MOM capacitor and forming method

Abstract

The present invention provides a MOM capacitor and a formation method, the capacitor comprising: an insulating layer; a metal layer, embedded in the insulating layer, the metal layer comprising a metal block, a first electrode, a second electrode, a first electrode interdigit connected to the first electrode, and a second electrode interdigit connected to the second electrode; the first electrode interdigit and the second electrode interdigit are alternately arranged, the metal block is located between the first electrode interdigit and the second electrode interdigit, the first electrode interdigit or the second electrode interdigit comprises a U-shaped structure, the metal block is located within the U-shaped structure, the insulating layer separates the first electrode and the second electrode, and simultaneously separates the first electrode interdigit, the second electrode interdigit and the metal block, the insulating layer within the U-shaped structure has a plurality of voids, the dielectric constant of the insulating layer material is greater than the dielectric constant of air. The voids contain air, and the dielectric constant of air is lower than the dielectric constant of the oxide, so the dielectric constant of the entire insulating layer is reduced, thereby reducing the capacitance value of the MOM capacitor.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a MOM capacitor and a forming method thereof. Background Art

[0002] Capacitors are a key component of integrated circuits and are widely used in various chips. Metal-Oxide-Metal (MOM) capacitors are a common type of capacitor and are widely used in semiconductor integrated circuits. For example, they are used in sample-and-hold modules, analog-to-digital converters, filters, and radio frequency communication modules.

[0003] The capacitance value of the MOM capacitor needed in different device different places may be different.In the prior art, capacitance value may be reduced by reducing the relative area of ​​upper plate and lower plate or increasing the distance between upper plate and lower plate, but due to in the manufacturing process of some integrated circuit, device is all designed according to minimum rule, the relative area of ​​line width, upper plate and lower plate and the distance between upper plate and lower plate are fixed, capacitance value can not be reduced by reducing the relative area of ​​upper plate and lower plate or increasing the distance between upper plate and lower plate, therefore, need to make a kind of MOM capacitor, the capacitance value of capacitor can be reduced. Summary of the Invention

[0004] The object of the present invention is to provide a MOM capacitor and a formation method thereof, which can reduce the capacitance value of the MOM capacitor.

[0005] In order to achieve the above object, the present invention provides a MOM capacitor, comprising:

[0006] Insulation layer;

[0007] at least one metal layer, the metal layer being embedded in the insulating layer, the metal layer comprising a metal block, a first electrode, a second electrode, a plurality of first electrode fingers connected to the first electrode, and a plurality of second electrode fingers connected to the second electrode;

[0008] The first electrode fingers and the second electrode fingers are arranged alternately at intervals, the metal block is located between the first electrode fingers and the second electrode fingers, the first electrode fingers or the second electrode fingers include several segments of U-shaped structures, and the metal block is located within the U-shaped structure, the insulating layer separates the first electrode from the second electrode, and also separates the first electrode fingers, the second electrode fingers and the metal block, the insulating layer within the U-shaped structure has several voids, and the dielectric constant of the insulating layer material is greater than the dielectric constant of air.

[0009] Optionally, in the MOM capacitor, the cavity is located near the metal block.

[0010] Optionally, in the MOM capacitor, each of the U-shaped structures includes at least one metal block.

[0011] Optionally, in the MOM capacitor, the insulating layer in each of the U-shaped structures has a plurality of cavities.

[0012] Optionally, in the MOM capacitor, the insulating layer material includes oxide.

[0013] Optionally, in the MOM capacitor, the first electrode fingers include several segments of U-shaped structures, and the second electrode fingers are long straight strips.

[0014] Optionally, in the MOM capacitor, the first electrode and the second electrode are parallel and opposite to each other.

[0015] Optionally, in the MOM capacitor, the first electrode fingers are all located on a side of the first electrode close to the second electrode.

[0016] Optionally, in the MOM capacitor, the second electrode fingers are all located on a side of the second electrode close to the first electrode.

[0017] Optionally, in the MOM capacitor, the metal layer is multi-layered, the multi-layered metal layers are arranged in parallel and are all embedded in the insulating layer, and the insulating layer separates the multi-layered metal layers.

[0018] Accordingly, the present invention provides a method for forming a MOM capacitor, comprising:

[0019] forming a metal layer, the metal layer comprising a metal block, a first electrode, a second electrode, a plurality of first electrode fingers connected to the first electrode, and a plurality of second electrode fingers connected to the second electrode, wherein the first electrode fingers and the second electrode fingers are alternately arranged, the metal block is located between the first electrode fingers and the second electrode fingers, the first electrode fingers or the second electrode fingers include a plurality of U-shaped structures, and the metal block is located within the U-shaped structures; and

[0020] An insulating layer is formed by depositing an insulating layer material so that the metal layer is embedded in the insulating layer. The insulating layer separates the first electrode fingers, the second electrode fingers and the metal block. The insulating layer in the U-shaped structure has a plurality of cavities.

[0021] In the MOM capacitor and formation method provided by the present invention, the first electrode fork or the second electrode fork is made to include a plurality of U-shaped segment structures, and the U-shaped segment structure has a metal block. In this way, when the insulating layer material is deposited to form the insulating layer, the flow of the oxide near the metal block in the U-shaped segment structure is affected by the metal block and the U-shaped segment structure, resulting in poor deposition effect of the insulating layer material, thereby forming a void. The void is filled with air, and the dielectric constant of the air is lower than the dielectric constant of the insulating layer material, so the dielectric constant of the entire insulating layer is reduced, thereby reducing the capacitance value of the MOM capacitor.

[0022] Furthermore, the insulating layer material includes oxide, and the dielectric constant of air is lower than that of oxide, so the dielectric constant of the entire insulating layer is reduced, thereby reducing the capacitance value of the MOM capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of a MOM capacitor according to an embodiment of the present invention;

[0024] Figure 2 1 is a flow chart of a method for forming a MOM capacitor according to an embodiment of the present invention;

[0025] In the figure: 110 - insulating layer, 120 - metal layer, 121 - metal block, 122 - first electrode, 123 - second electrode, 124 - first electrode interdigital finger, 125 - second electrode interdigital finger, 126 - U-shaped structure, 130 - cavity. DETAILED DESCRIPTION

[0026] The following is a more detailed description of the specific embodiments of the present invention with reference to schematic diagrams. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are only used for the purpose of conveniently and clearly illustrating the embodiments of the present invention.

[0027] Hereinafter, the terms "first," "second," and the like are used to distinguish between similar elements and are not necessarily used to describe a particular order or chronological sequence. It is to be understood that these terms used in this manner are interchangeable where appropriate. Similarly, if a method described herein comprises a series of steps, the order in which the steps are presented herein is not necessarily the only order in which the steps may be performed, and some of the steps described may be omitted or other steps not described herein may be added to the method.

[0028] Please refer to Figure 1 The present invention provides a MOM capacitor, comprising:

[0029] an insulating layer 110;

[0030] At least one metal layer 120, the metal layer 120 is embedded in the insulating layer, and the metal layer includes a metal block 121, a first electrode 122, a second electrode 123, a plurality of first electrode fingers 124 connected to the first electrode 121, and a plurality of second electrode fingers 125 connected to the second electrode 123;

[0031] Among them, the first electrode interdigital fingers 124 and the second electrode interdigital fingers 125 are arranged alternately at intervals, the metal block 121 is located between the first electrode interdigital fingers 124 and the second electrode interdigital fingers 125, the first electrode interdigital fingers 124 or the second electrode interdigital fingers 125 include several segments of U-shaped structures 126, and the metal block 121 is located in the U-shaped structure 126, the insulating layer 110 separates the first electrode 122 and the second electrode 123, and at the same time separates the first electrode interdigital fingers 124, the second electrode interdigital fingers 125 and the metal block 121, the insulating layer in the U-shaped structure 126 has several voids 130, and the dielectric constant of the insulating layer 110 is greater than the dielectric constant of air.

[0032] Preferably, the metal layer 120 comprises multiple layers, which are arranged in parallel and embedded in the insulating layer 110. The insulating layer 110 separates the multiple metal layers 120. Similarly, each metal layer 120 includes a metal block 121, a first electrode 122, a second electrode 123, a plurality of first electrode fingers 124 connected to the first electrode 122, and a plurality of second electrode fingers 125 connected to the second electrode 123. The first electrode fingers 124 and the second electrode fingers 125 are arranged alternately, with the metal block 121 located between the first electrode fingers 124 and the second electrode fingers 125. The first electrode fingers 124 or the second electrode fingers 125 include a plurality of U-shaped structures 126, and the metal block 121 is located within the U-shaped structures 126. Similarly, in each metal layer 120 , the insulating layer 110 separates the first electrode 122 , the second electrode 123 , the first electrode fingers 124 , the second electrode fingers 125 and the metal block 121 . The insulating layer 110 within the U-shaped structure 126 of each metal layer 120 has a plurality of cavities 130 .

[0033] Preferably, each U-shaped structure 126 includes at least one metal block 121. The insulating layer 110 in each U-shaped structure 126 has a plurality of cavities 130, and the cavities 130 are located near the metal block 121. Figure 1 Each U-shaped segment structure 126 has a cavity 130 therein.

[0034] In an embodiment of the present invention, the first electrode 122 and the second electrode 123 are parallel and opposite to each other, the first electrode interdigit 124 includes several segments of U-shaped structures 126, and the second electrode interdigit 125 is in the shape of a long straight strip. In other embodiments of the present invention, the second electrode interdigit 125 may include several segments of U-shaped structures 126, and the first electrode interdigit 124 may be in the shape of a long straight strip. The positive and negative polarity of the charges on the first electrode 122 and the second electrode 123 are different, the positive and negative polarity of the charges on the first electrode interdigit 124 and the second electrode interdigit 125 are different, the positive and negative polarity of the charges on the first electrode 122 and the first electrode interdigit 124 are the same, and the positive and negative polarity of the charges on the second electrode 123 and the second electrode interdigit 125 are the same. In addition to the capacitance between the first electrode 122 and the second electrode 123, there is also capacitance between the first electrode interdigit 124 and the second electrode interdigit 125. Although the first electrode finger 124 has a U-shaped segment structure, compared to when the first electrode finger 124 and the second electrode finger 125 are both straight strips, the first electrode finger 124 of the embodiment of the present invention includes several segments of U-shaped structures 126, and the second electrode finger 125 is a long straight strip, the relative area of ​​the first electrode finger 124 and the second electrode finger 125 does not increase.

[0035] In an embodiment of the present invention, the insulating layer 110 includes an oxide. For example, silicon dioxide, which can be formed by deposition. When depositing oxide to form the insulating layer 110, the flow of the oxide near the metal block 121 in the U-shaped segment structure 126 is affected by the wall of the U-shaped segment structure 126 of the first electrode fork 124 or the second electrode fork 125. The deposition effect of the oxide near the metal block 121 is poor, resulting in the formation of a cavity 130. The cavity 130 contains air, and the dielectric constant of air is lower than the dielectric constant of the oxide, so the dielectric constant of the entire insulating layer 110 is reduced, thereby reducing the capacitance value of the MOM capacitor.

[0036] In the embodiment of the present invention, the first electrode fingers 124 are all located on the side of the first electrode 122 close to the second electrode 123. The second electrode fingers 125 are all located on the side of the second electrode 123 close to the first electrode 122.

[0037] Accordingly, please refer to Figure 1 and Figure 2 The present invention also provides a method for forming a MOM capacitor, comprising:

[0038] S11: forming a metal layer 120, wherein the metal layer 120 includes a metal block 121, a first electrode 122, a second electrode 123, a plurality of first electrode fingers 124 connected to the first electrode 122, and a plurality of second electrode fingers 125 connected to the second electrode 123, wherein the first electrode fingers 124 and the second electrode fingers 125 are alternately arranged, the metal block 121 is located between the first electrode fingers 124 and the second electrode fingers 125, the first electrode fingers 124 or the second electrode fingers 125 include a plurality of U-shaped structures 126, and the metal block 121 is located within the U-shaped structure 126;

[0039] S12: An insulating layer 110 is formed by depositing an insulating layer material so that the metal layer 120 is embedded in the insulating layer 110. The insulating layer 110 separates the first electrode 122 and the second electrode 123, and also separates the first electrode fork 124, the second electrode fork 125 and the metal block 121. The insulating layer in the U-shaped structure has a plurality of voids.

[0040] Specifically, a substrate is provided, which may be a wafer. A metal layer material is formed on the surface of the substrate. The metal layer material is etched to form a metal block 121, a first electrode 122, a second electrode 123, a plurality of first electrode fingers 124 connected to the first electrode 122, and a plurality of second electrode fingers 125 connected to the second electrode 123 as a metal layer 120, wherein the first electrode fingers 124 and the second electrode fingers 125 are alternately arranged, the metal block 121 is located between the first electrode fingers 124 and the second electrode fingers 125, the first electrode fingers 124 or the second electrode fingers 125 include a plurality of U-shaped structures 126, and the metal block 121 is located within the U-shaped structure 126. The etching of the metal layer material to form the metal layer 120 complies with the minimum design rules of the process requirements of the MOM capacitor according to the embodiment of the present invention. The line width, the relative area of ​​the upper plate and the lower plate, and the distance between the upper plate and the lower plate meet the process requirements of the MOM capacitor according to the embodiment of the present invention.

[0041] Next, an oxide, such as silicon dioxide, is filled in the metal layer 120 to form the insulating layer 110. The method of filling the oxide can be a deposition method. When depositing the oxide, due to the presence of the metal block 121 and the presence of the U-shaped segment structure 126 around the metal block 121, the oxide in the U-shaped segment structure 126 is affected by the three walls of the metal block 121 and the nearby U-shaped segment structure 126, resulting in a poor effect of depositing the oxide. The deposited oxide layer contains several voids 130, and the size of the voids 130 may even be larger. What is contained in the voids 130 is air, and the dielectric constant of the oxide is greater than the dielectric constant of air, so the presence of the voids 130 indirectly reduces the dielectric constant of the insulating layer. The more the number of voids 130 and / or the larger the size of the voids 130, the more the dielectric constant of the insulating layer is reduced. The dielectric constant of the insulating layer 110 is reduced, and the capacitance value of the MOM capacitor is reduced. The more the dielectric constant of the insulating layer 110 is reduced, the more the capacitance value of the MOM capacitor is reduced.

[0042] If the MOM capacitor has at least two metal layers or multiple metal layers, a formation method similar to that of a MOM capacitor with a single metal layer is used. For example, in the case of two metal layers, after forming a first metal layer and an insulating layer filling the first metal layer, a second metal layer is formed, and then an insulating layer filling the second metal layer is formed. The case of multiple metal layers will not be described in detail here.

[0043] In summary, in the MOM capacitor and formation method provided in the embodiments of the present invention, the first electrode fork or the second electrode fork is made into a structure including several U-shaped segment structures, and the U-shaped segment structure has a metal block. In this way, when the insulating layer material is deposited to form the insulating layer, the flow of the oxide near the metal block in the U-shaped segment structure is affected by the metal block and the U-shaped segment structure, resulting in poor deposition effect of the insulating layer material, thereby forming a void, and the void is filled with air. The dielectric constant of the air is lower than the dielectric constant of the insulating layer material, so the dielectric constant of the entire insulating layer is reduced, thereby reducing the capacitance value of the MOM capacitor.

[0044] Furthermore, the insulating layer material includes oxide, and the dielectric constant of air is lower than that of oxide, so the dielectric constant of the entire insulating layer is reduced, thereby reducing the capacitance value of the MOM capacitor.

[0045] The above description is merely a preferred embodiment of the present invention and does not limit the present invention in any way. Any person skilled in the art who, without departing from the scope of the present invention, makes any equivalent substitution, modification, or other changes to the technical solution and technical content disclosed in the present invention shall be deemed to be within the scope of the present invention and still fall within the scope of protection of the present invention.

Claims

1. A MOM capacitor, characterized in that include: Insulation layer; at least one metal layer, the metal layer being embedded in the insulating layer, the metal layer comprising a metal block, a first electrode, a second electrode, a plurality of first electrode fingers connected to the first electrode, and a plurality of second electrode fingers connected to the second electrode; The first electrode fingers and the second electrode fingers are arranged alternately at intervals, the metal block is located between the first electrode fingers and the second electrode fingers, the first electrode fingers or the second electrode fingers include several segments of U-shaped structures, and the metal block is located within the U-shaped structure, the insulating layer separates the first electrode from the second electrode, and also separates the first electrode fingers, the second electrode fingers and the metal block, the insulating layer within the U-shaped structure has several voids, and the dielectric constant of the insulating layer material is greater than the dielectric constant of air.

2. MOM capacitor as claimed in claim 1, characterized in that, The cavity is located near the metal block.

3. MOM capacitor as claimed in claim 1, characterized in that, Each of the U-shaped structures includes at least one metal block.

4. MOM capacitor as claimed in claim 1, characterized in that, The insulating layer in each of the U-shaped structures has a plurality of cavities.

5. MOM capacitor according to claim 1, characterized in that, The insulating layer material includes oxide.

6. The MOM capacitor according to claim 1, wherein The first electrode fingers include a plurality of U-shaped structures, and the second electrode fingers are long straight strips.

7. The MOM capacitor according to claim 1, wherein The first electrode and the second electrode are parallel and opposite to each other.

8. The MOM capacitor according to claim 1, wherein The first electrode fingers are all located on a side of the first electrode close to the second electrode.

9. MOM capacitor according to claim 1, characterized in that, The second electrode fingers are all located on a side of the second electrode close to the first electrode.

10. The MOM capacitor according to claim 1, wherein The metal layer is multi-layered, and the multi-layered metal layers are arranged in parallel and embedded in the insulating layer. The insulating layer separates the multi-layered metal layers.

11. A method for forming a MOM capacitor according to any one of claims 1 to 10, characterized in that: include: forming a metal layer, the metal layer comprising a metal block, a first electrode, a second electrode, a plurality of first electrode fingers connected to the first electrode, and a plurality of second electrode fingers connected to the second electrode, wherein the first electrode fingers and the second electrode fingers are alternately arranged, the metal block is located between the first electrode fingers and the second electrode fingers, the first electrode fingers or the second electrode fingers include a plurality of U-shaped structures, and the metal block is located within the U-shaped structures; as well as An insulating layer is formed by depositing an insulating layer material so that the metal layer is embedded in the insulating layer. The insulating layer separates the first electrode fingers, the second electrode fingers and the metal block. The insulating layer in the U-shaped structure has a plurality of cavities.

Images