Integrated inductor and method of manufacturing the same, dc-dc converter

Abstract

The application provides an integrated inductor and a manufacturing method thereof, and a DC-DC converter integrated with the integrated inductor. The integrated inductor comprises a substrate, a first metal layer above the substrate, a first metal pattern formed in the first metal layer, a second metal layer above the first metal layer, a second metal pattern formed in the second metal layer, and an insulating layer between the first metal layer and the second metal layer, wherein a plurality of metal through holes are arranged in the insulating layer and penetrate the insulating layer from top to bottom. The first metal pattern in the first metal layer is connected with the second metal pattern in the second metal layer through the plurality of metal through holes in the insulating layer to form an inductor with a winding structure. The application can integrate the inductor in a chip, thereby saving the space occupied by the inductor on a printed circuit board.

Description

[Technical Field]

[0001] This invention relates to the field of integrated circuit technology, and in particular to an integrated inductor and its manufacturing method, and a DC-DC converter with an integrated inductor. [Background Technology]

[0002] To achieve miniaturization of Bluetooth headsets, it's necessary to integrate inductors into the chip. Integrated inductors reduce the area of ​​the printed circuit board, contributing to smaller Bluetooth headsets. Traditional circuits require inductors for DC-DC converters to be mounted on the printed circuit board. Please refer to... Figure 1 The diagram shows a circuit schematic of a DC-DC converter in the prior art. The inductor L1 is external and mounted on the printed circuit board. Therefore, each DC-DC converter requires four pins: VIN, LX, VO, and GND. More pins typically require a larger package, which is detrimental to the miniaturization of Bluetooth headsets. Furthermore, the inductor on the printed circuit board occupies a relatively large area, increasing the overall area of ​​the printed circuit board and also hindering miniaturization.

[0003] Therefore, it is necessary to propose a new technical solution to overcome the above problems. [Summary of the Invention]

[0004] The purpose of this invention is to provide an integrated inductor and its manufacturing method, as well as a DC-DC converter with an integrated inductor, which integrates the inductor in the chip, thereby saving space occupied by the inductor on the printed circuit board.

[0005] According to one aspect of the present invention, an integrated inductor is provided, comprising: a substrate; a first metal layer located above the substrate, wherein a first metal pattern is formed in the first metal layer; a second metal layer located above the first metal layer, wherein a second metal pattern is formed in the second metal layer; and an insulating layer located between the first metal layer and the second metal layer, wherein a plurality of metal vias are provided in the insulating layer extending downward through the insulating layer; wherein the first metal pattern in the first metal layer is connected to the second metal pattern in the second metal layer through the plurality of metal vias in the insulating layer to form a coiled inductor structure.

[0006] According to another aspect of the present invention, a DC-DC converter is provided, comprising: a control circuit; a power switch; and an integrated inductor as described above.

[0007] According to another aspect of the present invention, a method for manufacturing an integrated inductor is provided, comprising: providing a substrate, the substrate including a substrate and a first metal layer deposited above the substrate; etching away undefined regions in the first metal layer to obtain a first metal pattern; forming a first sub-insulating layer on the etched first metal layer; forming a magnetic core layer on the first sub-insulating layer; etching away undefined regions in the magnetic core layer to obtain a magnetic core; forming a second sub-insulating layer on the first sub-insulating layer and the magnetic core, wherein the first sub-insulating layer and the second sub-insulating layer constitute an insulating layer; forming a plurality of metal vias penetrating the insulating layer from top to bottom within the insulating layer; depositing a second metal layer on the insulating layer in which the plurality of metal vias are formed; and etching away undefined regions in the second metal layer to obtain a second metal pattern.

[0008] According to another aspect of the present invention, a method for manufacturing an integrated inductor is provided, comprising: providing a substrate, the substrate including a substrate and a first metal layer deposited above the substrate; etching away undefined regions in the first metal layer to obtain a first metal pattern; forming an insulating layer on the etched first metal layer; forming a plurality of metal vias extending downward through the insulating layer within the insulating layer; depositing a second metal layer on the insulating layer having the plurality of metal vias; and etching away undefined regions in the second metal layer to obtain a second metal pattern.

[0009] Compared to existing technologies, the integrated inductor of this invention comprises a first metal layer, a second metal layer, and an insulating layer. The insulating layer is located between the first and second metal layers, and a plurality of metal vias are formed within the insulating layer, extending downwards. The first metal pattern in the first metal layer is connected to the second metal pattern in the second metal layer via the plurality of metal vias in the insulating layer to form a coiled inductor structure. Thus, this invention allows for inductor integration within a chip, thereby saving space occupied by inductors on a printed circuit board. [Attached Image Description]

[0010] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0011] Figure 1 This is a circuit diagram of a DC-DC converter in the prior art;

[0012] Figure 2This is a circuit diagram of a DC-DC converter with an integrated inductor in one embodiment of the present invention.

[0013] Figure 3 For example, in one embodiment of the present invention Figure 2 A top view of the integrated inductor L1 shown;

[0014] Figure 4 For example, in one embodiment of the present invention Figure 2 A three-dimensional schematic diagram of the integrated inductor L1 shown;

[0015] Figure 5 In another embodiment of the present invention, as shown Figure 2 The top view of the integrated inductor L1 shown;

[0016] Figure 6 In another embodiment of the present invention, as shown Figure 2 A three-dimensional schematic diagram of the integrated inductor L1 shown;

[0017] Figure 7 For example, in one embodiment of the present invention Figure 6 A flowchart illustrating the manufacturing method of the integrated inductor;

[0018] Figure 8 For example, in one embodiment of the present invention Figure 4 The flowchart shows the manufacturing method of the integrated inductor. 【Detailed Implementation Methods】

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Unless otherwise specified, the terms "connected," "linked," and "connected" used herein to indicate electrical connection refer to direct or indirect electrical connection.

[0021] Please refer to Figure 2 As shown, it is a circuit diagram of a DC-DC converter with an integrated inductor in one embodiment of the present invention. Figure 2The DC-DC converter shown is a step-down DC-DC converter, which includes a step-down output circuit 210 and a control circuit 220. The step-down output circuit 210 includes an input power supply VIN, a first power switch MP2, a second power switch MN2, an inductor L1, and a capacitor C1. The input power supply VIN is grounded through the first power switch MP2 and the second power switch MN2 connected in series. The inductor L1 and the capacitor C1 are connected in series between the connection node LX between the first power switch MP2 and the second power switch MN2 and ground. The connection node between the inductor L1 and the capacitor C1 serves as the output terminal VO of the step-down output circuit 210. The step-down output circuit 210 reduces the voltage of the input power supply VIN by turning the first power switch MP2 and the second power switch MN2 on and off to obtain the output voltage VO. The control circuit 220 includes a first output terminal connected to the control terminal of the first power switch MP2 and a second output terminal connected to the control terminal of the second power switch MN2. Based on the output voltage VO of the step-down output circuit 210, it outputs a first control signal through the first output terminal to control the first power switch MP2 to turn on or off, and a second control signal through the second output terminal to control the second power switch MN2 to turn on or off, causing the first power switch MP2 and the second power switch MN2 to alternately turn on, thereby adjusting the output voltage VO to a certain set value. Figure 2 In the specific embodiment shown, the first power switch MP2 is a PMOS transistor, and the second power switch MN2 is an NMOS transistor.

[0022] exist Figure 2 In the embodiment shown, the inductor L1 is integrated into the chip 200. Specifically, the first power switch MP2, the second power switch MN2, the control circuit 220, and the inductor L1 are integrated into the chip 200, thus reducing the required number of pins to 3 pins (VIN, GND, VO) and saving space occupied by the inductor L1 on the printed circuit board.

[0023] Please refer to Figure 3 As shown, this is one embodiment of the present invention. Figure 2 The top view of the integrated inductor L1 is shown. Please refer to... Figure 4 As shown, this is one embodiment of the present invention. Figure 2 The diagram shows a three-dimensional schematic of the integrated inductor L1. Figure 3 and Figure 4The integrated inductor shown includes a substrate (not shown), a first metal layer 300, a second metal layer 400, and an insulating layer 500. The first metal layer 300 is located above the substrate and has a first metal pattern formed therein. The second metal layer 400 is located above the first metal layer 300 and has a second metal pattern formed therein. The insulating layer 500 is located between the first metal layer 300 and the second metal layer 400, and has a plurality of metal vias (or via metal, VIA, or through-hole) 510 extending downwards through the insulating layer 500. The first metal pattern in the first metal layer 300 is connected to the second metal pattern in the second metal layer 400 via the plurality of metal vias 510 in the insulating layer 500 to form a coiled inductor structure.

[0024] Unlike radio frequency (RF) circuits, DC-DC converters require larger inductance values. Since the inductor L1 in a DC-DC converter is a power inductor, it carries a large current and requires good heat dissipation. Therefore, it is manufactured using top-layer or second-layer metal, which dissipates heat more easily than bottom-layer metal. Furthermore, the farther the inductor is from the substrate, the smaller its parasitic capacitance to the substrate. Reducing parasitic capacitance reduces energy loss during switching. Therefore, in a preferred embodiment, the second metal layer 400 is the top-layer metal layer of the chip; the first metal layer 300 is the second-layer metal layer of the chip. Generally, the top-layer metal layer is made of aluminum, which is also beneficial for easy electrical connection with the package leads. The second-layer metal layer can be made of aluminum or copper. Copper has a lower resistivity than aluminum, resulting in lower parasitic resistance. Therefore, using copper for the second-layer metal layer has better advantages for the embodiments of the present invention.

[0025] exist Figure 3 and Figure 4In the specific embodiment shown, the first metal pattern within the first metal layer 300 includes a plurality of first metal strips 310 arranged in parallel; the second metal pattern within the second metal layer 400 includes a plurality of second metal strips 410 arranged in parallel. The first metal strips 310 and the second metal strips 410 are at a certain angle (e.g., 45 degrees) to form a staggered structure. A corresponding second metal strip 410 is provided between each pair of adjacent first metal strips 310. One end of the second metal strip 410 is connected to one end of one of the two adjacent first metal strips 310 through a metal through-hole 510 located below it, and the other end of the second metal strip 410 is connected to the other end of the other of the two adjacent first metal strips 310 through the metal through-hole 510 located below it. Thus, the plurality of first metal strips 310 and the plurality of second metal strips 410 are sequentially and alternately connected in series through the plurality of metal through-holes 510 to form a spiral inductor structure. Among various coil shapes, the spiral structure has a larger inductance value. Although Figure 4 The integrated inductor shown has many 90-degree corners, but in actual production, these corners are generally rounded (this cannot be idealized, so they are usually rounded). Figure 4 The integrated inductor shown has an approximate spiral structure.

[0026] The present invention is as follows Figure 3 and Figure 4 The integrated inductor shown is laid flat, meaning the length of the spiral inductor is parallel to the substrate plane of the chip. During layout design, due to limitations of layout tools, the angle between the first metal strip 310 and the second metal strip 410 is typically 90 degrees, 45 degrees, or 135 degrees, making rounded corners impossible. To reduce parasitic resistance, the first metal layer 300 and the second metal layer 400 are designed with a thickness of 3 to 10 micrometers. A thicker metal layer (equivalent to increasing the cross-sectional area of ​​the conductor) results in lower metal resistance, which helps reduce energy loss during inductor operation. Additionally, the width is designed to be as wide as possible; generally, the width of the first metal strip 310 in the first metal layer 300 and the second metal strip 410 in the second metal layer 400 should be greater than 5 micrometers. Wider metal layers also help reduce parasitic resistance.

[0027] It should be noted that, Figure 3 and Figure 4 The integrated inductor shown has a 4-turn spiral structure, but in practice it can have 1 or more turns. Figure 2In the illustrated embodiment, the integrated inductor L1 is integrated into a buck DC-DC converter. In another embodiment, the integrated inductor L1 can also be integrated into a boost DC-DC converter. That is, the circuit structure of the DC-DC converter with integrated inductor L1 in this invention can adopt the circuit structure of existing DC-DC converters, which will not be elaborated further here. Of course, Figure 3 and Figure 4 The integrated inductor L1 in the design can also be integrated into other chips that require inductance, and is not limited to DC-DC converters.

[0028] In a preferred embodiment, to save chip area, the integrated inductor L1 can house the power switch of the DC-DC converter (e.g., Figure 2 The PMOS transistor MP2 and NMOS transistor MN2 are stacked above each other, sharing an area. The power switch is connected using the lower metal layer; for example, if a four-layer metal process is used, the power switch is connected using the first and second metal layers, and the inductor is manufactured using the third (second-to-top) and fourth (top) metal layers, along with an insulating layer with metal vias between these two layers. In other words, in the DC-DC converter of this invention, the integrated inductor is placed above the power switch in the DC-DC converter, forming a stacked structure; the power switch in the DC-DC converter is connected using the lower metal layer of the integrated inductor.

[0029] The inductance value of the integrated inductor L1 in this invention can be approximately calculated using the following formula:

[0030]

[0031] Where μ0 is the permeability of free space, μs is the permeability of the magnetic core, n is the number of turns of the coil, S is the cross-sectional area of ​​the coil, l is the length of the coil, and k is a coefficient that depends on the radius and length of the coil.

[0032] Please refer to Figure 5 As shown, this is another embodiment of the present invention. Figure 2 The top view of the integrated inductor L1 shown. Figure 5 In the illustrated embodiment, the metal through-hole 510 located below one end or the other end of the second metal strip 410 is composed of a plurality of small metal through-holes arranged in parallel, while Figure 3 In the illustrated embodiment, the metal through-hole 510 located below one end or the other end of the second metal strip 410 is a large metal through-hole. Specifically in Figure 5In the example, one large metal through-hole is replaced by four small metal through-holes. In actual design, it can also consist of more small metal through-holes. That is, there can be one or more metal through-holes 510 located below one end or the other end of each of the second metal strips 410.

[0033] Please refer to Figure 6 As shown, this is another embodiment of the present invention. Figure 2 A three-dimensional schematic diagram of the integrated inductor L1 is shown. Figure 4 compared to, Figure 6 The integrated inductor L1 shown incorporates a magnetic core 600 within (or within) a spiral coil structure to enhance inductance. In one embodiment, the magnetic core 600 is made of Fe2O3.

[0034] Please refer to Figure 7 As shown, this is one embodiment of the present invention. Figure 6 The flowchart shows the manufacturing method of the integrated inductor. Figure 7 The manufacturing method of the integrated inductor shown includes the following steps.

[0035] Step 710: Provide a substrate, the substrate including a substrate and a first metal layer 300 deposited on the substrate.

[0036] Step 720: Etch away the undefined areas in the first metal layer 300 to obtain the first metal pattern.

[0037] Step 730: Form a first sub-insulating layer on the etched first metal layer 300. In one embodiment, the first sub-insulating layer is a silicon dioxide layer formed by wet oxidation.

[0038] Step 740: Form a magnetic core layer on the first sub-insulating layer. In one embodiment, the magnetic core layer is formed by sputtering.

[0039] Step 750: Etch away the undefined areas in the magnetic core layer to obtain the magnetic core 600.

[0040] Step 760: Form a second sub-insulating layer on the first sub-insulating layer and the magnetic core 600, wherein the first insulating layer and the second insulating layer constitute insulating layer 500. In one embodiment, the second sub-insulating layer is a silicon dioxide layer formed by wet oxidation.

[0041] Step 770: Form a plurality of metal through holes 510 extending from top to bottom through the insulating layer 500.

[0042] Step 780: Deposit a second metal layer 400 on the insulating layer 500 having a plurality of metal vias 510.

[0043] Step 790: Etch away the undefined areas in the second metal layer 400 to obtain the second metal pattern. The metal via 510 is used to connect the first metal pattern of the first metal layer 300, and its other end is connected to the second metal pattern of the second metal layer 400.

[0044] Please refer to Figure 8 As shown, this is one embodiment of the present invention. Figure 4 The flowchart shows the manufacturing method of the integrated inductor. Figure 8 The manufacturing method of the integrated inductor shown includes the following steps.

[0045] Step 810: Provide a substrate, the substrate including a substrate and a first metal layer 300 deposited on the substrate;

[0046] Step 820: Etch away the undefined areas in the first metal layer 300 to obtain the first metal pattern.

[0047] Step 830: An insulating layer 500 is formed on the etched first metal layer 300. In one embodiment, the insulating layer 500 is a silicon dioxide layer formed by wet oxidation.

[0048] Step 840: Form a plurality of metal through holes 510 extending from top to bottom through the insulating layer 500.

[0049] Step 850: Deposit a second metal layer 400 on the insulating layer 500 having a plurality of metal vias 510.

[0050] Step 860: Etch away the undefined areas in the second metal layer 400 to obtain the second metal pattern.

[0051] In summary, this invention provides an integrated inductor and a DC-DC converter with the integrated inductor. The integrated inductor includes a substrate (not shown), a first metal layer 300, a second metal layer 400, and an insulating layer 500. The first metal layer 300 is located above the substrate and has a first metal pattern formed therein. The second metal layer 400 is located above the first metal layer 300 and has a second metal pattern formed therein. The insulating layer 500 is located between the first metal layer 300 and the second metal layer 400, and has a plurality of metal vias (or metal vias) 510 extending downwards through the insulating layer 500. The first metal pattern in the first metal layer 300 is connected to the second metal pattern in the second metal layer 400 via the plurality of metal vias 510 in the insulating layer 500 to form a coiled inductor structure. In this way, the present invention can integrate inductors into the chip, thereby saving the space occupied by inductors on the printed circuit board and further reducing the printed circuit board area of ​​Bluetooth headsets.

[0052] In this invention, terms such as “connection,” “linked,” “connected,” and “joined” that indicate electrical connection, unless otherwise specified, indicate direct or indirect electrical connection.

[0053] It should be noted that any modifications made by those skilled in the art to the specific embodiments of the present invention do not depart from the scope of the claims. Accordingly, the scope of the claims is not limited to the foregoing specific embodiments.

Claims

1. An integrated inductor, characterized in that, It includes: Substrate; A first metal layer is located above the substrate, and a first metal pattern is formed in the first metal layer; A second metal layer is located above the first metal layer, and a second metal pattern is formed in the second metal layer; An insulating layer is located between the first metal layer and the second metal layer, and the insulating layer has a plurality of metal through holes extending from top to bottom through the insulating layer. The first metal pattern in the first metal layer is connected to the second metal pattern in the second metal layer through the plurality of metal through-holes in the insulating layer to form a coiled inductor structure. The second metal layer is the top metal layer of the chip; The first metal layer is the second-to-top metal layer of the chip. The top metal layer is made of aluminum. The second-to-top metal layer is made of copper. The first metal pattern within the first metal layer includes a plurality of first metal strips arranged in parallel. The second metal pattern within the second metal layer comprises a plurality of second metal strips arranged in parallel. The plurality of metal through holes connect the plurality of first metal strips and the plurality of second metal strips in series alternately to form a spiral structure inductor. A corresponding second metal strip is provided between each pair of adjacent first metal strips. One end of the second metal strip is connected to one end of one of the two adjacent first metal strips through the metal through hole located below it, and the other end of the second metal strip is connected to the other end of the other pair of adjacent first metal strips through the metal through hole located below it. The length direction of the inductor in the spiral structure is parallel to the plane of the substrate; The thickness of both the first metal layer and the second metal layer is 3 micrometers to 10 micrometers; The angle between the first metal strip and the second metal strip is 90 degrees, 45 degrees, or 135 degrees. The metal through-hole located below one or more of the other ends of each of the second metal strips is one or more; and The widths of both the first and second metal strips are greater than 5 micrometers. The inductance value of the integrated inductor is calculated using the following formula: Where μ0 is the free permeability, μ s Let be the core permeability, n be the number of turns in the coil, S be the cross-sectional area of ​​the coil, l be the length of the coil, and k be a coefficient dependent on the coil radius and length. It also includes: The magnetic core disposed within the inductor of the coiled structure The integrated inductor is used in a DC-DC converter, and the integrated inductor is placed above the power switch in the DC-DC converter in a stacked structure; The power switch in the DC-DC converter is connected by a metal connection located below the integrated inductor.

2. A DC-DC converter, characterized in that, It includes: Control circuit; Power switch; and The integrated inductor as described in claim 1.

3. The DC-DC converter according to claim 2, characterized in that, The control circuit, power switch, and integrated inductor are located in the same chip.

4. A method for manufacturing an integrated inductor as described in claim 1, characterized in that, It includes: A substrate is provided, the substrate comprising a substrate and a first metal layer deposited over the substrate; Undefined areas in the first metal layer are etched away to obtain the first metal pattern; A first sub-insulating layer is formed on the etched first metal layer; A magnetic core layer is formed on the first sub-insulating layer; The undefined regions in the core layer are etched away to obtain the core. A second sub-insulating layer is formed on the first sub-insulating layer and the magnetic core, wherein the first sub-insulating layer and the second sub-insulating layer constitute an insulating layer; A plurality of metal through holes are formed in the insulating layer from top to bottom; A second metal layer is deposited on the insulating layer in which the plurality of metal vias are formed; Undefined areas in the second metal layer are etched away to obtain the second metal pattern.

5. The method for manufacturing an integrated inductor according to claim 4, characterized in that, The first and second sub-insulating layers are silicon dioxide layers formed by wet oxidation. The magnetic core layer is formed by sputtering.

6. A method for manufacturing an integrated inductor as described in claim 1, characterized in that, It includes: A substrate is provided, the substrate comprising a substrate and a first metal layer deposited over the substrate; Undefined areas in the first metal layer are etched away to obtain the first metal pattern; An insulating layer is formed on the etched first metal layer; A plurality of metal through holes are formed in the insulating layer from top to bottom; A second metal layer is deposited on the insulating layer in which the plurality of metal vias are formed; Undefined areas in the second metal layer are etched away to obtain the second metal pattern.

7. The method for manufacturing an integrated inductor according to claim 6, characterized in that, The insulating layer is a silicon dioxide layer formed by wet oxidation.

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