Bump structure

Abstract

The invention provides a bump structure arranged on a chip. The bump structure comprises a first metal layer, a second metal layer and a supporting layer, the first metal layer is made of gold. The second metal layer is made of gold. The supporting layer is arranged between the first metal layer and the second metal layer, is arranged on the chip through the first metal layer and is electrically connected with the chip. The supporting layer is of a layered structure with the hardness higher than that of the first metal layer and the second metal layer and is composed of any one of nickel, cobalt and iron or a combination of the nickel, the cobalt and the iron.

Description

Technical Field

[0001] The present invention relates to a bump structure disposed on a chip. Background Art

[0002] In applications in different fields, there are often different hardness requirements for the bump structure on a chip. Currently, in order to meet the requirements of various bump hardnesses, bumps with different hardness values are applicable to different application scenarios. Generally, most of them are experimented by continuously adjusting the composition of the electroplating solution and the parameters in the process to meet the requirements of the bump hardness. However, the current method of adjusting the bump hardness is difficult to accurately achieve the above various requirements, resulting in a significant increase in the process time and cost. Summary of the Invention

[0003] The present invention provides a bump structure that can accurately meet the hardness requirements while significantly shortening the R & D process time.

[0004] A bump structure of the present invention is disposed on a chip, and includes a first metal layer, a second metal layer, and a support layer. Both the first metal layer and the second metal layer are composed of gold. The support layer is disposed between the first metal layer and the second metal layer, and is disposed on the chip through the first metal layer and electrically connected. The support layer is a layered structure with a hardness higher than that of the first metal layer and the second metal layer, and is composed of any one of nickel, cobalt, iron or a combination thereof.

[0005] In an embodiment of the present invention, the total thickness of the above bump structure is between 9 microns and 17 microns.

[0006] In an embodiment of the present invention, the Vickers hardness of the above bump structure is greater than or equal to 110.

[0007] In an embodiment of the present invention, the thickness of the above support layer is between 1 micron and 3 microns.

[0008] In an embodiment of the present invention, the thickness of the above second metal layer is between 1.5 microns and 3 microns.

[0009] In an embodiment of the present invention, the thickness of the above first metal layer is the total thickness of the bump structure minus the sum of the thicknesses of the support layer and the second metal layer.

[0010] In an embodiment of the present invention, the Vickers hardness of the above bump structure is between 50 and 74.

[0011] In an embodiment of the present invention, the thickness of the above support layer is between 1 micron and 2 microns.

[0012] In an embodiment of the present invention, the thickness of the above second metal layer is between 3.5 microns and 5 microns.

[0013] In an embodiment of the present invention, the thickness of the above-mentioned first metal layer is the total thickness of the bump structure minus the sum of the thickness of the support layer and the thickness of the second metal layer.

[0014] Based on the above, through structural design, the bump structure of the present invention introduces a support layer with relatively high hardness between the two metal layers, which can be simply and elastically adjusted to meet different application fields and more accurately achieve the hardness requirements.

[0015] To make the above features and advantages of the present invention more obvious and understandable, specific embodiments are hereinafter given and described in detail in conjunction with the accompanying drawings as follows. Description of the Drawings

[0016] Figure 1 is a schematic diagram of a bump structure according to an embodiment of the present invention;

[0017] Figure 2 is a schematic diagram of a bump structure according to another embodiment of the present invention. Detailed Description of the Embodiments

[0018] In the following detailed description, for the purpose of illustration rather than limitation, exemplary embodiments revealing specific details are set forth in order to provide a thorough understanding of the various principles of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without departing from the specific details disclosed herein. In addition, descriptions of well-known devices, methods, and materials may be omitted so as not to obscure the description of the various principles of the present invention.

[0019] With reference to the accompanying drawings of this embodiment, the present invention is more fully described. However, the present invention may also be embodied in various different forms and should not be limited to the embodiments described herein. The thickness, dimensions, or sizes of the layers or regions in the drawings are enlarged for clarity. The same or similar reference numerals represent the same or similar elements, and will not be repeated in the following paragraphs.

[0020] Unless otherwise specified, the term "between" used in this specification for defining a numerical range is intended to cover the range equal to the endpoint values and the range between the endpoint values. For example, if a dimension range is between a first value and a second value, it means that the dimension range can cover the first value, the second value, and any value between the first value and the second value.

[0021] Figure 1 is a schematic diagram of a bump structure according to an embodiment of the present invention. Please refer to Figure 1, in this embodiment, the bump structure 100 is disposed on the chip 10, and it includes a first metal layer 110, a second metal layer 120, and a support layer 130. The support layer 130 is disposed between the first metal layer 110 and the second metal layer 120, and is disposed on the chip 10 through the first metal layer 110 and electrically connected. In addition, both the first metal layer 110 and the second metal layer 120 are composed of gold, and the support layer 130 is a layered structure with a hardness higher than that of the first metal layer 110 and the second metal layer 120 and is composed of any one of nickel, cobalt, or iron. Accordingly, through the structural design, the bump structure 100 of this embodiment introduces a support layer 130 with a higher hardness between the first metal layer 110 and the second metal layer 120, which can simply and elastically respond to different application fields and more accurately meet the hardness requirements.

[0022] For example, the first metal layer 110, the second metal layer 120, and the support layer 130 are sequentially formed by an electroplating process. Since the two-metal layer 120 composed of gold can adopt the existing gold bump process conditions, there is no need to significantly adjust its plating solution and electroplating parameters (such as plating solution temperature, current density, annealing temperature, electroplating time, etc.) or re-experiment with suitable parameters. Only according to the actual application requirements, the support layer 130 is introduced at an appropriate position to further fine-tune the required hardness. For example, when the material used for the support layer 130 is a nickel layer, due to the fact that the hardness of the nickel layer material is harder than that of the gold layer, the complexity of fine-tuning the bump process parameters is relatively low. In this way, while meeting the hardness requirements and providing better bondability, the process difficulty and manufacturing cost can be significantly reduced, but the present invention is not limited thereto.

[0023] In this embodiment, the bump structure 100 can be applied to, for example, chip on glass, but the present invention is not limited thereto. In this application field, there are relatively high hardness requirements for the bump structure 100 (which can be called hard bumps). The Vickers hardness of the bump structure 100 is, for example, greater than or equal to 110 HV. In this way, it can ensure that the subsequent bonding material (such as an anisotropic conductive film (ACF)) can indeed deform and break after pressing to achieve the effect of electrical connection, but the present invention is not limited thereto. Here, the Vickers hardness of the bump structure 100 is the average hardness of the first metal layer 110, the second metal layer 120, and the support layer 130. The existing hard gold bump process conditions need to be adjusted and coordinated through a variety of electroplating parameters to achieve a Vickers hardness of about 90 to 105 HV, and for every 1 HV increase in Vickers hardness, it is necessary to re-adjust and experiment. In contrast, in this embodiment, through the design of the bump structure 100, the hardness can reach greater than or equal to 110 HV without spending a long adjustment process and experiment time to achieve better bondability.

[0024] In some embodiments, the chip 10 includes a substrate 11, pads 12, an under bump metal (UBM) layer 13, and a passivation layer 14. The substrate 10 is, for example, a wafer. The material of the pads 12 is, for example, aluminum or other suitable metals. The under bump metal (UBM) layer 13 is, for example, copper or other suitable metals. The material of the passivation layer 14 is, for example, silicon oxide, silicon nitride, or other suitable insulating materials. The chip 10 can be any suitable type of chip according to different application fields, and the present invention is not limited thereto.

[0025] In some embodiments, through the design of the thickness ratio among the first metal layer 110, the second metal layer 120, and the support layer 130, it is possible to be closer to the required hardness specifications. For example, the total thickness 100T of the bump structure 100 is between 9 microns and 17 microns, the thickness 130T of the support layer 130 is between 1 micron and 3 microns, the thickness 120T of the second metal layer 120 is between 1.5 microns and 3 microns, and the thickness 110T of the first metal layer 110 is the total thickness 100T of the bump structure 100 minus the sum of the thickness 130T of the support layer 130 and the thickness 120T of the second metal layer 120.

[0026] In this embodiment, the under bump metal layer 13 has a groove R1, such that the top surface 120u of the corresponding formed second metal layer 120 also has a groove R2. Therefore, both the first metal layer 110 and the second metal layer 120 have non-uniform thicknesses. The thickness 110T of the aforementioned first metal layer 110 can be the maximum thickness in the first metal layer 110 (the distance from the top surface of the first metal layer 110 to the bottom surface of the groove R1), and the thickness 120T of the second metal layer 120 can be the minimum thickness in the second metal layer 120 (the distance from the bottom surface of the groove R2 to the top surface of the support layer 130), as Figure 1 shown, but the present invention is not limited thereto. Here, the horizontal height at which the top surface 120u of the second metal layer 120 is located can be higher than the horizontal height at which the bottom of the groove R2 is located.

[0027] In some embodiments, in order to provide better bump support, the setting position of the support layer 130 can be adjacent to the top surface 100u of the bump structure 100. For example, it is adjacent to the top surface 120u of the second metal layer 120 and relatively far from the central region of the bump structure 100, but the present invention is not limited thereto.

[0028] It must be noted here that the following embodiments follow the component numbers and some contents of the above embodiments, where the same or similar numbers are used to represent the same or similar components, and the description of the same technical content is omitted. For the description of the omitted part, reference can be made to the foregoing embodiments, and the following embodiments will not be repeated.

[0029] Figure 2It is a schematic diagram of a bump structure according to another embodiment of the present invention. Please refer to Figure 2 , compared with Figure 1 's bump structure 100, the bump structure 200 of this embodiment can be applied to, for example, chip on film, such as inner lead bonding (ILB) process, but the present invention is not limited thereto. In this application field, the Vickers hardness of the bump structure 200 is, for example, between 50 and 74 (which can be regarded as a soft bump), and in this embodiment, by adjusting the thickness ratio and / or structural configuration of the first metal layer 210, the second metal layer 220 and the support layer 230 in the bump structure 200, this requirement can be met. Here, the existing soft gold bump process conditions can only achieve a Vickers hardness of about 40HV to at most nearly 50HV through the coordination of various electroplating parameter adjustments, and for each 1HV increase in Vickers hardness, the test needs to be readjusted. In contrast, in this embodiment, through the design of the bump structure 200, without spending a long adjustment process and test time, the hardness can reach between 50 and 74HV to achieve better bondability.

[0030] For example, in terms of the thickness ratio, the total thickness 200T of the bump structure 200 is between 9 microns and 17 microns, the thickness 230T of the support layer 230 is between 1 micron and 2 microns, the thickness 220T of the second metal layer 220 is between 3.5 microns and 5 microns, and the thickness 210T of the first metal layer 210 is the total thickness 200T of the bump structure 200 minus the sum of the thickness 230T of the support layer 230 and the thickness 220T of the second metal layer 220.

[0031] In addition, in terms of the structural configuration, the setting position of the support layer 230 can be away from the top surface 200u of the bump structure 200, that is, away from the top surface 220u of the second metal layer 220 and relatively close to the central region of the bump structure 200, but the present invention is not limited thereto.

[0032] It should be noted that although the support layer in the above embodiment is shown as a single-layered structure, however, the present invention does not limit the number of layers of the support layer. According to the actual design requirements, a multi-layer support layer can be used, and different layers of the support layer can also be composed of different metals, such as nickel layer / cobalt layer / iron layer stacked on each other, etc. By adjusting the number of layers and thickness, in this way, more application fields can be covered.

[0033] In summary, through structural design, the bump structure of the present invention introduces a support layer with higher hardness between the two metal layers, which can simply and elastically adapt to different application fields and more accurately meet the hardness requirements.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bump structure, arranged on a chip, characterized in that: The bump structure comprises: The first metal layer is composed of gold; A second metal layer composed of gold; and A support layer is disposed between the first metal layer and the second metal layer, and is disposed on the chip through the first metal layer and electrically connected, wherein the support layer is a layered structure with a hardness higher than that of the first metal layer and the second metal layer and is composed of any one of nickel, cobalt, and iron or a combination thereof.

2. The bump structure according to claim 1, characterized in that: The total thickness of the bump structure is between 9 micrometers and 17 micrometers.

3. The bump structure according to claim 2, characterized in that: The Vickers hardness of the bump structure is greater than or equal to 110.

4. The bump structure according to claim 3, characterized in that: The thickness of the support layer is between 1 micron and 3 microns.

5. The bump structure according to claim 3, characterized in that: The thickness of the second metal layer is between 1.5 micrometers and 3 micrometers.

6. The bump structure according to claim 3, characterized in that: The thickness of the first metal layer is the total thickness of the bump structure minus the sum of the thickness of the support layer and the thickness of the second metal layer.

7. The bump structure according to claim 2, characterized in that: The Vickers hardness of the bump structure is between 50 and 74.

8. The bump structure according to claim 7, characterized in that: The thickness of the support layer is between 1 micron and 2 microns.

9. The bump structure according to claim 7, characterized in that: The thickness of the second metal layer is between 3.5 micrometers and 5 micrometers.

10. The bump structure according to claim 7, characterized in that: The thickness of the first metal layer is the total thickness of the bump structure minus the sum of the thickness of the support layer and the thickness of the second metal layer.

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