CN108461594A - LED chip and its manufacturing method - Google Patents

Abstract

The invention discloses an LED chip and a manufacturing method thereof. The LED chip includes a substrate and an epitaxial structure on the substrate. The substrate is a sapphire substrate, and the crystal plane of the substrate is biased toward the M crystal plane or the R crystal plane along the C crystal plane. face to form a deflection angle. The LED chip of the present invention uses a special substrate, cooperates with corresponding process conditions, and grows a quasi-quantum wire epitaxial structure on the basis of not needing to prepare additional masks, further reduces the density of states, and enhances the quantum confinement effect, thereby improving luminescence or performance of electronic devices.

Description

LED chip and manufacturing method thereof

technical field

The invention relates to the technical field of semiconductor light emitting devices, in particular to an LED chip and a manufacturing method thereof.

Background technique

LED lighting is a lighting fixture made of the fourth-generation green light source LED. LED is called the fourth-generation lighting source or green light source. It has the characteristics of energy saving, environmental protection, long life, and small size. It can be widely used in various indications, displays, decorations, backlights, general lighting and urban night scenes.

The mainstream technology of existing optoelectronic devices is mostly quantum well structure.

Professor Arakawa et al. predicted in theory in 1986 that if there is no strong coupling between adjacent quantum wires or quantum dots, the lasers manufactured by them will be superior to quantum well lasers in terms of threshold current, modulation dynamics and spectral line characteristics. . Professor Sakaki predicted in 1987 that in quantum wires, due to the greatly reduced elastic scattering probability due to dimensional constraints, very high electron mobility can be obtained, so it can be used to make high-speed electronic devices.

The study of quantum wire structure materials is not only a basic issue in semiconductor physics and materials science, but also its excellent optical and electrical properties can be directly used to prepare devices with excellent performance. Therefore, a lot of money and technology have been invested at home and abroad. to engage in research in this field.

At present, how to improve the performance of device products is the focus of research.

Contents of the invention

The object of the present invention is to provide an LED chip and a manufacturing method thereof.

To achieve one of the objectives of the above invention, an embodiment of the present invention provides an LED chip, including a substrate and an epitaxial structure on the substrate, the substrate is a sapphire substrate, and the crystal plane of the substrate is along the The C crystal plane is biased towards the M crystal plane or the R crystal plane to form an off angle.

As a further improvement of an embodiment of the present invention, the range of the off-angle is 0.7°-1.5°.

As a further improvement of an embodiment of the present invention, the range of the off-angle is 0.8°-1°.

As a further improvement of an embodiment of the present invention, the epitaxial structure includes a quantum wire light-emitting layer, the quantum wire light-emitting layer is grown in a wrinkled shape according to the off-angle growth, and the light-emitting region of the quantum wire light-emitting layer is located between the The height of the superposition direction of the epitaxial structure is not less than 0.5nm.

As a further improvement of an embodiment of the present invention, the number of atomic layers in the light emitting region is not less than 10.

As a further improvement of an embodiment of the present invention, the epitaxial structure includes a buffer layer, a high-temperature AlGaN layer, an N-type AlGaN layer, an N-type AlGaN surface treatment layer, a quantum wire light-emitting layer, a quantum barrier layer, and an electron barrier layer from bottom to top. layer, a P-type cladding layer, and a P-type contact layer, wherein the quantum-ray emitting layer is an AlGaN/GaN multi-type quantum-ray emitting layer.

As a further improvement of an embodiment of the present invention, the epitaxial structure includes a low-defect GaN layer, an InGaN stress adjustment layer, an N-type AlGaN/GaN layer, an N-type InGaN surface treatment layer, a quantum wire light-emitting layer, and a quantum potential A barrier layer, an electron blocking layer, a P-type cladding layer, and a P-type contact layer, wherein the quantum-wire light-emitting layer is a GaN/InGaN multi-type quantum-wire light-emitting layer.

In order to achieve one of the purposes of the above invention, an embodiment of the present invention provides a method for manufacturing an LED chip, including steps:

Provide a substrate, the substrate is a sapphire substrate;

cutting and polishing the substrate so that the crystal plane of the substrate is biased toward the M crystal plane or the R crystal plane along the C crystal plane to form an off angle;

An epitaxial structure is formed on the substrate.

As a further improvement of an embodiment of the present invention, the range of the off-angle is 0.7°-1.5°.

As a further improvement of an embodiment of the present invention, the epitaxial structure includes a quantum wire light-emitting layer, the quantum wire light-emitting layer is grown in a wrinkled shape according to the off-angle growth, and the light-emitting region of the quantum wire light-emitting layer is located between the The height of the superposition direction of the epitaxial structure is not less than 0.5nm.

Compared with the prior art, the beneficial effect of the present invention is that: the LED chip in one embodiment of the present invention uses a special substrate, cooperates with the corresponding process conditions, and grows quasi-quantum wires on the basis of not needing to prepare additional masks. The epitaxial structure further reduces the density of states and enhances the quantum confinement effect, thereby improving the performance of light-emitting or electronic devices.

Description of drawings

Fig. 1 is a schematic diagram of an LED chip according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of the region of the quantum wire light-emitting layer according to an embodiment of the present invention;

Fig. 3 is a schematic diagram of an LED chip according to another embodiment of the present invention;

Fig. 4 is a step diagram of a method for manufacturing an LED chip according to an embodiment of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, method, or functional changes made by those skilled in the art according to these embodiments are included in the protection scope of the present invention.

Referring to FIG. 1 , it is a schematic diagram of an LED chip 100 according to an embodiment of the present invention.

The LED chip 100 includes a substrate 10 and an epitaxial structure 20 on the substrate 10 .

The substrate 10 is a sapphire substrate.

The substrate 10 can be a flat substrate or a patterned substrate.

The crystal plane of the substrate 10 forms an off angle along the C crystal plane to the M crystal plane or the R crystal plane.

Here, the LED chip 100 uses a special substrate, cooperates with corresponding process conditions, and grows a quasi-quantum wire epitaxial structure on the basis of not needing to prepare an additional mask, further reduces the density of states, enhances the quantum confinement effect, and thus improves luminescence or performance of electronic devices.

In this embodiment, the range of the off-angle is 0.7°˜1.5°.

Preferably, the deflection angle ranges from 0.8° to 1°.

In this embodiment, the epitaxial structure 20 is an example of an AlGaN-based ultraviolet light emitting diode epitaxial structure.

The epitaxial structure 20 includes a buffer layer 21, a high-temperature AlGaN layer 22, an N-type AlGaN layer 23, an N-type AlGaN surface treatment layer 24, a quantum light emitting layer 25, a quantum barrier layer 26, an electron blocking layer 27, and a P-type AlGaN layer from bottom to top. cladding layer 28 and P-type contact layer 29 .

Generally, as the wavelength of ultraviolet light becomes shorter, it is necessary to add a large amount of Al components in the light-emitting layer to increase the forbidden band width.

On the one hand, since the light-emitting layer is subjected to tensile stress, the light-emitting mode is TM mode, which is not conducive to light emission; on the other hand, a high Al content has a negative impact on the quality of the LED chip.

In this embodiment, a self-assembled AlGaN/GaN multi-quantum-like light-emitting layer is formed using a substrate 10 with a specific off-angle combined with an epitaxial process as a light-emitting layer, and the two-dimensional quantum confinement effect is used to increase the quantum energy level, thereby achieving the purpose of shortening the wavelength.

Each layer of the epitaxial structure 20 will be described in detail below.

The buffer layer 21 is an AlN layer. A sputtering machine can be used to prepare an AlN layer with a thickness of 15-25 nm on the substrate 10 . Here, the thickness of the buffer layer 21 is 20 nm as an example.

The high temperature AlGaN layer 22 is a non-doped AlGaN layer, and the thickness of the high temperature AlGaN layer 22 is 3um.

Here, the temperature of the equipment is controlled at 1120° C., and the pressure is controlled at 50 Torr.

The thickness of the N-type AlGaN layer 23 is 1.5um.

Here, the device temperature is controlled at 1100° C., the pressure is controlled at 50 Torr, and the doping concentration of the N-type AlGaN layer 23 is 8*10 ¹⁸ /cm3.

The thickness of the N-type AlGaN surface treatment layer 24 is 0.3um.

Here, the device temperature is controlled in the range of 980-1100° C., the pressure is controlled in the range of 100 Torr-200 Torr, and the N-type AlGaN surface treatment layer 24 is a low-doped surface treatment layer.

The quantum beam light-emitting layer 25 is an AlGaN/GaN multi-type quantum beam light-emitting layer.

Here, the equipment temperature is controlled in the range of 900-980° C., the pressure is controlled in the range of 100-200 Torr, and the molar ratio of Group V/Group III reactants is controlled in the range of 1000-3000.

The thickness of the quantum barrier layer 26 is 5-10 nm.

Here, the temperature of the equipment is controlled at 980° C., and the pressure is controlled at a range of 100 to 200 Torr.

It should be noted that the quantum wire light-emitting layer 25 and the quantum barrier layer 26 can be grown repeatedly, and here the repeated growth is taken 5-15 times as an example.

The electron blocking layer 27 is a P-type electron blocking layer, and the thickness of the electron blocking layer 27 is 30 nm.

Here, the temperature of the equipment is controlled in the range of 900-980° C., and the pressure is controlled at 50 Torr.

The P-type cladding layer 28 is a P-type AlGaN cladding layer, and the thickness of the P-type cladding layer 28 is 40 nm.

Here, the temperature of the equipment is controlled at 1000-1050° C., and the pressure is controlled at 50 Torr.

In addition, after the growth of the P-type cladding layer 28 , the growth process can restore the surface to be flat, so as to facilitate subsequent manufacturing processes.

The P-type contact layer 29 is a P-type GaN contact layer, and the thickness of the P-type contact layer 29 is 8 nm.

Here, the temperature of the equipment is controlled at 900-980° C., and the pressure is controlled at 50 Torr.

Of course, the above descriptions of temperature, pressure, thickness, etc. are only exemplary descriptions and are not limited thereto.

In this embodiment, the quantum beam light-emitting layer 25 is grown in a corrugated shape according to the off-angle growth of the substrate 10 .

Specifically, referring to FIG. 2, the N-type AlGaN surface treatment layer 24 is wrinkled, and the appropriate temperature and the moles of group V/III reactants are adjusted to grow the quantum beam light emitting layer 25 on the N-type AlGaN surface treatment layer 24. , under the premise that the off angle of the substrate 10 is properly selected and the temperature conditions of each layer are well controlled, the quantum wire light-emitting layer 25 will grow selectively along the "step" of the specific face of the crystal, and through the off angle and growth conditions, it can control The layer height of the quantum wire light emitting layer 25 is high, and then, a quantum barrier layer 26 with a higher forbidden band width than the quantum wire light emitting layer 25 is grown on the quantum wire light emitting layer 25 .

Here, the quantum wire light-emitting layer 25 is limited by two higher forbidden band widths in the longitudinal direction, and grows selectively along the atomic steps on the plane, and the combination of the two forms a quantum wire-like effect.

It should be noted that the thickness of the quantum wire light-emitting layer 25 is different in different regions. Referring to FIG. 2, the thickness of the quantum wire light-emitting layer 25 at the dotted line frame is relatively large, and the quantum wire light-emitting layer 25 at the dotted line frame is the one that really plays a role in emitting light. The active light-emitting area 25'.

The height of the light-emitting region 25' of the quantum wire light-emitting layer 25 in the stacking direction of the epitaxial structure 20 is not less than 0.5 nm, that is, the step height is not less than 0.5 nm.

The number of atomic layers in the light-emitting region 25' is not less than 10. Here, the growth of 10-50 atomic layers is taken as an example.

In another embodiment of the present invention, referring to FIG. 3 , the epitaxial structure 20 a is an epitaxial structure of a GaN semiconductor laser diode as an example.

The epitaxial structure 20a includes, from bottom to top, a low-defect GaN layer 21a, an InGaN stress adjustment layer 22a, an N-type AlGaN/GaN layer 23a, an N-type InGaN surface treatment layer 24a, a quantum wire light-emitting layer 25a, a quantum barrier layer 26a, an electron barrier layer 27a, P-type cladding layer 28a, and P-type contact layer 29a.

Here, the quantum wire light-emitting layer 25a composed of quasi-quantum wires has the advantage of two-dimensional quantum confinement, and has a smaller density of states, which makes the differential gain higher, thereby reducing the threshold current.

Each layer of the epitaxial structure 20a will be specifically described below.

The low-defect GaN layer 21a is formed using HVPE or Elog method.

The thickness of the InGaN stress adjustment layer 22a is 1um.

Here, the temperature of the equipment is controlled at 900° C., and the pressure is controlled at 200 Torr.

The thickness of the N-type AlGaN/GaN layer 23a is 1.5um.

Here, the device temperature is controlled at 1100° C., the pressure is controlled at 100 Torr, and the doping concentration of the N-type AlGaN/GaN layer 23 a is 8*10 ¹⁸ /cm3.

The thickness of the N-type InGaN surface treatment layer 24a is 0.3um.

Here, the device temperature is controlled in the range of 980-1100° C., the pressure is controlled in the range of 100 Torr-200 Torr, and the N-type InGaN surface treatment layer 24 a is a low-doped N-type InGaN surface treatment layer.

The quantum beam light-emitting layer 25a is a GaN/InGaN multi-type quantum beam light-emitting layer.

Here, the equipment temperature is controlled in the range of 780-800° C., the pressure is controlled in the range of 100-200 Torr, and the molar ratio of Group V/Group III reactants is controlled in the range of 1000-3000.

The thickness of the quantum barrier layer 26a is 5-10 nm.

Here, the temperature of the equipment is controlled at 900° C., and the pressure is controlled at a range of 100 to 200 Torr.

It should be noted that the quantum wire light-emitting layer 25 a and the quantum barrier layer 26 a can be grown repeatedly, and the repeated growth is taken 3 to 6 times as an example.

The electron blocking layer 27 a is a P-type electron blocking layer, and the thickness of the electron blocking layer 27 a is 30 nm.

Here, the temperature of the equipment is controlled in the range of 900-980° C., and the pressure is controlled at 50 Torr.

The P-type cladding layer 28 a is a P-type AlGaN/GaN cladding layer, and the thickness of the P-type cladding layer 28 a is 800 nm.

Here, the temperature of the equipment is controlled in the range of 1000-1050° C., and the pressure is controlled at 50 Torr.

The P-type contact layer 29 a is a P-type GaN contact layer, and the thickness of the P-type contact layer 29 a is 8 nm.

Here, the temperature of the equipment is controlled at 900-980° C., and the pressure is controlled at 50 Torr.

In this embodiment, the quantum wire light-emitting layer 25a is limited by two higher forbidden band widths in the longitudinal direction, and grows selectively along the atomic steps on the plane, and the combination of the two forms a quantum wire-like effect.

For other descriptions of the epitaxial structure 20a, reference may be made to the previous embodiment, which will not be repeated here.

An embodiment of the present invention also provides a method for manufacturing the LED chip 100. Combining the above structural description of the LED chip 100 and FIG. 4, the method for manufacturing the LED chip 100 includes steps:

Provide a substrate 10, the substrate 10 is a sapphire substrate;

Cutting and throwing the substrate 10 so that the crystal plane of the substrate 10 is biased toward the M crystal plane or the R crystal plane along the C crystal plane to form an off angle;

An epitaxial structure 20 is formed on the substrate 10 .

Here, the LED chip 100 uses a special substrate, cooperates with corresponding process conditions, and grows a quasi-quantum wire epitaxial structure on the basis of not needing to prepare an additional mask, further reduces the density of states, enhances the quantum confinement effect, and thus improves luminescence or performance of electronic devices.

In this embodiment, the range of the off-angle is 0.7°˜1.5°.

Preferably, the deflection angle ranges from 0.8° to 1°.

In this embodiment, the epitaxial structure 20 includes a quantum wire light-emitting layer 25, and the quantum-wire light-emitting layer 25 forms wrinkles according to the off-angle growth, and the height of the light-emitting region 25' of the quantum-wire light-emitting layer 25 in the stacking direction of the epitaxial structure 20 is different. Less than 0.5nm.

For other descriptions of the manufacturing method of the LED chip 100 in this embodiment, reference may be made to the description of the above-mentioned LED chip 100 , which will not be repeated here.

It should be understood that although this description is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the description is only for clarity, and those skilled in the art should take the description as a whole, and each The technical solutions in the embodiments can also be properly combined to form other embodiments that can be understood by those skilled in the art.

The series of detailed descriptions listed above are only specific descriptions for feasible implementations of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent implementation or implementation that does not depart from the technical spirit of the present invention All changes should be included within the protection scope of the present invention.

Claims (10)

1. a kind of LED chip, which is characterized in that the epitaxial structure including substrate and on the substrate, the substrate are indigo plant The crystal face of jewel substrate, the substrate is biased to M crystal faces or R crystal faces along C crystal faces and forms drift angle.

2. LED chip according to claim 1, which is characterized in that the angle range is 0.7 °~1.5 °.

3. LED chip according to claim 2, which is characterized in that the angle range is 0.8 °~1 °.

4. LED chip according to claim 1, which is characterized in that the epitaxial structure includes quantum wire luminescent layer, described Quantum wire luminescent layer grows according to the drift angle and forms accordion, and the luminous zone of the quantum wire luminescent layer is in the extension The height in folded structures direction is not less than 0.5nm.

5. LED chip according to claim 4, which is characterized in that the atom layer number of the luminous zone is not less than 10.

6. LED chip according to claim 4, which is characterized in that the epitaxial structure includes buffering successively from bottom to top Layer, high temperature AlGaN layer, N-type AlGaN layer, N-type AlGaN surface-treated layers, quantum wire luminescent layer, quantum barrier layer, electronic blocking Layer, p-type coating layer, p-type contact layer, wherein the quantum wire luminescent layer is the multiple class quantum wire luminescent layers of AlGaN/GaN.

7. LED chip according to claim 4, which is characterized in that the epitaxial structure includes low lack successively from bottom to top Fall into GaN layer, InGaN stress debugging layer, AlGaN/GaN layers of N-type, N-type InGaN surface-treated layers, quantum wire luminescent layer, quantum potential Barrier layer, electronic barrier layer, p-type coating layer, p-type contact layer, wherein the quantum wire luminescent layer is the multiple class amounts of GaN/InGaN Sub-line luminescent layer.

8. a kind of manufacturing method of LED chip, it is characterised in that including step：

A substrate is provided, the substrate is Sapphire Substrate；

It cuts and throws the substrate and the crystal face of the substrate is made to form drift angle along C crystal faces deviation M crystal faces or R crystal faces；

In forming epitaxial structure on the substrate.

9. the manufacturing method of LED chip according to claim 8, which is characterized in that the angle range be 0.7 °~ 1.5°。

10. the manufacturing method of LED chip according to claim 8, which is characterized in that the epitaxial structure includes quantum wire Luminescent layer, the quantum wire luminescent layer grow according to the drift angle and form accordion, and the quantum wire luminescent layer is luminous The height of epitaxial structure Direction of superposition described in Qu Yu is not less than 0.5nm.