Flip LED chip
By replacing Au with a stacked structure of Cr, Ni, Al, Cu and Ti or Ag in flip-chip LEDs, and optimizing the electrode design, the problems of high cost and low brightness are solved, achieving the effects of cost reduction and brightness improvement.
Patent Information
- Application Number
- CN202520251566.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-17
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2035-02-17
AI Technical Summary
The use of Au in existing flip-chip LEDs leads to high production costs and reduced reflectivity, which affects chip brightness.
A stacked structure of Cr, Ni, or a combination thereof is used as the contact layer, a composite reflective layer of Al and Cu layers, and a stacked structure of Ti, Pt, or Ag layers as the protective layer. The use of Au is eliminated, and the thickness ratio of each layer is controlled to optimize the electrode structure.
This reduces production costs, increases electrode reflectivity and chip brightness, and improves chip reliability and stability.
Smart Images
Figure CN223584644U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of semiconductor photoelectric device especially relates to a flip LED chip. BACKGROUND
[0002] The flip LED chip has the advantages of superior heat dissipation performance, high luminous efficiency, higher safety and reliability, small size easy to integrate and good optical matching, so that the flip LED chip has broad application prospect and market potential in the LED industry.
[0003] The flip LED chip structure includes epitaxial, current blocking layer, transparent conductive layer, electrode, reflection layer and the like structure, wherein the electrode generally adopts Ti / Al / Ni / Au, wherein Al is mainly used as a mirror, Au is beneficial to current control due to excellent contact performance, and can be used as a protective layer to protect active Al from oxidation. Ni is used as a barrier layer between Au and Al. But Au is expensive, the production cost is high, and it also reduces the reflectivity and affects the brightness of the chip. UTILITY MODEL CONTENT
[0004] The utility model solves the technical problem that the utility model provides a flip LED chip, which has high brightness and low cost.
[0005] In order to solve the above technical problem, the utility model provides a flip LED chip, which includes a substrate, a first semiconductor layer, a multi-quantum well layer, a second semiconductor layer, a current blocking layer, a transparent conductive layer and a second electrode which are sequentially stacked on the substrate.
[0006] The flip LED chip further includes a first through hole exposing the first semiconductor layer, a first electrode arranged in the first through hole and a reflective passivation layer, wherein the reflective passivation layer covers the transparent conductive layer, the bottom and sidewall of the first through hole, and the sidewall of the first electrode and the second electrode.
[0007] The first electrode and the second electrode each include a contact layer, at least one composite reflective layer, a connecting layer and a protective layer which are sequentially stacked.
[0008] The contact layer is a laminated structure composed of one or both of Cr layer and Ni layer.
[0009] The composite reflective layer includes an Al layer and a Cu layer which are sequentially stacked, and the ratio of the thickness of the Al layer to the thickness of the Cu layer is greater than or equal to 40:1.
[0010] The connecting layer is a laminated structure composed of Cr layer, Ni layer or both.
[0011] The protective layer is a laminated structure composed of one or at least two of Ti layer, Pt layer and Ag layer.
[0012] As an improvement of the above technical solution, the first electrode and the second electrode comprise at least three composite reflection layers, and the ratio of the thickness of the Al layer to the thickness of the Cu layer in the composite reflection layer gradually decreases in the direction from the contact layer to the connecting layer.
[0013] As an improvement of the above technical solution, the first electrode and the second electrode comprise three composite reflection layers.
[0014] In the direction from the contact layer to the connecting layer, the ratio of the thickness of the Al layer to the thickness of the Cu layer in the composite reflection layer is 50:1-48:1, 48:1-45:1, and 45:1-42:1, respectively.
[0015] As an improvement of the above technical solution, the thickness of the contact layer is
[0016] The thickness of the composite reflection layer is
[0017] The thickness of the connecting layer is
[0018] The thickness of the protective layer is
[0019] As an improvement of the above technical solution, the thickness of the contact layer is
[0020] The thickness of the composite reflection layer is
[0021] The thickness of the connecting layer is
[0022] The thickness of the protective layer is
[0023] As an improvement of the above technical solution, the thickness of the first electrode and the second electrode is
[0024] As an improvement of the above technical solution, the contact layer is a Cr layer, the connecting layer is a Ni layer, and the protective layer is an Ag layer.
[0025] The thickness of the first electrode and the second electrode is
[0026] As an improvement of the above technical solution, the total thickness of the first electrode and the second electrode is
[0027]
[0028] As the improvement of the above technical solution, the current blocking layer is one of SiO2 layer, Al2O3 layer, TiO2 layer or Ti3O5 layer or a laminated structure composed of at least two of them.
[0029] The transparent conductive layer is ITO layer, IZO layer or AZO layer.
[0030] The reflective passivation layer comprises alternately stacked SiO2 layer and TiO2 layer, or the reflective passivation layer comprises alternately stacked SiO2 layer and Ti3O5 layer.
[0031] As the improvement of the above technical solution, the first electrode and the second electrode do not contain Au.
[0032] The utility model discloses a flip LED chip, which has the following beneficial effects:
[0033] The first electrode and the second electrode in the flip LED chip of the utility model each comprise a contact layer, at least one composite reflective layer, a connecting layer and a protective layer which are sequentially stacked; the contact layer is a laminated structure composed of one of Cr layer and Ni layer or both; the composite reflective layer comprises Al layer and Cu layer which are sequentially stacked, and the ratio of the thickness of the Al layer to the thickness of the Cu layer is greater than or equal to 40:1; the connecting layer is a laminated structure composed of Cr layer, Ni layer or both; and the protective layer is a laminated structure composed of one of Ti layer, Pt layer and Ag layer or at least two of them. Based on the structure, the use of Au can be cancelled, the production cost is reduced, the reflectivity of the electrode is improved, and the brightness of the flip LED chip is improved. BRIEF DESCRIPTION OF DRAWINGS
[0034] Figure 1 Fig. 1 is a structural schematic view of a flip LED chip in an embodiment of the utility model;
[0035] Figure 2 Fig. 2 is a structural schematic view of a first electrode and a second electrode in an embodiment of the utility model;
[0036] Figure 3 Fig. 3 is a reflectivity comparison diagram of an embodiment of the utility model and a conventional flip LED chip;
[0037] In the figure, 1 is a substrate, 21 is a first semiconductor layer, 22 is a multi-quantum well layer, 23 is a second semiconductor layer, 3 is a current blocking layer, 4 is a transparent conductive layer, 5 is a first electrode, 6 is a second electrode, 7 is a reflective passivation layer, 8 is a first via hole, 51 is a contact layer, 52 is a composite reflective layer, 53 is a connecting layer, 54 is a protective layer, 521 is an Al layer, and 522 is a Cu layer. DETAILED DESCRIPTION
[0038] In order to make the purpose, technical scheme and advantages of the utility model more clear, the utility model will be described in further detail below.
[0039] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar notations denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only and are merely used to explain the present application, and should not be understood as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.
[0040] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.
[0041] In addition, the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.
[0042] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0043] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0044] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.
[0045] This embodiment provides a flip-chip LED, which includes: a substrate 1, a first semiconductor layer 21, a multiple quantum well layer 22, a second semiconductor layer 23, a current blocking layer 3, a transparent conductive layer 4, and a second electrode 6, which are sequentially stacked on the substrate 1.
[0046] The flip-chip LED also includes a first through-hole 8 exposing the first semiconductor layer 21, a first electrode 5 disposed in the first through-hole 8, and a reflective passivation layer 7; the reflective passivation layer 7 covers the transparent conductive layer 4, the bottom and sidewalls of the first through-hole 8, and the sidewalls of the first electrode 5 and the second electrode 6.
[0047] The first electrode 5 and the second electrode 6 each include a contact layer 51, at least one composite reflective layer 52, a connecting layer 53 and a protective layer 54 stacked in sequence;
[0048] The contact layer 51 is a stacked structure composed of one or two of Cr and Ni layers.
[0049] The composite reflective layer 52 includes an Al layer 521 and a Cu layer 522 stacked sequentially, and the ratio of the thickness of the Al layer 521 to the thickness of the Cu layer 522 is ≥40:1.
[0050] The connecting layer 53 is a stacked structure consisting of a Cr layer, a Ni layer, or both.
[0051] The protective layer 54 is one of a Ti layer, a Pt layer, and an Ag layer, or a laminated structure composed of at least two of them.
[0052] Based on the structure of the first electrode 5 and the second electrode 6, the use of Au in the traditional electrode structure can be cancelled, the cost of the electrode is greatly reduced, and the cost of the flip LED chip is further reduced. Meanwhile, the first electrode 5 and the second electrode 6 of the embodiment can also improve the reflectivity of light, and thus the brightness of the flip LED chip is improved.
[0053] It should be noted that in the traditional electrode structure, gold (Au) is introduced for the following reasons: 1. Au has stable chemical properties and is not easy to be oxidized, and can form good protection for active aluminum (Al); 2. Au has good electrical conductivity, which can reduce current loss and optimize current distribution; 3. It has good welding performance, which ensures good contact between the electrode and the pad. After the use of Au is cancelled, the problems of poor electrical conductivity, current spreading, and reduced chemical stability are faced. Therefore, in the embodiment, firstly, the Al layer 521 and the Cu layer 522 are introduced as the composite reflective layer 52, and the thickness ratio of the two is controlled to be ≥40:1, which makes the composite reflective layer 52 have high reflectivity and still has good stability, improving the reliability. Secondly, the protective layer 54 is introduced, which is made of Ti, Pt or Ag, which can be combined with Cu in the composite reflective layer 52, optimize the ohmic contact, and optimize the current distribution; at the same time, these materials can form a good coating on the surface of the composite reflective layer 52, thereby effectively protecting the composite reflective layer 52 and improving the chemical stability of the first electrode 5 and the second electrode 6. Finally, the connecting layer 53 is introduced between the composite reflective layer 52 and the protective layer 54, which can further optimize the connection stability between the composite reflective layer 52 and the protective layer 54, and improve the reliability of the flip LED chip.
[0054] Specifically, the substrate 1 in the embodiment can be a sapphire substrate, a sapphire-SiO2 composite substrate, a Si substrate, or a SiC substrate, but is not limited thereto. Preferably, the sapphire substrate is used.
[0055] Specifically, the flip LED chip in the embodiment can be a red, green, yellow or violet LED chip. Different types of semiconductor layers and multi-quantum well layers 22 can be selected based on the control of the light-emitting wavelength. For example, in some embodiments, when the flip LED chip is a blue or green LED chip, the first semiconductor layer 21 can be an N-type GaN layer, the multi-quantum well layer 22 can be an InGaN-GaN multi-quantum well layer, and the second semiconductor layer 23 can be a P-type GaN layer and a P-type InGaN layer, but the embodiment is not limited thereto. In other embodiments, when the flip LED chip is a violet LED chip, the first semiconductor layer 21 can be an N-type AlGaN layer, the multi-quantum well layer 22 can be an AlGaN-AlGaN multi-quantum well layer, and the second semiconductor layer 23 can be a P-type AlGaN layer and a P-type GaN layer, but the embodiment is not limited thereto.
[0056] The current blocking layer 3 can block the current from being transmitted vertically below the second electrode 6, so that the current is transmitted horizontally in the current spreading layer, thereby optimizing the distribution of the current, reducing the absorption of light by the second electrode 6, improving the light extraction efficiency, and improving the uniformity of light emission and avoiding local overheating, thereby improving the reliability of the flip LED chip. Specifically, the current blocking layer 3 can be one of the commonly used SiO2 layer, Al2O3 layer, TiO2 layer or Ti3O5 layer, or a laminated structure composed of at least two of them, but the embodiment is not limited thereto. Preferably, the current blocking layer 3 is a SiO2 layer. Specifically, the thickness of the current blocking layer 3 is 0.1-100 nm, preferably 0.1-10 nm. Preferably, the thickness of the current blocking layer 3 is 0.1-10 nm.
[0057]
[0058] Further, in order to optimize the distribution of the current, the current blocking layer 3 is arranged below the second electrode 6, and the projection of the second electrode 6 on the surface where the current blocking layer 3 is located at least partially covers the current blocking layer 3.
[0059] Specifically, the transparent conductive layer 4 can be the commonly used ITO layer, IZO layer, AZO layer, ATO layer or FTO layer, but the embodiment is not limited thereto. Preferably, in one embodiment, the transparent conductive layer 4 is an ITO layer, which has strong conductivity, can optimize the current spreading, has high light transmittance, can improve the light extraction efficiency, and thereby improves the light-emitting brightness of the flip LED chip. Specifically, the thickness of the transparent conductive layer 4 is 0.1-100 nm, preferably 0.1-10 nm. Preferably, the thickness of the transparent conductive layer 4 is 0.1-10 nm.
[0060] Specifically, the reflective passivation layer 7 is a commonly used DBR layer, which not only can reflect light, but also can play a passivation role. Specifically, the reflective passivation layer 7 in the embodiment includes alternately stacked SiO2 layers and TiO2 layers; or the reflective passivation layer 7 includes alternately stacked SiO2 layers and Ti3O5 layers, but the embodiment is not limited thereto.
[0061] Specifically, the thickness of the contact layer 51 in the present embodiment is Exemplarily, the thickness of the contact layer 51 is or but not limited to this. Preferably, the thickness of the contact layer 51 is more preferably, the thickness of the contact layer 51 is The contact layer 51 can optimize the ohmic contact between the first semiconductor layer 21 and the first electrode 5, and the transparent conductive layer 4 and the second electrode 6, and also play a role in strengthening the connection between the two and improving the reliability of the flip-chip LED.
[0062] Specifically, the thickness of the composite reflective layer 52 in the present embodiment is If the thickness is small, the reflectivity of light is low, and the light extraction efficiency cannot be effectively improved. More specifically, the thickness of the composite reflective layer 52 is Exemplarily, the thickness of the composite reflective layer 52 is or but not limited to this. More preferably, the thickness of the composite reflective layer 52 is
[0063] Specifically, in the present embodiment, the ratio of the thickness of the Al layer 521 to the thickness of the Cu layer 522 is ≥ 40:1, so as to prevent the introduction of the Cu layer 522 from causing the reflectivity of the first electrode 5 and the second electrode 6 to decrease, thereby reducing the light extraction efficiency. More specifically, the ratio of the thickness of the Al layer 521 to the thickness of the Cu layer 522 is (40-55):1, so as to prevent the migration of Al under the action of current and improve the reliability of the first electrode 5 and the second electrode 6. Exemplarily, the ratio of the thickness of the Al layer 521 to the thickness of the Cu layer 522 is 43:1, 46:1, 49:1, 52:1 or 54:1, but not limited to this.
[0064] Specifically, in the present embodiment, the thickness of the connecting layer 53 is Exemplarily, the thickness of the connecting layer 53 is or but not limited to this. Preferably, the thickness of the connecting layer 53 is more preferably, the thickness of the connecting layer 53 is
[0065] Specifically, in the present embodiment, the thickness of the protective layer 54 is Exemplarily, the thickness of the protective layer 54 is or but not limited to this. Preferably, the thickness of the protective layer 54 is
[0066]
[0067] Based on the above structure of the first electrode 5 and the second electrode 6, and the thickness control of each layer, the total thickness of the first electrode 5 and the second electrode 6 can be reduced to The production cost is reduced and the process time is shortened.
[0068] Preferably, in some embodiments, the contact layer 51 is a Cr layer, the connecting layer 53 is a Ni layer, and the protective layer 54 is an Ag layer; based on this structure, the thickness of the first electrode 5 and the second electrode 6 is More specifically, the total thickness of the first electrode 5 and the second electrode 6 is
[0069]
[0070] Preferably, in some embodiments, the first electrode 5 and the second electrode 6 include at least three composite reflective layers 52, and the ratio of the thickness of the Al layer 521 to the thickness of the Cu layer 522 in the composite reflective layer 52 gradually decreases in the direction from the contact layer 51 to the connecting layer 53. Based on this control, the luminous brightness and reliability can be further improved.
[0071] More preferably, in some embodiments, the first electrode 5 and the second electrode 6 include three composite reflective layers 52; and the ratio of the thickness of the Al layer 521 to the thickness of the Cu layer 522 in the composite reflective layer 52 is 50:1~48:1, 48:1~45:1, and 45:1~42:1, in order.
[0072] The flip-chip LED chip obtained in this embodiment (denoted as test) and a conventional flip-chip LED chip (electrode structure: Ti / Al / Ni / Au, denoted as base) were subjected to reflectivity and film thickness tests. Among them, Figure 2 The reflectivity test results are shown in the figure, and it can be seen from the figure that the reflectivity of this embodiment is significantly higher than that of the conventional flip-chip LED chip. More specifically, at 450 nm, the reflectivity of the test group is 73.70%, and the reflectivity of the base group is only 64.4%. Tests show that the film thickness of the test group is The film thickness of the base group is
[0073] The flip-chip LED chip obtained in this embodiment (denoted as test) and a conventional flip-chip LED chip (electrode structure: Ti / Al / Ni / Au, denoted as base) were subjected to reliability tests. The specific test conditions are: the flip-chip LED chip is lit at 85°C, 85% RH, and a current of 5 mA for 1000 h, and the leakage characteristics are tested with -10V, ≥1μA is judged as leakage failure, and less than that is effective; the results show that the failure rate of the test group is 7.6%, and the failure rate of the base group is 6.8%. The failure rate of the flip-chip LED chip of this embodiment is basically the same as that of the conventional flip-chip LED chip.
[0074] In the description of the application, reference has been made to descriptive terms such as "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" meant to connote "one" or "some" but not "all" the features, structures, materials, or characteristics described in connection with the embodiments or examples. The use of terms such as "first", "second" and "third" does not imply a chronological or logical
[0075] While the embodiments of the application have been illustrated and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and alterations can be made therein without departing from the spirit and scope of the application, which is defined by the following claims and their equivalents.
Claims
1. A flip-chip LED, characterized in that, It includes a substrate, and a first semiconductor layer, a multiple quantum well layer, a second semiconductor layer, a current blocking layer, a transparent conductive layer, and a second electrode are sequentially stacked on the substrate. The flip-chip LED also includes a first via exposing the first semiconductor layer, a first electrode disposed within the first via, and a reflective passivation layer; the reflective passivation layer covers the transparent conductive layer, the bottom and sidewalls of the first via, and the sidewalls of the first electrode and the second electrode; Both the first electrode and the second electrode include a contact layer, at least one composite reflective layer, a connecting layer and a protective layer stacked sequentially. The contact layer is a stacked structure composed of one or two of Cr and Ni layers; The composite reflective layer comprises an Al layer and a Cu layer stacked sequentially, and the ratio of the thickness of the Al layer to the thickness of the Cu layer is ≥40:1; The connecting layer is a stacked structure consisting of a Cr layer, a Ni layer, or both. The protective layer is a stacked structure consisting of one or more of the following: Ti layer, Pt layer, and Ag layer.
2. The flip-chip LED as described in claim 1, characterized in that, The first electrode and the second electrode include at least three composite reflective layers, and along the direction from the contact layer to the connection layer, the ratio of the thickness of the Al layer to the thickness of the Cu layer in the composite reflective layer gradually decreases.
3. The flip-chip LED as described in claim 1, characterized in that, The first electrode and the second electrode each include a three-layer composite reflective layer; Along the direction from the contact layer to the connecting layer, the ratio of the thickness of the Al layer to the thickness of the Cu layer in the composite reflective layer is 50:1 to 48:1, 48:1 to 45:1, and 45:1 to 42:1, respectively.
4. The flip-chip LED as described in claim 1, characterized in that, The thickness of the contact layer is The thickness of the composite reflective layer is ≥ The thickness of the connecting layer is The thickness of the protective layer is 5. The flip-chip LED as described in claim 1, characterized in that, The thickness of the contact layer is The thickness of the composite reflective layer is The thickness of the connecting layer is The thickness of the protective layer is 6. The flip-chip LED as described in claim 1, characterized in that, The thickness of the first electrode and the second electrode is ≤ 7. The flip-chip LED as described in claim 3, characterized in that, The contact layer is a Cr layer, the connecting layer is a Ni layer, and the protective layer is an Ag layer; The thickness of the first electrode and the second electrode is ≤ 8. The flip-chip LED as described in claim 7, characterized in that, The total thickness of the first electrode and the second electrode is 9. The flip-chip LED as described in claim 1, characterized in that, The current blocking layer is a stacked structure composed of one or at least two of the following: SiO2 layer, Al2O3 layer, TiO2 layer or Ti3O5 layer. The transparent conductive layer is an ITO layer, an IZO layer, or an AZO layer; The reflective passivation layer comprises alternating layers of SiO2 and TiO2; or the reflective passivation layer comprises alternating layers of SiO2 and Ti3O5.
10. The flip-chip LED as described in claim 1, characterized in that, Neither the first electrode nor the second electrode contains Au.