Test structure of groove-type MIM (Metal-Insulator-Metal) capacitor
By designing a trench-type MIM capacitor test structure, the leakage current condition of the planar area can be tested separately, solving the problem of locating leakage current in trench-type MIM capacitors and improving test accuracy and process optimization efficiency.
Patent Information
- Application Number
- CN202422997326.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-05
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2034-12-05
AI Technical Summary
In the process development of trench MIM capacitors, it is difficult to quickly identify the cause of leakage failure, especially the inability to distinguish between leakage at the trench and at the plane, which makes it difficult for engineers to quickly identify the optimization direction.
A test structure for a trench-type MIM capacitor was designed. By applying voltage and testing current between the second part of the first upper plate and the first lower plate, the leakage current of the planar region can be tested separately, thereby helping to determine the leakage current problem in the trench region.
It enables precise location of leakage problems in trench-type MIM capacitors, helping engineers quickly analyze leakage sources and optimize processes, thus improving testing accuracy and efficiency.
Smart Images
Figure CN223664757U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of integrated circuit technology, and in particular to a test structure for a trench-type MIM capacitor. Background Technology
[0002] There are many technical challenges in the development of trench metal-insulator-metal capacitor (MIM) technology, including monitoring the sheet resistance of the upper and lower plates, the contact resistance (Rc) between the upper plate and the metal via, and the connectivity issues of vias at different depths. Unlike planar MIM capacitors, the lower plate of a trench MIM capacitor is connected to the underlying metal wire through a trench.
[0003] The vertical trench etching process for trench-type MIM capacitors presents challenges, such as difficulty in controlling trench etching roughness and the uniformity of metal deposition on the capacitor plates, leading to leakage issues. In the development of trench-type MIM capacitors, quickly identifying the cause of leakage failure and pinpointing the leakage source, particularly whether it originates in the trench, is crucial for engineers to quickly identify optimization directions. However, current testing of leakage at the upper and lower plates of the capacitor includes leakage at both the trench and the flat surface, making it impossible to definitively determine whether the leakage is caused by the trench. Utility Model Content
[0004] One of the purposes of this invention is to provide a test structure for a trench-type MIM capacitor that can test the leakage current in the planar region (i.e., the plane) of the trench-type MIM capacitor, thereby helping to determine the leakage current problem in the trench region of the trench-type MIM capacitor.
[0005] To achieve the above objectives, the test structure of the trench-type MIM capacitor provided by this utility model includes: a first dielectric layer located on a bottom metal layer; a first trench penetrating the first dielectric layer and corresponding to at least a portion of the metal position of the bottom metal layer; a first lower electrode plate located on the first dielectric layer, covering the inner surface of the first trench and extending to cover a portion of the first dielectric layer on both sides of the first trench, and electrically connected to the bottom metal layer; a first isolation layer located on the first lower electrode plate and covering the first lower electrode plate; and a first upper electrode plate including a first portion and a second portion spaced apart, wherein the first portion fills the first trench, covers the first isolation layer within the first trench and extends to cover a portion of the first isolation layer on both sides of the first trench, and the second portion is located on the side of the first trench and covers a portion of the first isolation layer above the non-trench area of the first dielectric layer.
[0006] Optionally, a diffusion barrier layer is provided between the first dielectric layer and the bottom metal layer.
[0007] Optionally, a second dielectric layer is provided on the first upper electrode plate, the second dielectric layer has a through-hole contact structure, the through-hole contact structure is electrically connected to the second part, and a top metal layer is formed on the second dielectric layer, the top metal layer is electrically connected to the through-hole contact structure.
[0008] Optionally, both the bottom metal layer and the top metal layer are made of copper.
[0009] Optionally, the area of the first part and the area of the second part are equal.
[0010] Optionally, the first lower electrode plate includes a tantalum layer and a titanium nitride layer sequentially stacked on the first dielectric layer, and the first upper electrode plate includes a titanium nitride layer.
[0011] Optionally, the first isolation layer is an ONO layer.
[0012] Optionally, the test structure of the trench-type MIM capacitor is used to assist in testing the leakage current of the trench-type MIM capacitor; the trench-type MIM capacitor includes a second trench, a second lower electrode, a second isolation layer, and a second upper electrode; the second trench penetrates the first dielectric layer and corresponds to at least a portion of the metal position of the bottom metal layer; the second lower electrode is located on the first dielectric layer, covers the inner surface of the second trench and extends to cover a portion of the first dielectric layer on both sides of the second trench, and is electrically connected to the bottom metal layer; the second isolation layer covers the second lower electrode within the second trench and extends to cover a portion of the second lower electrode on both sides of the second trench; the second upper electrode fills the second trench and covers the second isolation layer.
[0013] Optionally, the first lower electrode plate and the second lower electrode plate belong to the same metal layer, and the first upper electrode plate and the second upper electrode plate belong to the same metal layer.
[0014] Optionally, the trench-type MIM capacitor is a lateral overflow integrated capacitor of a CMOS image sensor.
[0015] In the test structure of the trench-type MIM capacitor provided by this utility model, a first dielectric layer is located on a bottom metal layer; a first trench penetrates the first dielectric layer and corresponds to at least a portion of the metal position of the bottom metal layer; a first lower electrode plate is located on the first dielectric layer, covering the inner surface of the first trench and extending to cover a portion of the first dielectric layer on both sides of the first trench, and is electrically connected to the bottom metal layer; a first isolation layer is located on the first lower electrode plate and covers the first lower electrode plate; a first upper electrode plate includes a first portion and a second portion spaced apart, the first portion filling the first trench, covering the first isolation layer in the first trench and extending to cover a portion of the first isolation layer on both sides of the first trench, and the second portion located on the side of the first trench and covering a portion of the first isolation layer above the non-trench area of the first dielectric layer. By applying voltage and testing current between the second part of the first upper plate and the first lower plate of the test structure of the trench MIM capacitor, the leakage current between the second part of the first upper plate and the first lower plate of the test structure can be tested. That is, the leakage current in the non-trench region (i.e., the plane) of the test structure can be tested. Combined with the test results of the original leakage current of the trench MIM capacitor, including the trench region and the plane region, it can be determined whether there is a leakage problem in the trench region of the trench MIM capacitor. This can help engineers quickly analyze the leakage source and then optimize the corresponding process in a targeted manner. Attached Figure Description
[0016] Figure 1 This is a cross-sectional schematic diagram of the test structure of a trench-type MIM capacitor provided in an embodiment of the present invention.
[0017] Figure 2 This is a schematic diagram of the test structure of a trench-type MIM capacitor provided in an embodiment of the present invention.
[0018] Figure 3 This is a cross-sectional structural diagram of a trench-type MIM capacitor provided in an embodiment of the present invention.
[0019] Explanation of reference numerals in the attached figures: 101-Bottom metal layer; 102-Diffusion barrier layer; 103-First dielectric layer; 104-First trench; 105-First lower electrode plate; 106-First isolation layer; 107-First upper electrode plate; 107a-First part; 107b-Second part; 108a, 108b-Conducting hole contact structure; 109-Top metal layer; 110-Second trench; 111-Second lower electrode plate; 112-Second isolation layer; 113-Second upper electrode plate; 114-Anti-reflective layer; 115-Isolation film; 116-Passivation layer. Detailed Implementation
[0020] The test structure of the trench-type MIM capacitor proposed in this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this utility model will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this utility model.
[0021] In the description of this application, it should be understood that the terms "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, and "at least one" can mean one, two, or more, unless otherwise explicitly specified.
[0022] Figure 1 This is a cross-sectional schematic diagram of the test structure of a trench-type MIM capacitor provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the test structure of a trench-type MIM capacitor provided in an embodiment of the present invention.
[0023] refer to Figure 1 and Figure 2As shown, the test structure of the trench-type MIM capacitor provided in this embodiment includes a first dielectric layer 103, a first trench 104, a first lower electrode 105, a first isolation layer 106, and a first upper electrode 107. A first dielectric layer 103 is located on a bottom metal layer 101; a first trench 104 penetrates the first dielectric layer 103 and corresponds to at least a portion of the metal position of the bottom metal layer 101; a first lower electrode plate 105 is located on the first dielectric layer 103 and covers the inner surface of the first trench 104 and extends to cover a portion of the first dielectric layer 103 on both sides of the first trench 104, and is electrically connected to the bottom metal layer 101; a first insulating layer 106 is located on the first lower electrode plate 105 and covers the first lower electrode plate 105; a first upper electrode plate 107 includes a spaced first portion 107a and a second portion 107b, the first portion 107a fills the first trench 104, covers the first insulating layer 106 within the first trench 104 and extends to cover a portion of the first insulating layer 106 on both sides of the first trench 104, the second portion 107b is located on the side of the first trench 104 and covers a portion of the first insulating layer 106 above the non-trench area of the first dielectric layer 103.
[0024] Specifically, the bottom metal layer 101 may include metal traces (i.e., metal) and dielectric material filling the spaces between the metal traces. The metal in the bottom metal layer 101 may include, but is not limited to, copper or aluminum.
[0025] The first dielectric layer 103 is located on the bottom metal layer 101. Exemplarily, the material of the first dielectric layer 103 includes, but is not limited to, silicon dioxide.
[0026] In this embodiment, as Figure 2 As shown, a diffusion barrier layer 102 may be disposed between the first dielectric layer 103 and the bottom metal layer 101. The diffusion barrier layer 102 is used to prevent metals such as copper in the bottom metal layer 101 from diffusing into the first dielectric layer 103, so as to avoid the metal diffusion in the bottom metal layer 101 affecting the electrical performance of the test structure. The diffusion barrier layer 102 includes, but is not limited to, a nitrogen-doped silicon carbide (NDC) dielectric layer, which is a thin film containing four elements: nitrogen (N), silicon (Si), hydrogen (H), and carbon (C).
[0027] The first lower electrode plate 105 is located on the first dielectric layer 103, covering the sidewalls and bottom surface of the first trench 104 and extending to cover both sides of the first dielectric layer 103, and is electrically connected to the bottom metal layer 101. Specifically, the first lower electrode plate 105 is electrically connected to the metal traces in the bottom metal layer 101 through the first trench 104, and the first lower electrode plate 105 is led out through the bottom metal layer 101.
[0028] In this embodiment, the first lower electrode 105 includes a tantalum (Ta) layer and a titanium nitride (TiN) layer sequentially stacked on the first dielectric layer 103, but is not limited thereto. It should be noted that in this embodiment, the first lower electrode 105 is a double-layer structure including two material layers; in other embodiments, the first lower electrode 105 can also be a single-layer structure or a three-layer structure, which can be set according to the structure of the trench-type MIM capacitor corresponding to the test structure.
[0029] The first isolation layer 106 is located on and covers the first lower electrode plate 105. In this embodiment, the material of the first isolation layer 106 can be a high dielectric constant (HIK) dielectric material. High dielectric constant dielectric materials include, but are not limited to, silicon oxide or silicon nitride. For example, the first isolation layer 106 is an ONO layer, which includes, from bottom to top, an oxide layer, a nitride layer, and an oxide layer, where the oxide layer includes, but is not limited to, silicon oxide, and the nitride layer includes, but is not limited to, silicon nitride.
[0030] The first upper electrode plate 107 includes a first portion 107a and a second portion 107b spaced apart. The first portion 107a fills the first trench 104, covers the first isolation layer 106 within the first trench 104, and extends to cover portions of the first isolation layer 106 on both sides of the first trench 104. The second portion 107b is located on the side of the first trench 104 and covers the portion of the first isolation layer 106 above the non-trench area (i.e., the plane) of the first dielectric layer 103.
[0031] For example, the first upper electrode 107 includes a titanium nitride (TiN) layer, but is not limited thereto. It should be noted that in this embodiment, the first upper electrode 107 is a single-layer structure including a single material layer; in other embodiments, the first upper electrode 107 may also be a double-layer structure or a triple-layer structure, etc., which can be set according to the structure of the trench-type MIM capacitor corresponding to the test structure.
[0032] refer to Figure 1 As shown, a second dielectric layer (not shown in the figure) may be disposed on the first upper electrode plate 107. The second dielectric layer has a through-hole contact structure 108a that penetrates the second dielectric layer. The through-hole contact structure 108a is electrically connected to the second part 107b. A top metal layer 109 is formed on the second dielectric layer. The top metal layer 109 is electrically connected to the through-hole contact structure 108a. The second part 107b of the first upper electrode plate 107 is led out through the through-hole contact structure 108a and the top metal layer 109 above it.
[0033] For example, the material of the via contact structure 108a includes, but is not limited to, copper. The material of the metal in the top metal layer 109 includes, but is not limited to, copper.
[0034] In this embodiment, the test structure of the trench MIM capacitor (hereinafter referred to as the "test structure") is used to assist in testing the leakage current of the trench MIM capacitor (hereinafter referred to as the "capacitor").
[0035] CMOS image sensor (CIS) sensing technology has been used in many applications, such as machine vision, automotive, analytical instruments, and absorption imaging. In such applications, wider dynamic range (WDR) performance and lower signal-to-noise ratio (SNR) can improve sensing accuracy under a wide range of lighting conditions. Several WDR techniques have been reported to date, one of which employs a lateral overflow integrated capacitor (LOFIC) to accumulate overflow electrons from a photodiode (PD) and a floating node (FD) capacitor, readout signals with different sensitivities in a single exposure. One WDR CIS exceeding 120 dB introduces a lateral overflow integrated trench capacitor (LOFIC) greater than 100 fF to improve the maximum SNR and SNR at the signal switching point.
[0036] In this embodiment, the trench-type MIM capacitor can be a lateral overflow integrated capacitor of a CMOS image sensor, but is not limited to this. The trench-type MIM capacitor can be a MIM capacitor embedded between two metal layers in the back end of an integrated circuit.
[0037] Figure 3 This is a cross-sectional structural diagram of a trench-type MIM capacitor provided in one embodiment of the present invention. Figure 3 As shown, a trench-type MIM capacitor may include a second trench 110, a second lower electrode 111, a second isolation layer 112, and a second upper electrode 113; the second trench 110 penetrates the first dielectric layer 103 and corresponds to at least a portion of the metal position of the bottom metal layer 101; the second lower electrode 111 is located on the first dielectric layer 103, covers the inner surface of the second trench 110 and extends to cover a portion of the first dielectric layer 103 on both sides of the second trench 110, and is electrically connected to the bottom metal layer 101; the second isolation layer 112 covers the second lower electrode within the second trench 110 and extends to cover a portion of the second lower electrode 111 on both sides of the second trench 110, and the two side edges of the second lower electrode 111 may extend beyond the two side edges of the second isolation layer 112; the second upper electrode 113 fills the second trench 110 and covers the second isolation layer 112.
[0038] Continue to refer to Figure 3As shown, the trench-type MIM capacitor may further include an anti-reflection layer 114, an isolation film 115, and a passivation layer 116; the anti-reflection layer 114 is located on the second upper electrode 113; the isolation film 115 is located on the anti-reflection layer 114, covering the sidewalls of the anti-reflection layer 114 and the second upper electrode 113, and covering part of the top surface of the second lower electrode 111, and the material of the isolation film 115 includes, but is not limited to, silicon oxide; the passivation layer 116 covers the isolation film 115, and the material of the passivation layer 116 includes, but is not limited to, silicon nitride.
[0039] A through-hole contact structure 108b is formed on the top surface of the second upper electrode plate 113. The through-hole contact structure 108b is electrically connected to the second upper electrode plate 113 and electrically connected to the top metal layer 109. The second upper electrode plate 113 is led out through the through-hole contact structure 108b and the top metal layer 109.
[0040] It should be noted that in this embodiment, the second lower electrode 111 of the trench-type MIM capacitor and the first lower electrode 105 of the test structure belong to the same metal layer, and the second upper electrode 113 of the trench-type MIM capacitor and the first upper electrode 107 of the test structure belong to the same metal layer. Thus, the test structure provided in this application can be fabricated simultaneously with its corresponding capacitor. The electrical performance of the test structure can be used to characterize the electrical performance of the capacitor, which helps improve testing accuracy. Furthermore, the process is relatively simple, helping to save manufacturing costs. Correspondingly, the second trench 110 of the trench-type MIM capacitor and the first trench 104 of the test structure can both be located in the first dielectric layer 103, and the first isolation layer 106 and the second isolation layer 112 can belong to the same isolation layer. In other embodiments, the second trench 110 of the trench-type MIM capacitor and the first trench 104 of the test structure can be located in different dielectric layers, the second lower electrode 111 and the first lower electrode 105 can belong to different metal layers, and the second upper electrode 113 and the first upper electrode 107 can belong to different metal layers.
[0041] In this embodiment, the size of the first part 107a of the first upper plate 107 in the test structure can be the same as the size of the second upper plate 113 in the capacitor, and the size of the first trench 104 and the second trench 110 can be the same. In other words, the size of each structure in the region where the first upper plate 107 is located can be the same as the size of the corresponding structure in the capacitor. This can improve the test accuracy of the test structure. The size includes, but is not limited to, width, length and / or thickness.
[0042] refer to Figure 2As shown, in the first upper plate 107, the top surface area of the first part 107a is equal to the top surface area of the second part 107b, or in other words, the layout area of the first part 107a is equal to the layout area of the second part 107b. The layout area of the first part 107a can be the same as the layout area of the second upper plate 113 in the capacitor. In this way, the leakage current of the structure corresponding to the second part 107b tested by the test structure of the trench MIM capacitor can accurately reflect the leakage current of the planar area in the capacitor.
[0043] For example, a voltage can be applied to the second upper plate 113 and the second lower plate 111 of the capacitor through the bottom metal layer 101 and the top metal layer 109 to create a voltage difference between the second upper plate 113 and the second lower plate 111, and the leakage current can be tested to obtain leakage results including the planar region and the trench region of the capacitor. A voltage can also be applied to the second part 107b of the first upper plate 107 and the first lower plate 105 of the test structure through the bottom metal layer 101 and the top metal layer 109 to create a voltage difference between the second part 107b and the first lower plate 105, and the leakage current of the test structure can be tested to obtain leakage results including the planar region of the capacitor. Combining the two results can determine whether there is a leakage problem in the trench region of the trench type MIM capacitor.
[0044] This application also provides an exemplary method for fabricating a test structure for a trench-type MIM capacitor. (Reference) Figure 1 As shown, the fabrication method includes: after chemical mechanical polishing of the bottom metal layer 101, a diffusion barrier layer 102 and a first dielectric layer 103 are sequentially deposited on the bottom metal layer 101; the first dielectric layer 103 and the diffusion barrier layer 102 are etched to form a first trench 104, the first trench 104 exposing at least a portion of the metal of the bottom metal layer 101; a lower electrode metal layer is formed on the first dielectric layer 103, the lower electrode metal layer covering the top surface of the first dielectric layer 103 and the sidewalls and bottom surface of the first trench 104; a first isolation layer 106 is formed on the lower electrode metal layer covering the lower electrode metal layer; and the first isolation layer 106 is formed on the lower electrode metal layer covering the lower electrode metal layer. An upper electrode metal layer is formed on layer 106; the upper electrode metal layer is patterned to form a first upper electrode 107; a portion of the first isolation layer 106 and a portion of the lower electrode metal layer are etched away, and the remaining at least a portion of the lower electrode metal layer serves as the first lower electrode 105; a second dielectric layer is deposited on the first upper electrode 107; a via contact structure 108a is formed in the second dielectric layer, and the via contact structure 108a is electrically connected to the second portion 107b of the first upper electrode 107; a top metal layer 109 is formed on the dielectric material, and a portion of the metal traces of the top metal layer 109 are electrically connected to the via contact structure 108a.
[0045] In the test structure of the trench-type MIM capacitor provided by this utility model, the first dielectric layer 103 is located on the bottom metal layer 101; the first trench 104 penetrates the first dielectric layer 103 and corresponds to at least a portion of the metal position of the bottom metal layer 101; the first lower electrode 105 is located on the first dielectric layer 103, covers the inner surface of the first trench 104 and extends to cover a portion of the first dielectric layer 103 on both sides of the first trench 104, and is electrically connected to the bottom metal layer 101; the first isolation layer 106 is located on the first lower electrode 105 and covers the first lower electrode 105; the first upper electrode 107 includes a spaced first portion 107a and a second portion 107b, the first portion 107a fills the first trench 104, covers the first isolation layer 106 in the first trench 104 and extends to cover a portion of the first isolation layer 106 on both sides of the first trench, and the second portion 107b is located on the side of the first trench 104 and covers a portion of the first isolation layer 106 above the non-trench area of the first dielectric layer 103. By applying voltage and testing current between the second part 107b of the first upper plate and the first lower plate 105 of the test structure of the trench MIM capacitor, the leakage current between the second part 107b of the first upper plate and the first lower plate 105 of the test structure can be tested. That is, the leakage current in the non-trench region (i.e., the plane) of the test structure can be tested. Combined with the test results of the original leakage current of the trench MIM capacitor, including the trench region and the plane region, it can be determined whether there is a leakage problem in the trench region of the trench MIM capacitor. This can help engineers quickly analyze the leakage source and then optimize the corresponding process in a targeted manner.
[0046] The above description is only a description of the preferred embodiment of the present utility model and is not intended to limit the scope of the present utility model. Any person skilled in the art can make possible changes and modifications to the technical solution of the present utility model by using the methods and techniques disclosed above without departing from the spirit and scope of the present utility model. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the content of the technical solution of the present utility model shall fall within the protection scope of the technical solution of the present utility model.
Claims
1. A test structure for a trench-type MIM capacitor, characterized in that, include: The first dielectric layer is located on the bottom metal layer; The first trench penetrates the first dielectric layer and corresponds to at least a portion of the metal position of the bottom metal layer; The first lower electrode plate is located on the first dielectric layer, covers the inner surface of the first trench and extends to cover a portion of the first dielectric layer on both sides of the first trench, and is electrically connected to the bottom metal layer. A first isolation layer is located on and covers the first lower electrode plate; as well as The first upper electrode plate includes a first portion and a second portion spaced apart. The first portion fills the first trench, covers the first isolation layer within the first trench, and extends to cover portions of the first isolation layer on both sides of the first trench. The second portion is located on the side of the first trench and covers a portion of the first isolation layer above the non-trench area of the first dielectric layer.
2. The test structure for the trench-type MIM capacitor as described in claim 1, characterized in that, A diffusion barrier layer is provided between the first dielectric layer and the bottom metal layer.
3. The test structure for the trench-type MIM capacitor as described in claim 1, characterized in that, A second dielectric layer is provided on the first upper electrode plate. The second dielectric layer has a through-hole contact structure. The through-hole contact structure is electrically connected to the second part. A top metal layer is formed on the second dielectric layer. The top metal layer is electrically connected to the through-hole contact structure.
4. The test structure for the trench-type MIM capacitor as described in claim 3, characterized in that, Both the bottom metal layer and the top metal layer are made of copper.
5. The test structure for a trench-type MIM capacitor as described in claim 1, characterized in that, The area of the first part and the area of the second part are equal.
6. The test structure for a trench-type MIM capacitor as described in claim 1, characterized in that, The first lower electrode plate includes a tantalum layer and a titanium nitride layer sequentially stacked on the first dielectric layer, and the first upper electrode plate includes a titanium nitride layer.
7. The test structure for a trench-type MIM capacitor as described in claim 1, characterized in that, The first isolation layer is an ONO layer.
8. The test structure for a trench-type MIM capacitor as described in claim 1, characterized in that, The test structure of the trench-type MIM capacitor is used to assist in testing the leakage current of the trench-type MIM capacitor; the trench-type MIM capacitor includes a second trench, a second lower electrode, a second isolation layer, and a second upper electrode; the second trench penetrates the first dielectric layer and corresponds to at least a portion of the metal position of the bottom metal layer; the second lower electrode is located on the first dielectric layer, covers the inner surface of the second trench and extends to cover a portion of the first dielectric layer on both sides of the second trench, and is electrically connected to the bottom metal layer; The second insulating layer covers the second lower electrode plate within the second trench and extends to cover portions of the second lower electrode plate on both sides of the second trench; the second upper electrode plate fills the second trench and covers the second insulating layer.
9. The test structure for a trench-type MIM capacitor as described in claim 8, characterized in that, The first lower electrode plate and the second lower electrode plate belong to the same metal layer, and the first upper electrode plate and the second upper electrode plate belong to the same metal layer.
10. The test structure for a trench-type MIM capacitor as described in claim 8, characterized in that, The trench-type MIM capacitor is a lateral overflow integrated capacitor of a CMOS image sensor.