAT structure, especially due to the alignment mark offset problem caused by the PVD process.
A WAT test structure is designed, wherein the first metal layer includes a common component and a plurality of test components, and the test components have different areas. When the position of the first metal layer varies with respect to the second metal layer, it is electrically connected to different test components through the contact hole structure to generate different test resistances to determine the offset state.
Through monitoring of different test resistances, the specific test components electrically connected to the contact hole structure can be accurately judged, thereby determining the offset state of the first metal layer, and solving the problem of accurate judgment caused by the offset of the alignment mark.
Smart Images
Figure CN119650549A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a WAT test structure and a WAT test method. Background Art
[0002] In the integrated circuit manufacturing process, a WAT (Wafer Acceptance Test) structure is usually manufactured around each integrated circuit chip on the wafer, and then the WAT structure is tested after manufacturing is completed to test the corresponding manufacturing process. If the WAT structure is found to have failures such as short circuit, open circuit or leakage during various tests such as electrical testing after wafer manufacturing is completed, the cause of the failure is analyzed by performing failure analysis on the WAT structure, so as to make corresponding adjustments and improvements to the process.
[0003] Figure 1 The figure shows a common WAT structure, which includes a first metal layer 100, a second metal layer 300 and a plurality of contact hole structures 200. The first metal layer 100 is stacked on the second metal layer 300. The second metal layer 300 at the bottom layer includes a plurality of metal strips arranged in sequence. The first metal layer 100 at the top layer is arranged in a serpentine shape. The plurality of contact hole structures 200 are spaced between the first metal layer 100 and the second metal layer 300. After the first metal layer 100 and the second metal layer 300 are aligned by alignment marks, the offset state of the first metal layer 100 when aligned with the second metal layer 300 can be known by monitoring the resistance value of the WAT structure.
[0004] However, under some process conditions, the alignment mark itself is prone to offset. For example, the top metal layer is generally formed by a PVD process (Physical Vapor Deposition). Due to the process characteristics of the PVD process itself, the alignment mark is often offset, resulting in the inability to accurately judge the offset state of the first metal layer 100 based on the existing WAT structure. Summary of the invention
[0005] The object of the present invention is to provide a WAT test structure and a WAT test method to solve one or more problems in the prior art.
[0006] In order to solve the above technical problems, the present invention provides a WAT test structure, the WAT test structure comprising: a first metal layer, a second metal layer and a contact hole structure, the first metal layer and the second metal layer are stacked and spaced apart, and the second metal layer is electrically connected to the first metal layer through the contact hole structure;
[0007] Among them, the first metal layer includes a common component and multiple test components located on the same plane, and the multiple test components are electrically connected to the outside through the common components respectively. Different test components have different areas. When the position of the first metal layer relative to the second metal layer changes, the second metal layer is electrically connected to different test components through the contact hole structure, so that the WAT test structure produces different test resistances.
[0008] Optionally, in the WAT test structure, the common component extends on the plane and has a first axis, and the plurality of test components are electrically connected to the common component on the same side of the first axis.
[0009] Optionally, in the WAT test structure, an extension direction of each test component on the plane forms an angle with the first axis, and different test components have different extension directions.
[0010] Optionally, in the WAT test structure, the common component has an outwardly convex arc edge on one side of the first axis, and the plurality of test components are sequentially connected to the arc edge.
[0011] Optionally, in the WAT test structure, the common component includes an elliptical portion, the long axis of the elliptical portion is the first axis, and the plurality of test components are electrically connected to the elliptical portion on the same side of the long axis.
[0012] Optionally, in the WAT test structure, one of the test components is an alignment component, when the first metal layer is aligned with the second metal layer and is in an alignment position, the second metal layer is electrically connected to the alignment component through the contact hole structure; the alignment component extends on the plane and has a second axis, and the second axis is at an angle to the first axis;
[0013] The rest of the test components are offset components, and a plurality of the offset components are distributed on both sides of the second axis of the alignment component.
[0014] Optionally, in the WAT test structure, different offset components located on the same side of the alignment component are located at different angles of the alignment component.
[0015] Optionally, in the WAT test structure, when the alignment component is electrically connected to the contact hole structure, the WAT test structure has a first test resistance, and when each of the offset components is electrically connected to the contact hole structure, the WAT test structure has a second test resistance, and the area of each of the offset components is designed with reference to the area of the alignment component, so that the ratio of the area of each of the offset components to the alignment component is a target ratio, so that the second test resistance when each of the offset components is electrically connected to the contact hole structure can be calculated based on the first test resistance.
[0016] The present invention also provides a WAT testing method, comprising:
[0017] Obtaining a test resistance using the WAT test structure as described in any of the preceding items; and,
[0018] The offset state of the first metal layer is determined according to the test resistance.
[0019] Optionally, in the WAT test method, one of the test components is an alignment component, and when the first metal layer is aligned with the second metal layer and is in an alignment position, the second metal layer is electrically connected to the alignment component through the contact hole structure;
[0020] The method for judging the offset state of the first metal layer according to the test resistance includes:
[0021] Determining the test component that is actually electrically connected to the contact hole structure according to the test resistance; and
[0022] The offset state of the first metal layer is determined according to the relative positional relationship between the test component actually electrically connected to the contact hole structure and the alignment component.
[0023] In summary, the WAT test structure provided by the present invention comprises: a first metal layer, a second metal layer and a contact hole structure, wherein the first metal layer and the second metal layer are stacked and spaced, and the second metal layer is electrically connected to the first metal layer through the contact hole structure; wherein the first metal layer comprises a common component and a plurality of test components located on the same plane, and the plurality of test components are electrically connected to the outside through the common component respectively, and different test components have different areas, and when the position of the first metal layer relative to the second metal layer changes, the second metal layer is electrically connected to different test components through the contact hole structure, so that the WAT test structure generates different test resistances. In the WAT test structure provided by the present invention, since different test components of the first metal layer have different areas, when different test components are electrically connected to the contact hole structure and electrically connected to the second metal layer, different test resistances will be obtained by monitoring the WAT structure, and on this basis, the specific test component electrically connected to the contact hole structure can be determined according to the size of the test resistance, and then the offset state of the first metal layer can be determined. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a structural schematic diagram of an existing WAT structure;
[0025] Figure 2 A cross-sectional schematic diagram of a WAT structure provided by an embodiment of the present invention;
[0026] Figure 3 A schematic plan view of a WAT structure provided by an embodiment of the present invention;
[0027] Figure 4 A schematic diagram of an alignment offset in an embodiment of the present invention;
[0028] Figure 5 A schematic diagram of another alignment offset in an embodiment of the present invention;
[0029] The descriptions of the reference numerals are as follows:
[0030] 100-first metal layer; 200-contact hole structure; 300-second metal layer;
[0031] 10-first metal layer; 20-contact hole structure; 30-second metal layer;
[0032] 11- common components; 12- test components;
[0033] 121-alignment component; 122-offset component;
[0034] 1221 - first offset component; 1222 - second offset component. DETAILED DESCRIPTION
[0035] In order to make the purpose, advantages and features of the present invention clearer, the present invention is described in detail in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis required to be shown in each drawing is different, and sometimes different proportions are used. It should be recognized that relative terms such as "above", "below", "top", "bottom", "above" and "below" shown in the drawings can be used to describe the relationship between various elements. These relative terms are intended to cover different orientations of elements other than the orientations depicted in the drawings. For example, if the device is inverted relative to the view in the drawings, for example, an element described as "above" another element will now be below the element. It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third" and the like in the specification are only used to distinguish between the various components, elements, steps, etc. in the specification, rather than to represent the logical relationship or sequential relationship between the various components, elements, steps, etc.
[0036] See also Figure 2 An embodiment of the present invention provides a WAT test structure, including: a first metal layer 10, a second metal layer 30 and a contact hole structure 20; the first metal layer 10 and the second metal layer 30 are stacked and spaced apart, and in more applications, the first metal layer 10 is stacked above the second metal layer 30, that is, the first metal layer 10 refers to an upper metal layer, and the second metal layer 30 is a lower metal layer; the second metal layer 30 is electrically connected to the first metal layer 10 through the contact hole structure 20.
[0037] Among them, see Figure 3 The first metal layer 10 includes a common component 11 and a plurality of test components 12 arranged on the same plane. The plurality of test components 12 are electrically connected to the outside through the common component 11 respectively. Different test components 12 have different areas. When the position of the first metal layer 10 relative to the second metal layer 30 changes, the second metal layer 30 is electrically connected to different test components 12 through the contact hole structure 20, so that the WAT test structure generates different test resistances.
[0038] It can be understood that if the plane where the first metal layer 10 is located is a plane formed by the intersection of the x-axis and the y-axis, then the change in the position of the first metal layer 10 relative to the second metal layer 30 means that the position coordinates (x, y) of the first metal layer 10 on the plane change. In addition, the plane where each of the test components 12 is located is also the plane where the first metal layer 10 is located, that is, the common component 11 and each of the test components 12 are parallel to the second metal layer 30. In this way, when the position of the first metal layer 10 relative to the second metal layer 30 changes in the x-direction and / or y-direction, the test component 12 electrically connected to the contact hole structure 20 will also change, so that the WAT test structure produces different test resistances.
[0039] Accordingly, an embodiment of the present invention further provides a WAT testing method, comprising the following steps:
[0040] S1, obtaining a test resistor using the WAT test structure described in this embodiment; and
[0041] S2, judging the offset state of the first metal layer 10 according to the test resistance.
[0042] The WAT test structure provided in the embodiment of the present invention has different areas of different test components 12 of the first metal layer 10. When the second metal layer 30 is electrically connected to different test components 12 through the contact hole structure 20, different test resistances will be obtained by monitoring the WAT structure. On this basis, the specific test component 12 electrically connected to the contact hole structure 20 can be determined according to the size of the test resistance, and the offset state of the first metal layer 10 can be determined.
[0043] like Figure 3 As shown, the common component 11 extends on the plane and has a first axis L1 , and the plurality of test components 12 are electrically connected to the common component 11 on the same side of the first axis L1 .
[0044] When the first metal layer 10 is aligned with the second metal layer 30, even if the first metal layer 10 is offset relative to the second metal layer 30, the offset is within a small range. Therefore, setting a plurality of the test components 12 on the same side of the common component 11 can better determine the offset state of the first metal layer 10. If the test component 12 is also set on the other side of the common component 11, the test component 12 set on the other side will become a redundant component, which will be difficult to determine the offset state of the first metal layer 10 and will also increase the overall occupied area of the first metal layer 10.
[0045] Preferably, the extension direction of each test component 12 on the plane forms an angle with the first axis L1, and different test components 12 have different extension directions, so that the first metal layer 10 can be judged in different offset states.
[0046] Preferably, the common component 11 has a convex arc edge on one side of the first axis L1, and the plurality of test components 12 are sequentially connected to the arc edge. The arc edge is more conducive to the plurality of test components 12 being connected to the common component 11 from different directions, thereby facilitating the plurality of test components 12 to be arranged on the same side of the first axis L1 of the common component 11.
[0047] like Figure 3 For example, the common component 11 may include an elliptical portion, the long axis of the elliptical portion is the first axis L1, and the plurality of test components 12 are electrically connected to the elliptical portion on the same side of the long axis. It should be noted that the elliptical portion does not constitute a limitation to the present application, and the contour of the common component 11 on the other side of the first axis L1 may also be any other shape.
[0048] Further, one of the test components 12 is an alignment component 121, and the other test components 12 are offset components 122. When the first metal layer 10 and the second metal layer 30 are aligned and in the alignment position, the second metal layer 30 is electrically connected to the alignment component 121 through the contact hole structure 20. When the first metal layer 10 deviates from the alignment position, the second metal layer 30 is electrically connected to one of the offset components 122 through the contact hole structure 20. That is, it can be understood that the alignment component 121 is the test component 12 electrically connected to the contact hole structure 20 when the alignment position of the first metal layer 10 is not deviated, and the offset component 122 is the test component 12 that may be electrically connected to the contact hole structure 20 when the alignment position of the first metal layer 10 is deviated.
[0049] Preferably, the alignment component 121 extends on the plane and has a second axis L2, and the second axis L2 is at an angle to the first axis L1. A plurality of the offset components 122 are arranged on both sides of the second axis L2 of the alignment component 121. It can also be understood that a plurality of the offset components 122 are distributed in different directions of the alignment component 121. In addition, preferably, different offset components 122 located on the same side of the alignment component 121 are located at different angles to the alignment component 121.
[0050] Reference Figure 3The “different directions” mentioned here can be understood as the offset component 122 being located on the left or right side of the alignment component 121, and the “different angles” mentioned here can be understood as the offset component 122 being located on the upper left, lower left, upper right or lower right of the alignment component 121, etc. Figure 3 As shown in the example, on the left side of the offset component 122, one offset component 122 is located at the upper left corner of the alignment component 121, and the other offset component 122 is located at the lower left corner of the alignment component 121. In this way, the offset of the first metal layer at different offset angles and directions can be determined based on the test resistance.
[0051] It should be noted that the angle of the offset component 121 relative to the alignment component 121 can be defined by the relative position relationship between a first position point on the alignment component 121 and a second position point on the offset component 121. The first position point and the second position point generally refer to positions where the alignment component 121 and each of the offset components 121 are likely to contact the contact hole structure 20 when the first metal layer 10 is stacked on the second metal layer 30. Figure 3 The position of the contact hole structure 20 shown in FIG. 1 is the position where the alignment component 121 is electrically connected to the contact hole structure 20, which can also be understood as the first position point. Figure 4 The position of the contact hole structure 20 shown in FIG. 1 is the position where the offset component 121 is electrically connected to the contact hole structure 20 , which can also be understood as the second position point.
[0052] When the alignment component 121 is electrically connected to the contact hole structure 20, the WAT test structure has a first test resistance, and when each of the offset components 122 is electrically connected to the contact hole structure 20, the WAT test structure has a second test resistance. Preferably, the area of each of the offset components 122 is designed with reference to the area of the alignment component 121, so that the ratio of the area of each of the offset components 122 to the alignment component 121 is a target ratio, so that the second test resistance when each of the offset components 122 is electrically connected to the contact hole structure 20 can be calculated based on the first test resistance.
[0053] The following is an explanation with reference to specific examples.
[0054] Figure 3The figure shows a specific example of the WAT structure provided by an embodiment of the present invention. The first metal layer 10 includes one alignment component 121 and four offset components 122. Two offset components 122 are provided on each side of the alignment component 121. For the convenience of description, the four offset components 122 are respectively referred to as the first offset component, the second offset component, the third offset component and the fourth offset component in the order of being sequentially connected to the common component 11. The first offset component and the second offset component are located on the left side of the alignment component 121, and the first offset component is located at the upper left of the alignment component 121, and the second offset component is located at the lower left of the alignment component 121. The third offset component and the fourth offset component are located on the right side of the alignment component 121, and the third offset component is located at the lower right of the alignment component 121, and the fourth offset component is located at the upper right of the alignment component 121. With reference to the area of the alignment component 121, the areas of the four offset components 122 are designed so that the test resistance satisfies:
[0055] R2=(7~9)*R1; R3=(2~5)*R1; R4=(11~14)*R1; R5≥18*R1;
[0056] Among them, R1 is the test resistance when the alignment component 121 is connected to the contact hole structure 20, and R2, R3, R4, and R5 are the test resistances when the first offset component, the second offset component, the third offset component, and the fourth offset component are electrically connected to the contact hole structure 20 respectively.
[0057] In this example, the area of the offset component 122 relatively close to the alignment component 121 is relatively small, and the area of the offset component 122 relatively far from the alignment component 121 is relatively large. However, the areas of the offset components 122 may be designed to increase or decrease in accordance with the connection sequence with the common component 11. The relative test resistance size relationship caused by the specific area design size does not constitute a limitation to the present application, and it is sufficient that the test resistance size relationship is uniquely corresponding.
[0058] According to the WAT test structure provided in this embodiment, in the above step S2, the method for judging the offset state of the first metal layer 10 according to the test resistance may further include the following steps:
[0059] Determining the test component 12 that is actually electrically connected to the contact hole structure 20 according to the test resistance; and
[0060] The offset state of the first metal layer 10 is determined according to the relative positional relationship between the test component 12 and the alignment component 121 which are actually electrically connected to the contact hole structure 20 .
[0061] The test component 12 here can be the alignment component 121 or one of the offset components 122. If it is concluded according to the test resistance that the test component 12 that is actually electrically connected to the contact hole structure 20 is the alignment component 121, it means that the first metal layer 10 is in the alignment position and no offset occurs. If it is concluded according to the test resistance that the test component 12 that is actually electrically connected to the contact hole structure 20 is the offset component 122, it means that the position of the first metal layer 10 is offset. The specific offset situation is determined based on the positional relationship between the offset component 122 and the alignment component 121.
[0062] The WAT testing method provided by the embodiment of the present invention is described below by way of example in conjunction with the WAT structure of the above example.
[0063] like Figure 4 As shown, if the test resistance = R2 = (7~9)*R1, it means that the first offset component 1211 is electrically connected to the contact hole structure 20, and the first metal layer 10 is offset to the lower right (the first position point is located to the lower right of the second position point). The first metal layer 10 should be rotated to the upper left so that the first metal layer 10 returns to the alignment position.
[0064] like Figure 5 As shown, if the test resistance = R3 = (2~5)*R1, it means that the second offset component 1222 is electrically connected to the contact hole structure 20, and the first metal layer 10 is offset to the upper right (the first position point is located to the lower right of the second position point). The first metal layer 10 should be rotated to the lower left so that the first metal layer 10 returns to the alignment position.
[0065] The method of judging the offset state of the first metal layer 10 based on other test resistors is similar to the above two examples, and will not be described in detail here.
[0066] In summary, the WAT test structure provided by the embodiment of the present invention includes: a first metal layer, a second metal layer and a contact hole structure, the first metal layer and the second metal layer are stacked and spaced, and the second metal layer is electrically connected to the first metal layer through the contact hole structure; wherein the first metal layer includes a common component and a plurality of test components located on the same plane, the plurality of test components are electrically connected to the outside through the common component respectively, and different test components have different areas. When the position of the first metal layer relative to the second metal layer changes, the second metal layer is electrically connected to different test components through the contact hole structure, so that the WAT test structure generates different test resistances. In the WAT test structure provided by the embodiment of the present invention, since different test components of the first metal layer have different areas, when different test components are electrically connected to the contact hole structure and electrically conductive with the second metal layer, monitoring the WAT structure will obtain different test resistances. On this basis, the specific test component electrically connected to the contact hole structure can be determined according to the size of the test resistance, and then the offset state of the first metal layer can be determined.
[0067] It should be noted that, although the present invention has been disclosed as a preferred embodiment, any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.
Claims
1. A WAT test structure, characterized in that: include: A first metal layer, a second metal layer and a contact hole structure, wherein the first metal layer and the second metal layer are stacked and spaced apart, and the second metal layer is electrically connected to the first metal layer through the contact hole structure; Among them, the first metal layer includes a common component and multiple test components located on the same plane, and the multiple test components are electrically connected to the outside through the common components respectively. Different test components have different areas. When the position of the first metal layer relative to the second metal layer changes, the second metal layer is electrically connected to different test components through the contact hole structure, so that the WAT test structure produces different test resistances.
2. The WAT test structure according to claim 1, characterized in that: The common component extends on the plane and has a first axis, and a plurality of the test components are electrically connected to the common component on the same side of the first axis.
3. The WAT test structure as claimed in claim 2, characterized in that: An extension direction of each of the test components on the plane forms an angle with the first axis, and different test components have different extension directions.
4. The WAT test structure according to claim 2, characterized in that: The common component has an outwardly convex arc edge on one side of the first axis, and the plurality of test components are sequentially connected to the arc edge.
5. The WAT test structure according to claim 4, characterized in that: The common component includes an elliptical portion, the long axis of the elliptical portion is the first axis, and the plurality of test components are electrically connected to the elliptical portion on the same side of the long axis.
6. The WAT test structure according to any one of claims 2 to 5, characterized in that: One of the test components is an alignment component, when the first metal layer is aligned with the second metal layer and is in an alignment position, the second metal layer is electrically connected to the alignment component through the contact hole structure; the alignment component extends on the plane and has a second axis, and the second axis is at an angle to the first axis; The rest of the test components are offset components, and a plurality of the offset components are distributed on both sides of the second axis of the alignment component.
7. The WAT test structure according to claim 6, characterized in that: Different offset assemblies located on the same side of the alignment assembly are located at different angles of the alignment assembly.
8. The WAT test structure according to claim 6, characterized in that: When the alignment component is electrically connected to the contact hole structure, the WAT test structure has a first test resistance, and when each of the offset components is electrically connected to the contact hole structure, the WAT test structure has a second test resistance. The area of each of the offset components is designed with reference to the area of the alignment component, so that the ratio of the area of each of the offset components to the alignment component is a target ratio, so that the second test resistance when each of the offset components is electrically connected to the contact hole structure can be calculated based on the first test resistance.
9. A WAT testing method, characterized in that: include: A test resistor is obtained by using the WAT test structure as claimed in any one of claims 1 to 8; And, judging the offset state of the first metal layer according to the test resistance.
10. The WAT testing method according to claim 9, characterized in that: One of the test components is an alignment component, and when the first metal layer is aligned with the second metal layer and is in an alignment position, the second metal layer is electrically connected to the alignment component through the contact hole structure; The method for judging the offset state of the first metal layer according to the test resistance includes: Determining the test component that is actually electrically connected to the contact hole structure according to the test resistance; as well as, The offset state of the first metal layer is determined according to the relative positional relationship between the test component actually electrically connected to the contact hole structure and the alignment component.