CN106848006A - Flip LED chips and preparation method thereof - Google Patents

Abstract

The invention provides a flip-chip LED chip and a preparation method thereof, comprising the following steps: 1) providing a growth substrate, and sequentially growing an n-type GaN layer, a light-emitting layer multi-quantum well and a p-type GaN layer on the growth substrate; 2) Form the first deep groove that runs through the p-type GaN layer and the multi-quantum well of the light-emitting layer; 3) Form an ohmic contact and a current spreading layer on the surface of the p-type GaN layer; 4) Form a reflective layer on the surface of the ohmic contact and current spreading layer; 5) Forming a reflective layer protection layer on the reflective layer surface, inner side and bottom of the first deep groove; 6) forming an aluminum oxide layer on the surface of the structure obtained in step 5) by atomic layer deposition; 7) forming a first opening and an aluminum oxide layer in the aluminum oxide layer The second opening; 8) forming an N electrode in the second opening, and forming a P electrode in the first opening and on the surface of the aluminum oxide layer. The aluminum oxide layer prepared by atomic layer deposition has better insulation performance and metal barrier performance, thus ensuring the reliable performance of the flip chip under high current use.

Description

Flip-chip LED chip and preparation method thereof

technical field

The invention belongs to the technical field of semiconductors, in particular to a flip-chip LED chip and a preparation method thereof.

Background technique

A light emitting diode (Light Emitting Diode, referred to as LED) is a semiconductor solid-state light-emitting device, which is made by using the principle of semiconductor P-N junction electroluminescence. LED devices have good photoelectric properties such as low turn-on voltage, small size, fast response, good stability, long life, and no pollution. Therefore, they are widely used in outdoor and indoor lighting, backlighting, display, traffic indication and other fields.

There are three types of LED chip structures, namely horizontal structure (front mounted chip), vertical structure (vertical structure chip) and flip chip structure (flip chip); the flip chip structure means that the P and N electrodes of the chip are on the same side of GaN, and the quantum well The emitted light mainly escapes through the transparent sapphire surface. There is no problem of shading the front-mounted chip and vertical chip electrodes and gold wires on the package. The current is directly injected through the metal of the reflective layer. The current distribution is uniform, and the voltage is low and the brightness is high. It is suitable for high power and large The use of chips with current density, flip chip products have the advantages of no wire bonding, low voltage, high light efficiency, low thermal resistance, high reliability, high saturation current density, etc., and have gradually become the key development direction of the market.

However, in the flip-chip process, Ag and Al materials that will diffuse when heated are used, and SiO2 is used as the insulating material of the positive and negative electrodes and the barrier layer material of the metal, so the reliability cannot be guaranteed under the condition of high current use. .

During the flip-chip manufacturing process, an insulating material is required to insulate the positive and negative electrodes, and at the same time, this layer of insulating material needs to play a role in blocking metal diffusion. Currently, the insulating material is usually PECVD (Plasma Enhanced Chemical Vapor Deposition) Deposited SiO ₂ , and the dielectric constant of SiO ₂ is about 3.9, and most of the film has cavities, and the stress of the film is relatively large, and the shape of the substrate material is relatively large, which is prone to abnormal fracture, which affects the reliability of the chip. There is no guarantee;

The existence of SiO ₂ as an insulating layer is as follows: 1. The barrier ability of SiO ₂ to metal is insufficient, causing the Barrier (barrier layer) and N-hole metal to diffuse at the etched frame when heated, resulting in leakage; 2. SiO ₂ film layer Affected by the substrate morphology, fractures are prone to occur at the boundary of the Barrier, causing the metal in the Pad to penetrate into the N-hole metal along the SiO ₂ cracks, resulting in leakage.

Contents of the invention

In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a flip-chip LED chip and its preparation method, which is used to solve the problem of insufficient barrier ability to metals in the prior art using _SiO2 as an insulating layer. As a result, barrier and N-hole metals will want to diffuse at the etched border when heated, resulting in leakage problems and being affected by the substrate morphology. Fractures are prone to occur at the border of the barrier, causing the metal in the pad to penetrate along the cracks of SiO ₂ To the N-hole metal, causing leakage problems.

In order to achieve the above purpose and other related purposes, the present invention provides a method for preparing a flip-chip LED chip, the preparation method comprising the following steps:

1) A growth substrate is provided, and an n-type GaN layer, a light-emitting layer multiple quantum well, and a p-type GaN layer are sequentially grown on the growth substrate;

2) forming a first deep groove penetrating through the p-type GaN layer and the multi-quantum well of the light-emitting layer, the bottom of the first deep groove is located in the n-type GaN layer;

3) forming an ohmic contact and a current spreading layer on the surface of the p-type GaN layer, the area of the ohmic contact and the current spreading layer being smaller than the area of the p-type GaN layer;

4) forming a reflective layer on the surface of the ohmic contact and the current spreading layer;

5) forming a reflective layer protective layer on the reflective layer surface, inner side and bottom of the first deep groove, the reflective protective layer at the bottom of the first deep groove is separated from the sidewall of the first deep groove a certain distance;

6) forming an aluminum oxide layer on the surface of the structure obtained in step 5) by atomic layer deposition;

7) Forming a first opening and a second opening in the aluminum oxide layer, the first opening exposes the protective layer of the reflective layer on the surface of the reflective layer, and the second opening exposes the protective layer on the surface of the second reflective layer. said reflective layer protective layer at the bottom of a deep groove;

8) forming an N electrode in the second opening, and forming a P electrode in the first opening and on the surface of the aluminum oxide layer.

As a preferred solution of the method for preparing a flip-chip LED chip of the present invention, the growth substrate is a sapphire substrate, a GaN substrate, a silicon substrate or a silicon carbide substrate.

As a preferred solution of the preparation method of the flip-chip LED chip of the present invention, step 1) and step 2) also include forming a second deep groove in the structure obtained in step 1), so that the structure obtained in step 1) The step of dividing into several independent chip units, the second deep groove runs through the p-type GaN layer, the light-emitting layer multi-quantum well and the n-type GaN layer, and the bottom of the second deep groove is located within the growth substrate.

As a preferred solution of the preparation method of the flip-chip LED chip of the present invention, BCl ₃ , Cl ₂ and Ar plasma are used to selectively etch the p-type GaN layer, the multi-quantum well of the light-emitting layer, the n-type GaN layer and the growth substrate to form the second deep groove.

As a preferred solution of the preparation method of the flip-chip LED chip of the present invention, BCl ₃ , Cl ₂ and Ar plasma are used to selectively etch the p-type GaN layer, the multi-quantum well of the light-emitting layer and the n-type GaN layer to form the first deep groove.

As a preferred solution of the method for preparing the flip-chip LED chip of the present invention, a magnetron sputtering process or a reactive plasma deposition process is used to deposit an ITO thin film on the surface of the p-type GaN layer as the ohmic contact and current spreading layer.

As a preferred solution of the method for preparing the flip-chip LED chip of the present invention, a ZnO thin film is deposited on the surface of the p-type GaN layer as the ohmic contact and current spreading layer by magnetron sputtering process or MOCVD process.

As a preferred solution of the preparation method of the flip-chip LED chip of the present invention, the reflective layer is formed on the surface of the ohmic contact and the current spreading layer by using a magnetron sputtering process, and the material of the reflective layer is Ag-TiW or Ag-TiW-Pt.

As a preferred solution of the method for preparing the flip-chip LED chip of the present invention, the reflective layer is formed on the surface, inner side, and bottom of the first deep groove by using a magnetron sputtering process or an electron beam vapor phase evaporation process. The protective layer, the material of the reflective layer protective layer is one or a combination of Cr, Al, TiW, Pt, Ti, Au, Ni.

As a preferred solution of the preparation method of the flip-chip LED chip of the present invention, the aluminum oxide layer covers the reflective layer protection layer and the exposed reflective layer, the ohmic contact and current spreading layer, the p -type GaN layer, the light-emitting layer multiple quantum wells, the n-type GaN layer, and the thickness of the aluminum oxide layer is 200-5000 angstroms.

The present invention also provides a flip-chip LED chip, which includes: a growth substrate, an n-type GaN layer, a light-emitting layer with multiple quantum wells, a p-type GaN layer, an ohmic contact and a current spreading layer, a reflective layer, a reflective Layer protection layer, aluminum oxide layer, N electrode and P electrode; Wherein,

The n-type GaN layer, the light-emitting layer multi-quantum well, the p-type GaN layer, the ohmic contact and current spreading layer, and the reflective layer are sequentially stacked on the upper surface of the growth substrate from bottom to top ; A first deep groove is formed in the n-type GaN layer, the multi-quantum well of the light-emitting layer and the p-type GaN layer, and the first deep groove runs through the p-type GaN layer and the multi-quantum well of the light-emitting layer well, and the bottom of the first deep groove is located in the n-type GaN layer; a through hole is formed in the ohmic contact and current spreading layer and the reflective layer, and the through hole and the first deep groove Corresponding up and down, and the lateral dimension of the through hole is larger than the lateral dimension of the first deep groove;

The protective layer of the reflective layer is located on the surface of the reflective layer, the inner side and the bottom of the first deep groove, and the protective layer of the reflective layer at the bottom of the first deep groove is separated from the sidewall of the first deep groove by a certain distance. Pitch;

The aluminum oxide layer covers the reflective layer protection layer and fills the through hole and the first deep groove; a first opening and a second opening are formed in the aluminum oxide layer, and the first opening exposes The reflective layer protective layer located on the surface of the reflective layer, the second opening exposes the reflective layer protective layer located at the bottom of the first deep groove;

The N electrode is located in the second opening, and the P electrode is located in the first opening and on the surface of the aluminum oxide layer.

As a preferred solution of the flip-chip LED chip of the present invention, the aluminum oxide layer is prepared by an atomic layer deposition method, and the thickness of the aluminum oxide layer is 200 angstroms to 5000 angstroms.

As mentioned above, the flip-chip LED chip and its preparation method of the present invention have the following beneficial effects: the Al ₂ O ₃ material prepared by ALD (atomic layer deposition) is deposited layer by layer with a single atomic layer, and the film layer density is high and denser. , and it is not easily affected by the substrate morphology, and has good coverage for the step area with a large aspect ratio. The Al ₂ O ₃ layer prepared by atomic layer deposition is used as an insulating layer and a metal barrier layer. Compared with SiO ₂ deposited by PECVD, it has Better insulation performance and metal barrier performance, so as to ensure the reliable performance of flip chip under high current use.

Description of drawings

Fig. 1 is a flow chart showing a method for preparing a flip-chip LED chip of the present invention.

FIG. 2 to FIG. 3 are schematic structural diagrams of step S1 in the manufacturing method of the flip-chip LED chip of the present invention.

FIG. 4 is a schematic structural view of step S2 in the method for preparing a flip-chip LED chip of the present invention.

FIG. 5 is a schematic structural view of step S3 in the method for preparing a flip-chip LED chip according to the present invention.

FIG. 6 is a schematic structural view of step S4 in the method for preparing a flip-chip LED chip according to the present invention.

FIG. 7 is a schematic structural view of step S5 in the method for preparing a flip-chip LED chip according to the present invention.

FIG. 8 is a schematic structural view of steps S6 and S7 in the method for preparing a flip-chip LED chip according to the present invention.

FIG. 9 is a schematic structural view of step S8 in the method for preparing a flip-chip LED chip according to the present invention.

Component designation description

100 growth substrates

101 n-type GaN layer

102 Light-emitting layer multiple quantum wells

103 p-type GaN layer

104 First Deep Groove

105 ohm contact and current spreading layer

106 reflective layer

107 reflective protective layer

108 aluminum oxide layer

109 first opening

110 second opening

111 N electrode

112 P electrode

113 Second deep groove

detailed description

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to FIG. 1 to FIG. 9. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, although the diagrams only show components related to the present invention rather than actual implementation. The number, shape, and size of the components are drawn, and the type, quantity, and proportion of each component can be changed at will during actual implementation, and the layout of the components may also be more complicated.

Please refer to Fig. 1, the present invention provides a kind of preparation method of flip-chip LED chip, and described preparation method comprises the following steps:

1) A growth substrate is provided, and an n-type GaN layer, a light-emitting layer multiple quantum well, and a p-type GaN layer are sequentially grown on the growth substrate;

2) forming a first deep groove penetrating through the p-type GaN layer and the multi-quantum well of the light-emitting layer, the bottom of the first deep groove is located in the n-type GaN layer;

3) forming an ohmic contact and a current spreading layer on the surface of the p-type GaN layer, the area of the ohmic contact and the current spreading layer being smaller than the area of the p-type GaN layer;

4) forming a reflective layer on the surface of the ohmic contact and the current spreading layer;

5) forming a reflective layer protective layer on the reflective layer surface, inner side and bottom of the first deep groove, the reflective protective layer at the bottom of the first deep groove is separated from the sidewall of the first deep groove a certain distance;

6) forming an aluminum oxide layer on the surface of the structure obtained in step 5) by atomic layer deposition;

7) Forming a first opening and a second opening in the aluminum oxide layer, the first opening exposes the protective layer of the reflective layer on the surface of the reflective layer, and the second opening exposes the protective layer on the surface of the second reflective layer. said reflective layer protective layer at the bottom of a deep groove;

8) forming an N electrode in the second opening, and forming a P electrode in the first opening and on the surface of the aluminum oxide layer.

In step 1), referring to step S1 in FIG. 1 and FIG. 2, a growth substrate 100 is provided, on which an n-type GaN layer 101, a light-emitting layer multiple quantum well 102, and a p-type GaN are sequentially grown. Layer 103.

As an example, the growth substrate 100 may be, but not limited to, a sapphire substrate, a GaN substrate, a silicon substrate or a silicon carbide substrate suitable for the growth of GaN and its semiconductor epitaxial materials.

As an example, the n-type GaN layer 101 , the light-emitting layer multiple quantum well 102 and the p-type GaN layer 103 are epitaxially grown in sequence on the growth substrate 100 .

As an example, please refer to FIG. 3 , after step 1), it also includes forming a second deep groove 113 in the structure obtained in step 1), so as to divide the structure obtained in step 1) into several independent chip units. The second deep groove 113 runs through the p-type GaN layer 103 , the light-emitting layer multiple quantum well 102 and the n-type GaN layer 101 , and the bottom of the second deep groove 113 is located in the growth substrate 100 .

As an example, the second deep groove 113 is formed in the structure obtained in step 1) using photolithography and etching processes. The specific method is: first, coat a photoresist layer on the surface of the structure obtained in step 1) ( not shown), using a photolithography process to pattern the photoresist layer to form the pattern of the second deep groove 113 in the photoresist layer; secondly, according to the patterned photoresist layer BCl ₃ , Cl ₂ and Ar plasma are used to selectively etch the p-type GaN layer 103, the light-emitting layer multiple quantum well 102, the n-type GaN layer 101 and the growth substrate 100 to form the first Two deep grooves 113; finally, remove the photoresist layer.

In step 2), referring to step S2 in FIG. 1 and FIG. 4, a first deep groove 104 penetrating through the p-type GaN layer 103 and the light-emitting layer multiple quantum well 102 is formed, and the first deep groove 104 The bottom of the n-type GaN layer is located in the n-type GaN layer 101.

As an example, the first deep groove 104 penetrating through the p-type GaN layer 103 and the light-emitting layer multiple quantum well 102 is formed in the chip unit by using photolithography and etching processes. The specific method is as follows: first, in The surface of the chip unit is coated with a photoresist layer (not shown), and the photoresist layer is patterned by a photolithography process to form the pattern of the first deep groove 104 in the photoresist layer; Secondly, according to the patterned photoresist layer, BCl ₃ , Cl ₂ and Ar plasma are used to selectively etch the p-type GaN layer 103, the light-emitting layer multi-quantum well 102 and the n-type GaN layer 101 to form the first deep groove 104; finally, remove the photoresist layer.

In step 3), referring to step S3 in FIG. 1 and FIG. 5, an ohmic contact and current spreading layer 105 is formed on the surface of the p-type GaN layer 103, and the area of the ohmic contact and current spreading layer 105 is smaller than that of the The area of the p-type GaN layer 103.

As an example, the specific method for forming the ohmic contact and current spreading layer 105 on the surface of the p-type GaN layer 103 is as follows: firstly, depositing ITO (Indium Tin Oxide) film; secondly, a photoresist layer (not shown) is coated on the surface of the ITO film, and the photoresist layer is patterned by a photolithography process, so that in the photoresist layer Define the pattern of the ohmic contact and the current spreading layer 105; then, etch the ITO thin film according to the patterned photoresist layer to form the ohmic contact and the current spreading layer 105, and finally, remove the light Resist layer.

As an example, the thickness of the ITO (Indium Tin Oxide) thin film deposited on the surface of the p-type GaN layer 103 by magnetron sputtering process or reactive plasma deposition process may be, but not limited to, 50 angstroms to 3000 angstroms.

As an example, the specific method for forming the ohmic contact and current spreading layer 105 on the surface of the p-type GaN layer 103 is as follows: first, deposit a ZnO thin film on the surface of the p-type GaN layer 103 by using a magnetron sputtering process or an MOCVD process ; Secondly, a photoresist layer (not shown) is coated on the surface of the ZnO film, and the photoresist layer is patterned using a photolithography process to define the ohmic contact and The pattern of the current spreading layer 105; then, etching the ZnO thin film according to the patterned photoresist layer to form the ohmic contact and the current spreading layer 105, and finally, removing the photoresist layer.

As an example, the thickness of the ZnO thin film deposited on the surface of the p-type GaN layer 103 by magnetron sputtering process or reactive plasma deposition process may be, but not limited to, 50 angstroms to 3000 angstroms.

In step 4), referring to step S4 in FIG. 1 and FIG. 6 , a reflective layer 106 is formed on the surface of the ohmic contact and current spreading layer 105 .

As an example, the reflective layer 106 is formed on the surface of the ohmic contact and current spreading layer 105 using a magnetron sputtering process, and the material of the reflective layer 106 can be but not limited to Ag-TiW (Ag and TiW) or Ag -TiW-Pt (Ag, TiW and Pt), wherein, the thickness of Ag can be but not limited to 750 angstroms to 3000 angstroms, the thickness of TiW can be but not limited to 100 angstroms to 1000 angstroms, and the thickness of Pt can be but not limited to 100 angstroms to 1000 angstroms.

As an example, the area of the reflective layer 106 is slightly larger than the area of the ohmic contact and current spreading layer 105 .

In step 5), please refer to the S5 step and FIG. 7 in FIG. 1, a reflective layer protection layer 107 is formed on the surface, inner side and bottom of the first deep groove 104 of the reflective layer 106, and is located in the first deep groove. The reflective protection layer 107 at the bottom of 104 is spaced from the sidewall of the first deep groove 104 by a certain distance.

As an example, a magnetron sputtering process or an electron beam vapor phase evaporation process is used to form the reflective layer protection layer 107 on the surface, inner side, and bottom of the first deep groove 104 of the reflective layer 106, and the reflective layer protection layer 107 The material can be but not limited to one or a combination of Cr, Al, TiW, Pt, Ti, Au, Ni.

As an example, the thickness of the reflective protective layer 107 may be, but not limited to, 20 angstroms to 20000 angstroms, wherein the thickness of TiW is 200 angstroms to 5000 angstroms, the thickness of Cr is 20 angstroms to 500 angstroms, and the thickness of Pt is 200 angstroms. Å to 1000 Å, the thickness of Ti is in the range of 200 Å to 1000 Å, the thickness of Au is in the range of 2000 Å to 5000 Å, and the thickness of Ni is in the range of 200 Å to 2000 Å.

As an example, the reflective layer protection layer 107 located at the bottom of the first deep groove 104 serves as a contact material for the subsequently formed N electrode.

As an example, when the reflective protection layer 107 has a multi-layer structure, the top layer is a Ni layer.

In step 6), referring to step S6 in FIG. 1 , an aluminum oxide layer 108 is formed on the surface of the structure obtained in step 5) by atomic layer deposition.

As an example, the aluminum oxide layer 108 covers the reflective layer protection layer 107 and the exposed reflective layer 106, the ohmic contact and current spreading layer 105, the p-type GaN layer 103, the light emitting layer The thicknesses of the quantum well 102, the n-type GaN layer 101, and the aluminum oxide layer 108 may be, but not limited to, 200 angstroms to 5000 angstroms.

The aluminum oxide layer 108 prepared by ALD (atomic layer deposition) is a single atomic layer deposited layer by layer, the film layer density is high, denser, and is not easily affected by the shape of the substrate, covering the step area with a large aspect ratio Good performance, the aluminum oxide layer 108 prepared by atomic layer deposition method has better insulation performance and metal barrier performance than _SiO2 deposited by PECVD as an insulating layer and metal barrier layer, thereby ensuring that the flip chip is used in high current Under the reliable performance.

In step 7), please refer to step S7 in FIG. 1 and FIG. 8, a first opening 109 and a second opening 110 are formed in the aluminum oxide layer 108, and the first opening 109 exposes the 106 on the reflective protective layer 107 , the second opening 110 exposes the reflective protective layer 107 at the bottom of the first deep groove 104 .

As an example, the specific method for forming the first opening 109 and the second opening 110 in the aluminum oxide layer 108 is as follows: first, coat a photoresist layer (not shown) on the surface of the aluminum oxide layer 108, The photoresist layer is patterned by etching process, so as to define the patterns of the first opening 109 and the second opening 110 in the photoresist layer; then, according to the patterned photoresist layer The aluminum oxide layer 108 is etched to form the first opening 109 and the second opening 110 in the aluminum oxide layer 108 .

In step 8), referring to step S8 in FIG. 1 and FIG. 9, an N electrode 111 is formed in the second opening 110, and a P electrode is formed in the first opening 109 and on the surface of the aluminum oxide layer 108. 112.

As an example, an N electrode 111 is formed in the second opening 110 by an evaporation process, and a P electrode 112 is formed in the first opening 109 and on the surface of the aluminum oxide layer 108 .

As an example, the material of the N electrode 111 and the P electrode 112 may be one or a combination of Cr, Pt, Ti, Au, Sn. The thickness of Cr is 50-1000 angstroms, the thickness of Pt is 200-1000 angstroms, the thickness of Ti is 200-1000 angstroms, the thickness of Au is 2000-5000 angstroms, and the thickness of Sn is 200-2000 angstroms.

The present invention also provides a flip-chip LED chip, please refer to Figure 2 to Figure 9, the flip-chip LED chip is prepared by the preparation method described in the above scheme, the final structure of the flip-chip LED chip is shown in Figure 9 As shown, the flip-chip LED chip includes: growth substrate 100, n-type GaN layer 101, light-emitting layer multiple quantum wells 102, p-type GaN layer 103, ohmic contact and current spreading layer 105, reflective layer 106, reflective layer protection layer 107, aluminum oxide layer 108, N electrode 111, and P electrode 112; wherein, the n-type GaN layer 101, the light-emitting layer multiple quantum well 102, the p-type GaN layer 103, the ohmic contact and the current spreading layer 105 and the reflective layer 106 are sequentially stacked on the upper surface of the growth substrate 100 from bottom to top; A first deep groove 104 is formed, the first deep groove 104 runs through the p-type GaN layer 103 and the light-emitting layer multiple quantum well 102, and the bottom of the first deep groove 104 is located in the n-type GaN layer 101; a through hole is formed in the ohmic contact and current spreading layer 105 and the reflective layer 106, the through hole runs through the ohmic contact and current spreading layer 105 and the reflective layer 106, and is connected to the first A deep groove 104 corresponds up and down, and the lateral dimension of the through hole is larger than the lateral dimension of the first deep groove 104; the reflective layer protection layer 107 is located on the surface of the reflective layer 106, inside and the first deep groove 104 bottom, the reflective layer protection layer 107 at the bottom of the first deep groove 104 is spaced from the sidewall of the first deep groove 104 by a certain distance; the aluminum oxide layer 108 covers the reflective layer protection layer 107 and fill the through hole and the first deep groove 104; a first opening 109 and a second opening 110 are formed in the aluminum oxide layer 108, and the first opening 109 exposes the The reflective layer protection layer 107, the second opening 110 exposes the reflective layer protection layer 107 at the bottom of the first deep groove 104; the N electrode 111 is located in the second opening 110, the The P-electrode 112 is located in the first opening 109 and on the surface of the aluminum oxide layer 108 .

As an example, the aluminum oxide layer 108 is prepared by an atomic layer deposition method, and the thickness of the aluminum oxide layer 108 is 200 angstroms to 5000 angstroms.

It should be noted that, since the aluminum oxide layer 108 covers the reflective layer protection layer 107 and fills the through hole and the first deep groove 104, the through hole and the first deep groove 104 are not marked in FIG. the first deep groove 104; similarly, since the N electrode 111 is located in the second opening 110, and the P electrode 112 is located in the first opening 109, the first opening 109 is not marked in FIG. The opening 109 and the second opening 110 .

In summary, the present invention provides a flip-chip LED chip and a preparation method thereof. The preparation method of the flip-chip LED chip includes the following steps: 1) providing a growth substrate, and sequentially growing n-type LED chips on the growth substrate GaN layer, light-emitting layer multiple quantum wells, and p-type GaN layer; 2) forming a first deep groove that runs through the p-type GaN layer and the light-emitting layer multiple quantum wells, and the bottom of the first deep groove is located at the n 3) form an ohmic contact and a current spreading layer on the surface of the p-type GaN layer, the area of the ohmic contact and the current spreading layer is smaller than the area of the p-type GaN layer; 4) in the ohmic contact and the surface of the current spreading layer to form a reflective layer; 5) form a reflective layer protection layer on the surface, inside, and bottom of the first deep groove of the reflective layer, and the reflective layer protective layer at the bottom of the first deep groove and the The sidewalls of the first deep groove are separated by a certain distance; 6) an aluminum oxide layer is formed on the surface of the structure obtained in step 5) by atomic layer deposition; 7) a first opening and a second opening are formed in the aluminum oxide layer , the first opening exposes the reflective layer protection layer on the surface of the reflective layer, and the second opening exposes the reflective layer protection layer at the bottom of the first deep groove; 8) in the An N electrode is formed in the second opening, and a P electrode is formed in the first opening and on the surface of the aluminum oxide layer. The Al ₂ O ₃ material prepared by ALD (atomic layer deposition) is a single atomic layer deposited layer by layer, the film layer density is high, denser, and not easily affected by the substrate morphology, and the coverage of the step area with a large aspect ratio Well, the _Al2O3 layer prepared by atomic layer deposition as the insulating layer and metal barrier layer has better insulating properties and metal barrier properties _{than SiO2} deposited by PECVD, so as to ensure the flip chip under high current use Reliable performance.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (12)

1. A preparation method of a flip LED chip is characterized by comprising the following steps:

1) providing a growth substrate, and sequentially growing an n-type GaN layer, a light-emitting layer multi-quantum well and a p-type GaN layer on the growth substrate;

2) forming a first deep groove penetrating through the p-type GaN layer and the light-emitting layer multi-quantum well, wherein the bottom of the first deep groove is positioned in the n-type GaN layer;

3) forming an ohmic contact and a current spreading layer on the surface of the p-type GaN layer, wherein the area of the ohmic contact and the current spreading layer is smaller than that of the p-type GaN layer;

4) forming a reflecting layer on the surface of the ohmic contact and the current expansion layer;

5) forming a reflective layer protection layer on the surface and the inner side of the reflective layer and at the bottom of the first deep groove, wherein the reflective layer protection layer at the bottom of the first deep groove is separated from the side wall of the first deep groove by a certain distance;

6) forming an aluminum oxide layer on the surface of the structure obtained in the step 5) by adopting an atomic layer deposition method;

7) forming a first opening and a second opening in the aluminum oxide layer, wherein the reflective layer protection layer on the surface of the reflective layer is exposed out of the first opening, and the reflective layer protection layer at the bottom of the first deep groove is exposed out of the second opening;

8) and forming an N electrode in the second opening, and forming a P electrode in the first opening and on the surface of the aluminum oxide layer.

2. The method of manufacturing a flip LED chip of claim 1, wherein: the growth substrate is a sapphire substrate, a GaN substrate, a silicon substrate or a silicon carbide substrate.

3. The method of manufacturing a flip LED chip of claim 1, wherein: the method comprises the following steps that a second deep groove is formed in the structure obtained in the step 1) between the step 1) and the step 2) so as to divide the structure obtained in the step 1) into a plurality of independent chip units, the second deep groove penetrates through the p-type GaN layer, the light-emitting layer multi-quantum well and the n-type GaN layer, and the bottom of the second deep groove is located in the growth substrate.

4. The method of manufacturing a flip LED chip of claim 3, wherein: by BCl₃、Cl₂And Ar plasma selectively etches the p-type GaN layer, the light-emitting layer multi-quantum well, the n-type GaN layer and the growth substrate to form the second deep groove.

5. The method of manufacturing a flip LED chip of claim 1, wherein: by BCl₃、Cl₂And selectively etching the p-type GaN layer, the light-emitting layer multi-quantum well and the n-type GaN layer by Ar plasma to form the first deep groove.

6. The method of manufacturing a flip LED chip of claim 1, wherein: and depositing an ITO film on the surface of the p-type GaN layer by utilizing a magnetron sputtering process or a reactive plasma deposition process to serve as the ohmic contact and current expansion layer.

7. The method of manufacturing a flip LED chip of claim 1, wherein: and depositing a ZnO film on the surface of the p-type GaN layer by utilizing a magnetron sputtering process or an MOCVD process to serve as the ohmic contact and current expansion layer.

8. The method of manufacturing a flip LED chip of claim 1, wherein: and forming the reflecting layer on the surfaces of the ohmic contact layer and the current expansion layer by utilizing a magnetron sputtering process, wherein the reflecting layer is made of Ag-TiW or Ag-TiW-Pt.

9. The method of manufacturing a flip LED chip of claim 1, wherein: and forming the reflecting layer protective layer on the surface and the inner side of the reflecting layer and at the bottom of the first deep groove by adopting a magnetron sputtering process or an electron beam vapor evaporation process, wherein the material of the reflecting layer protective layer is one or a combination of more of Cr, Al, TiW, Pt, Ti, Au and Ni.

10. The method of manufacturing a flip LED chip of claim 1, wherein: the aluminum oxide layer coats the reflecting layer protection layer and the exposed reflecting layer, the ohmic contact and current expansion layer, the p-type GaN layer, the light-emitting layer multi-quantum well and the n-type GaN layer, and the thickness of the aluminum oxide layer is 200-5000 angstroms.

11. A flip LED chip, comprising: the LED comprises a growth substrate, an N-type GaN layer, a light-emitting layer multi-quantum well, a P-type GaN layer, an ohmic contact and current expansion layer, a reflecting layer protective layer, an aluminum oxide layer, an N electrode and a P electrode; wherein,

the n-type GaN layer, the light-emitting layer multi-quantum well, the p-type GaN layer, the ohmic contact and current expansion layer and the reflecting layer are sequentially stacked on the upper surface of the growth substrate from bottom to top; a first deep groove is formed in the n-type GaN layer, the light-emitting layer multi-quantum well and the p-type GaN layer, the first deep groove penetrates through the p-type GaN layer and the light-emitting layer multi-quantum well, and the bottom of the first deep groove is located in the n-type GaN layer; through holes are formed in the ohmic contact and current expansion layer and the reflecting layer, the through holes vertically correspond to the first deep grooves, and the transverse dimension of each through hole is larger than that of each first deep groove;

the reflecting layer protection layer is positioned on the surface and the inner side of the reflecting layer and at the bottom of the first deep groove, and the reflecting layer protection layer positioned at the bottom of the first deep groove is separated from the side wall of the first deep groove by a certain distance;

the aluminum oxide layer covers the reflecting layer protection layer and fills the through hole and the first deep groove; a first opening and a second opening are formed in the aluminum oxide layer, the reflective layer protection layer positioned on the surface of the reflective layer is exposed out of the first opening, and the reflective layer protection layer positioned at the bottom of the first deep groove is exposed out of the second opening;

the N electrode is positioned in the second opening, and the P electrode is positioned in the first opening and on the surface of the aluminum oxide layer.

12. The flip LED chip of claim 11, wherein: the aluminum oxide layer is prepared by adopting an atomic layer deposition method, and the thickness of the aluminum oxide layer is 200-5000 angstroms.