An LED chip
Patent Information
- Application Number
- CN202522050400.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-24
- Publication Date
- 2026-09-11
- Estimated Expiration
- 2035-09-24
Smart Images
Figure CN224746885U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of light-emitting diode technology, and more particularly to an LED chip. Background Technology
[0002] With the rapid development of light-emitting diode (LED) technology, LED lighting has replaced traditional lighting sources in many fields. Technologies such as RGB backlighting and RGB direct display are also constantly iterating and upgrading. LED chip size is getting smaller and smaller. Currently, Mini LED, Micro LED and other products have become the focus of various chip manufacturers.
[0003] The current LED market is highly competitive, and the requirements for the luminous efficacy of LED chips are becoming increasingly stringent. However, conventional LED chips suffer from reduced luminous efficiency and brightness due to light-blocking and absorption effects of electrodes and epitaxial layers. Therefore, how to reduce the probability of light emitted by LED chips being blocked or absorbed by electrodes and epitaxial layers, and thus improve the luminous efficiency and brightness of LED chips, is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content
[0004] To address the aforementioned technical problems, this application provides an LED chip that reduces the probability of light emitted by the LED chip being blocked or absorbed by electrodes and absorbed by the epitaxial layer, thereby improving the luminous efficiency and brightness of the LED chip.
[0005] To achieve the above objectives, this application provides the following technical solution:
[0006] This application provides an LED chip, including:
[0007] Substrate;
[0008] An epitaxial stack is located on one side of the substrate. The epitaxial stack includes a first type semiconductor layer, an active layer, and a second type semiconductor layer stacked in a direction away from the substrate. The epitaxial stack has a first groove and a second groove. The first groove penetrates the second type semiconductor layer and the active layer and exposes a portion of the first type semiconductor layer. The second groove penetrates at least a portion of the second type semiconductor layer.
[0009] A current blocking layer, the current blocking layer covering the second groove and extending to cover a portion of the surface of the second type semiconductor layer opposite to the substrate;
[0010] A current spreading layer, the current spreading layer covering a portion of the surface of the second type semiconductor layer facing away from the substrate;
[0011] A first electrode and a second electrode, wherein the first electrode is located on the side of the first type semiconductor layer exposed in the first groove away from the substrate, and the second electrode is located on the side of the current blocking layer away from the substrate, and the second electrode is in contact with the current spreading layer.
[0012] Optionally, the second groove extends through the second type of semiconductor layer and at least partially through the active layer.
[0013] Optionally, the second groove extends through the second type semiconductor layer and the active layer, and extends through at least a portion of the first type semiconductor layer.
[0014] Optionally, the depth of the first groove and the depth of the second groove are equal.
[0015] Optionally, the current blocking layer includes a first current blocking portion and a second current blocking portion;
[0016] The first current blocking portion covers the second groove and extends to cover a portion of the surface of the second type semiconductor layer facing away from the substrate;
[0017] The second current blocking portion surrounds the first current blocking portion, and there is an annular groove between the first current blocking portion and the second current blocking portion. The second electrode fills the annular groove and contacts the portion of the second type semiconductor layer that faces away from the substrate.
[0018] Optionally, the LED chip further includes a reflective layer located on the side of the substrate opposite to the epitaxial stack;
[0019] The current blocking layer further includes a third current blocking portion located on the surface of the first type semiconductor layer exposed in the first groove away from the substrate. The first electrode covers the third current blocking portion and is in contact with a portion of the surface of the first type semiconductor layer exposed in the first groove.
[0020] Optionally, the reflective layer is a distributed Bragg reflector layer.
[0021] Optionally, the current spreading layer is located between the second current blocking portion and the second electrode, and extends to cover a portion of the surface of the second type semiconductor layer facing away from the substrate.
[0022] Optionally, the current blocking layer is a SiO2 layer, a Si3N4 layer, or an Al2O3 layer.
[0023] Optionally, the thickness of the current blocking layer ranges from 1500 Å to 6000 Å, including the endpoint values.
[0024] Compared with existing technologies, the above technical solution has the following advantages:
[0025] The LED chip provided in this application includes a substrate and an epitaxial stack located on one side of the substrate. The epitaxial stack includes a first type semiconductor layer, an active layer, and a second type semiconductor layer stacked along a direction away from the substrate. The epitaxial stack has a first groove and a second groove. The first groove penetrates the second type semiconductor layer and the active layer, and exposes a portion of the first type semiconductor layer, so that a first electrode can be disposed on the side of the first type semiconductor layer exposed by the first groove away from the substrate. The second groove at least penetrates a portion of the second type semiconductor layer. The second groove is covered by a current blocking layer, and the current blocking layer extends to cover the portion of the second type semiconductor layer away from the substrate. On the other hand, the second electrode is located on the side of the current blocking layer away from the substrate, and the second electrode is in contact with the current spreading layer covering the part of the surface of the second type semiconductor layer away from the substrate. With this configuration, a current blocking layer is provided below the second electrode, so that the injected current is injected into the second type semiconductor layer from the outside of the second electrode through the current spreading layer. As a result, the core light-emitting region of the epitaxial stack (mainly referring to the active layer) is not directly below the second electrode, or in other words, the active layer directly below the second electrode emits very little light. This initially reduces the probability that the light emitted by the active layer is blocked or absorbed by the second electrode and absorbed by the epitaxial layer below the second electrode.
[0026] Considering the randomness of the direction of light emitted from the active layer, some light will still obliquely strike the epitaxial stack below the second electrode, causing light absorption. Furthermore, light obliquely striking the lower surface of the second electrode will be reflected and then pass through the epitaxial stack below the second electrode again, causing further light absorption. Especially for small-sized RGB backlight or RGB direct display chips, the area of the second electrode (such as the P electrode) accounts for a large proportion of the entire chip area. The epitaxial layer below the second electrode (such as the P electrode) has a significant impact on the absorption of light emitted from the active layer. Therefore, furthermore, at least a portion of the epitaxial stack below the second electrode is etched away to form a second groove. That is, the second groove penetrates at least a portion of the second type semiconductor layer, and can also penetrate at least a portion of the active layer, and even penetrate at least a portion of the first type semiconductor layer, in order to further reduce the probability of the epitaxial layer below the second electrode absorbing the light emitted from the active layer, thereby improving the overall luminous efficiency and brightness of the LED chip. At the same time, the second groove formed by etching at least part of the epitaxial stack below the second electrode is covered and protected by a current blocking layer. The current blocking layer can not only block the current from being injected directly from below the second electrode, but also isolate the exposed epitaxial stack (such as the first type semiconductor layer) of the second electrode and the second groove from contact, preventing short circuits. It can also passivate the bottom surface and sidewalls of the second groove, preventing leakage at the second groove. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 This is a cross-sectional structural diagram of an LED chip provided in an embodiment of this application;
[0029] Figure 2 for Figure 1 A top view of the LED chip shown.
[0030] Figure 3 This is a cross-sectional structural diagram of another LED chip provided in an embodiment of this application;
[0031] Figure 4 This is a cross-sectional structural diagram of another LED chip provided in an embodiment of this application;
[0032] Figure 5 Formed by etching Figure 1 The photomask pattern of the second groove in the LED chip shown;
[0033] Figure 6 Formed by etching Figure 1 The image shows the photomask pattern of the current blocking layer in the LED chip.
[0034] Figure 7 This is a cross-sectional structural diagram of another LED chip provided in an embodiment of this application;
[0035] Figure 8 This is a cross-sectional structural diagram of another LED chip provided in an embodiment of this application.
[0036] Explanation of reference numerals in the attached figures:
[0037] 100 LED chip; 10 substrate; 20 epitaxial stack; 21 first type semiconductor layer; 22 active layer; 23 second type semiconductor layer; 30 current spreading layer; 40 reflective layer; T1 first groove; T2 second groove; CB current blocking layer; CB1 first current blocking part; CB2 second current blocking part; CB3 third current blocking part; MESA light-emitting outer surface; PAD1 first electrode; PAD2 second electrode; ST annular groove. Detailed Implementation
[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0039] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate; this is merely a way of distinguishing objects with the same properties in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.
[0040] Secondly, this application provides a detailed description in conjunction with schematic diagrams. When detailing the embodiments of this application, for ease of explanation, the accompanying drawings illustrating the device structure may be partially enlarged, not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.
[0041] As described in the background section, the current LED market is highly competitive, and the requirements for the luminous efficacy of LED chips are becoming increasingly stringent. However, conventional LED chips suffer from reduced luminous efficiency and brightness due to the light-blocking and light-absorbing effects of the electrodes and the epitaxial layer. Therefore, how to reduce the probability of light emitted by LED chips being blocked or absorbed by the electrodes and absorbed by the epitaxial layer, thereby improving the luminous efficiency and brightness of LED chips, is a technical problem that urgently needs to be solved by those skilled in the art.
[0042] In view of this, embodiments of this application provide an LED chip, Figure 1 This illustration shows a cross-sectional structural diagram of an LED chip provided in an embodiment of this application. Figure 2 It shows Figure 1 The diagram shown is a top view of the LED chip, combined with... Figure 1 and Figure 2 As shown, the LED chip 100 includes a substrate 10 and an epitaxial stack 20 located on one side of the substrate 10. The epitaxial stack 20 includes a first type semiconductor layer 21, an active layer 22, and a second type semiconductor layer 23 stacked in a direction away from the substrate 10. The epitaxial stack 20 has a first groove T1 and a second groove T2. The first groove T1 penetrates the second type semiconductor layer 23 and the active layer 22 and exposes a portion of the first type semiconductor layer 21. The second groove T2 penetrates at least a portion of the second type semiconductor layer 23.
[0043] Optionally, the first semiconductor layer 21 can be an N-type GaN layer, and the second semiconductor layer 23 can be a P-type GaN layer.
[0044] The active layer 22, also known as the multiple quantum well layer, consists of alternating layers of barrier and well layers, where electrons and holes recombine to emit light.
[0045] It is understandable that after the first type semiconductor layer 21, the active layer 22, and the second type semiconductor layer 23 are sequentially grown on the substrate 10 to form an epitaxial stack 20, the epitaxial stack 20 is subjected to mesa dry etching to form a first groove T1 and a light-emitting mesa MESA, so that the first electrode PAD1 can be formed on the side of the first type semiconductor layer 21 exposed in the first groove T1 away from the substrate 10.
[0046] like Figure 1 and Figure 2 As shown, the LED chip provided in this embodiment further includes a current blocking layer CB, which covers the second groove T2, specifically the bottom surface and sidewalls of the second groove T2. The current blocking layer CB extends to cover a portion of the surface of the second semiconductor layer 23 facing away from the substrate 10. A second electrode PAD2 is disposed on the side of the current blocking layer CB facing away from the substrate 10. The second electrode PAD2 is in contact with the current spreading layer 30, which covers a portion of the surface of the second semiconductor layer 23 facing away from the substrate 10. In other words, both the second groove T2 and the current blocking layer CB are located below the second electrode PAD2, and the current blocking layer CB completely fills and covers the second groove T2.
[0047] Optionally, the current blocking layer CB can be a film layer such as SiO2 layer, Si3N4 layer or Al2O3 layer, so that the current blocking layer CB is an insulating dielectric layer.
[0048] Optionally, the thickness of the current blocking layer CB can be in the range of 1500Å-6000Å, including the endpoint values, to ensure the isolation effect of the current blocking layer CB and to fully passivate the bottom surface and sidewalls of the second groove T2.
[0049] Optionally, the current spreading layer 30 is a transparent indium tin oxide (ITO) layer. The second electrode PAD2 covers a portion of the surface of the current spreading layer 30 to make contact with it.
[0050] Optionally, the thickness of the current spreading layer 30 can range from 300 Å to 2300 Å, including the endpoint values.
[0051] Understandably, a current blocking layer is first formed on the side of the second semiconductor layer 23 away from the substrate 10. The current blocking layer covers the bottom surface and sidewalls of the second groove T2. Then, the current blocking layer is etched to form a current blocking layer CB with a photolithographic pattern.
[0052] Similarly, a current spreading layer is first formed on the side of the second type semiconductor layer 23 away from the substrate 10, and then the current spreading layer is etched to form a current spreading layer 30 with a photolithographic pattern.
[0053] Therefore, in the LED chip provided in this application embodiment, a current blocking layer CB is provided below the second electrode PAD2, so that the injected current is mainly injected from the outside of the second electrode PAD2 through the current spreading layer 30 into the second type semiconductor layer 23. As a result, the core light-emitting area of the epitaxial stack (mainly referring to the active layer 22) is mainly outside the area corresponding to the second electrode PAD2, not directly below the second electrode PAD. In other words, the active layer 22 directly below the second electrode PAD2 emits less light, thereby initially reducing the probability that the light emitted by the active layer 22 is blocked or absorbed by the second electrode PAD2 and absorbed by the epitaxial layer below the second electrode PAD2.
[0054] Considering the randomness of the direction of light emitted from the active layer 22, some light will still obliquely strike the second electrode PAD2 and the epitaxial stack 20 below the second electrode PAD2, causing light absorption. Furthermore, the light obliquely striking the lower surface of the second electrode PAD2 will be reflected and pass through the epitaxial stack 20 below the second electrode PAD2 again, causing light absorption loss. Especially for small-sized RGB backlight or RGB direct display chips, the area of the second electrode (such as the P electrode) accounts for a large proportion of the entire chip area, and the epitaxial layer below the second electrode (such as the P electrode) has a significant impact on the absorption of light emitted from the active layer. Therefore, in the LED chip provided in this application embodiment, at least a portion of the epitaxial stack 20 below the second electrode PAD2 is etched away to form a second groove T2, that is, the second groove T2 at least penetrates a portion of the second type semiconductor layer 23, in order to further reduce the probability of the epitaxial stack 20 below the second electrode PAD2 absorbing the light emitted from the active layer 22, thereby improving the overall luminous efficiency and brightness of the LED chip.
[0055] Meanwhile, the second groove T2 formed by etching at least part of the epitaxial stack 20 below the second electrode PAD2 is covered and protected by the current blocking layer CB. The current blocking layer CB can not only block the direct injection of current from below the second electrode PAD2, but also isolate the second electrode PAD2 and the exposed epitaxial stack 20 (such as the first type semiconductor layer 21) of the second groove T2 from contact, preventing short circuits. It can also passivate the bottom surface and sidewalls of the second groove T2, preventing leakage at the second groove T2.
[0056] In this embodiment, the epitaxial stack 20 has a second groove T2, and the second groove T2 penetrates at least a portion of the second type semiconductor layer 23. That is, the minimum depth of the second groove T2 is the penetration of a portion of the second type semiconductor layer 23, and the maximum depth of the second groove T2 is the penetration of the second type semiconductor layer 23, the active layer 22, and the first type semiconductor layer 21. The following describes the specific cases.
[0057] The first case, such as Figure 3 As shown, Figure 3 A cross-sectional structural schematic diagram of another LED chip provided in an embodiment of this application is shown. It can be seen that the second groove T2 only penetrates a portion of the second type semiconductor layer 23, or the second groove T2 only penetrates the second type semiconductor layer 23; in this way, the absorption loss of light emitted by the active layer 22 by the second type semiconductor layer 23 below the second electrode PAD2 can be reduced.
[0058] The second scenario, such as Figure 4 As shown, Figure 4 This illustration shows a cross-sectional structure diagram of another LED chip provided in an embodiment of this application. As can be seen, the second groove T2 penetrates the second type semiconductor layer 23 and at least part of the active layer 22. Specifically, the second groove T2 can penetrate the second type semiconductor layer 23 and part of the active layer 22, or it can penetrate the second type semiconductor layer 23 and the active layer 22. In this way, the absorption loss of light emitted by the active layer 22 by the second type semiconductor layer 23 and the active layer 22 below the second electrode PAD2 can be reduced.
[0059] The third scenario, such as Figure 1 As shown, the second groove T2 penetrates the second type semiconductor layer 23 and the active layer 22, and penetrates at least part of the first type semiconductor layer 21. Specifically, the second groove T2 can penetrate the second type semiconductor layer 23, the active layer 22 and part of the first type semiconductor layer 21, or it can penetrate the second type semiconductor layer 23, the active layer 22 and the first type semiconductor layer 21. In this way, the absorption loss of light emitted by the active layer 22 by the second type semiconductor layer 23, the active layer 22 and the first type semiconductor layer 21 under the second electrode PAD2 can be reduced.
[0060] It is understandable that if the depth of the first groove T1 and the depth of the second groove T2 are equal, specifically, if both the first groove T1 and the second groove T2 penetrate the second type semiconductor layer 23 and the active layer 22, exposing a portion of the first type semiconductor layer 21, then the first groove T1 and the second groove T2 can be completed in the same etching step. As previously known, by performing mesa dry etching on the epitaxial stack 20 grown on the substrate 10 to form the first groove T1 and the light-emitting mesa MESA, the second groove T2 can also be formed simultaneously, thereby saving process steps.
[0061] If the depths of the first groove T1 and the second groove T2 are not the same, then the first groove T1 and the second groove T2 need to be etched step by step. For example, firstly, the epitaxial stack 20 grown on the substrate 10 is etched using a mesa dry etching process to form the first groove T1 and the light-emitting mesa MESA; then, the epitaxial stack 20 is etched again, which can be done using a process similar to mesa dry etching (such as positive photolithography) to form the second groove T2. The etching gas can generally be Cl2, BCl3, etc. For ease of understanding, Figure 5 Etching formation is shown Figure 1 The photomask pattern of the second recess T2 in the LED chip shown. Figure 5 The blank circle in the middle corresponds to the second groove T2 in the LED chip.
[0062] Optionally, in some embodiments of this application, in conjunction with Figure 1 , Figures 3-4 as well as Figure 6 As shown, Figure 6 Etching formation is shown Figure 1 The photomask pattern of the current blocking layer CB in the LED chip shown (showing the correspondence with the current blocking layer CB) shows that the current blocking layer CB can include a first current blocking portion CB1 and a second current blocking portion CB2. The first current blocking portion CB1 covers the second groove T2 and extends to cover a portion of the surface of the second type semiconductor layer 23 facing away from the substrate 10. The second current blocking portion CB2 surrounds the first current blocking portion CB1. There is an annular groove ST between the first current blocking portion CB1 and the second current blocking portion CB2. The second electrode PAD2 fills the annular groove ST and contacts the portion of the surface of the second type semiconductor layer 23 facing away from the substrate 10.
[0063] This configuration not only allows the first current blocking section CB1 and the second current blocking section CB2 to collectively block the main current from being injected into the second type semiconductor layer 23 directly below the second electrode PAD2, but also allows the second electrode PAD2 to contact the portion of the second type semiconductor layer 23 facing away from the substrate 10 through the annular groove ST between the first and second current blocking sections CB1 and CB2. This enhances the adhesion between the second electrode PAD2 and the current blocking layer CB and the second type semiconductor layer 23, thereby improving the wire bonding capability of the second electrode PAD2. If the second electrode PAD2 were entirely in contact with the current blocking layer CB and not with the second type semiconductor layer 23, the adhesion between the second electrode PAD2 and the current blocking layer CB would be poor, making the second electrode PAD2 prone to detachment. In addition, although the second electrode PAD2 injects current into the contact portion of the second type semiconductor layer 23 through the annular groove ST between the first current blocking part CB1 and the second current blocking part CB2, the light emitted by the current injected by the second electrode PAD2 through the annular groove ST between the first current blocking part CB1 and the second current blocking part CB2 is less because the contact resistance between the second electrode PAD2 and the second type semiconductor layer 23 is high.
[0064] It should be noted that, as Figure 1 As shown, the second electrode PAD2 contacts the surface of a portion of the second type semiconductor layer 23 through the annular groove ST between the first current blocking portion CB1 and the second current blocking portion CB2. A portion of the active layer 22 corresponding to the annular groove ST will emit light. The light emitted by this portion of the active layer 22 is highly likely to be absorbed by the epitaxial stack 20 below the second electrode PAD2. Furthermore, the light emitted by the active layer 22, after being reflected by the second electrode PAD2 within the annular groove ST, is also highly likely to be absorbed by the epitaxial stack 20 below the second electrode PAD2. In the LED chip provided in this embodiment, at least a portion of the epitaxial stack 20 below the second electrode PAD2 is etched into a second groove T2, which can significantly reduce the absorption of light emitted by the epitaxial stack 20 below the second electrode PAD2 under the aforementioned conditions, further improving the luminous efficiency and brightness of the LED chip.
[0065] Further optional, in some embodiments of this application, such as Figure 1 , Figures 3-4 As shown, the LED chip 100 may also include a reflective layer 40 located on the side of the substrate 10 away from the epitaxial stack 20. With this configuration, light emitted from the active layer 30 and directed toward the substrate 10 can be reflected by the reflective layer 40 and then emitted from the side of the second electrode PAD2.
[0066] Optionally, the reflective layer 40 can be a distributed Bragg reflector (DBR) layer, specifically including an alternately stacked first refractive index layer and a second refractive index layer, one of which is a high refractive index layer and the other is a low refractive index layer, and the optical thickness of both the first refractive index layer and the second refractive index layer is 1 / 4 optical wavelength.
[0067] It can be noted that light emitted from the active layer 30 and directed toward the substrate 10 may be reflected by the reflective layer 40, and may also be blocked and absorbed by the first electrode PAD1. Therefore, alternatively, such as... Figure 1 , Figures 3-4 As shown, the current blocking layer CB may further include a third current blocking portion CB3. The third current blocking portion CB3 is located on the surface of the first type semiconductor layer 21 exposed in the first groove T1 away from the substrate 10. The first electrode PAD1 covers the third current blocking portion CB3, and the first electrode PAD1 is in contact with a portion of the surface of the first type semiconductor layer 21 exposed in the first groove T1. With this configuration, the third current blocking portion CB3 and the first electrode PAD1 can be combined to form an omnidirectional reflector (ODR), so that the light incident on the area where the first electrode PAD1 is located, reflected by the reflective layer 40, is reflected again, further improving the luminous efficiency and brightness of the LED chip.
[0068] Alternatively, in some embodiments of this application, such as Figure 7 As shown, Figure 7 A cross-sectional structural diagram of another LED chip provided in this application embodiment is shown. It can be seen that the current blocking layer CB may only include the first current blocking portion CB1. The first current blocking portion CB1 covers the second groove T2 and extends to cover the part of the surface of the second type semiconductor layer 23 away from the substrate 10. At this time, the second electrode PAD2 covers part of the surface of the current spreading layer 30. While contacting and connecting with the current spreading layer 30, the second electrode PAD2 can contact the part of the surface of the second type semiconductor layer 23 away from the substrate 10 through the gap between the first current blocking portion CB1 and the current spreading layer 30, thereby enhancing the adhesion of the second electrode PAD2 to the current blocking layer CB and the second type semiconductor layer 23, and thus enhancing the wire bonding capability of the second electrode PAD2.
[0069] Alternatively, in some embodiments of this application, such as Figure 8 As shown, Figure 8A cross-sectional structural diagram of another LED chip provided in this application embodiment is shown. It can be seen that the current blocking layer CB includes a first current blocking part CB1 and a second current blocking part CB2, but does not include a third current blocking part CB3. The specific configuration and effects of the first current blocking part CB1 and the second current blocking part CB2 are as described in the foregoing embodiment, and will not be repeated here.
[0070] Optionally, in some embodiments of this application, such as Figure 1 , Figures 3-4 as well as Figure 8 As shown, the current spreading layer 30 is partially located between the second current blocking portion CB2 and the second electrode PAD2, and partially extends to cover the surface of the second type semiconductor layer 23 facing away from the substrate 10. Other optional features include... Figure 7 As shown, the current spreading layer 30 may also be located only on the surface of the second type semiconductor layer 23 facing away from the substrate 10, depending on the specific situation. The current spreading layer 30 can be annealed in a rapid annealing furnace to form ohmic contacts and improve the transmittance of the thin film. The annealing temperature range can be 500℃-650℃, and the annealing time can be 1min-15min. Then, using a positive photoresist as a mask, the current spreading layer is wet-etched to form a certain current spreading layer pattern, and the photoresist is removed after etching.
[0071] Alternatively, negative photoresist can be used as a mask, and metal deposition of the electrode PAD can be performed by electron beam evaporation. The total thickness of the metal film can range from 1μm to 5μm. After evaporation, the PAD pattern is formed by metal stripping and photoresist removal.
[0072] In summary, the LED chip provided in this application includes a substrate and an epitaxial stack located on one side of the substrate. The epitaxial stack includes a first type semiconductor layer, an active layer, and a second type semiconductor layer stacked along a direction away from the substrate. The epitaxial stack has a first groove and a second groove. The first groove penetrates the second type semiconductor layer and the active layer, and exposes a portion of the first type semiconductor layer, so that a first electrode is disposed on the side of the first type semiconductor layer exposed by the first groove away from the substrate. The second groove at least penetrates a portion of the second type semiconductor layer. The second groove is covered by a current blocking layer, and the current blocking layer extends to cover a portion of the surface of the second type semiconductor layer away from the substrate. The second electrode... The second electrode is located on the side of the current blocking layer away from the substrate, and is in contact with the current spreading layer covering the part of the second type semiconductor layer away from the substrate. With this configuration, a current blocking layer is provided below the second electrode, so that the injected current is mainly injected into the second type semiconductor layer from the outside of the second electrode through the current spreading layer. As a result, the core light-emitting region of the epitaxial stack (mainly referring to the active layer) is mainly in the area outside the corresponding second electrode, not directly below the second electrode. In other words, the active layer directly below the second electrode emits very little light, thereby initially reducing the probability that the light emitted by the active layer is blocked or absorbed by the second electrode and absorbed by the epitaxial layer below the second electrode.
[0073] Considering the randomness of the direction of light emitted from the active layer, some light will still obliquely strike the second electrode and the epitaxial stack below the second electrode, causing light absorption. Furthermore, the light obliquely striking the lower surface of the second electrode will be reflected and pass through the epitaxial stack below the second electrode again, causing further light absorption loss. Especially for small-sized RGB backlight or RGB direct display chips, the area of the second electrode (such as the P electrode) accounts for a large proportion of the entire chip area, and the epitaxial layer below the second electrode (such as the P electrode) has a significant impact on the absorption of light emitted from the active layer. Therefore, in the LED chip provided in this application embodiment, at least a portion of the epitaxial stack below the second electrode is etched away to form a second groove, that is, the second groove at least penetrates a portion of the second type semiconductor layer, in order to further reduce the probability of the epitaxial stack below the second electrode absorbing the light emitted from the active layer, thereby improving the overall luminous efficiency and brightness of the LED chip. At the same time, the second groove formed by etching at least part of the epitaxial stack below the second electrode is covered and protected by a current blocking layer. The current blocking layer can not only block the current from being injected directly from below the second electrode, but also isolate the exposed epitaxial stack (such as the first type semiconductor layer) of the second electrode and the second groove from contact, preventing short circuits. It can also passivate the bottom surface and sidewalls of the second groove, preventing leakage at the second groove.
[0074] The various parts of this manual are described in a combination of parallel and progressive methods. Each part focuses on the differences between the other parts, and the same or similar parts can be referred to each other.
[0075] The features described above regarding the disclosed embodiments can be substituted or combined with each other to enable those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An LED chip, characterized by, include: Substrate; An epitaxial stack is located on one side of the substrate. The epitaxial stack includes a first type semiconductor layer, an active layer, and a second type semiconductor layer stacked in a direction away from the substrate. The epitaxial stack has a first groove and a second groove. The first groove penetrates the second type semiconductor layer and the active layer and exposes a portion of the first type semiconductor layer. The second groove penetrates at least a portion of the second type semiconductor layer. A current blocking layer, the current blocking layer covering the second groove and extending to cover a portion of the surface of the second type semiconductor layer opposite to the substrate; A current spreading layer, the current spreading layer covering a portion of the surface of the second type semiconductor layer facing away from the substrate; A first electrode and a second electrode, wherein the first electrode is located on the side of the first type semiconductor layer exposed in the first groove away from the substrate, and the second electrode is located on the side of the current blocking layer away from the substrate, and the second electrode is in contact with the current spreading layer.
2. The LED chip of claim 1, wherein, The second groove extends through the second type of semiconductor layer and through at least a portion of the active layer.
3. The LED chip of claim 1, wherein, The second groove extends through the second type semiconductor layer and the active layer, and extends through at least a portion of the first type semiconductor layer.
4. The LED chip according to claim 3, characterized in that, The depth of the first groove is equal to the depth of the second groove.
5. The LED chip according to any one of claims 1-4, characterized in that, The current blocking layer includes a first current blocking portion and a second current blocking portion; The first current blocking portion covers the second groove and extends to cover a portion of the surface of the second type semiconductor layer facing away from the substrate; The second current blocking portion surrounds the first current blocking portion, and there is an annular groove between the first current blocking portion and the second current blocking portion. The second electrode fills the annular groove and contacts the portion of the second type semiconductor layer that faces away from the substrate.
6. The LED chip according to claim 5, characterized in that, The LED chip also includes a reflective layer located on the side of the substrate opposite to the epitaxial stack; The current blocking layer further includes a third current blocking portion located on the surface of the first type semiconductor layer exposed in the first groove away from the substrate. The first electrode covers the third current blocking portion and is in contact with a portion of the surface of the first type semiconductor layer exposed in the first groove.
7. The LED chip according to claim 6, characterized in that, The reflective layer is a distributed Bragg reflector layer.
8. The LED chip according to claim 5, characterized in that, The current spreading layer is located between the second current blocking portion and the second electrode, and extends to cover a portion of the surface of the second type semiconductor layer facing away from the substrate.
9. The LED chip according to claim 1, characterized in that, The current blocking layer is a SiO2 layer, a Si3N4 layer, or an Al2O3 layer.
10. The LED chip according to claim 1, characterized in that, The thickness of the current blocking layer ranges from 1500 Å to 6000 Å, including the endpoint values.