CN105938862A - GaN-based light-emitting diode chip and preparation method thereof - Google Patents

Abstract

The invention discloses a GaN-based light-emitting diode chip and a preparation method thereof, belonging to the technical field of semiconductors. The GaN-based light-emitting diode chip includes a substrate, and an N-type GaN layer, a light-emitting layer, and a P-type GaN layer stacked on the substrate in sequence. The P-type GaN layer is provided with steps extending to the N-type GaN layer, and the P-type GaN layer is provided with a step extending to the N-type GaN layer. The GaN layer is provided with a current blocking layer, a transparent conductive layer, and a P-type electrode in sequence, an N-type electrode is provided on the N-type GaN layer, and grooves extending to the substrate are provided on the P-type GaN layer and the N-type GaN layer. The groove is set on the edge of the chip, and the groove, the N-type GaN layer, the transparent conductive layer, and the side wall of the step are successively provided with an optical anti-reflection film and a passivation layer, and the GaN, the optical anti-reflection film, the passivation layer, and the air The refractive index changes sequentially. The invention can effectively buffer the large refractive index difference between the GaN and the passivation layer, and improve the luminous efficiency of the LED chip.

Description

A GaN-based light-emitting diode chip and its preparation method

technical field

The invention relates to the technical field of semiconductors, in particular to a GaN-based light-emitting diode chip and a preparation method thereof.

Background technique

Light Emitting Diode (LED for short) has the advantages of energy saving, environmental protection, high reliability, and long life. As a solid-state lighting source, it has become a research hotspot due to its broad application prospects. In recent years, LEDs have been widely used in daily life, such as lighting, signal display, backlight, car lights and large-screen display. Require.

LED chips are the core components of LEDs. GaN-based LED chips generally include a substrate, an N-type GaN layer, a light-emitting layer, and a P-type GaN layer stacked on the substrate in sequence. Extending to the steps of the N-type GaN layer, a current blocking layer, a transparent conductive layer, and a P-type electrode are sequentially arranged on the P-type GaN layer, and an N-type electrode is arranged on the N-type GaN layer.

In the process of realizing the present invention, the inventor finds that there are at least the following problems in the prior art:

The refractive index of GaN is very different from that of air. Only part of the light emitted by the light-emitting layer can be emitted from the chip, and most of it is confined in GaN, resulting in low luminous efficiency of the LED chip.

Contents of the invention

In order to solve the problem of low luminous efficiency of LED chips in the prior art, an embodiment of the present invention provides a GaN-based light emitting diode chip and a manufacturing method thereof. Described technical scheme is as follows:

On the one hand, an embodiment of the present invention provides a GaN-based light-emitting diode chip. The GaN-based light-emitting diode chip includes a substrate, and an N-type GaN layer, a light-emitting layer, and a P-type GaN layer sequentially stacked on the substrate. , the P-type GaN layer is provided with a step extending from the P-type GaN layer to the N-type GaN layer, and the P-type GaN layer is sequentially provided with a current blocking layer, a transparent conductive layer, and a P-type electrode, The N-type GaN layer is provided with an N-type electrode, and the P-type GaN layer and the N-type GaN layer are provided with grooves extending to the substrate, and the grooves are arranged on the edge of the chip , the groove, the N-type GaN layer, the transparent conductive layer, and the sidewall of the step are sequentially provided with an optical anti-reflection film and a passivation layer, and the refractive index of the passivation layer is between GaN The refractive index of the optical anti-reflection coating is between the refractive index of GaN and the refractive index of the passivation layer.

Optionally, the width of the groove is 10-30 μm.

Optionally, the depth of the groove is 6-10 μm.

Optionally, the passivation layer has a refractive index of 1.5-2.5.

Preferably, the material of the passivation layer is one of SiN, SiO ₂ , SiON and Al ₂ O ₃ .

Optionally, the optical anti-reflection coating has a refractive index of 1.5-2.5.

Preferably, the material of the optical anti-reflection film is SiN or SiON.

Optionally, the thickness of the optical anti-reflection coating is an odd multiple of a quarter of the wavelength of light emitted by the light-emitting layer in the optical anti-reflection coating.

Optionally, the thickness of the passivation layer is an odd multiple of a quarter of the wavelength of light emitted by the light emitting layer in the passivation layer.

On the other hand, an embodiment of the present invention provides a method for preparing a GaN-based light-emitting diode chip, the preparation method comprising:

An N-type GaN layer, a light-emitting layer, and a P-type GaN layer are sequentially grown on the substrate to form an epitaxial layer;

providing steps extending from the P-type GaN layer to the N-type GaN layer on the P-type GaN layer;

A groove extending to the substrate is provided on the P-type GaN layer and the N-type GaN layer, and the groove is arranged on the edge of the epitaxial layer;

forming a current blocking layer and a transparent conductive layer on the p-type GaN layer;

setting a P-type electrode on the transparent conductive layer, and setting an N-type electrode on the N-type GaN layer;

An optical antireflection film and a passivation layer are formed on the groove, the N-type GaN layer, the transparent conductive layer, and the sidewall of the step, and the refractive index of the passivation layer is between that of GaN The refractive index of the optical anti-reflection coating is between the refractive index of GaN and the refractive index of the passivation layer.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

An optical anti-reflection film and a passivation layer are sequentially provided on the groove, the N-type GaN layer, the transparent conductive layer, and the sidewall of the step, and the refractive index of the passivation layer is between the refractive index of GaN and the refractive index of air. Between, the refractive index of the optical anti-reflection coating is between the refractive index of GaN and the refractive index of the passivation layer, which can effectively buffer the large refractive index difference between GaN and air, and reduce the light generated by the light-emitting layer at different refractive indices. The total reflection of the material interface improves the luminous efficiency of the LED chip.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic structural view of a GaN-based light-emitting diode chip provided in Embodiment 1 of the present invention;

FIG. 2 is a flowchart of a method for manufacturing a GaN-based light-emitting diode chip provided by Embodiment 2 of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Embodiment one

An embodiment of the present invention provides a GaN-based light-emitting diode chip. Referring to FIG. Layer 4, the P-type GaN layer 4 is provided with a step 100 extending from the P-type GaN layer 4 to the N-type GaN layer 2, and the P-type GaN layer 4 and the N-type GaN layer 2 are provided with grooves extending to the substrate 1 200, the P-type GaN layer 4 is sequentially provided with a current blocking layer 5, a transparent conductive layer 6, a P-type electrode 7, an N-type GaN layer 2 is provided with an N-type electrode 8, a groove 200, an N-type GaN layer 2, a transparent An optical anti-reflection film 9 and a passivation layer 10 are sequentially provided on the conductive layer 6 and the sidewall of the step 100 .

In this embodiment, the refractive index of the passivation layer 10 is between the refractive index of GaN and the refractive index of air, and the refractive index of the optical anti-reflection coating 9 is between the refractive index of GaN and the refractive index of the passivation layer 10. between.

Specifically, the substrate 1 is a sapphire substrate, the light-emitting layer 3 is alternately stacked InGaN layers and GaN layers, the current blocking layer 5 is a _SiO2 layer, and the transparent conductive layer 6 is Indium Tin Oxide (ITO for short), The P-type electrode 7 and the N-type electrode 8 are metal layers.

Optionally, the width of the groove 200 may be 10-30 μm, so as to effectively buffer the large refractive index gap between GaN and air.

Optionally, the depth of the groove 200 may be 6˜10 μm, so that the groove extends to the substrate.

Optionally, the refractive index of the passivation layer 10 may be 1.5˜2.5. Since the refractive index of GaN is 2.5 and the refractive index of air is 1, a passivation layer with a refractive index of 1.5-2.5 can be selected so that the refractive index of the passivation layer is between the refractive index of GaN and the refractive index of air.

Preferably, the material of the passivation layer 10 may be one of SiN, SiO ₂ , SiON, and Al ₂ O ₃ . The refractive index of SiN is 1.8-2.2, the refractive index of SiO ₂ is 1.5-1.6, the refractive index of SiON is 1.5-1.9, and the refractive index of Al ₂ O ₃ is 1.6-1.7, all of which can achieve the refractive index of 1.5-2.5. passivation layer.

Optionally, the refractive index of the optical anti-reflection coating 9 may be 1.5-2.5, so that the refractive index of the optical anti-reflection coating is between the refractive index of GaN and the refractive index of the passivation layer 10 .

Preferably, the material of the optical anti-reflection film 9 can be SiN or SiON. The refractive index of SiN is 1.8-2.2, and the refractive index of SiON is 1.5-1.9, both of which can realize optical anti-reflection coatings with a refractive index of 1.5-2.5.

Optionally, the thickness of the optical antireflection coating 9 may be an odd multiple of a quarter of the wavelength of the light emitted by the light emitting layer 3 in the optical antireflection coating 9 . Experiments have proved that when the thickness of the optical anti-reflection coating 9 is an odd multiple of a quarter of the wavelength of the light emitted by the light-emitting layer 3 in the optical anti-reflection coating, the emitted light is coherent and destructive, and the refracted light is the strongest, so the optical enhancement The thickness of the transparent film is designed to be an odd multiple of a quarter of the wavelength of the light emitted by the light-emitting layer in the optical anti-reflection coating, so that the light emitted by the light-emitting layer can be transmitted from the anti-reflection film to the greatest extent, and the luminous efficiency of the LED chip can be reduced. Raise to the top.

Optionally, the thickness of the passivation layer 10 can be an odd multiple of a quarter of the wavelength of the light emitted by the light-emitting layer 3 in the passivation layer 10, so that the light emitted by the light-emitting layer can be transmitted from the anti-reflection coating to the greatest extent. , to increase the luminous efficiency of the LED chip to the highest.

In practical applications, the current blocking layer 5 is disposed under the P-type electrode, and the current blocking layer 5 can change the direction of current flow to prevent the current from concentrating under the P-type electrode 7 .

In the embodiment of the present invention, an optical antireflection film and a passivation layer are sequentially provided on the groove, the N-type GaN layer, the transparent conductive layer, and the sidewall of the step, and the refractive index of the passivation layer is between the refractive index of GaN and that of air. The refractive index of the optical anti-reflection coating is between the refractive index of GaN and the refractive index of the passivation layer, which can effectively buffer the large refractive index gap between GaN and air and reduce the light generated by the light-emitting layer. Total reflection at the interface of different refractive index materials improves the luminous efficiency of the LED chip.

Embodiment two

An embodiment of the present invention provides a method for preparing a GaN-based light-emitting diode chip, which is suitable for preparing the GaN-based light-emitting diode chip provided in Example 1. See FIG. 2 . The preparation method includes:

Step 201: growing an N-type GaN layer, a light-emitting layer, and a P-type GaN layer sequentially on a substrate to form an epitaxial layer.

Specifically, this step 201 may include:

An N-type GaN layer, a light-emitting layer, and a P-type GaN layer are sequentially grown on the substrate by using Metal-organic Chemical Vapor Deposition (MOCVD) equipment.

Optionally, after step 201, the preparation method may further include:

The surface of the epitaxial wafer formed by the N-type GaN layer, the light-emitting layer and the P-type GaN layer was cleaned with aqua regia and 511 solution.

Among them, the 511 solution is a mixture of H ₂ SO ₄ , H ₂ O ₂ , and H ₂ O with a volume ratio of 5:1:1.

Step 202: setting steps extending from the P-type GaN layer to the N-type GaN layer on the P-type GaN layer.

Specifically, this step 202 may include:

Coating photoresist on the P-type GaN layer;

Expose and develop the photoresist to form a photoresist with a set pattern;

Under the protection of photoresist, the P-type GaN layer, the light-emitting layer, and the N-type GaN layer are etched using Inductive Coupled Plasma (ICP) technology to form a layer extending from the P-type GaN layer to the N-type GaN layer. the steps of the floor;

Remove photoresist.

Step 203: setting grooves extending to the substrate on the P-type GaN layer and the N-type GaN layer.

In this embodiment, the groove is arranged on the edge of the epitaxial layer.

Specifically, this step 203 may include:

Coating photoresist on the P-type GaN layer and the N-type GaN layer;

Expose and develop the photoresist to form a photoresist with a set pattern;

Under the protection of photoresist, the P-type GaN layer and N-type GaN layer are etched by ICP technology to form grooves extending to the substrate;

Remove photoresist.

Step 204: forming a current blocking layer and a transparent conductive layer on the P-type GaN layer.

Specifically, forming a current blocking layer on the P-type GaN layer may include:

A current blocking layer is deposited on the P-type GaN layer, the N-type GaN layer, and the side walls of the steps by using plasma enhanced chemical vapor deposition (Plasma Enhanced Chemical Vapor Deposition, PECVD for short);

Coating photoresist on the current blocking layer;

Expose and develop the photoresist to form a photoresist with a set pattern;

Under the protection of the photoresist, the current blocking layer is etched to form a current blocking layer with a set pattern;

Remove photoresist.

Optionally, forming a transparent conductive layer on the P-type GaN layer may include:

Depositing a transparent conductive layer on the current blocking layer, the P-type GaN layer, the N-type GaN layer, and the side walls of the steps by electron beam evaporation or magnetron sputtering technology;

Coating photoresist on the transparent conductive layer;

Expose and develop the photoresist to form a photoresist with a set pattern;

Under the protection of the photoresist, the transparent conductive layer is etched to form a transparent conductive layer with a set pattern;

Remove photoresist.

Step 205: disposing a P-type electrode on the transparent conductive layer, and disposing an N-type electrode on the N-type GaN layer.

Specifically, this step 205 may include:

Form a metal layer on the transparent conductive layer and the N-type GaN layer by electron beam evaporation or magnetron sputtering technology;

P-type electrodes and N-type electrodes are formed by lift-off technology.

Step 206: forming an optical anti-reflection film and a passivation layer on the groove, the N-type GaN layer, the transparent conductive layer, and the sidewall of the step.

In this embodiment, the refractive index of the passivation layer is between that of GaN and that of air, and the refractive index of the optical anti-reflection coating is between that of GaN and that of the passivation layer.

Specifically, this step 206 may include:

Using PECVD, Atmospheric Pressure Chemical Vapor Deposition (APCVD for short), or Atomic Layer Deposition (ALD for short) technology on the groove, N-type GaN layer, transparent conductive layer, and the sidewall of the step Deposit optical anti-reflection coating and passivation layer on it;

Coating photoresist on the passivation layer;

Expose and develop the photoresist to form a photoresist with a set pattern;

Under the protection of the photoresist, the passivation layer and the optical anti-reflection film are etched to form the optical anti-reflection film and the passivation layer of the set pattern;

Remove photoresist.

Specifically, the substrate is a sapphire substrate, the light-emitting layer is an alternately stacked InGaN layer and GaN layer, the current blocking layer is a _SiO2 layer, the transparent conductive layer is ITO, and the P-type electrode and N-type electrode are metal layers.

Optionally, the width of the groove may be 10-30 μm.

Optionally, the depth of the groove may be 6-10 μm.

Optionally, the refractive index of the passivation layer may be 1.5˜2.5.

Preferably, the material of the passivation layer can be one of SiN, SiO ₂ , SiON, and Al ₂ O ₃ .

Optionally, the refractive index of the optical anti-reflection coating may be 1.5-2.5.

Preferably, the material of the optical anti-reflection coating can be SiN or SiON.

Optionally, the thickness of the optical anti-reflection coating may be an odd multiple of a quarter of the wavelength of light emitted by the light-emitting layer in the optical anti-reflection coating.

Optionally, the thickness of the passivation layer may be an odd multiple of a quarter of the wavelength of light emitted by the light emitting layer in the passivation layer.

In the embodiment of the present invention, an optical antireflection film and a passivation layer are sequentially provided on the groove, the N-type GaN layer, the transparent conductive layer, and the sidewall of the step, and the refractive index of the passivation layer is between the refractive index of GaN and that of air. The refractive index of the optical anti-reflection coating is between the refractive index of GaN and the refractive index of the passivation layer, which can effectively buffer the large refractive index gap between GaN and air and reduce the light generated by the light-emitting layer. Total reflection at the interface of different refractive index materials improves the luminous efficiency of the LED chip.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. A GaN-based light-emitting diode chip, the GaN-based light-emitting diode chip comprising a substrate, and an N-type GaN layer, a light-emitting layer, and a P-type GaN layer sequentially stacked on the substrate, the P-type GaN layer A step extending from the P-type GaN layer to the N-type GaN layer is provided on the top, and a current blocking layer, a transparent conductive layer, and a P-type electrode are arranged on the P-type GaN layer in sequence, and on the N-type GaN layer An N-type electrode is provided, wherein the P-type GaN layer and the N-type GaN layer are provided with grooves extending to the substrate, the grooves are arranged on the edge of the chip, and the The groove, the N-type GaN layer, the transparent conductive layer, and the sidewall of the step are sequentially provided with an optical anti-reflection film and a passivation layer, and the refractive index of the passivation layer is between that of GaN The refractive index of the optical anti-reflection coating is between the refractive index of GaN and the refractive index of the passivation layer. 2 . The GaN-based light-emitting diode chip according to claim 1 , wherein the groove has a width of 10-30 μm. 3. The GaN-based light-emitting diode chip according to claim 1 or 2, characterized in that the depth of the groove is 6-10 μm. 4. The GaN-based light-emitting diode chip according to claim 1 or 2, characterized in that the refractive index of the passivation layer is 1.5-2.5. 5 . The GaN-based light-emitting diode chip according to claim 4 , wherein the material of the passivation layer is one of SiN, SiO ₂ , SiON, and Al ₂ O ₃ . 6. The GaN-based light-emitting diode chip according to claim 1 or 2, wherein the refractive index of the optical anti-reflection coating is 1.5-2.5. 7 . The GaN-based light-emitting diode chip according to claim 6 , wherein the optical anti-reflection film is made of SiN or SiON. 8. The GaN-based light-emitting diode chip according to claim 1 or 2, wherein the thickness of the optical anti-reflection coating is 1/4 of the wavelength of the light emitted by the light-emitting layer in the optical anti-reflection coating an odd multiple of one. 9. The GaN-based light-emitting diode chip according to claim 1 or 2, wherein the thickness of the passivation layer is 1/4 of the wavelength of the light emitted by the light-emitting layer in the passivation layer Odd multiples. 10. A preparation method for a GaN-based light-emitting diode chip, characterized in that the preparation method comprises: An N-type GaN layer, a light-emitting layer, and a P-type GaN layer are sequentially grown on the substrate to form an epitaxial layer; providing steps extending from the P-type GaN layer to the N-type GaN layer on the P-type GaN layer; A groove extending to the substrate is provided on the P-type GaN layer and the N-type GaN layer, and the groove is arranged on the edge of the epitaxial layer; forming a current blocking layer and a transparent conductive layer on the p-type GaN layer; setting a P-type electrode on the transparent conductive layer, and setting an N-type electrode on the N-type GaN layer; An optical anti-reflection film and a passivation layer are formed on the groove, the N-type GaN layer, the transparent conductive layer, and the sidewall of the step, and the refractive index of the passivation layer is between that of GaN The refractive index of the optical anti-reflection coating is between the refractive index of GaN and the refractive index of the passivation layer.