A fast response copper-based electro-sensitive resistance chip and a preparation method thereof

Abstract

The application discloses a kind of quick response copper-based electro-sensitive resistance chip and preparation method, it is related to chip preparation related field.The application is by constructing microneedle array structure and nanometer roughening structure on the surface of copper-based electrode layer, and honeycomb-like conductive framework structure and microcrack structure are formed in electro-sensitive function layer, simultaneously by spatial alignment microneedle array structure and honeycomb-like conductive framework structure form corresponding relationship, to establish continuous conduction system between electrode interface and electro-sensitive layer inside;Further combined with the gradient structure formed by high-conductivity transition layer and high-resistance sensitive layer, the effective regulation of electric field distribution is realized, whereby, current can be along the preset path quickly establish conduction channel, significantly reduce response time and threshold voltage, and improve nonlinear coefficient and working stability, under the same conditions, the response time of the chip of the application can be reduced to nanosecond level, nonlinear performance and stability are all superior to traditional structure, and performance improvement comes from the spatial coupling relationship between multiple structures.

Description

Technical Field

[0001] This invention relates to the field of chip fabrication, and in particular to a fast-response copper-based inductor chip and its fabrication method. Background Technology

[0002] A varistor (also known as a voltage-sensitive resistor) is a type of semiconductor device with nonlinear current-voltage characteristics. It is widely used in overvoltage protection, circuit surge suppression, and transient voltage absorption. In the current technology, most common varistors use ZnO-based semiconductor ceramic materials, which form grain boundary barriers by doping with Bi2O3, Sb2O3, etc., thereby achieving nonlinear conductivity. However, as electronic devices develop towards higher integration and higher response speed, higher requirements are placed on the response time, conduction threshold, and stability of varistors.

[0003] Existing technologies typically improve performance by optimizing material formulations or introducing single structures. For example, roughening the electrode surface can enhance the electric field distribution, or introducing porous structures in the inductor layer can improve the conduction path. Alternatively, microcracks can be generated by controlling the sintering process to regulate conduction behavior. However, most of these technologies are single-structure or simple superposition improvements, and there is a lack of clear spatial correspondence and collaborative design between different structures. This results in the inability to form an effective linkage between the electric field distribution, conduction path, and triggering mechanism, thus limiting further improvements in the response speed and nonlinear performance of inductors. In addition, the conduction paths in existing technologies are mostly randomly distributed, making it difficult to achieve a stable and controllable fast conduction process. Summary of the Invention

[0004] Therefore, in order to overcome the above-mentioned shortcomings, the present invention provides a fast-response copper-based inductor chip and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a fast-response copper-based inductor chip, comprising a copper-based electrode layer, an inductor functional layer, and a protective encapsulation layer. The inductor functional layer is disposed on the surface of the copper-based electrode layer, and the surface of the copper-based electrode layer is provided with a composite interface structure. The composite interface structure includes a microneedle array structure and a nano-roughened structure covering its surface, wherein the tip curvature radius of the microneedle array is 0.1–5 μm. The inductor functional layer is a layered gradient structure constructed along the thickness direction, comprising: a highly conductive transition layer near the electrode side; a conductive network embedding layer located in the middle; and a high-resistance sensitive layer away from the electrode side. The protective encapsulation layer is disposed on top of the inductor functional layer. The conductive network embedding layer is provided with a three-dimensional interconnected honeycomb conductive skeleton structure. The conductive skeleton has an open structure and forms a discontinuous interface coating structure with the surrounding electrosensitive material. Microcrack structures are distributed along the boundary of the honeycomb conductive skeleton inside the electrosensitive functional layer. The microcracks are non-through structures when no voltage is applied, but form conductive paths under the action of electric field or heat. The top of the microneedle array at least partially overlaps with the node region of the honeycomb conductive skeleton in the vertical projection direction. Preferably, the distribution density of the microneedle array is 10. 4 ~10 8 The number of microneedles per cm² is 20% to 80%, and the overlap ratio between the top of the microneedle array and the honeycomb conductive skeleton node is 20% to 80%.

[0006] Preferably, the resistivity of the highly conductive transition layer is 1 / 10 to 1 / 100 of that of the highly resistive sensitive layer, and its thickness accounts for 10% to 30% of the total thickness of the electrosensitive functional layer.

[0007] Preferably, the honeycomb conductive skeleton has a pore size of 1 to 50 μm and a spatial connectivity of 60% to 95%.

[0008] Preferably, the width of the microcracks is 10 nm to 2 μm, and their distribution density is 10. 2 ~10 5 Strips / mm².

[0009] Preferably, the electrosensitive functional layer is further provided with a high-resistivity phase region distributed along the boundary of the honeycomb conductive skeleton, and the resistivity of the high-resistivity phase region is 2 to 20 times that of the surrounding electrosensitive material.

[0010] Preferably, the electrosensitive functional layer is a ZnO-based semiconductor ceramic material, doped with Bi2O3, Sb2O3 and transition metal oxides, and the total doping amount is 0.5% to 5%.

[0011] Preferably, the specific steps are as follows: S1 etches and field-induced processes on copper-based electrodes to form a microneedle array structure and a nano-coarsened composite structure on their surface. S2 prepares an electrosensitive paste containing a conductive framework precursor and a sacrificial template material; S3 uses a partitioned deposition method to sequentially construct a highly conductive transition layer, a conductive network embedding layer, and a high-resistance sensitive layer on the surface of the copper-based electrode. S4 decomposes the sacrificial template material through a sintering process to form a three-dimensional interconnected honeycomb conductive skeleton structure, and forms a microcrack structure at the boundary of the conductive skeleton. S5 employs a transient rapid sintering process to achieve densification. The sacrificial template material is an organic microsphere or organic fiber with a particle size of 0.5–20 μm and a decomposition temperature 100–300 °C lower than the sintering temperature. The transient rapid sintering is a pulsed current sintering or flash sintering process, with a sintering time of 1 to 300 seconds; S3 employs multi-nozzle printing or multiple screen printing methods to achieve the partitioning of different component materials; After sintering, rapid cooling is performed at a cooling rate of ≥50℃ / min to fix the honeycomb conductive skeleton structure and microcrack structure.

[0012] Preferably, the forming area of ​​the microneedle array structure and the generating area of ​​the conductive skeleton structure are spatially matched by template positioning or pattern alignment, so that the top of the microneedle array and the honeycomb conductive skeleton node area correspond in the vertical direction.

[0013] The beneficial effects of this invention are: This invention constructs a microneedle array structure and a nano-coarsened structure on the surface of a copper-based electrode layer, and forms a honeycomb conductive framework structure and a microcrack structure in the inductor-sensitive functional layer. Simultaneously, spatial alignment establishes a correspondence between the microneedle array structure and the honeycomb conductive framework structure, thereby establishing a continuous conductive system between the electrode interface and the interior of the inductor-sensitive layer. Furthermore, by combining a gradient structure formed by a highly conductive transition layer and a highly resistive sensitive layer, effective control of the electric field distribution is achieved. This allows the current to quickly establish a conductive channel along a preset path, significantly reducing response time and threshold voltage, and improving nonlinear coefficient and operational stability. Experimental results show that, under the same conditions, the response time of the chip of this invention can be reduced to the nanosecond level, and its nonlinear performance and stability are superior to traditional structures. Moreover, the performance improvement stems from the spatial coupling relationship between the multiple structures. Attached Figure Description

[0014] Figure 1 This is a cross-sectional structural diagram of the present invention.

[0015] Among them: copper-based electrode layer-1, electrosensitive functional layer-2, protective encapsulation layer-3, microneedle array structure-11, nano-coarsened structure-12, high conductivity transition layer-21, conductive network embedding layer-22, high resistance sensitive layer-23, conductive skeleton structure-221, and microcrack structure-24. Detailed Implementation

[0016] To further explain the technical solution of the present invention, a detailed description is provided below through specific embodiments.

[0017] like Figure 1As shown, a fast-response copper-based inductor chip includes a copper-based electrode layer 1, an inductor functional layer 2, and a protective encapsulation layer 3 arranged sequentially from bottom to top. The inductor functional layer 2 is directly constructed on the surface of the copper-based electrode layer 1 and forms an interface connection with it. The copper-based electrode layer 1 is made of high-purity copper material with a thickness of 100 μm, and a composite interface structure is integrally formed on its surface. The composite interface structure includes a microneedle array structure 11 and a nano-coarsened structure 12 covering its surface. The microneedle array structure 11 is distributed in an array and extends perpendicularly to the surface of the copper-based electrode layer 1. Its height is 5 μm, its bottom diameter is 3 μm, its tip curvature radius is 0.8 μm, and its distribution density is 5 × 10⁻⁶. 5 pcs / cm 2 The nano-coarsened structure 12 is composed of nanoparticles with an average particle size of 80 nm and covers the surface and gap area of ​​the microneedle array structure 11, thereby forming a multi-scale contact interface between the copper-based electrode layer 1 and the electrosensitive functional layer 2, and the protective encapsulation layer 3 is disposed on the top of the electrosensitive functional layer 2.

[0018] The electrosensitive functional layer 2 comprises, along its thickness direction, a highly conductive transition layer 21, a conductive network embedding layer 22, and a high-resistivity sensitive layer 23. The highly conductive transition layer 21 is closely attached to the top of the microneedle array structure 11 and fills its gaps; it has a thickness of 10 μm and a resistivity of 5 Ω·cm. The conductive network embedding layer 22 is disposed above the highly conductive transition layer 21, and has a thickness of 20 μm. The high-resistivity sensitive layer 23 is disposed on the side of the conductive network embedding layer 22 away from the electrode, and has a thickness of 20 μm and a resistivity of 300 Ω·cm. This creates a resistance gradient connection within the electrosensitive functional layer 2, and forms a three-dimensional interconnected honeycomb structure within the conductive network embedding layer 22. The conductive framework structure 221 has an open-pore interconnected structure with a pore diameter of about 10 μm, a connectivity of about 80%, and a framework wall thickness of about 1 μm. A portion of the honeycomb conductive framework structure 221 overlaps at least partially with the top of the microneedle array structure 11 in the vertical projection direction, with an overlap ratio of about 50%. This forms a corresponding connection between the electrode interface structure and the internal conductive framework in space. The honeycomb conductive framework structure 221 forms a discontinuous encapsulation relationship with the surrounding electrosensitive material, with the contact conductive area accounting for about 60% and the non-contact area accounting for about 40%, thus constituting a discrete conductive unit structure.

[0019] Microcrack structures 24 are further disposed in the boundary region of the honeycomb conductive framework structure 221. The microcrack structures 24 are distributed along the framework interface and are coupled to it. Their width is about 200 nm, their length is 5 to 20 μm, and their density is about 1 × 10⁻⁶. 4 strips / mm 2When no voltage is applied, it is a non-continuous structure. Under the action of electric field or heat, it forms a transient conductive connection with the honeycomb conductive skeleton structure 221. At the same time, a high-resistivity phase region 25 is also provided in the boundary region of the honeycomb conductive skeleton structure 221. Its resistivity is about 1000 Ω·cm, which is about 3 times that of the surrounding electrosensitive material. Thus, a local resistance gradient connection relationship is formed between the conductive skeleton structure 221 and the electrosensitive material. Through the above structure, a continuous interlayer connection system is formed in space between the copper-based electrode layer 1, the microneedle array structure 11, the honeycomb conductive skeleton structure 221 and the microcrack structure 24.

[0020] A method for fabricating the aforementioned fast-response copper-based inductor chip, which achieves the aforementioned connection relationship through pre-construction of structure and spatial alignment control, specifically includes the following steps: First, chemical etching is performed on the copper-based electrode layer 1 (15% FeCl3 solution, 40°C, 120s) and an electric field-induced treatment is applied (10V, 60s) to form a microneedle array structure 11 in situ on its surface, and a nano-coarsened structure 12 is further formed on its surface, thereby obtaining a composite interface structure; Second, an inductor paste is prepared, which includes ZnO-based powder (0.5μm particle size), a conductive framework precursor (5wt%), and The sacrificial template material is PMMA microspheres with a particle size of 8 μm and a decomposition temperature of 350℃. Subsequently, a highly conductive transition layer 21 (10 μm thick), a conductive network embedding layer 22 (20 μm thick), and a high-resistivity sensitive layer 23 (20 μm thick) are sequentially deposited on the surface of the composite interface structure using multiple screen printing processes. During the deposition process, the printing area is controlled by a mask positioning process to ensure that the distribution area of ​​the sacrificial template in the conductive network embedding layer 22 is spatially aligned with the top position of the microneedle array structure 11, thereby ensuring that the subsequently formed honeycomb conductive skeleton structure 221 corresponds spatially with the microneedle array structure 11.

[0021] In the subsequent sintering process, the temperature was increased to 1200℃ at a rate of 10℃ / min and held for 30min, causing the sacrificial template material to decompose and forming a honeycomb-shaped conductive skeleton structure 221 in situ inside the conductive network embedded layer 22. Simultaneously, under the action of material shrinkage and interfacial stress, microcrack structures 24 were formed along the boundary region of the honeycomb-shaped conductive skeleton structure 221, creating an interfacial connection between the conductive skeleton structure 221 and the microcrack structure 24 in space. Subsequently, a flash sintering process was used for rapid densification (electric field strength 300V / cm, time 60s), and after sintering, the temperature was increased to 80℃. Rapid cooling at a cooling rate of ℃ / min is used to fix the structural morphology and connection relationship of the honeycomb conductive skeleton structure 221 and the microcrack structure 24. Through the continuous process of “composite interface structure formation—layered deposition—template decomposition—skeleton structure 221 generation—microcrack structure 24 formation—spatial alignment locking”, the microneedle array structure 11 and the honeycomb conductive skeleton structure 221 form a stable spatial correspondence, and the microcrack structure 24 forms a controlled distribution along the skeleton interface, thereby realizing the synchronous construction of the connection relationship and spatial matching relationship between the structures in the claims.

[0022] Example 1: A chip was fabricated according to the above method, with the following structural parameters: Copper-based electrode layer 1 thickness: 100 μm; Microneedle array structure 11: height 5 μm, bottom diameter 3 μm, tip curvature radius 0.8 μm, density 5 × 10⁻⁶. 5 The microneedle array 11 has a particle size of 80 nm and a density of approximately 50%. The total thickness of the electrosensitive functional layer 2 is 50 μm, including: a highly conductive transition layer 21 with a thickness of 10 μm and a resistivity of 5 Ω·cm; a conductive network embedding layer 22 with a thickness of 20 μm; a high-resistivity sensitive layer 23 with a thickness of 20 μm and a resistivity of 300 Ω·cm; parameters of the honeycomb conductive framework structure 221: pore size 10 μm, connectivity 80%, wall thickness 1 μm; and parameters of the microcrack structure 24: width 200 nm, length 5–20 μm, density 1 × 10⁻⁶. 4 strips / mm²; High resistivity phase region 25: resistivity 1000Ω·cm; Comparative Example 1: The surface of the copper-based electrode layer 1 is planar, without the microneedle array structure 11, and the rest of the structure is the same as in Example 1.

[0023] Comparative Example 2: The conductive network embedding layer 22 does not contain a sacrificial template, forming a dense structure, and the rest is the same.

[0024] Comparative Example 3: Microcrack formation was suppressed by reducing the cooling rate to 5°C / min, with the rest remaining the same.

[0025] Comparative Example 4: The electrosensitive functional layer 2 is a uniform single-layer structure with a total thickness of 50 μm and a resistivity of approximately 200 Ω·cm.

[0026] Comparative Example 5: The microneedle array 11 and the honeycomb conductive skeleton structure 221 are randomly distributed without alignment control (overlap ratio <10%).

[0027] Test methods and equipment: semiconductor parameter analyzer; voltage range: 0~500V; test environment: 25℃, humidity 50%; response time: step voltage method (10V→200V); nonlinear coefficient α: calculated according to standard formula; stability test: 1000 cycles of loading.

[0028] Table 1: Comparison of Electrical Performance Table 2: Stability Tests The experimental results show that Example 1 is significantly better than the comparative examples in terms of response time, threshold voltage, nonlinear coefficient, and stability. Removing the microneedle array structure 11 leads to a decrease in electric field concentration, significantly prolonging the response time and increasing the threshold voltage. Removing the honeycomb conductive skeleton structure 221 weakens the internal three-dimensional conduction path, reducing nonlinear characteristics. Suppressing the formation of the microcrack structure 24 causes conduction triggering lag and a decrease in response speed. Eliminating the gradient structure results in uneven electric field distribution and the worst overall performance. While retaining each structure but without spatial alignment, the performance is improved but still significantly worse than Example 1. This indicates that the present invention is not a simple superposition of individual structures, but rather achieves a continuous and efficient conduction system between the electrode interface and the inside of the inductive functional layer through the spatial correspondence of the microneedle array structure 11, the honeycomb conductive skeleton structure 221, and the microcrack structure 24, thereby achieving a synergistic improvement in fast response and high nonlinear characteristics.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fast-response copper-based inductor chip, characterized in that: It includes a copper-based electrode layer, an electrosensitive functional layer, and a protective encapsulation layer. The electrosensitive functional layer is disposed on the surface of the copper-based electrode layer. The surface of the copper-based electrode layer is provided with a composite interface structure. The composite interface structure includes a microneedle array structure and a nano-coarsened structure covering its surface. The tip curvature radius of the microneedle array is 0.1 to 5 μm. The electrosensitive functional layer is a layered gradient structure constructed along the thickness direction, including: a highly conductive transition layer near the electrode side; a conductive network embedding layer located in the middle; and a highly resistive sensitive layer away from the electrode side. The protective encapsulation layer is disposed on top of the electrosensitive functional layer. The conductive network embedding layer is provided with a three-dimensional interconnected honeycomb conductive skeleton structure. The conductive skeleton has an open structure and forms a discontinuous interface coating structure with the surrounding electrosensitive material. Microcrack structures are distributed along the boundary of the honeycomb conductive skeleton inside the electrosensitive functional layer. The microcracks are non-through structures when no voltage is applied, but form conductive paths under the action of electric field or heat. The top of the microneedle array at least partially overlaps with the node region of the honeycomb conductive skeleton in the vertical projection direction.

2. The fast-response copper-based inductor chip according to claim 1, characterized in that: The distribution density of the microneedle array is 10. 4 ~10 6 The number of microneedles per cm² is 20% to 80%, and the overlap ratio between the top of the microneedle array and the honeycomb conductive skeleton node is 20% to 80%.

3. The fast-response copper-based inductor chip according to claim 1, characterized in that: The resistivity of the highly conductive transition layer is 1 / 10 to 1 / 100 of that of the highly resistive sensitive layer, and its thickness accounts for 10% to 30% of the total thickness of the electrosensitive functional layer.

4. The fast-response copper-based inductor chip according to claim 1, characterized in that: The honeycomb-shaped conductive framework has a pore size of 1–50 μm and a spatial connectivity of 60%–95%.

5. The fast-response copper-based inductor chip according to claim 1, characterized in that: The width of the microcracks is 10 nm to 2 μm, and their distribution density is 10. 2 ~10 5 Strips / mm².

6. The fast-response copper-based inductor chip according to claim 1, characterized in that: The electrosensitive functional layer also includes a high-resistivity phase region distributed along the boundary of the honeycomb conductive skeleton, the resistivity of which is 2 to 20 times that of the surrounding electrosensitive material.

7. The fast-response copper-based inductor chip according to claim 1, characterized in that: The electrosensitive functional layer is a ZnO-based semiconductor ceramic material, doped with Bi2O3, Sb2O3 and transition metal oxides, with a total doping amount of 0.5% to 5%.

8. A method for fabricating a fast-response copper-based inductor chip as described in any one of claims 1 to 7, characterized in that: The specific steps are as follows: S1 etches and field-induced processes on copper-based electrodes to form a microneedle array structure and a nano-coarsened composite structure on their surface. S2 prepares an electrosensitive paste containing a conductive framework precursor and a sacrificial template material; S3 uses a partitioned deposition method to sequentially construct a highly conductive transition layer, a conductive network embedding layer, and a high-resistance sensitive layer on the surface of the copper-based electrode. S4 decomposes the sacrificial template material through a sintering process to form a three-dimensional interconnected honeycomb conductive skeleton structure, and forms a microcrack structure at the boundary of the conductive skeleton. S5 employs a transient rapid sintering process to achieve densification. The sacrificial template material is an organic microsphere or organic fiber with a particle size of 0.5–20 μm and a decomposition temperature 100–300 °C lower than the sintering temperature. The transient rapid sintering is a pulsed current sintering or flash sintering process, with a sintering time of 1 to 300 seconds; S3 employs multi-nozzle printing or multiple screen printing methods to achieve the partitioning of different component materials; After sintering, rapid cooling is performed at a cooling rate of ≥50℃ / min to fix the honeycomb conductive skeleton structure and microcrack structure.

9. The fast-response copper-based inductor chip and its fabrication method according to claim 1, characterized in that: The formation area of ​​the microneedle array structure and the generation area of ​​the conductive skeleton structure are spatially matched by template positioning or pattern alignment, so that the top of the microneedle array and the honeycomb conductive skeleton node area correspond in the vertical direction.

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