Capacitor structure
By increasing the width of the finger plates in the capacitor structure, the problems of increased resistance and easy breakdown of the insulation layer in MOM capacitors in high-frequency circuits are solved, improving the quality factor and reliability of the capacitor while maintaining the integration of the chip.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SEMICON MFG INT (SHANGHAI) CORP
- Filing Date
- 2022-06-10
- Publication Date
- 2026-07-21
AI Technical Summary
Existing MOM capacitors in semiconductor integrated circuits suffer from insufficient quality factor and reliability of capacitor structure, especially in high-frequency circuits where resistance increases and the insulation layer is prone to breakdown.
Design a capacitor structure in which the width of the finger plates gradually increases in a specific ratio, thereby increasing the overall area of the capacitor, reducing resistance and the risk of insulation breakdown, and conforming to the high-frequency current density distribution law.
By increasing the width of the finger plates, the resistance of the capacitor structure is reduced, the quality factor is improved, and the reliability of the capacitor is enhanced, while avoiding excessive area increase that could affect integration.
Smart Images
Figure CN117276252B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor manufacturing, and in particular to a capacitor structure. Background Technology
[0002] In semiconductor integrated circuits, integrated capacitors fabricated on the same chip as transistor circuits are widely used. They mainly come in two forms: metal-insulator-metal (MIM) capacitors and metal-oxide-metal (MOM) capacitors. MIM capacitors use upper and lower metal layers as capacitor plates. Fabricating MIM capacitors generally requires additional photolithography layers, and the breakdown voltage of the capacitor dielectric layer and the capacitance size are inherently contradictory. Furthermore, planar capacitors typically require a large area, which is detrimental to device integration. MOM capacitors, on the other hand, use a combination of finger structures and stacked layers to fabricate larger capacitance values in a relatively smaller area. In addition, MOM capacitors do not require additional photoresist layers and masks, making the fabrication process simpler and less expensive than that of MIM capacitors.
[0003] However, existing MOM capacitors still have many problems. Summary of the Invention
[0004] The technical problem solved by this invention is to provide a capacitor structure that improves the quality factor and reliability of the capacitor structure.
[0005] To solve the above-mentioned technical problems, the present invention provides a capacitor structure, comprising: a first electrode and a second electrode arranged parallel to each other along a first direction, wherein a first region and a plurality of second regions are arranged along a second direction between the first electrode and the second electrode, the first region being located between adjacent second regions, and the first direction being perpendicular to the second direction; a plurality of first finger-shaped plates arranged parallel to each other along the second direction and respectively connected to the first electrode, the first finger-shaped plates having a first width dimension along the second direction and being located on the first region; and a plurality of second finger-shaped plates arranged parallel to each other along the second direction and respectively connected to the second electrode, the second finger-shaped plates having a second width dimension along the second direction and being located on the first region. In the first region, a plurality of first finger-shaped electrode plates and a plurality of second finger-shaped electrode plates are arranged in a crisscross pattern; a plurality of third finger-shaped electrode plates are arranged parallel to the second direction and connected to the first electrode terminal, the third finger-shaped electrode plates having a third width dimension along the second direction, the third finger-shaped electrode plates being located in the second region, the third width dimension being greater than the first width dimension and the second width dimension; a plurality of fourth finger-shaped electrode plates are arranged parallel to the second direction and connected to the second electrode terminal, the fourth finger-shaped electrode plates having a fourth width dimension along the second direction, the fourth finger-shaped electrode plates being located in the second region, the fourth width dimension being greater than the first width dimension and the second width dimension, and the plurality of third finger-shaped electrode plates and the plurality of fourth finger-shaped electrode plates are arranged in a crisscross pattern.
[0006] Optionally, the first width dimension is equal to the second width dimension.
[0007] Optionally, the ratio of the third width dimension to the first width dimension is fixed.
[0008] Optionally, the ratio of the third width dimension to the first width dimension is 1.5:1 to 3:1.
[0009] Optionally, the ratio of the fourth width dimension to the first width dimension is fixed.
[0010] Optionally, the ratio of the fourth width dimension to the second width dimension is 1.5:1 to 3:1.
[0011] Optionally, the third width dimension and the fourth width dimension increase sequentially along the direction from the first region to the second region.
[0012] Optionally, the sequential increase of the third width dimension and the fourth width dimension along the direction from the first region to the second region includes: the third width dimension and the fourth width dimension being sequentially increased by a fixed step multiple compared to the first width dimension along the direction from the first region to the second region.
[0013] Optionally, the step size multiple is 0.05 to 0.15.
[0014] Optionally, the sequential increase of the third width dimension and the fourth width dimension along the direction from the first region to the second region includes: the third width dimension and the fourth width dimension being sequentially increased by a fixed step width dimension compared to the first width dimension along the direction from the first region to the second region.
[0015] Optionally, the step width dimension is 1 / e times the first width dimension.
[0016] Optionally, there is a first spacing dimension between adjacent first and second finger electrodes; and a second spacing dimension between adjacent third and fourth finger electrodes, wherein the first spacing dimension is equal to the second spacing dimension.
[0017] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects:
[0018] The capacitor structure provided by this invention includes: a plurality of third finger-shaped plates arranged parallel to the second direction and respectively connected to the first electrode; each third finger-shaped plate having a third width dimension along the second direction and located on the second region; the third width dimension being greater than the first width dimension and the second width dimension; and a plurality of fourth finger-shaped plates arranged parallel to the second direction and respectively connected to the second electrode; each fourth finger-shaped plate having a fourth width dimension along the second direction and located on the second region; the fourth width dimension being greater than the first width dimension and the second width dimension, and the plurality of third finger-shaped plates and the plurality of fourth finger-shaped plates being arranged in an interlaced manner. By increasing the width dimensions of the third finger-shaped plates and the fourth finger-shaped plates, the overall area of the capacitor structure is increased, thereby reducing the resistance of the capacitor structure and improving the quality factor of the capacitor structure.
[0019] Furthermore, due to the skin effect in high-frequency circuits, the current density of the finger plates closer to the outer edge is higher. Therefore, by increasing the area of the third and fourth finger plates in the second region, the resistance of the third and fourth finger plates is reduced, thereby reducing the voltage on the third and fourth finger plates and decreasing the risk of the insulation layer between adjacent third and fourth finger plates being broken down, thus improving the reliability of the capacitor structure.
[0020] Furthermore, along the direction from the first region to the second region, the third and fourth width dimensions increase sequentially. Since the current density distribution due to the skin effect in high-frequency circuits gradually increases from the inside to the outside, setting the third and fourth width dimensions to increase sequentially better aligns with the current density distribution under the skin effect in high-frequency resistors. This ensures that the increased area of the capacitor structure is moderate, avoiding excessive increase in capacitor structure area that could affect the integration density of devices within the chip.
[0021] Furthermore, the ratio of the third width dimension to the first width dimension is fixed; the ratio of the fourth width dimension to the first width dimension is also fixed. By setting the ratios of the third width dimension to the first width dimension and the fourth width dimension to the first width dimension to be fixed, the process difficulty can be effectively reduced. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of a capacitor structure.
[0023] Figure 2 This is a schematic diagram of the current density distribution of a cylindrical conductor under the skin effect;
[0024] Figure 3 This is a schematic diagram of the capacitor structure according to an embodiment of the present invention. Detailed Implementation
[0025] As described in the background section, existing MOM capacitors still have many problems. These will be explained in detail below with reference to the accompanying drawings.
[0026] Please refer to Figure 1A capacitor structure 100 includes: a first electrode 101 and a second electrode 102 arranged in parallel along a first direction X; a plurality of first finger-shaped plates 101a arranged in parallel along a second direction Y and respectively connected to the first electrode 101, the first finger-shaped plates 101a having a first width dimension d1 along the second direction Y, the first direction X being perpendicular to the second direction Y; and a plurality of second finger-shaped plates 102a arranged in parallel along the second direction Y and respectively connected to the second electrode 102, the second finger-shaped plates 102a having a second width dimension d2 along the second direction Y, the first width dimension d1 being equal to the second width dimension d2, and the plurality of first finger-shaped plates 101a and the plurality of second finger-shaped plates 102a being arranged in an interlaced manner.
[0027] Please refer to Figure 2 When a conductor is connected to a high-frequency circuit, the skin effect causes the current density to be unevenly distributed within the conductor. Specifically, the current density is highest near the surface and decreases exponentially with increasing depth. The skin depth δ usually refers to the depth within the conductor where the current is located in the high-frequency circuit, i.e.:
[0028]
[0029] Where ρ is the resistivity of the conductor, f is the frequency of the high-frequency circuit, and μ is the permeability of the conductor. A drawback of the skin effect is that it reduces the effective cross-section of a cylindrical conductor in a high-frequency circuit, thus increasing its resistance. This is because the conductor resistance in the skin effect is expressed as:
[0030]
[0031] Among them, R DC Let be the conductor resistance in a low-frequency circuit, and r be the radius of the cylindrical conductor cross-section. Further calculations yield:
[0032]
[0033] Therefore, under the skin effect, the higher the frequency f in a high-frequency circuit, the greater the conductor resistance.
[0034] Please continue to refer to this. Figure 1 In this embodiment, when the capacitor structure 100 is connected to a high-frequency circuit, the resistance R corresponding to the skin effect is:
[0035]
[0036] Where a is half the length of the first electrode 101 or the second electrode 102 along the second direction Y, and b is half the width of the first electrode 101 or the second electrode 102 along the first direction X. Because the resistance R of the capacitor structure 100 increases in high-frequency circuits, and the quality factor Q of the capacitor structure 100 is inversely proportional to the resistance R, that is, when the resistance R of the capacitor structure 100 increases, the quality factor Q of the capacitor structure 100 decreases.
[0037] Furthermore, according to the skin effect, the current density of the first finger plate 101a and the second finger plate 102a closer to the outer edge in the capacitor structure 100 is greater, and the corresponding voltage value is also greater. When the voltage value exceeds the threshold, it is easy to cause breakdown of the insulating layer between adjacent first finger plates 101a and second finger plates 102a.
[0038] To address the aforementioned problems, this invention provides a capacitor structure that increases the overall area of the capacitor structure by increasing the width of the third and fourth finger plates, thereby reducing the resistance of the capacitor structure and improving its quality factor. Furthermore, due to the skin effect in high-frequency circuits, the current density is higher on the outermost finger plates. Therefore, by increasing the area of the third and fourth finger plates within the second region, their resistance is reduced, thereby lowering the voltage on the third and fourth finger plates and reducing the risk of breakdown of the insulation layer between adjacent third and fourth finger plates, thus improving the reliability of the capacitor structure.
[0039] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0040] Figure 3 This is a schematic diagram of the capacitor structure according to an embodiment of the present invention.
[0041] Please refer to Figure 3A capacitor structure 200 includes: a first electrode 201 and a second electrode 202 arranged parallel to each other along a first direction X; a first region I and a plurality of second regions II arranged along a second direction Y, with the first region I located between adjacent second regions II; the first direction X being perpendicular to the second direction Y; a plurality of first finger-shaped plates 201a arranged parallel to each other along the second direction Y and connected to the first electrode 201 respectively; the first finger-shaped plates 201a having a first width dimension d1 along the second direction Y and located on the first region I; and a plurality of second finger-shaped plates 202a arranged parallel to each other along the second direction Y and connected to the second electrode 202 respectively; the second finger-shaped plates 202a having a second width dimension d2 along the second direction Y and located on the first region I. A first finger-shaped electrode plate 201a and a plurality of second finger-shaped electrode plates 202a are arranged in a crisscross pattern; a plurality of third finger-shaped electrode plates 201b are connected to the first electrode terminal 201 and arranged parallel to the second direction Y, the third finger-shaped electrode plates 201b having a third width dimension d3 along the second direction Y, the third finger-shaped electrode plates 201b being located on the second region II, the third width dimension d3 being greater than the first width dimension d1 and the second width dimension d2; a plurality of fourth finger-shaped electrode plates 202b are connected to the second electrode terminal 202 and arranged parallel to the second direction Y, the fourth finger-shaped electrode plates 202b having a fourth width dimension d4 along the second direction Y, the fourth finger-shaped electrode plates 202b being located on the second region II, the fourth width dimension d4 being greater than the first width dimension d1 and the second width dimension d2, and the plurality of third finger-shaped electrode plates 201b and the plurality of fourth finger-shaped electrode plates 202b are arranged in a crisscross pattern.
[0042] In this embodiment, by increasing the width of the third finger plate 201b and the fourth finger plate 202b, the overall area of the capacitor structure 200 is increased, thereby reducing the resistance of the capacitor structure 200 and improving its quality factor. Furthermore, due to the skin effect in high-frequency circuits, the current density is higher closer to the outer finger plate. Therefore, by increasing the area of the third finger plate 201b and the fourth finger plate 202b within the second region II, the resistance of the third finger plate 201b and the fourth finger plate 202b is reduced, thereby reducing the voltage on the third finger plate 201b and the fourth finger plate 202b, reducing the risk of the insulation layer between adjacent third finger plates 201b and fourth finger plates 202b being broken down, and thus improving the reliability of the capacitor structure 200.
[0043] In this embodiment, the first width dimension d1 is equal to the second width dimension d2.
[0044] In this embodiment, the third width dimension d3 and the fourth width dimension d4 increase sequentially along the direction from the first region I to the second region II. Since the current density distribution of the skin effect in high-frequency circuits gradually increases from the inside to the outside, setting the third width dimension d3 and the fourth width dimension d4 to increase sequentially better conforms to the current density distribution under the skin effect in high-frequency resistors. This ensures that the area of the capacitor structure 200 is moderately increased, avoiding excessive increase in the area of the capacitor structure 200 from affecting the integration density of devices in the chip.
[0045] In this embodiment, along the direction from the first region I to the second region II, the third width dimension d3 and the fourth width dimension d4 are successively increased by a fixed step size multiple compared to the first width dimension d1.
[0046] The step size multiple is 0.05 to 0.15 times. In this embodiment, the step size multiple is 0.1 times. If the first width dimension d1 is w1, then along the direction from the first region I to the second region II, the third width dimension d3 and the fourth width dimension d4 are successively 1.1w1, 1.2w1, 1.3w1, ... compared to the first width dimension.
[0047] In other embodiments, the sequential increase of the third and fourth width dimensions along the direction from the first region to the second region includes: the third and fourth width dimensions being increased by a fixed step width dimension relative to the first width dimension along the direction from the first region to the second region; the step width dimension is 1 / e times the first width dimension. For example, if the first width dimension is w1, then along the direction from the first region to the second region, the third and fourth width dimensions are successively: w1*(1+1 / e), w1*(1+2 / e), w1*(1+3 / e)... By setting the ratio of the third width dimension to the first width dimension and the ratio of the fourth width dimension to the first width dimension to be fixed, the process difficulty can be effectively reduced.
[0048] In other embodiments, the ratio of the third width dimension to the first width dimension and the ratio of the fourth width dimension to the first width dimension may also be fixed values. For example, the ratio of the third width dimension to the first width dimension is 1.5:1 to 3:1; and the ratio of the fourth width dimension to the first width dimension is 1.5:1 to 3:1.
[0049] In this embodiment, there is a first spacing dimension c1 between adjacent first finger electrode plates 201a and second finger electrode plates 202a; there is a second spacing dimension c2 between adjacent third finger electrode plates 201b and fourth finger electrode plates 202b, and the first spacing dimension c1 is equal to the second spacing dimension c2.
[0050] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.
Claims
1. A capacitor structure, characterized in that, include: A first electrode and a second electrode are arranged parallel to each other along a first direction. Between the first electrode and the second electrode, there is a first region and a plurality of second regions arranged along a second direction. The first region is located between adjacent second regions. The first direction is perpendicular to the second direction. A plurality of first finger-shaped electrode plates arranged parallel to the second direction are respectively connected to the first electrode end. The first finger-shaped electrode plates have a first width dimension along the second direction and are located on the first region. A plurality of second finger-shaped plates are connected to the second electrode and arranged in parallel along the second direction. The second finger-shaped plates have a second width dimension along the second direction. The second finger-shaped plates are located on the first region, and the plurality of first finger-shaped plates and the plurality of second finger-shaped plates are arranged in an interlaced manner. A plurality of third finger-shaped electrode plates arranged parallel to the second direction are respectively connected to the first electrode terminal. The third finger-shaped electrode plates have a third width dimension along the second direction. The third finger-shaped electrode plates are located on the second region. The third width dimension is greater than the first width dimension and the second width dimension. A plurality of fourth finger-shaped electrode plates are connected to the second electrode terminal and arranged in parallel along the second direction. The fourth finger-shaped electrode plates have a fourth width dimension along the second direction. The fourth finger-shaped electrode plates are located on the second region. The fourth width dimension is greater than the first width dimension and the second width dimension. The plurality of third finger-shaped electrode plates and the plurality of fourth finger-shaped electrode plates are arranged in an interlaced manner.
2. The capacitor structure as described in claim 1, characterized in that, The first width dimension is equal to the second width dimension.
3. The capacitor structure as described in claim 2, characterized in that, The ratio of the third width dimension to the first width dimension is fixed.
4. The capacitor structure as described in claim 3, characterized in that, The ratio of the third width dimension to the first width dimension is 1.5:1 to 3:
1.
5. The capacitor structure as described in claim 2, characterized in that, The ratio of the fourth width dimension to the first width dimension is fixed.
6. The capacitor structure as described in claim 5, characterized in that, The ratio of the fourth width dimension to the second width dimension is 1.5:1 to 3:
1.
7. The capacitor structure as described in claim 2, characterized in that, Along the direction from the first region to the second region, the third width dimension and the fourth width dimension increase successively.
8. The capacitor structure as described in claim 7, characterized in that, The sequential increase of the third and fourth width dimensions along the direction from the first region to the second region includes: the third and fourth width dimensions being increased by a fixed step multiple compared to the first width dimension along the direction from the first region to the second region.
9. The capacitor structure as described in claim 8, characterized in that, The step size multiple is 0.05 to 0.15 times.
10. The capacitor structure as described in claim 7, characterized in that, The sequential increase of the third and fourth width dimensions along the direction from the first region to the second region includes: the third and fourth width dimensions being increased by a fixed step width dimension compared to the first width dimension along the direction from the first region to the second region.
11. The capacitor structure as described in claim 10, characterized in that, The step width dimension is 1 / e times the first width dimension.
12. The capacitor structure as described in claim 1, characterized in that, There is a first spacing dimension between adjacent first and second finger plates; there is a second spacing dimension between adjacent third and fourth finger plates, and the first spacing dimension is equal to the second spacing dimension.