Composite electrode structure, graphite mold and semiconductor packaging structure

Abstract

The utility model relates to a composite electrode structure, a graphite mold and a semiconductor packaging structure. The composite electrode structure comprises a first alloy layer; the electrode layer is located on one side of the first alloy layer, and the electrode layer comprises a copper-diamond composite material; the second alloy layer is located on the side, away from the first alloy layer, of the electrode layer, and the difference value of the thermal expansion coefficients of the first alloy layer and the electrode layer and the difference value of the thermal expansion coefficients of the second alloy layer and the electrode layer are both smaller than a threshold value. The composite electrode structure is good in thermal conductivity and high in reliability.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a composite electrode structure, a graphite mold, and a semiconductor packaging structure. Background Art

[0002] With the development of semiconductor technology, electronic devices are moving towards miniaturization, lightweight, high performance, and multi-functionality. Due to the rapid increase in chip integration, the heat generated per unit area of ​​integrated circuits is increasing. In order to quickly dissipate heat, higher requirements are placed on the performance of packaging materials.

[0003] In traditional technology, semiconductor devices usually use a ceramic tube shell packaging structure, which consists of an anode electrode, a cathode electrode, and an insulating ceramic ring. The three are interconnected by oxygen-free copper flange welding to achieve the sealing of the ceramic tube shell and protect the chip from the influence of the external environment.

[0004] However, the structure in the traditional technology has poor reliability. Utility Model Content

[0005] Based on this, it is necessary to provide a composite electrode structure, graphite mold, and semiconductor packaging structure that take into account both thermal conductivity and reliability to address the above technical problems.

[0006] In a first aspect, the present application provides a composite electrode structure, comprising:

[0007] a first alloy layer;

[0008] an electrode layer, located on one side of the first alloy layer, the electrode layer comprising a copper-diamond composite material;

[0009] The second alloy layer is located on a side of the electrode layer away from the first alloy layer, wherein the difference in thermal expansion coefficient between the first alloy layer and the electrode layer, and the difference in thermal expansion coefficient between the second alloy layer and the electrode layer are both less than a threshold value, and the first alloy layer, the electrode layer, and the second alloy layer are integrally formed.

[0010] In one embodiment, the materials of the first alloy layer and the second alloy layer respectively include at least one of a molybdenum-copper alloy and a tungsten-copper alloy.

[0011] In one embodiment, the porosity of the first alloy layer and the second alloy layer is respectively greater than or equal to 40%.

[0012] In one embodiment, the copper-diamond composite material includes a copper matrix and diamond particles; wherein the diamond particles have a particle size of 100 to 300 μm.

[0013] In one embodiment, the electrode layer further comprises:

[0014] The modified material layer is located on the surface of the diamond particles; wherein the material of the modified material layer includes at least one of B, Mo, W, Ti, and Ni.

[0015] In one embodiment, the thickness of the modified material layer is 100-300 nm.

[0016] In one embodiment, the composite electrode structure further comprises:

[0017] A flange layer is located on the outer peripheral side of the first alloy layer, the second alloy layer, and the electrode layer, and the flange layer is integrally formed with at least one of the first alloy layer, the second alloy layer, and the electrode layer.

[0018] In a second aspect, the present application provides a graphite mold for forming a composite electrode structure; wherein the graphite mold comprises:

[0019] A mold body, wherein the mold body is provided with a pouring port, a first cavity, a second cavity, and a third cavity; wherein the first cavity, the second cavity, and the third cavity are sequentially connected in the thickness direction of the mold body, and the pouring port is connected to the third cavity; the first cavity is used to accommodate a first alloy material, the second cavity is used to accommodate a copper-diamond composite material, and the third cavity is used to accommodate a second alloy material;

[0020] a first partition, located between the first chamber and the second chamber;

[0021] The second partition is located between the second chamber and the third chamber; wherein,

[0022] A plurality of through holes are respectively formed on the first separator and the second separator, and the diameter of the through holes is smaller than the diameter of the diamond particles in the copper-diamond composite material.

[0023] In one embodiment, the graphite mold further comprises:

[0024] a fourth chamber, the fourth chamber being located on an outer periphery of the first chamber, the second chamber, and the third chamber and being in communication with at least one of the first chamber, the second chamber, and the third chamber;

[0025] At least one third partition is located between the fourth chamber and a chamber connected to the fourth chamber; a plurality of through holes are formed on the third partition, and the aperture of the through holes is smaller than the particle size of the diamond particles in the copper-diamond composite material.

[0026] In a third aspect, the present application provides a semiconductor packaging structure, comprising two composite electrode structures as described above, wherein the two composite electrode structures serve as two electrodes of a chip to be packaged.

[0027] The composite electrode structure, graphite mold, and semiconductor packaging structure described above include a first alloy layer, an electrode layer, and a second alloy layer stacked in sequence. The electrode layer comprises a copper-diamond composite material, thereby utilizing the high thermal conductivity of copper-diamond to significantly reduce the thermal resistance of the composite electrode structure and improve the thermal conductivity of the device. The difference in thermal expansion coefficient between the first alloy layer and the electrode layer, as well as the difference in thermal expansion coefficient between the second alloy layer and the electrode layer, are both less than a threshold value, resulting in close thermal expansion coefficients for the first, second, and electrode layers, effectively eliminating thermal stress mismatch caused by welding dissimilar metals. The first, electrode, and second alloy layers are integrally formed, improving the reliability of the composite electrode structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic structural diagram of a composite electrode structure in one embodiment;

[0030] Figure 2 This is a second structural diagram of a composite electrode structure in one embodiment;

[0031] Figure 3 Schematic diagram of the structure of a graphite mold in one embodiment;

[0032] Figure 4 A schematic structural diagram of a graphite mold in another embodiment;

[0033] Figure 5 is a schematic diagram of a composite electrode structure in one embodiment;

[0034] Figure 6 FIG. 1 is a schematic structural diagram of a semiconductor packaging structure in one embodiment.

[0035] Description of reference numerals:

[0036] 10-first alloy layer, 20-electrode layer, 30-second alloy layer, 40-flange layer, 51-first chamber, 52-second chamber, 53-third chamber, 61-first partition, 62-second partition, 70-injection port, 54-fourth chamber, 63-third partition, 100-composite electrode structure, 101-electrode main layer, 102-chip to be packaged. DETAILED DESCRIPTION

[0037] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0039] It will be understood that the terms "first", "second", etc. used in this application may be used to describe various elements in this document, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element.

[0040] Spatially relative terms such as "under," "beneath," "beneath," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the drawings is turned over, the element or feature described as "under" or "beneath" or "beneath" the other elements will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" can include both upper and lower orientations. In addition, the device can also include alternative orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0041] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intervening element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc., if there is transmission of electrical signals or data between the connected objects.

[0042] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0043] In one embodiment, Figure 1 As shown, a composite electrode structure is provided, comprising: a first alloy layer 10, an electrode layer 20, and a second alloy layer 30, wherein:

[0044] The electrode layer 20 is located on one side of the first alloy layer 10 , and the electrode layer 20 includes a copper-diamond composite material.

[0045] The copper-diamond composite material can include a copper matrix and diamond particles, with the diamond particles having a particle size of 100 to 300 μm. Diamond has extremely high thermal conductivity and a low thermal expansion coefficient. Therefore, the copper-diamond composite material obtained by combining diamond and copper has excellent heat dissipation performance, utilizing the high thermal conductivity of copper-diamond to improve the thermal conductivity of the device. The copper-diamond composite material can also adjust the diamond filling ratio (the volume ratio of copper to diamond) to achieve a combination and balance of thermal conductivity, thermal expansion, and electrical conductivity.

[0046] The second alloy layer 30 is located on a side of the electrode layer 20 away from the first alloy layer 10 .

[0047] The difference in thermal expansion coefficient between the first alloy layer 10 and the electrode layer 20, as well as the difference in thermal expansion coefficient between the second alloy layer 30 and the electrode layer 20, are both less than a threshold value. In other words, the thermal expansion coefficients of the first alloy layer 10, the second alloy layer 30, and the electrode layer 20 are close, which can reduce thermal stress mismatch and improve lifespan.

[0048] The first alloy layer, the electrode layer, and the second alloy layer are integrally formed, so that the connection between the first alloy layer, the electrode layer, and the second alloy layer is tighter and the reliability is higher.

[0049] In this embodiment, the composite electrode structure includes a first alloy layer 10, an electrode layer 20, and a second alloy layer 30 stacked in sequence. The electrode layer 20 includes a copper-diamond composite material. By utilizing the high thermal conductivity of copper-diamond, the thermal resistance of the composite electrode structure can be greatly reduced, and the thermal conductivity performance of the device can be improved. The difference in thermal expansion coefficient between the first alloy layer 10 and the electrode layer 20, as well as the difference in thermal expansion coefficient between the second alloy layer 30 and the electrode layer 20 are all less than a threshold value, so that the thermal expansion coefficients of the first alloy layer 10, the second alloy layer 30, and the electrode layer 20 are close, which can effectively eliminate the thermal stress mismatch caused by welding dissimilar metals with different thermal expansion coefficients, thereby improving the reliability of the composite electrode structure.

[0050] In one embodiment, the materials of the first alloy layer and the second alloy layer respectively include at least one of a molybdenum-copper alloy and a tungsten-copper alloy.

[0051] Molybdenum copper / tungsten copper has a thermal expansion coefficient close to that of copper diamond, which can reduce thermal stress. Furthermore, molybdenum copper / tungsten copper are easier to machine and grind than diamond, making them easier to process. This ensures that the electrode surface flatness meets design standards and that pressure distribution uniformity meets design requirements. Required positioning holes can also be machined into the outer shape.

[0052] The porosity of the first alloy layer and the second alloy layer is respectively greater than or equal to 40%.

[0053] The first and second alloy layers are porous molybdenum-copper alloy plates and / or porous tungsten-copper alloy plates with a porosity of 40% or greater, facilitating machining. While positioning holes can be machined into the first alloy layer, the second alloy plate, which requires no positioning, can be left flat. Neither the first nor the second alloy layer contains diamond particles, facilitating machining.

[0054] In this embodiment, the materials of the first alloy layer and the second alloy layer are designed to include at least one of molybdenum-copper alloy and tungsten-copper alloy respectively, so that the first alloy layer and the second alloy layer are easy to process and can be made into a desired shape.

[0055] In one embodiment, the electrode layer further includes: a modified material layer located on the surface of the diamond particles.

[0056] The material of the modified material layer includes at least one of B, Mo, W, Ti, and Ni.

[0057] Wherein, the thickness of the modified material layer is 100 to 300 nm.

[0058] Among them, the modified material layer is coated on the surface of the diamond particles to improve the interface thermal conductivity. The principle is that the wettability of copper and diamond is very poor. By coating the modified material (transition metal and the carbide formed by it), the surface bonding state can be improved.

[0059] In this process, multiple layers of different elements or inorganic compounds are coated on the diamond particles. Preferably, synthetic or natural diamond powder having an average particle size between 20 microns and 120 microns is coated with multiple layers of different elements or inorganic compounds. The coating method used is fluidized bed chemical vapor deposition. Alternatively, autocatalytic (electrodeless) aqueous electroless plating can be used. The coated lower layer can be deposited using one method, while the other layers can be deposited using other methods. The individual layers of the coating can be composed of elements or compounds selected from the following group: Cr, W, Mo, Co, Cu, Ti, Si, SiC, TiN, TiC, Ta and Zr. A preferred embodiment of the diamond coating includes a four-layer system, in which the particles are first coated with a layer of Cr, followed by a layer of W, then a layer of Co, and then a layer of Cu. The thickness of each layer is between 30 nanometers and 2 microns.

[0060] In this embodiment, by providing a modified material layer, the bonding degree between copper and diamond particles is improved, thereby ensuring the performance of the copper-diamond composite material.

[0061] In one embodiment, Figure 2 As shown, the composite electrode structure further includes a flange layer 40. The flange layer 40 is located on the outer periphery of the first alloy layer 10, the second alloy layer 30, and the electrode layer 20, and is integrally formed with at least one of the first alloy layer 10, the second alloy layer 30, and the electrode layer 20.

[0062] Among them, the flange layer 40 is located on the outer peripheral side of the first alloy layer 10, the second alloy layer 30, and the electrode layer 20, so as to facilitate the interconnection of the composite electrode structure of the first alloy layer 10, the second alloy layer 30, and the electrode layer 20 with other components to realize the preparation of the packaging structure.

[0063] Among them, the material of the flange layer 40 can include pure copper powder or oxygen-free copper with a thickness of 0.5 to 0.8 mm, so that the flange layer 40 can be deformed well and can meet the plastic deformation requirements of the cold pressing welding process. For example, the anode electrode flange and the cathode electrode flange are both made of copper and are very thin. Under the action of mechanical pressure, the two copper sheets undergo plastic deformation and are squeezed together to achieve interconnection.

[0064] Among them, the flange layer 40 is integrally formed with at least one of the first alloy layer 10, the second alloy layer 30, and the electrode layer 20, thereby eliminating the welding step of the electrode and the flange in the related art. The direct integral forming does not require welding, and the obtained electrode structure has higher reliability.

[0065] In this embodiment, the flange layer 40 is designed to facilitate interconnection between the composite electrode structure and other components, thereby realizing the preparation of a packaging structure.

[0066] In one embodiment, Figure 3 As shown, the present application provides a graphite mold for forming a composite electrode structure. The graphite mold includes: a mold body, a first separator 61, and a second separator 62, wherein:

[0067] The mold body is provided with a pouring port 70, a first chamber 51, a second chamber 52, and a third chamber 53. The first chamber 51, the second chamber 52, and the third chamber 53 are sequentially connected in the thickness direction of the mold body, with the pouring port 70 communicating with the third chamber 53. The first chamber 51 is used to accommodate the first alloy material, the second chamber 52 is used to accommodate the copper-diamond composite material, and the third chamber 53 is used to accommodate the second alloy material.

[0068] The first partition plate 61 is located between the first chamber 51 and the second chamber 52 .

[0069] The second partition plate 62 is located between the second chamber 52 and the third chamber 53 .

[0070] Among them, a plurality of through holes are respectively opened on the first partition 61 and the second partition 62, and the aperture of the through holes is smaller than the particle size of the diamond particles in the copper diamond composite material, thereby ensuring that the diamond particles are only concentrated in the second chamber 52 in the center, and there are no diamond particles in all other chambers, which facilitates the subsequent grinding processing of the first alloy layer 10 and the second alloy layer 30.

[0071] Among them, the first partition 61 and the second partition 62 are porous partitions with a thickness of 0.01 to 0.1 mm. The material of the porous partition is molybdenum or tungsten. The pore size is smaller than the particle size of the diamond particles, which blocks all diamond particles in the second chamber 52, but can ensure that the liquid copper flows to each chamber.

[0072] Among them, the preparation process can be to first fill the diamond particles into the second cavity 52 of the graphite mold, and fill the molybdenum / tungsten metal into the first cavity 51 and the third cavity 53 of the graphite mold, and then in a vacuum high-temperature furnace, melt the copper powder and flow it into the graphite mold, and gradually penetrate into each cavity under the action of air pressure, forming a copper-diamond composite material in the second cavity 52, and forming alloy layers (molybdenum-copper alloy / tungsten-copper alloy) in the first cavity 51 and the third cavity 53 respectively.

[0073] In this embodiment, a graphite mold is provided, which can produce the composite electrode structure in the above embodiment. The composite electrode structure produced by means of the graphite mold is integrally formed, has better reliability, and can ensure that the diamond particles are only present in the electrode layer 20, which facilitates the subsequent processing and grinding of the first alloy layer 10 and the second alloy layer 30 (because the diamond particles are too hard, if they are present in the first alloy layer 10 and the second alloy layer 30, it will cause processing and grinding difficulties).

[0074] In one embodiment, Figure 4 As shown, the graphite mold further includes a fourth cavity 54. The fourth cavity 54 is located on the outer periphery of the first cavity 51, the second cavity 52 and the third cavity 53, and is communicated with at least one of the first cavity 51, the second cavity 52 and the third cavity 53.

[0075] The fourth chamber 54 is used to accommodate pure copper material, serving as the flange layer 40 of the composite electrode structure. The fourth chamber 54 is connected to at least one of the first chamber 51, the second chamber 52, and the third chamber 53, so that the fourth chamber 54 is integrally formed with at least one of the first chamber 51, the second chamber 52, and the third chamber 53.

[0076] At least one third partition plate 63 is located between the fourth chamber 54 and a chamber connected to the fourth chamber 54. The third partition plate 63 is provided with a plurality of through holes, the aperture of which is smaller than the diameter of the diamond particles in the copper-diamond composite material.

[0077] Among them, the preparation process can be to first fill the diamond particles in the second cavity of the graphite mold, fill the molybdenum / tungsten metal in the first cavity and the third cavity of the graphite mold, and there is no metal in the fourth cavity. Then, in a vacuum high-temperature furnace, the copper powder is melted and flows into the graphite mold. Under the action of air pressure, it gradually penetrates into each cavity, forming a copper-diamond composite material in the second cavity, forming alloy layers (molybdenum-copper alloy / tungsten-copper alloy) in the first cavity and the third cavity respectively, and forming pure copper or oxygen-free copper in the fourth cavity. After the copper is completely infiltrated, it is cooled to obtain an integrally formed copper diamond electrode with a copper flange. The upper and lower first alloy layers and the second alloy layers are ground to control the flatness and roughness within the design requirements, and finally the entire layer is nickel-plated with a nickel plating thickness of 6 to 10 μm to complete the preparation of the composite electrode.

[0078] For example, Figure 5 Schematic diagram of the composite electrode structure 100 manufactured in this application, including a middle electrode main body layer 101 (first alloy layer, electrode layer, second alloy layer) and an edge flange layer 40.

[0079] In this embodiment, the composite electrode structure produced with the help of the graphite mold is integrally formed, and the flange layer and the electrode body (electrode layer, first alloy layer, second alloy layer) are integrally formed and manufactured as a whole. Therefore, compared with the process of separately producing the electrode body and the flange in the related art and then welding the electrode body and the flange together, the composite electrode structure produced by the present application omits the welding process, so it is more reliable and more convenient.

[0080] Based on the same inventive concept, an embodiment of the present invention further provides a semiconductor packaging structure. Figure 6 A schematic diagram of a semiconductor packaging structure provided by an embodiment of the present invention is shown in FIG. Figure 6 As shown, the semiconductor package structure includes two composite electrode structures 100 according to any of the above embodiments, with the two composite electrode structures 100 serving as the two electrodes (positive electrode and negative electrode) of the packaged chip 102. Therefore, the semiconductor package structure also has the beneficial effects of the composite electrode structures in the above embodiments. The similarities can be understood by referring to the above explanation of the composite electrode structures and will not be repeated below.

[0081] Throughout this specification, references to terms such as "some embodiments," "other embodiments," and "desired embodiments" indicate that a particular feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative descriptions of these terms do not necessarily refer to the same embodiment or example.

[0082] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A composite electrode structure, characterized in that: include: a first alloy layer; an electrode layer, located on one side of the first alloy layer, the electrode layer comprising a copper-diamond composite material; The second alloy layer is located on a side of the electrode layer away from the first alloy layer, wherein the difference in thermal expansion coefficient between the first alloy layer and the electrode layer, and the difference in thermal expansion coefficient between the second alloy layer and the electrode layer are both less than a threshold value, and the first alloy layer, the electrode layer, and the second alloy layer are integrally formed.

2. The composite electrode structure according to claim 1, characterized in that: The first alloy layer is a porous molybdenum-copper alloy plate and / or a porous tungsten-copper alloy plate; the second alloy layer is a porous molybdenum-copper alloy plate and / or a porous tungsten-copper alloy plate; the porosity of the first alloy layer and the second alloy layer is respectively greater than or equal to 40%.

3. The composite electrode structure according to claim 1, characterized in that: The electrode layer further comprises: The modified material layer is located on the surface of the diamond particles in the copper-diamond composite material.

4. The composite electrode structure according to claim 3, characterized in that: The thickness of the modified material layer is 100-300 nm.

5. The composite electrode structure according to claim 1, characterized in that: The composite electrode structure further comprises: A flange layer is located on the outer peripheral side of the first alloy layer, the second alloy layer, and the electrode layer, and the flange layer is integrally formed with at least one of the first alloy layer, the second alloy layer, and the electrode layer.

6. The composite electrode structure according to claim 5, characterized in that: The thickness of the flange layer is 0.5-0.8 mm.

7. A graphite mold, characterized in that: Used to form a composite electrode structure; wherein the graphite mold comprises: A mold body, wherein the mold body is provided with a pouring port, a first cavity, a second cavity, and a third cavity; wherein the first cavity, the second cavity, and the third cavity are sequentially connected in the thickness direction of the mold body, and the pouring port is connected to the third cavity; the first cavity is used to accommodate a first alloy material, the second cavity is used to accommodate a copper-diamond composite material, and the third cavity is used to accommodate a second alloy material; a first partition, located between the first chamber and the second chamber; The second partition is located between the second chamber and the third chamber; wherein, A plurality of through holes are respectively formed on the first separator and the second separator, and the diameter of the through holes is smaller than the diameter of the diamond particles in the copper-diamond composite material.

8. The graphite mold according to claim 7, characterized in that The graphite mold also includes: a fourth chamber, the fourth chamber being located on an outer periphery of the first chamber, the second chamber, and the third chamber and being in communication with at least one of the first chamber, the second chamber, and the third chamber; At least one third partition is located between the fourth chamber and a chamber connected to the fourth chamber; a plurality of through holes are formed on the third partition, and the aperture of the through holes is smaller than the particle size of the diamond particles in the copper-diamond composite material.

9. A semiconductor packaging structure, characterized in that: It comprises two composite electrode structures according to any one of claims 1 to 6, and the two composite electrode structures serve as two electrodes of a chip to be packaged respectively.

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