Metal multilayer structure capable of reducing stress influence
By setting a sandwich-structured metal transition layer in a multi-layered metal structure, the problems of high stress and low adhesion between metal layers are solved, thereby improving the adhesion strength and reducing the stress between metal layers, and enhancing the stability and solderability of the electrode.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SICHUAN GUANGYI MICROELECTRONICS CO LTD
- Filing Date
- 2025-05-09
- Publication Date
- 2026-05-19
AI Technical Summary
In the existing technology, the preparation of multilayer metal structures suffers from high stress and low adhesion, which can easily lead to the breakage of metal connection surfaces, affecting the stability and solderability of the electrodes.
A metal transition layer consisting of alternating layers of two metals is placed between two metal structures. By adjusting the thickness difference of the transition layer, a mixture is formed between adjacent metals, which enhances adhesion strength and reduces stress.
It improves the adhesion between metal layers, reduces the stress at the metal connection interface, and enhances the stability and solderability of the electrode.
Smart Images
Figure CN224265383U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of semiconductor silicon-based chip technology, and more specifically, to a multilayer metal structure that reduces the effects of stress. Background Technology
[0002] Semiconductor power devices are widely used in consumer, industrial, and automotive electronics sectors. Whether integrated into circuit boards or used as individual devices, the stability of power devices is essential. In all integrated circuit failure cases, metal electrode-related anomalies consistently rank first, significantly jeopardizing the normal operation of circuits or devices.
[0003] Current power devices generally employ a vertical conduction mode, meaning current flows in from the upper electrode and out from the lower electrode. The upper electrode typically connects to the active region of the device and is patterned in various ways depending on the design requirements; the lower electrode is generally connected to the silicon substrate and subsequently connected to the package frame to form the output terminal.
[0004] For better stability and solderability, multilayer metals are generally used as electrodes, with each layer having a specific function. The bottom metal layer serves as a bonding layer with silicon, ensuring adhesion between the metal film and silicon and preventing metal detachment. The outer metal layer serves as a conductive and soldering layer, primarily supporting wire bonding or frame soldering and leading out the electrode ports. The middle metal layer serves as a buffer or barrier layer, preventing the bottom and outer metals from penetrating each other, or as a cutoff layer for wire bonding or frame soldering, ensuring wire bonding or soldering quality.
[0005] In electrode layers formed by multilayer metal structures, the stress and adhesion between the metal layers become important performance considerations, directly affecting the quality of the electrode itself. Metal evaporation is generally used in the fabrication of the back electrode metal; however, the high stress and poor adhesion between the metal layers make them prone to breaking at the metal-to-metal interface.
[0006] In view of the above, this application is hereby submitted. Utility Model Content
[0007] The technical problem to be solved by this invention is that multi-layer metal structures made by metal evaporation method have high stress and poor adhesion, making them easy to break at the interface between metals. The purpose is to provide a multi-layer metal structure that reduces stress. By setting a metal transition layer between two metals in a sandwich structure, the adhesion between metal layers can be greatly improved and the stress at the metal connection interface can be reduced.
[0008] This utility model is achieved through the following technical solution:
[0009] A multi-layer metal structure for reducing stress effects includes a first metal layer and a second metal layer disposed adjacent to each other; a metal transition layer is disposed between the first metal layer and the second metal layer.
[0010] The metal transition layer includes a first transition layer, a second transition layer, a third transition layer, and a fourth transition layer disposed sequentially between the first metal layer and the second metal layer;
[0011] The materials of the first transition layer and the third transition layer are the same as the material of the first metal layer;
[0012] The materials of the second transition layer and the fourth transition layer are the same as those of the second metal layer.
[0013] This invention improves the adhesion between metal layers and reduces stress at the metal connection interface by setting a metal transition layer formed by alternating two metals between two metal structures.
[0014] In one specific embodiment, the thickness of the first transition layer and the thickness of the fourth transition layer are greater than the thickness of the second transition layer and the thickness of the third transition layer.
[0015] In one specific embodiment, the thicknesses of the second transition layer and the third transition layer are: The thicknesses of the first transition layer and the fourth transition layer are
[0016] In one specific embodiment, the thickness of the first transition layer and the thickness of the third transition layer are greater than the thickness of the second transition layer and the thickness of the fourth transition layer.
[0017] In one specific embodiment, the thicknesses of the second transition layer and the fourth transition layer are: The thicknesses of the first transition layer and the third transition layer are
[0018] In one specific embodiment, the thickness of the first transition layer and the thickness of the third transition layer are less than the thickness of the second transition layer and the thickness of the fourth transition layer.
[0019] In one specific embodiment, the thickness of the first transition layer and the thickness of the third transition layer are: The thicknesses of the second and fourth transition layers are
[0020] This invention defines structures with various transition layer thicknesses to create thickness differences between adjacent metals in the metal transition layer. This allows a thin transition layer to be easily diffused through or fused by a thicker metal above or below, forming a mixture of the two metals that functions like an alloy, enhancing the adhesion strength between the two metal layers and reducing stress.
[0021] In one specific embodiment, the first metal layer is Ti and the second metal layer is Ni.
[0022] In one specific embodiment, the first metal layer is Ni and the second metal layer is Ag.
[0023] In one specific embodiment, the first metal layer, the first transition layer, the second transition layer, the third transition layer, the fourth transition layer, and the second metal layer are all deposited using a metal evaporation process.
[0024] Compared with the prior art, this utility model has the following advantages and beneficial effects:
[0025] 1. The present invention provides a multi-layer metal structure for reducing stress effects. By setting a metal transition layer between two metal layers in a sandwich structure, which is formed by alternating two metals, the adhesion between the metal layers can be greatly improved and the stress at the metal connection interface can be reduced.
[0026] 2. The present invention provides a multi-layer metal structure for reducing stress effects, which defines a variety of structures with different transition layer thicknesses, so that different metals adjacent to each other in the metal transition layer form a thickness difference. In this way, a very thin transition layer can be easily diffused through or compensated for by another thicker metal above and below, thereby forming a mixture of two metals, which plays a similar role to an alloy, enhances the adhesion strength between the two metal layers, and reduces stress. Attached Figure Description
[0027] To more clearly illustrate the technical solutions of the exemplary embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 The multilayer metal structure provided in Embodiment 1 of this utility model;
[0029] Figure 2 The metal multilayer structure provided in Embodiment 2 of this utility model;
[0030] Figure 3 The multilayer metal structure provided in Embodiment 3 of this utility model;
[0031] Figure 4 The metal multilayer structure provided in Comparative Example 1 of this utility model. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.
[0033] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to implement the present invention. In other embodiments, well-known structures are not specifically described in order to avoid obscuring the present invention.
[0034] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0035] In the description of this utility model, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this utility model.
[0036] When preparing the back electrode metal, metal evaporation is generally used. However, the stress between the metal layers is high and the adhesion is low, making it easy to break off from the metal-to-metal interface.
[0037] To solve the above technical problems,
[0038] This invention provides a multilayer metal structure for reducing stress effects, comprising a first metal layer and a second metal layer disposed adjacent to each other; a metal transition layer is disposed between the first metal layer and the second metal layer.
[0039] The metal transition layer includes a first transition layer, a second transition layer, a third transition layer, and a fourth transition layer disposed sequentially between the first metal layer and the second metal layer;
[0040] The materials of the first transition layer and the third transition layer are the same as the material of the first metal layer;
[0041] The materials of the second transition layer and the fourth transition layer are the same as those of the second metal layer.
[0042] This invention improves the adhesion between metal layers and reduces stress at the metal connection interface by setting a metal transition layer formed by alternating two metals between two metal structures.
[0043] In one specific embodiment, the thickness of the first transition layer and the thickness of the fourth transition layer are greater than the thickness of the second transition layer and the thickness of the third transition layer.
[0044] In one specific embodiment, the thicknesses of the second transition layer and the third transition layer are: The thicknesses of the first transition layer and the fourth transition layer are
[0045] In one specific embodiment, the thickness of the first transition layer and the thickness of the third transition layer are greater than the thickness of the second transition layer and the thickness of the fourth transition layer.
[0046] In one specific embodiment, the thicknesses of the second transition layer and the fourth transition layer are: The thicknesses of the first transition layer and the third transition layer are
[0047] In one specific embodiment, the thickness of the first transition layer and the thickness of the third transition layer are less than the thickness of the second transition layer and the thickness of the fourth transition layer.
[0048] In one specific embodiment, the thickness of the first transition layer and the thickness of the third transition layer are: The thicknesses of the second and fourth transition layers are
[0049] This invention defines structures with various transition layer thicknesses to create thickness differences between adjacent metals in the metal transition layer. This allows a thin transition layer to be easily diffused through or fused by a thicker metal above or below, forming a mixture of the two metals that functions like an alloy, enhancing the adhesion strength between the two metal layers and reducing stress.
[0050] In one specific embodiment, the first metal layer is Ti and the second metal layer is Ni.
[0051] In one specific embodiment, the first metal layer is Ni and the second metal layer is Ag.
[0052] In one specific embodiment, the first metal layer, the first transition layer, the second transition layer, the third transition layer, the fourth transition layer, and the second metal layer are all deposited using a metal evaporation process.
[0053] Example 1
[0054] like Figure 1 As shown, this utility model provides a metal multilayer structure for reducing stress effects, including a silicon wafer. The back side of the silicon wafer is sequentially deposited using metal evaporation, comprising a Ti metal layer, a Ti-Ni transition layer, a Ni metal layer, a Ni-Ag transition layer, and an Ag metal layer; the thickness of the Ti metal layer is... The thickness of the Ni metal layer is The thickness of the Ag metal layer is
[0055] The Ti-Ni transition layer comprises sequentially deposited layers. Thick Ti, Thick Ni, Thick Ti, Thick Ni;
[0056] The Ni-Ag transition layer comprises sequentially deposited... Thick Ni, Thick Ag, Thick Ni, Thick Ag.
[0057] Example 2
[0058] like Figure 2 As shown, this utility model provides a metal multilayer structure for reducing stress effects, including a silicon wafer. The back side of the silicon wafer is sequentially deposited using metal evaporation, comprising a Ti metal layer, a Ti-Ni transition layer, a Ni metal layer, a Ni-Ag transition layer, and an Ag metal layer; the thickness of the Ti metal layer is... The thickness of the Ni metal layer is The thickness of the Ag metal layer is
[0059] The Ti-Ni transition layer comprises sequentially deposited layers. Thick Ti, Thick Ni, Thick Ti, Thick Ni;
[0060] The Ni-Ag transition layer comprises sequentially deposited... Thick Ni, Thick Ag, Thick Ni, Thick Ag.
[0061] Example 3
[0062] like Figure 3 As shown, this utility model provides a metal multilayer structure for reducing stress effects, including a silicon wafer. The back side of the silicon wafer is sequentially deposited using metal evaporation, comprising a Ti metal layer, a Ti-Ni transition layer, a Ni metal layer, a Ni-Ag transition layer, and an Ag metal layer; the thickness of the Ti metal layer is... The thickness of the Ni metal layer is The thickness of the Ag metal layer is
[0063] The Ti-Ni transition layer comprises sequentially deposited layers. Thick Ti, Thick Ni, Thick Ti, Thick Ni;
[0064] The Ni-Ag transition layer comprises sequentially deposited... Thick Ni, Thick Ag, Thick Ni, Thick Ag.
[0065] Comparative Example 1
[0066] like Figure 4 As shown in the comparative example, a multilayer metal structure includes a silicon wafer, on the back side of which a Ti metal layer, a Ni metal layer, and an Ag metal layer are sequentially deposited by metal evaporation.
[0067] Test case
[0068] The silicon wafers prepared in Examples 1-3 and Comparative Example 1 were subjected to adhesion (tensile test cross section) tests. The test results show that the cross section of the silicon wafer in Comparative Example 1 was between the metals during the tensile test, indicating that the adhesion between the metals was abnormal. However, the cross section of Examples 1-3 of this utility model was at the silicon wafer, indicating that the adhesion between the metals was better.
[0069] The silicon wafers prepared in Examples 1-3 and Comparative Example 1 were subjected to warpage (indirectly reflecting stress) tests. The warpage of the structure in Comparative Example 1 was between 128 and 140, while the warpage of the structure in Examples 1-3 of this utility model was between 70 and 100. Therefore, this utility model obtained a multilayer metal structure with better stress and adhesion.
[0070] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.
Claims
1. A multilayer metal structure for reducing stress effects, characterized in that, It includes a first metal layer and a second metal layer disposed adjacent to each other; a metal transition layer is disposed between the first metal layer and the second metal layer; The metal transition layer includes a first transition layer, a second transition layer, a third transition layer, and a fourth transition layer disposed sequentially between the first metal layer and the second metal layer; The materials of the first transition layer and the third transition layer are the same as the material of the first metal layer; The materials of the second transition layer and the fourth transition layer are the same as those of the second metal layer.
2. The multilayer metal structure for reducing stress effects according to claim 1, characterized in that, The thickness of the first transition layer and the thickness of the fourth transition layer are greater than the thickness of the second transition layer and the thickness of the third transition layer.
3. A multilayer metal structure for reducing stress effects according to claim 2, characterized in that, The thickness of the second and third transition layers is 15~20 Å, and the thickness of the first and fourth transition layers is 145~155 Å.
4. A multilayer metal structure for reducing stress effects according to claim 1, characterized in that, The thickness of the first transition layer and the thickness of the third transition layer are greater than the thickness of the second transition layer and the thickness of the fourth transition layer.
5. A multilayer metal structure for reducing stress effects according to claim 4, characterized in that, The thickness of the second and fourth transition layers is 15~20 Å, and the thickness of the first and third transition layers is 145~155 Å.
6. A multilayer metal structure for reducing stress effects according to claim 1, characterized in that, The thickness of the first transition layer and the thickness of the third transition layer are less than the thickness of the second transition layer and the thickness of the fourth transition layer.
7. A multilayer metal structure for reducing stress effects according to claim 6, characterized in that, The thickness of the first transition layer and the thickness of the third transition layer are 15~20 Å, and the thickness of the second transition layer and the fourth transition layer are 145~155 Å.
8. A multilayer metal structure for reducing stress effects according to claim 1, characterized in that, The first metal layer is Ti, and the second metal layer is Ni.
9. A multilayer metal structure for reducing stress effects according to claim 1, characterized in that, The first metal layer is Ni, and the second metal layer is Ag.
10. A multilayer metal structure for reducing stress effects according to claim 1, characterized in that, The first metal layer, the first transition layer, the second transition layer, the third transition layer, the fourth transition layer, and the second metal layer are all deposited using a metal evaporation process.