A new spiral inductor with star-shaped shielding net

Abstract

The present invention discloses a novel spiral inductor with a star-shaped shielding mesh, comprising a substrate, an inductor body, and a shielding mesh. The substrate is a dielectric material that carries the inductor and can be divided into multiple layers, with metal layers on the upper surface of the top substrate, the lower surface of the bottom substrate, and between adjacent substrate layers. The inductor body is a set of metal patterns used to implement the inductor function, including a spiral line, input pads, and output pads. The shielding mesh is a set of metal patterns on a different metal layer from the inductor body, including a central grounding hole, a star line, and edge grounding holes. The spiral line, input pads, output pads, and star line are arranged on the metal layer. The present invention provides a simple, low-cost spiral inductor for integrated circuit design, helping to improve the shielding effect of integrated inductors, thereby reducing coupling interference and the overall cost of high-performance integrated circuits, promoting performance improvements and system capabilities of microwave monolithic integrated circuits and mixed analog-digital integrated circuits.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuits, and in particular relates to a novel spiral inductor with a star-shaped shielding network. Background Art

[0002] Spiral inductors are important components in integrated circuits. As reactance devices, they provide RF chokes and filtering functions. A typical spiral inductor is constructed by applying a spiral pattern to the metal surface, with the upper and lower metal layers shielded by large ground planes or unshielded. Spiral inductors are also commonly used in integrated circuits, and their simulation, design, and fabrication methods are relatively mature.

[0003] Traditional spiral inductors are relatively mature, but they have significant drawbacks, primarily related to electromagnetic field shielding. Because the inductor radiates electromagnetic waves or receives external electromagnetic waves during operation, this degrades filtering performance, necessitating shielding.

[0004] There are generally two means of shielding: large-area ground layer shielding and circuit well shielding formed by substrate doping.

[0005] Using large-area ground planes for shielding is not easy to achieve in typical semiconductor processing techniques. The mainstream semiconductor processes are silicon-based and compound semiconductor. Silicon-based processes often do not support continuous, large-area metal layer processes; whereas compound semiconductor processes have very few metal layers available, often only two, making it difficult to provide sufficient metal layers to achieve the aforementioned large-area shielding. Traditional large-area grounding methods use parallel wires and grid lines as shielding meshes. However, because the line layout direction and the inductor's magnetic field are irregularly intersecting, this can cause problems such as localized loop currents, resulting in reduced inductor performance or shielding effectiveness, and therefore presents drawbacks.

[0006] The method of forming circuit wells by substrate doping requires local ion implantation in the integrated circuit design to constrain the electromagnetic field distribution and thus achieve a certain shielding effect. This method is complex, has many steps, and is costly. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned existing technologies and provide a new spiral inductor with a star-shaped shielding network, providing a spiral inductor with a simple design and low cost for integrated circuit design, helping to improve the shielding effect of the integrated inductor, thereby reducing coupling interference, reducing the overall cost of high-performance integrated circuits, and promoting the performance improvement and system capability improvement of microwave monolithic integrated circuits and digital-analog hybrid integrated circuits.

[0008] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0009] A novel spiral inductor with a star-shaped shielding net comprises a substrate, an inductor body and a shielding net;

[0010] The substrate is a dielectric material that carries the inductor and can be divided into multiple layers, with metal layers on the upper surface of the top substrate, the lower surface of the bottom substrate, and between adjacent substrate layers;

[0011] The inductor body is a set of metal patterns used to realize the inductor function, including spiral wires, input pads and output pads. The input pads and output pads are interfaces for interconnecting the inductor body with the external circuit;

[0012] The shielding mesh is a set of metal patterns on a different metal layer from the inductor body, including a central grounding hole, a star line, and edge grounding holes;

[0013] The central grounding hole and the edge grounding hole provide a grounding channel, and together with the star line form a shielding structure to achieve the purpose of restraining the inductive electromagnetic field, thereby achieving electromagnetic shielding;

[0014] The spiral line, input pad, output pad and star line are arranged on the metal layer.

[0015] To optimize the above technical solutions, specific measures taken also include:

[0016] When the substrate is used in the semiconductor manufacturing process, typical semiconductor dielectric materials are gallium arsenide, gallium nitride or silicon;

[0017] When used in non-semiconductor processes, common dielectric substrates such as FR-4, ceramic substrates or quartz substrates are used.

[0018] The aforementioned spiral line is a metal film with a spiral shape, a certain line width and thickness, and is applied on the surface of the substrate.

[0019] The above-mentioned input pads and output pads are circular or other shaped metal films with a certain thickness, which are applied on the surface of the substrate.

[0020] The central grounding hole and edge grounding hole are hollow cylindrical or solid columnar metals with a certain height and a circular or other shaped cross section that penetrate the substrate. The outer diameter of the central grounding hole is larger than that of the edge grounding hole.

[0021] The star-shaped lines are radial, and each radial wall has a metal film with a certain line width and thickness, which is applied on the surface of the substrate.

[0022] The metals used for the above-mentioned spiral line, input pad, output pad, central ground hole, edge ground hole and star line are gold, copper, aluminum, aluminum-copper plating, aluminum-nickel plating, copper-gold plating or various alloys.

[0023] The centers of the star line, spiral line and edge grounding hole mentioned above coincide with each other.

[0024] The present invention has the following beneficial effects:

[0025] The inductor of the present invention is an inductor with a shielding structure that can be realized by a process and has practical application value.

[0026] 1. Using star-shaped lines to replace the traditional full-surface metal layer to achieve inductor shielding. Star-shaped lines have better machinability in semiconductor technology than full-surface metal layers, and have better manufacturability in CMOS semiconductor processes, solving the problem that large-area full-surface metal layers cannot be manufactured in CMOS processes.

[0027] 2. Connect the star line to the grounding system through the central shielding hole and the edge grounding hole. After the star line is grounded as a shielding net, the inductance performance is better;

[0028] 3. The size of the central grounding hole is significantly larger than that of the edge grounding hole, resulting in a smaller distribution parameter and improved inductance performance;

[0029] 4. The inductor of the present invention is simple in design and has better EMI performance than traditional unshielded inductors in CMOS semiconductor processes. It can be designed using traditional inductor design tools without the need for dedicated design tools and can be widely used in applications such as semiconductor devices and thick-film circuit devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a diagram of the inductor structure in Example 2 of the present invention;

[0031] Marked in the figure: 101-substrate, 102-star line, 103-spiral line, 104-edge grounding hole, 105-central grounding hole, 106-input pad, 107-output pad, M1-first metal layer, M2-second metal layer, M3-third metal layer, M4-fourth metal layer. DETAILED DESCRIPTION

[0032] The embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0033] A novel spiral inductor with a star-shaped shielding net comprises a substrate, an inductor body and a shielding net;

[0034] The substrate is the dielectric material that carries the inductor and can be divided into multiple layers. There are metal layers on the upper surface of the top substrate, the lower surface of the bottom substrate, and between adjacent substrate layers.

[0035] The metal layer referred to herein is the metal layer where the spiral, input pads, output pads, and star lines are located. The substrate is generally made of typical semiconductor dielectric materials, such as gallium arsenide, gallium nitride, and silicon. When used in non-semiconductor processes, fiberglass composite boards (such as FR-4), ceramic substrates (such as Rogers 4350B, Al2O3, etc.), and quartz substrates may also be used. The manufacturing process of the substrate is not within the scope of protection of this invention, but the stacking, thickness, size, and shape of the finished inductor made based on any of these substrates are within the scope of protection of this invention.

[0036] The inductor body is a set of metal patterns, including spiral wires, input pads, and output pads;

[0037] A helix is ​​a thin metal film with a specific width and thickness that appears as a spiral. It is applied to the surface of a substrate. The metal used for the helix is ​​typically gold, copper, or aluminum. Other options include aluminum-coated copper, aluminum-coated nickel, copper-coated gold, and various alloys.

[0038] This helix formed of any type of metal is within the scope of protection of this invention. The shape, line width, and thickness of the helix are subject to a variety of options and designs. Any helical deformation, line width, and thickness of the helix, as well as any combination of these, are within the scope of protection of this invention.

[0039] The input and output pads are metal films of a certain thickness that are circular or in other shapes (such as circular, I-shaped, triangular, etc.) and are applied to the surface of the substrate. The metal used for the input and output pads is generally gold, copper, or aluminum. Aluminum-coated copper, aluminum-coated nickel, copper-coated gold, etc. can also be used. Various alloys can also be used. Input and output pads implemented with any type of metal are within the scope of protection of the present invention. The shape, line width, thickness, etc. of the input and output pads can be selected and designed in a variety of ways. Any shape, line width, thickness, or any combination of any shape, line width, and thickness of the input and output pads are within the scope of protection of the present invention.

[0040] The shielding mesh is a set of metal patterns on a different metal layer from the inductor body, including a central grounding hole, a star line, and edge grounding holes;

[0041] The inductor body alone can realize the inductor function, and the input pad and the output pad are interfaces for interconnecting it with the external circuit.

[0042] The central and edge grounding holes of the shielding mesh provide grounding channels, forming a shielding structure together with the star wires to confine the inductor's electromagnetic field, thereby achieving electromagnetic shielding. This structural design is simple. Compared with traditional methods, the shielding wires rarely cut into the inductor's magnetic field, eliminating the problem of localized circulation in the shielding layer. It also eliminates the need for localized doping of the substrate, eliminating the processes and costs associated with ion implantation, achieving low-cost, effective shielding. It offers advantages in both low cost and simple design.

[0043] The central grounding hole and the edge grounding hole are hollow cylindrical or solid columnar metals with a certain height that penetrate the substrate and have a circular or other shaped cross-section (such as square, I-shaped, triangular, etc.). The outer diameter of the central grounding hole is significantly larger than that of the edge grounding hole.

[0044] The metal used for the central grounding hole and the edge grounding hole is generally gold, copper, or aluminum. Aluminum-coated copper, aluminum-coated nickel, copper-coated gold, etc. can also be used. Various alloys can also be used. The central grounding hole and the edge grounding hole implemented with any type of metal are all within the scope of protection of the present invention. The shape, wall thickness (for hollow shape), height, inner dimension (for hollow shape), outer dimension, etc. of the central grounding hole and the edge grounding hole can be selected and designed in a variety of ways. Any combination of the cross-sectional shape, hollowness, and height of the central grounding hole and the edge grounding hole is also within the scope of protection of the present invention.

[0045] The star-shaped line is a metal film that is radial and each radial wall has a certain line width and thickness, and is applied to the surface of the substrate. The metal used for the star-shaped line is generally gold, copper, and aluminum. It can also be made of aluminum plated with copper, aluminum plated with nickel, copper plated with gold, etc., and can also be made of a variety of alloys. This star-shaped line implemented with any kind of metal is within the protection scope of the present invention. There are many options and designs for the shape, line width, thickness, etc. of the star-shaped line. Under the condition of complying with the radial style, any deformed arm of the star-shaped line (such as a straight arm, an arc-shaped arm, an arm of unequal width, etc.), any line width, any thickness, and any combination of any deformed arm (such as a straight arm, an arc-shaped arm, an arm of unequal width, etc.), any line width, and any thickness are all within the protection scope of the present invention.

[0046] Example 1

[0047] The steps for implementing the inductor of the present invention using common processes, two-layer substrates, and three layers of metal are as follows:

[0048] Process the shape of substrate A according to design requirements;

[0049] Apply metal layer B and metal layer A to the upper and lower surfaces of substrate A respectively, and cover or not cover the entire substrate shape according to design requirements;

[0050] Drill through holes in substrate A and the metal layer;

[0051] Etching excess metal layer on the upper surface of metal layer B to form a star-shaped line;

[0052] Metallize the completed through-holes between substrate A and the metal layer to connect the star line, metal layer B and metal layer A;

[0053] The substrate B is applied (by pasting, casting or other manufacturing methods) on the upper surface of the metal layer B; at this time, the upper surface of the metal layer B and the lower surface of the substrate B are bonded;

[0054] Apply a metal layer C on the upper surface of the substrate B, covering or not covering the entire substrate shape according to design requirements;

[0055] Etching excess metal layers on the upper surface of the metal layer C to form a spiral line, an input pad, and an output pad;

[0056] So far, the structure of the present invention is completed.

[0057] Note: The above implementation steps only illustrate the steps implemented using a common process, two substrate layers, and three metal layers. Design and manufacturing steps using more substrate layers and metal layers will differ from the above steps. These implementation steps are not within the scope of protection of this invention.

[0058] Example 2

[0059] like Figure 1 As shown, this embodiment 2 is a spiral inductor with three substrate layers and four metal layers, consisting of a substrate 101, a star line 102, a spiral line 103, an edge grounding hole 104, a central grounding hole 105, an input pad 106, an output pad 107, a first metal layer M1, a second metal layer M2, a third metal layer M3, and a fourth metal layer M4.

[0060] The centers of the star line 102 , the spiral line 103 , and the edge grounding hole 104 coincide with each other.

[0061] Substrate 101 consists of three layers: the top surface of the top substrate, the bottom surface of the bottom substrate, and the intermediate layers between adjacent substrates. From the top surface downward, the metal layers are: first metal layer M1, second metal layer M2, third metal layer M3, and fourth metal layer M4. Each substrate layer is single-crystal silicon, 25 microns thick; the metal layers are aluminum, 1 micron thick.

[0062] The spiral, input pad, and output pad are located on the first metal layer, M1. The spiral has a constant turn pitch and width, an outer diameter of 10 mm, three turns, and a spiral width of 0.1 mm. Both the input and output pads are circular, with a diameter of 0.5 mm. The outer edges of the input and output pads are tangentially connected to the inner and outer turns of the spiral, respectively.

[0063] The star line is located on the second metal layer M2, with a total of 16 arms distributed at equal angles; the arms are straight arms, with a length of 6 mm from the central grounding hole to the edge grounding hole, including the length of the overlapping arms; the arm width is 0.6 mm.

[0064] The third metal layer M3 has no metal pattern layer. The fourth metal layer M4 is a whole metal layer used as a ground layer without any special shape.

[0065] The edge grounding holes 104 and the central grounding hole 105 are hollow cylindrical metals with a wall thickness of 0.1 mm. The outer diameter of the edge grounding hole 104 is 0.4 mm, and the outer diameter of the central grounding hole is 1 mm. The metal used for the central grounding hole and the edge grounding holes is gold.

[0066] Implementation steps of the present invention:

[0067] Base substrate as per design requirements;

[0068] Apply a third metal layer M3 and a fourth metal layer M4 on the upper and lower surfaces of the bottom substrate respectively;

[0069] The third metal layer is entirely corroded and removed;

[0070] Growing an intermediate layer substrate on the upper surface of the third metal layer M3;

[0071] Applying a second metal layer M2 on the upper surface of the intermediate substrate;

[0072] Etching excess metal layer on the second metal layer M2 to form a star-shaped line 102;

[0073] A through hole is drilled in the substrate, passing through the bottom substrate, the middle substrate, the second metal layer M2, the third metal layer M3 and the fourth metal layer M4, and a mechanical hole without metal inside is formed at the edge grounding hole 104 and the central grounding hole 105;

[0074] The mechanical holes are metallized to form metal inner walls in the holes, and the star line and the fourth metal layer M4 are connected to form edge grounding holes 104 and central grounding holes 105;

[0075] Growing a top substrate on the upper surface of the second metal layer M2;

[0076] Applying a first metal layer M1 on the top surface of the top substrate;

[0077] Etching excess metal layers on the first metal layer M1 to form a spiral line 103, an input pad 106 and an output pad 107;

[0078] At this point, the spiral inductor structure having three substrate layers and four metal layers of the present invention is completed.

[0079] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A new spiral inductor with a star-shaped shielding network, characterized in that: Including substrate, inductor body and shielding net; The substrate is a dielectric material that carries the inductor and can be divided into multiple layers, with metal layers on the upper surface of the top substrate, the lower surface of the bottom substrate, and between adjacent substrate layers; The inductor body is a set of metal patterns used to realize the inductor function, including spiral wires, input pads and output pads. The input pads and output pads are interfaces for interconnecting the inductor body with the external circuit; The shielding mesh is a set of metal patterns on a different metal layer from the inductor body, including a central grounding hole, a star line, and edge grounding holes; The central grounding hole and the edge grounding hole provide a grounding channel and together with the star line form a shielding structure to achieve the purpose of restraining the inductive electromagnetic field, thereby achieving electromagnetic shielding. The central grounding hole and the edge grounding hole are hollow cylinders with a circular cross-section and a certain height that penetrate the substrate. The outer diameter of the central grounding hole is larger than that of the edge grounding hole. The spiral line, input pad, output pad and star line are arranged on the metal layer.

2. A novel spiral inductor with a star-shaped shielding network according to claim 1, characterized in that: When the substrate is used in a semiconductor manufacturing process, a typical semiconductor dielectric material is used, such as gallium arsenide, gallium nitride or silicon; When used in non-semiconductor processes, common dielectric substrates such as FR-4, ceramic substrates or quartz substrates are used.

3. The novel spiral inductor with a star-shaped shielding network according to claim 1, characterized in that: The spiral line is a metal film in a spiral shape with a certain line width and thickness, which is applied on the surface of the substrate.

4. The novel spiral inductor with a star-shaped shielding network according to claim 1, characterized in that: The input pad and the output pad are metal films with a certain thickness and are circular or in other shapes and are applied on the surface of the substrate.

5. The novel spiral inductor with a star-shaped shielding network according to claim 1, characterized in that: The star-shaped lines are radial, and each radial wall has a metal film with a certain line width and thickness, which is applied on the surface of the substrate.

6. The novel spiral inductor with a star-shaped shielding network according to claim 1, characterized in that: The metals used for the spiral line, input pad, output pad, central grounding hole, edge grounding hole and star line are gold, copper, aluminum, aluminum-copper plating, aluminum-nickel plating, copper-gold plating or various alloys.

7. The novel spiral inductor with a star-shaped shielding network according to claim 1, characterized in that: The centers of the star line, the spiral line and the edge grounding hole coincide with each other.

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