Thin-film resistor and circuit board

Abstract

A thin-film resistor and a circuit board. The thin-film resistor comprises: a substrate layer and a first resistor layer, wherein the first resistor layer is stacked on at least one surface of the substrate layer; a protrusion structure is provided on the side of the substrate layer that is close to the first resistor layer; and the maximum plane width X of the bottom of the protrusion structure satisfies 0.1 μm≤X≤50 μm, the maximum plan width of the bottom of the protrusion structure refers to the maximum horizontal-distance value of the bottom of the protrusion structure in a widthwise direction, and the bottom width of the protrusion structure refers to the horizontal distance between the lowest position adjacent to one side edge of the protrusion structure and the lowest position adjacent to the other side edge of the protrusion structure. The maximum plane width of the bottom of a protrusion structure is defined, such that the sheet-resistance uniformity and resistance stability of a first resistor layer are improved.

Description

Thin film resistors and circuit boards

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 27, 2023, with application number 202310772748.2 and invention name “A Thin Film Resistor and Circuit Board”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the technical field of chip resistors, and in particular to a thin film resistor and a circuit board. Background Art

[0003] With the development of integrated electronic components, higher requirements are being placed on the performance and miniaturization of electronic components. Among them, thin-film resistors, as embedded resistor structures, use integrated passive components to significantly reduce the surface parasitic effects and volume of semiconductor devices at high frequencies. They have the characteristics of high precision, increased packaging density, and improved device reliability. They are widely used in applications such as high-performance amplifiers, line drivers, consumer electronics, and power management. Among them, the resistance layer of thin-film resistors is stacked on the surface of the substrate layer, so the uniformity of the square resistance of the resistance layer is easily affected by the substrate layer; poor uniformity of the resistance value and square resistance of the resistance layer will seriously affect the performance stability of the electronic components.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide a thin film resistor and a circuit board, which solve the technical problems in the prior art of uneven square resistance and poor resistance stability of the surface of the first resistor layer close to the base layer.

[0006] An embodiment of the present application provides a thin film resistor, comprising: a first resistor layer stacked on at least one surface of a base layer; a raised structure provided on a side of the base layer close to the first resistor layer; a maximum plane width X of the bottom of the raised structure satisfies 0.1 μm ≤ X ≤ 50 μm, wherein the maximum plane width of the bottom of the raised structure refers to the maximum value of the horizontal distance of the bottom width of the raised structure, and the bottom width of the raised structure refers to the horizontal distance between the lowest point of adjacent positions of an edge on one side of the raised structure and the lowest point of adjacent positions of an edge on the other side of the raised structure.

[0007] Optionally, the size range of the maximum plane width of the bottom of the protruding structure is distributed according to a preset percentage;

[0008] The preset percentage includes: 50%-100% of the maximum plane width X of the bottom portion satisfies 0.1≤X≤8μm.

[0009] Optionally, the preset percentages include: 0%-10% of the bottom maximum plane width X satisfies 0.1≤X<3μm, 50%-100% of the bottom maximum plane width X satisfies 3≤X<6μm, 0%-30% of the bottom maximum plane width X satisfies 6≤X<8μm; 0%-10% of the bottom maximum plane width X satisfies X≥8μm, wherein the total percentage of the protruding structures within the four width ranges is less than or equal to 100%.

[0010] Optionally, the shape of the protrusion structure includes at least one of the following: polygonal pyramid, inverted cone, cone, needle, tree branch, crown, hook, stalactite, hanging ice, spiral, sawtooth and corrugated.

[0011] Optionally, the base layer includes a first conductive layer or a dielectric layer.

[0012] Optionally, the thin film resistor further includes a film layer, and the film layer is located on a surface of the first resistor layer away from the base layer.

[0013] Optionally, a second conductive layer is provided on a side of the film layer away from the first resistance layer.

[0014] Optionally, the second conductive layer is a single layer or multiple layers.

[0015] Optionally, a second resistance layer is provided between the film layer and the second conductive layer.

[0016] Optionally, the first resistance layer is formed on the surface of the base layer by at least one of electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition.

[0017] A second aspect of the present application provides a circuit board, comprising the thin film resistor according to any of the above embodiments.

[0018] The present application discloses a thin-film resistor and a circuit board. The thin-film resistor comprises: a base layer and a first resistor layer; the first resistor layer is laminated on at least one surface of the base layer; the base layer has a raised structure disposed on a side adjacent to the first resistor layer; and the raised structure has a maximum bottom planar width X satisfying 0.1 μm ≤ X ≤ 50 μm, where the maximum bottom planar width of the raised structure refers to the maximum horizontal distance of the bottom width of the raised structure, and the bottom width of the raised structure refers to the horizontal distance between the lowest point of adjacent positions on one edge of the raised structure and the lowest point of adjacent positions on the other edge of the raised structure. By limiting the maximum bottom planar width of the raised structure, the present application improves the uniformity and stability of the sheet resistance of the first resistor layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a schematic structural diagram of a thin film resistor provided in an embodiment of the present application;

[0020] FIG2 is a surface contour line diagram of a side of a substrate layer close to a first resistor layer provided in an embodiment of the present application;

[0021] FIG3 is a schematic structural diagram of another thin film resistor provided in an embodiment of the present application;

[0022] FIG4 is a schematic structural diagram of another thin film resistor provided in an embodiment of the present application;

[0023] FIG5 is a schematic structural diagram of another thin film resistor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present application and are not intended to limit the present application. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions of the present application, not all of the structures.

[0025] It should be noted that the terms "first," "second," and so on in the specification, claims, and drawings of this application are used to distinguish different objects, rather than to limit a specific order. The following embodiments of this application can be implemented independently or in combination with each other, and this embodiment of the application does not impose specific limitations on this.

[0026] FIG1 is a schematic structural diagram of a thin film resistor provided in an embodiment of the present application.

[0027] As shown in Figure 1, the thin film resistor includes: a base layer 10 and a first resistor layer 20; the first resistor layer 20 is stacked on at least one surface of the base layer 10; the base layer 10 is provided with a protruding structure 11 on the side close to the first resistor layer 20; the maximum plane width of the bottom of the protruding structure 11 is different, and the maximum plane width X of the bottom of the protruding structure 11 satisfies 0.1μm≤X≤50μm, wherein the maximum plane width of the bottom of the protruding structure 11 refers to the maximum value of the horizontal distance of the bottom width of the protruding structure 11, and the bottom width of the protruding structure 11 refers to the horizontal distance between the lowest point of the adjacent position of the edge of one side of the protruding structure 11 and the lowest point of the adjacent position of the edge of the other side of the protruding structure 11.

[0028] It should be noted that the lowest point of the adjacent positions of the two side edges of a protruding structure 11 is the position closest to the other side of the base layer 10, that is, the position from the peak to the trough in the waveform of the protruding structure 11 that meets the conditions. As shown between the dotted lines in Figure 1 is a complete protruding structure 11.

[0029] In order to eliminate the interference of clutter noise on the test results, the waveform of the protruding structure 11 needs to conform to the corresponding peak height. Figure 2 is a surface contour line diagram of a side of the substrate layer 10 close to the first resistor layer 20 provided in an embodiment of the present application. The contour line diagram of the thin film resistor refers to the undulating state curve diagram obtained after scanning the surface profile of the thin film resistor. Specifically, the peaks of the protruding structure 11 can be distinguished based on the fact that the horizontal distance between the top of the peak and the top of the adjacent peak is greater than or equal to half the maximum plane width of the bottom of the peak. In this case, the peak and the adjacent peak can be determined as the peaks of two protruding structures 11; or under a laser confocal microscope, the peaks in the surface contour line diagram are determined by one-to-one correspondence between the peaks and the corresponding protruding structures 11 in the laser image.

[0030] As shown in FIG2 , the distance between the troughs on two adjacent sides of the crest of a protrusion structure 11 is the maximum plane width X.

[0031] Optionally, when the prepared thin-film resistor is applied to a circuit, the base layer 10 needs to be etched away, leaving the first resistor layer 20 in the circuit, thereby serving as a resistor element. The first resistor layer 20 is formed on the surface of the base layer 10, meaning that the square resistance of the first resistor layer 20 is affected by the surface condition of the base layer 10. After extensive experimental verification, researchers found that the maximum planar width X at the bottom of the protrusion structure 11 significantly affects the uniformity of the square resistance of the first resistor layer 20.

[0032] Optionally, the size range of the maximum plane width of the bottom of the protruding structure 11 is distributed according to a preset percentage; the preset percentage includes: 50%-100% of the maximum plane width X of the bottom satisfies 0.1≤X≤8μm.

[0033] Optionally, the percentage of the bottom maximum plane width X that satisfies 0.1≤X≤8 μm is limited to the above range, so that the uniformity of the square resistance of the first resistance layer 20 is further improved.

[0034] Optionally, the preset percentages include: 0%-10% of the bottom maximum plane width X satisfies 0.1≤X<3μm, 50%-100% of the bottom maximum plane width X satisfies 3≤X<6μm, 0%-30% of the bottom maximum plane width X satisfies 6≤X<8μm; 0%-10% of the bottom maximum plane width X satisfies X≥8μm, wherein the total percentage of the protruding structures within the four width ranges is less than or equal to 100%.

[0035] Optionally, the raised structure 11 is a structure obtained by roughening the surface of the base layer 10, and is a structure formed by stacking multiple small grains. For example, the preset percentage can be set to 5% of the bottom maximum plane width X meeting 0.1≤X<3μm, 72% of the bottom maximum plane width X meeting 3≤X<6μm, 15% of the bottom maximum plane width X meeting 6≤X<8μm, and 8% of the bottom maximum plane width X meeting X≥8μm, where 5%+72%+15%+8%=100%. Based on a large amount of experimental data, further refinement of the percentage of the maximum plane width can further improve the square resistance uniformity of the first resistive layer 20.

[0036] Optionally, the proportion of the protruding structures 11 maintaining 3≤X<6μm is relatively large, usually greater than 70%, and the proportion of the protruding structures 11 maintaining X≥8μm is as small as possible, which can be selected to be less than 8%. At this time, the square resistance uniformity of the thin film resistor is better.

[0037] The raised structure 11 in this embodiment is formed by the accumulation of fine grains. The height d1 of the raised structure 11 is the vertical distance from the lowest point of the two adjacent side edges of the raised structure 11 to the top of the raised structure (see Figure 2). The bottom width X of the raised structure 11 is the horizontal distance between the lowest point of the adjacent position on one side of the raised structure and the lowest point of the adjacent position on the other side of the raised structure 11 (see Figure 2).

[0038] Optionally, the contour line diagram shown in Figure 2 can be generated by a white light interferometer, a 3D profilometer test, a laser confocal microscope, a scanning electron microscope roughness reconstruction or other surface morphology testing instruments, and a contour line scan is performed on the side of the base layer 10 having the protruding structure 11, and the undulating height curve of the surface morphology profile in the scanning extension direction is obtained, which is the above-mentioned contour line diagram.

[0039] Optionally, the height of the protrusion structure 11 is 1-15 μm. For example, the height of the protrusion structure 11 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm, or other values ​​within the above range.

[0040] Optionally, the thickness of the first resistance layer 20 is generally set to 5 nm-3 μm, and can be optionally set to 10 nm-200 nm.

[0041] For example, the thickness of the first resistor layer 20 can be set to 10 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm. Alternatively, the thickness of the first resistor layer 20 can be set to 10 nm, 25 nm, 50 nm, 75 nm, 100 nm, 125 nm, 150 nm, 175 nm, or 200 nm. The sputtering thickness of the first resistor layer 20 is adjusted based on the desired resistance value.

[0042] Optionally, the first resistance layer 20 is formed on the surface of the base layer 10 by at least one of electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition.

[0043] Optionally, the material of the first resistance layer 20 includes at least one of elements such as Ni, Cr, Si, P, N, Ti, Pt, Ta, Mo, Sn, and O.

[0044] Optionally, the material of the first resistor layer 20 includes at least one of the following: NiCrSi, NiCrAlSi, NiP, NiCr, AlN, TiN, Pt, Cr, Cr-SiO, Cr-Si, Ti-Si, Ti-W, TaN, Mo, and Ni-Sn. Furthermore, the first resistor layer 20 may have a single-layer structure or a multi-layer structure. The materials used in the multi-layer structure may be the same or different. The selection of materials or layer structures is determined by those skilled in the art based on actual needs.

[0045] Optionally, the shape of the protruding structure 11 includes at least one of the following: polygonal pyramid, inverted cone, cone, needle, tree branch, crown, hook, stalactite, hanging ice, spiral, serrated, corrugated or other regular or irregular shapes.

[0046] Alternatively, referring to FIG1 , the protruding structure 11 shown in FIG1 is in the shape of an irregular spike, so as to increase the bonding force between the base layer 10 and the first resistance layer 20 .

[0047] Optionally, the base layer 10 includes a first conductive layer or a dielectric layer.

[0048] Optionally, the base layer 10 is a single-layer structure or a multi-layer structure, wherein the material of the first conductive layer and the second conductive layer of the single-layer structure or the multi-layer structure includes at least one of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver and gold. That is, the base layer 10 can be copper foil, aluminum foil, titanium foil, zinc foil, iron foil, nickel foil, chromium foil, cobalt foil, silver foil or gold foil, or an alloy foil containing at least two of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver and gold, or a composite foil composed of at least two of copper foil, aluminum foil, titanium foil, zinc foil, iron foil, nickel foil, chromium foil, cobalt foil, silver foil and gold foil. In addition, the materials used in the multi-layer structure of the base layer 10 can be the same material or different materials. The choice of material is a choice made by those skilled in the art according to their needs. Materials for the dielectric layer of a single-layer or multi-layer structure include PET (Polyethylene Terephthalate), PP (Polypropylene), PS (Polystyrene), ABF (Acrylonitrile-Butadiene-Styrene Terpolymer) film, BT resin, polyacrylic acid, polyurethane, polyimide, etc., which are not listed in detail here. Among them, BT resin is a thermosetting resin formed by adding bismaleimide (BMI) and triazine as the main resin components, and epoxy resin, polyphenylene ether resin (PPE) or allyl compound as a modifying component.

[0049] FIG3 is a schematic structural diagram of another thin film resistor provided in an embodiment of the present application.

[0050] Optionally, as shown in FIG. 3 , the thin film resistor further includes a film layer 30 ; the film layer 30 is disposed on a side of the first resistor layer 20 away from the base layer 10 .

[0051] Optionally, the thickness of the film layer 30 is 0.5 μm-100 μm.

[0052] For example, the thickness of the film layer 30 may be 2 μm, 5 μm, 7 μm, 10 μm, 12 μm, 15 μm, 20 μm, 30 μm, 40 μm, 55 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0053] Optionally, the film layer 30 is selected from at least one of polystyrene, vinyl acetate, polyester, polyethylene, polyamide, rubber or acrylic thermoplastic resins, phenolic, epoxy, thermoplastic polyimide, urethane, melamine or alkyd thermosetting resins, and ABF resin.

[0054] Illustratively, film layer 30 is selected from at least one of modified epoxy resin, modified acrylic resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene naphthalate, polystyrene, polyvinyl chloride, polysulfone, polyphenylene sulfide, polyetheretherketone, polyphenylene oxide, polytetrafluoroethylene, liquid crystal polymer, polyoxaline, epoxy glass cloth, and BT resin. The specific thickness and material of film layer 30 can be selected and set by those skilled in the art based on actual needs.

[0055] In addition to the film layer 30 provided on the surface of the thin-film resistor, a second conductive layer 40 is optionally provided on the side of the film layer 30 away from the first resistive layer 20. Figure 4 is a schematic diagram of the structure of another thin-film resistor provided in an embodiment of the present application. Optionally, the second conductive layer 40 is a single layer or multiple layers.

[0056] Optionally, the second conductive layer 40 shown in FIG4 is a single layer. By disposing the second conductive layer 40 on the side of the film layer 30 away from the first resistor layer 20, a foil-clad laminate containing a resistor layer structure is formed. This foil-clad laminate has a four-layer structure and can be directly applied to rigid or flexible circuit boards. The newly disposed second conductive layer 40 can be a single layer or a multi-layer structure. The material of the second conductive layer 40 can be the same as or different from the material used for the base layer 10 in the thin film resistor. Those skilled in the art can configure it according to actual needs.

[0057] Alternatively, FIG5 is a schematic diagram of the structure of another thin film resistor provided by an embodiment of the present application. As shown in FIG5 , a second resistor layer 50 is provided between the film layer 30 and the second conductive layer 40 .

[0058] Optionally, an asymmetric structure is formed by providing a second resistor layer 50 between the film layer 30 and the second conductive layer 40. The material of the newly provided second resistor layer 50 may be the same as or different from the material used for the first resistor layer 20 in the thin film resistor, and those skilled in the art may configure the material based on actual needs.

[0059] It should be noted that in this embodiment, the thickness of the base layer 10, the thickness of the first resistive layer 20, the thickness of the film layer 30, and the maximum width are all obtained by preparing sample slices and then measuring them under an electron microscope. The magnification of the electron microscope is 2000-70,000x, and the specific magnification is conventionally selected by those skilled in the art as needed. The maximum planar width of the bottom of the protruding structure 11 is determined by measuring the sample using an instrument to obtain a contour image, and then measuring the maximum planar width of the bottom of the protruding structure 11 based on the obtained contour image.

[0060] The performance of the thin film resistor provided by this application is introduced below with a specific embodiment.

[0061] For example, taking the base layer 10 as an example of copper foil, the copper foil used is electrolytic copper foil, and then the first resistance layer 20 is formed on the surface of the copper foil by vacuum sputtering. The test method of square resistance is to use a square resistance meter to test the resistance layer on the surface of the thin film resistor. The test conditions are: use a four-probe test head, connect the square resistance meter to the test head, and apply a DC voltage of 1V to the test head. Then the four-probe test head is used to test the area of ​​2cm*2cm. Among them, the surface curvature of the probe is Sr=0.9mm, the pressure of the probe is 0.45±0.15N or 50±15gf, and the probe spacing is 3mm. The measured square resistance uniformity of the thin film resistor is shown in Table 1. Table 1 measures the square resistance uniformity of four groups of thin film resistors. Among them, No. 1 is a first resistance layer 20 set on the surface of a conventional copper foil. The first resistance layer 20 is made of NiCr with a thickness of 30nm. In No. 2, a first resistor layer 20 is provided on 80% of the copper foil surface where the maximum bottom plane width X satisfies 0.1≤X≤8μm. NiCr is used for the first resistor layer 20 and has a thickness of 30nm. In No. 3, a first resistor layer 20 is provided on 10% of the copper foil surface where the maximum bottom plane width X satisfies 0.1≤X<3μm, 50% of the copper foil surface where the maximum bottom plane width X satisfies 3≤X<6μm, 30% of the copper foil surface where the maximum bottom plane width X satisfies 6≤X<8μm, and 10% of the copper foil surface where the maximum bottom plane width X satisfies X≥8μm. NiCr is used for the first resistor layer 20 and has a thickness of 30nm. In number 4, a first resistor layer 20 is provided on the surface of the copper foil where 5% of the maximum bottom plane width X satisfies 0.1≤X<3μm, 70% of the maximum bottom plane width X satisfies 3≤X<6μm, 15% of the maximum bottom plane width X satisfies 6≤X<8μm, and 10% of the maximum bottom plane width X satisfies X≥8μm. NiCr is selected for the first resistor layer 20 and has a thickness of 30nm. In number 5, a first resistor layer 20 is provided on the surface of the copper foil where 0% of the maximum bottom plane width X satisfies 0.1≤X<3μm, 80% of the maximum bottom plane width X satisfies 3≤X<6μm, 15% of the maximum bottom plane width X satisfies 6≤X<8μm, and 5% of the maximum bottom plane width X satisfies X≥8μm. NiCr is selected for the first resistor layer 20 and has a thickness of 30nm. In number 6, a first resistor layer 20 is provided on the copper foil surface where 5% of the maximum bottom plane width X satisfies 0.1≤X<3μm, 60% of the maximum bottom plane width X satisfies 3≤X<6μm, and 30% of the maximum bottom plane width X satisfies 6≤X<8μm; and 5% of the maximum bottom plane width X satisfies X≥8μm. NiCr is selected for the first resistor layer 20 and has a thickness of 30nm.In number 7, a first resistor layer 20 is provided on the copper foil surface where 5% of the maximum bottom plane width X satisfies 0.1≤X<3μm, 30% of the maximum bottom plane width X satisfies 3≤X<6μm, 50% of the maximum bottom plane width X satisfies 6≤X<8μm, and 15% of the maximum bottom plane width X satisfies X≥8μm. The first resistor layer 20 is made of NiCr with a thickness of 30nm.

[0062] Table 1 Square resistance uniformity of thin film resistors

[0063] In the embodiment of the present application, the calculation upper limit value of the square resistance uniformity = (M max -M ave ) / M ave × 100%; lower limit = (M ave -M min ) / M ave ×100%; where M max is the maximum value, M min is the minimum value, M ave is the average value.

[0064] In the embodiment of the present application, statistics were also collected on the scrap rate of the etched circuit boards of the above-mentioned experimental samples. The statistics are shown in Table 2.

[0065] Table 2 Scrap rate of etched circuit boards with thin film resistors

[0066] As can be seen from the results in Table 2, the scrap rates of the etched circuit boards prepared with the first resistor layer 20 on the surfaces of the conventional copper foil No. 1 and the copper foil No. 7 were the highest. The scrap rates of the etched circuit boards of the other test groups within the preset percentage range were relatively low, especially the test group No. 5, which had a scrap rate of only 0.5%. It can be seen that the thin film resistors prepared by adopting the solution disclosed in the present application are not only conducive to the preparation of a resistor layer with high uniformity of square resistance, but also can reduce the scrap rate of the etched circuit boards, reduce waste, and meet the performance requirements of circuit board preparation.

[0067] An embodiment of the present application further provides a circuit board, which includes the thin film resistor in any of the above embodiments.

[0068] The circuit board provided in the embodiment of the present application includes the thin film resistor in the above embodiment. Therefore, the circuit board provided in the embodiment of the present application also has the beneficial effects described in the above embodiment, which will not be repeated here.

[0069] In the description of the embodiments of this application, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0070] Finally, it should be noted that the above are only preferred embodiments of the present application and the technical principles employed. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the inventive concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A thin film resistor, characterized in that: The thin film resistor comprises: a base layer and a first resistor layer; The first resistance layer is stacked on at least one surface of the base layer; the base layer is provided with a protrusion structure on a side close to the first resistance layer; The maximum plane width X of the bottom of the protruding structure satisfies 0.1μm≤X≤50μm, wherein the maximum plane width of the bottom of the protruding structure refers to the maximum value of the horizontal distance of the bottom width of the protruding structure, and the bottom width of the protruding structure refers to the horizontal distance between the lowest point of the adjacent position of the edge on one side of the protruding structure and the lowest point of the adjacent position of the edge on the other side of the protruding structure.

2. The thin film resistor according to claim 1, characterized in that: The size range of the maximum plane width of the bottom of the protrusion structure is distributed according to a preset percentage; The preset percentage includes: 50%-100% of the maximum plane width X of the bottom portion satisfies 0.1≤X≤8 μm.

3. The thin film resistor according to claim 2, characterized in that: The preset percentages include: 0%-10% of the maximum plane width X of the bottom satisfies 0.1≤X<3μm, 50%-100% of the maximum plane width X of the bottom satisfies 3≤X<6μm, 0%-30% of the maximum plane width X of the bottom satisfies 6≤X<8μm; 0%-10% of the maximum plane width X of the bottom satisfies X≥8μm, wherein the sum of the percentages of the protruding structures within the four width ranges is less than or equal to 100%.

4. The thin film resistor according to claim 1, characterized in that: The shape of the protrusion structure includes at least one of the following: a polygonal pyramid, an inverted cone, a cone, a needle, a tree branch, a tree crown, a hook, a stalactite, an ice hanging shape, a spiral, a sawtooth shape, and a corrugated shape.

5. The thin film resistor according to claim 1, characterized in that: The base layer includes a first conductive layer or a dielectric layer.

6. The thin film resistor according to claim 1, characterized in that: The thin film resistor further includes a film layer, and the film layer is located on a surface of the first resistor layer on a side away from the base layer.

7. The thin film resistor according to claim 6, characterized in that: A second conductive layer is disposed on a side of the film layer away from the first resistance layer.

8. The thin film resistor according to claim 7, characterized in that: The second conductive layer is a single layer or multiple layers.

9. The thin film resistor according to claim 8, characterized in that: A second resistance layer is provided between the film layer and the second conductive layer.

10. The thin film resistor according to any one of claims 1 to 9, characterized in that: The first resistance layer is formed on the surface of the base layer by at least one of electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition.

11. A circuit board, characterized in that: The circuit board comprises the thin film resistor according to any one of claims 1 to 10.

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