CN108039400B - Preparation method and structure of double-color LED chip - Google Patents
Preparation method and structure of double-color LED chip Download PDFInfo
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- CN108039400B CN108039400B CN201711382408.XA CN201711382408A CN108039400B CN 108039400 B CN108039400 B CN 108039400B CN 201711382408 A CN201711382408 A CN 201711382408A CN 108039400 B CN108039400 B CN 108039400B
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- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
Abstract
The invention relates to the technical field of semiconductors, in particular to a preparation method and a structure of a bicolor LED chip, wherein the preparation method comprises the following steps: (a) growing a blue light material on a substrate; (b) preparing a plurality of green light lamp core grooves on the blue light material, wherein the blue light material forms a plurality of blue light structures; (c) growing a green light material in the green light lamp wick groove, wherein the green light material forms a plurality of green light structures; (d) and (5) manufacturing an electrode. According to the invention, the single chip process for preparing the blue light material and the green light material on the same substrate simultaneously reduces the using amount of the fluorescent powder when the white light LED is produced, so that the problem of light weakening caused by a large amount of discretely distributed fluorescent powder particles is solved, the integration level is improved, the LED cost is reduced, and the color temperature is adjusted more flexibly.
Description
Technical Field
The invention belongs to the technical field of semiconductors, and particularly relates to a preparation method and a structure of a bicolor LED chip.
Background
An LED, also known as a light emitting diode, is a semiconductor electronic device that converts electrical energy into light energy. The LED light source has the advantages of energy conservation, environmental protection, safety, long service life and the like, is widely applied to various fields and is called as a fourth-generation light source. Such electronic devices appeared as early as 1962, and only low-intensity red light was emitted in the early stage, and other versions of monochromatic light were developed later, and the light emitted so far has spread to visible light, infrared light and ultraviolet light, and the light intensity has been improved to a comparable level. LEDs have been used for indicator lamps, display panels, etc. and as technology has advanced, light emitting diodes have been widely used for displays, television lighting, and illumination. Wherein the LED chip is the most core part of the LED.
White LEDs currently produced are mostly made by coating a blue LED (near-UV, wavelength 450nm to 470nm) with a yellowish phosphor, usually by doping cerium-doped yttrium aluminum garnet (Ce) 3 + YAG) crystals are ground to a powder and mixed in a dense binder. When the LED chip emits blue light, part of the blue light is efficiently converted by the crystal into a broad spectrum (spectrum centered around 580nm) of mainly yellow light. Since yellow light stimulates the red and green receptors of the eye, and mixes the blue light of the LED itself, making it look like white light, which is often referred to as "moonlit white".
The LED chip prepared by the prior art has more fluorescent powder, a large number of fluorescent powder particles which are distributed discretely exist in a fluorescent powder adhesive layer, and strong scattering phenomenon can occur when light enters the fluorescent powder adhesive layer. This scattering enhances the absorption of light by the phosphor glue layer on the one hand, and also results in a significant amount of light being reflected, i.e. the light transmitted through the phosphor layer is significantly reduced. LED packaging is a very fine and fussy procedure, and various chips are mixed, so that the problems of poor reliability and high packaging difficulty exist.
Therefore, how to provide a high-transmittance and high-integration LED chip is a hot issue at present.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a preparation method and a structure of a double-color LED chip. The technical problem to be solved by the invention is realized by the following technical scheme:
a preparation method of a bicolor LED chip comprises the following steps:
(a) growing a blue light material on a substrate;
(b) preparing a plurality of green light lamp core grooves on the blue light material, wherein the blue light material forms a plurality of blue light structures;
(c) growing a green light material in the green light lamp wick groove, wherein the green light material forms a plurality of green light structures;
(d) and (5) manufacturing an electrode.
The preparation method of the double-color LED chip comprises the following steps of (a):
(a1) selecting a sapphire substrate;
(a2) growing a first GaN buffer layer on the surface of the sapphire substrate;
(a3) growing a first GaN stable layer on the surface of the first GaN buffer layer;
(a4) growing a first n-type GaN layer on the surface of the first GaN stabilizing layer;
(a5) preparing a first InGaN/GaN multi-quantum well structure on the surface of the first n-type GaN layer to serve as a first active layer;
(a6) growing a first p-type AlGaN barrier layer on the surface of the first active layer;
(a7) and growing a first p-type GaN layer on the surface of the first p-type AlGaN barrier layer.
The preparation method of the double-color LED chip comprises the following steps of (b):
(b1) depositing a first oxide layer on the surface of the first p-type GaN layer;
(b2) etching a rectangular window on the first oxide layer by using a wet etching process;
(b3) etching the layer material below the rectangular window by using a dry etching process until the layer material reaches the inside of the first GaN buffer layer to form a groove body;
(b4) removing the first oxide layer, and depositing a second oxide layer;
(b5) and etching the second oxide layer on the surface by using a dry etching process to form an oxidation isolation layer on the periphery of the tank body.
In the preparation method of the double-color LED chip, the length of the rectangular window is larger than 50 μm and smaller than 300 μm, and the width of the rectangular window is larger than 50 μm and smaller than 300 μm.
According to the preparation method of the double-color LED chip, the thickness of the second oxide layer is 20-100 nm.
In the preparation method of the double-color LED chip, the second oxide layer is made of SiO 2 。
According to the preparation method of the double-color LED chip, the In content In the first InGaN/GaN multi-quantum well structure is 10-20%.
The preparation method of the double-color LED chip comprises the following steps of (c):
(c1) growing a second GaN buffer layer in the green light lamp core groove;
(c2) growing a second GaN stable layer on the surface of the second GaN buffer layer;
(c3) growing a second n-type GaN layer on the surface of the second GaN stabilizing layer;
(c4) preparing a second InGaN/GaN multi-quantum well structure on the surface of the second n-type GaN layer to serve as a second active layer;
(c5) growing a second p-type AlGaN barrier layer on the surface of the second active layer;
(c6) and growing a second p-type GaN layer on the surface of the second p-type AlGaN barrier layer.
The preparation method of the double-color LED chip comprises the following steps of (d):
(d1) forming a lower electrode contact window on the first GaN stabilizing layer and forming an upper electrode contact window on the first p-type GaN layer and the second p-type GaN layer;
(d2) evaporating a metal oxide electrode;
(d3) metal is deposited and the leads are lithographically etched to complete the preparation of the electrodes.
The structure of the double-color LED chip is prepared by the method.
Compared with the prior art, the invention has the beneficial effects that:
1. the bicolor LED chip prepared by the invention can generate light with two colors, so that the using amount of fluorescent powder can be reduced when a white light LED is produced, and the problem of weakened light caused by a large amount of discretely distributed fluorescent powder particles is solved;
2. the preparation process improves the integration level of the LED chip and reduces the cost of the LED chip;
3. the color temperature of the prepared two-color LED chip can be adjusted more flexibly.
Drawings
Fig. 1 is a schematic flow chart of a method for manufacturing a dual-color LED chip according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a blue light material of a dual-color LED chip according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an InGaN/GaN multiple quantum well structure in a blue light structure of a dual-color LED chip according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a green light wick groove of a dual-color LED chip according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a blue light structure and a green light structure of a dual-color LED chip according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a quantum well structure in a green light structure of a dual-color LED chip according to an embodiment of the present invention;
fig. 7 is a schematic top cross-sectional structure view of a dual-color LED chip according to an embodiment of the present invention;
fig. 8 is a schematic side-view cross-sectional structure diagram of a dual-color LED chip according to an embodiment of the present invention;
fig. 9 is a schematic top view of another dual-color LED chip according to an embodiment of the present invention;
fig. 10 is a schematic side-view cross-sectional structure diagram of another bi-color LED chip according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.
Example 1:
referring to fig. 1, fig. 1 is a schematic flow chart of a method for manufacturing a dual-color LED chip according to an embodiment of the present invention, where the method includes:
(a) growing a blue light material on a substrate;
(b) preparing a plurality of green light lamp core grooves on the blue light material, wherein the blue light material forms a plurality of blue light structures;
(c) growing a green light material in the green light lamp wick groove, wherein the green light material forms a plurality of green light structures;
(d) and (5) manufacturing an electrode.
In this embodiment, by preparing a two-color LED chip on a substrate, the following advantageous effects can be produced.
1. The bicolor LED chip prepared by the embodiment can generate light with two colors, so that the using amount of fluorescent powder can be reduced when the white light LED is produced, and the problem of light weakening caused by a large amount of discretely distributed fluorescent powder particles is solved;
2. the preparation process of the embodiment improves the integration level of the LED chip and reduces the cost of the LED chip;
3. the color temperature of the bicolor LED chip prepared by the embodiment can be adjusted more flexibly.
Example 2:
the present embodiment is different from the above embodiments in that the present embodiment describes the above embodiments in more detail.
And S10, growing a blue light material on the substrate. Referring to fig. 2, fig. 2 is a schematic structural diagram of a blue light material of a dual-color LED chip according to an embodiment of the present invention.
S101, selecting a sapphire (0001) substrate 11.
S102, growing a first GaN buffer layer 101 with the thickness of 3000-5000 nm on the sapphire substrate 11 at the growth temperature of 400-600 ℃, wherein the first GaN buffer layer 101 preferably has the thickness of 4000nm and the optimal growth temperature of 500 ℃ through experimental demonstration.
S103, heating to 900-1050 ℃, and growing a first GaN stable layer 102 with the thickness of 500-1500 nm on the surface of the first GaN buffer layer 101, wherein the first GaN stable layer 102 preferably has the thickness of 1000nm through experimental demonstration, and the optimal growth temperature is 1000 ℃.
S104, keeping the temperature unchanged, and growing a first n-type GaN layer 103 doped with Si and having a thickness of 200-1000 nm on the surface of the first GaN stabilizing layer 102, wherein the doping concentration is 1 multiplied by 10 18 cm -3 ～5×10 19 cm -3 . The experiment proves that the first n-type GaN layer 103 preferably grows to have the thickness of 400nm, the optimal growth temperature is 1000 ℃, and the optimal doping concentration is 1 multiplied by 10 19 cm -3 。
And S105, growing a first InGaN/GaN multi-quantum well structure on the surface of the first n-type GaN layer 103 to serve as a first active layer 104. Referring to fig. 3, fig. 3 is a schematic structural diagram of an InGaN/GaN multiple quantum well structure in a blue light structure of a dual-color LED chip according to an embodiment of the present invention. The growth temperature of the first InGaN quantum well layer 104b is 650-750 ℃, and the growth temperature of the first GaN barrier layer 104a is 750-850 ℃; the period of the first quantum well is 8-30, the thickness of the first InGaN quantum well layer 104b is 1.5-3.5 nm, the content of In is 10% -20%, the content is determined according to the wavelength of light, and the higher the content is, the longer the wavelength of light is; the thickness of the first GaN barrier layer 104a is 5-10 nm. The experimental demonstration proves that the preferable growth temperature of the first InGaN quantum well layer 104b is 750 ℃, and the preferable thickness is 2.8 nm; the first GaN barrier layer 104a is preferably grown at 850 ℃ and preferably 5nm thick. The first quantum well period is preferably 20.
S106, growing a first p-type AlGaN barrier layer 105 doped with Mg with the thickness of 10-40 nm on the surface of the first active layer 104, wherein the growth temperature is 850-950 ℃. The experiment proves that the thickness of the first p-type AlGaN barrier layer 105 is preferably 20nm, and the optimal growth temperature is 900 ℃.
S107, growing a first p-type GaN layer 106 with the thickness of 100-300 nm on the surface of the first p-type AlGaN barrier layer 105 for contact. Among them, it is experimentally demonstrated that the first p-type GaN layer 106 is preferably 200nm thick with an optimal growth temperature of 900 ℃.
S11, preparing a plurality of green light lamp core grooves on the blue light material, wherein the blue light material forms a plurality of blue light structures. Referring to fig. 4, fig. 4 is a schematic structural diagram of a green light wick groove of a dual-color LED chip according to an embodiment of the present invention.
S111, depositing a first oxide layer on the surface of the first P-type GaN layer 106, wherein the first oxide layer is preferably made of SiO 2 The thickness is 300-800 nm. Experiments prove that the optimal value of the thickness of the first oxide layer is 500 nm;
s112, etching a rectangular window with the length being more than 50 microns, less than 300 microns, the width being more than 50 microns and less than 300 microns on the first oxide layer by utilizing a wet etching process; according to experimental demonstration, the optimal value of the length of the rectangular window is 100 μm, and the optimal value of the width of the rectangular window is 100 μm;
s113, etching the layer material of the rectangular window by using a dry etching process until the first GaN buffer layer 101 forms a groove body.
And S114, removing the first oxide layer on the surface, and depositing a second oxide layer on the first P-type GaN layer 106. Preferably, the second oxide layer material is SiO 2 The thickness is 20 to 100 nm. The experiment proves that the optimal value of the thickness of the second oxide layer is 50 nm.
And S115, etching the second oxide layer on the surface of the first P-type GaN layer 106 by using a dry method. An oxidation isolation layer 12 is formed around the tank body.
And S12, growing a green light material in the green light lamp wick groove, wherein the green light material forms a plurality of green light structures. Referring to fig. 5, fig. 5 is a schematic structural diagram of a blue light structure and a green light structure of a dual-color LED chip according to an embodiment of the present invention.
S121, growing a second GaN buffer layer 201 with the thickness of 3000-5000 nm in the green light lamp core groove, wherein the growth temperature is 400-500 ℃. The second GaN buffer layer 201 preferably has a thickness of 4000nm, and the optimal growth temperature is 500 ℃.
S122, growing a second GaN stabilizing layer 202 with the thickness of 500-1500 nm on the surface of the second GaN buffer layer 201, wherein the growing temperature is 900-1050 ℃, and experiments prove that the second GaN stabilizing layer 202 is preferably 1000nm in thickness, and the optimal growing temperature is 1000 ℃.
S123, keeping the temperature unchanged, and growing a second n-type GaN layer 203 doped with Si with the thickness of 200-1000 nm on the surface of the second GaN stabilizing layer 202, wherein the doping concentration is 1 multiplied by 10 18 cm -3 ～5×10 19 cm -3 . The experiment proves that the second n-type GaN layer 203 preferably grows to the thickness of 400nm, the optimal growth temperature is 1000 ℃, and the optimal doping concentration is 1 multiplied by 10 19 cm -3 。
And S124, growing a second InGaN/GaN multi-quantum well structure on the surface of the second n-type GaN layer 203 to serve as a second active layer 204. Referring to fig. 6, fig. 6 is a schematic structural diagram of a quantum well structure in a green light structure of a two-color LED chip structure according to an embodiment of the present invention; the green LED may change the quantum well structure. Wherein the growth temperature of the second InGaN quantum well layer 204b is 650-750 ℃, and the growth temperature of the second GaN barrier layer 204a is 750-850 ℃; the period of the second quantum well is 8-30, the thickness of the second InGaN quantum well layer 204b is 1.5-3.5 nm, the content of In is 20% -30%, the content is determined according to the wavelength of light, and the higher the content is, the longer the wavelength of light is; the thickness of the second GaN barrier layer 204a is 5-10 nm. The experiment proves that the preferable growth temperature of the second InGaN quantum well layer 204b is 750 ℃, and the preferable thickness is 2.8 nm; the second GaN barrier layer 204a preferably has a growth temperature of 850 ℃ and a thickness of 5 nm. The second quantum well period is preferably 20.
S125, growing a second p-type AlGaN barrier layer 205 doped with Mg with the thickness of 10-40 nm on the surface of the second active layer, wherein the growth temperature is 850-950 ℃. The experiment proves that the thickness of the second p-type AlGaN barrier layer 205 is preferably 20nm, and the optimal growth temperature is 900 ℃.
And S126, growing a second p-type GaN layer 206 with the thickness of 100-300 nm on the surface of the second p-type AlGaN barrier layer 205 for contact. Among them, the second p-type GaN layer 206 is preferably 200nm thick as experimentally demonstrated, and has an optimal growth temperature of 900 ℃.
And S13, manufacturing an electrode.
S131, depositing a third oxide layer on the surface of the whole chip by utilizing a PECVD process, preferably, the third oxide layer is made of SiO 2 The thickness is 300-800 nm. The experiment proves that the optimal value of the thickness of the third oxide layer is 500 nm.
And S132, etching a lower electrode window on the third oxide layer by using a dry etching process, wherein the lower electrode window is positioned on the first GaN stable layer 102.
S133, removing the third oxide layer, and depositing a fourth oxide layer 107, preferably, the fourth oxide layer 107 is made of SiO 2 A lower electrode contact window is formed on the first GaN stabilization layer 102, and an upper electrode contact window is formed on the first p-type GaN layer 106 and the second p-type GaN layer 206 by using a dry etching process.
S134, evaporating a metal Cr/Pt/Au electrode, wherein the thickness of Cr is 20-40 nm, the thickness of Pt is 20-40 nm, and the thickness of Au is 800-1500 nm; experiments prove that the optimal thickness value of Cr is 30nm, the optimal thickness value of Pt is 30nm, and the optimal thickness value of Au is 1200 nm. Then annealing treatment is carried out at the temperature of 300-500 ℃ to form a metal compound, and redundant metal is removed to form the upper electrode 21 and the lower electrode 22. Referring to fig. 7 and fig. 8, fig. 7 is a schematic top sectional structure view of a dual-color LED chip according to an embodiment of the present invention; fig. 8 is a schematic side-view cross-sectional structure diagram of a dual-color LED chip according to an embodiment of the present invention. The annealing optimal value is 350 ℃ through experimental demonstration.
S135, depositing metal, photoetching a lead, depositing a passivation layer by adopting a PECVD process,preferably, the passivation layer material is SiO 2 . And pattern photoetching is carried out to expose the area where the electrode pad is positioned so as to lead a gold wire in the following process.
After the above steps, the sapphire substrate 11 is thinned to 150 μm or less on the back side, and a reflective layer such as metal Al, Ni, Ti, or the like is plated on the back side. And then scribing to form the LED chip.
Example 3:
the difference from the above embodiments is that the present embodiment provides another method for fabricating a green structure.
And S20, growing a blue light material on the substrate. Referring to fig. 2, fig. 2 is a schematic structural diagram of a blue light material of a dual-color LED chip according to an embodiment of the present invention.
S201, selecting a sapphire (0001) substrate 11.
S202, growing a first GaN buffer layer 101 with the thickness of 3000-5000 nm on the sapphire substrate 11 at the growth temperature of 400-600 ℃, wherein the first GaN buffer layer 101 preferably has the thickness of 4000nm and the optimal growth temperature of 500 ℃ through experimental demonstration.
S203, heating to 900-1050 ℃, and growing the first GaN stabilizing layer 102 with the thickness of 500-1500 nm on the surface of the first GaN buffer layer 101, wherein the first GaN stabilizing layer 102 preferably has the thickness of 1000nm through experimental demonstration, and the optimal growth temperature is 1000 ℃.
S204, keeping the temperature unchanged, and growing a Si-doped first n-type GaN layer 103 with the thickness of 200-1000 nm on the surface of the first GaN stabilizing layer 102, wherein the doping concentration is 1 multiplied by 10 18 cm -3 ～5×10 19 cm -3 . The experiment proves that the first n-type GaN layer 103 preferably grows to have the thickness of 400nm, the optimal growth temperature is 1000 ℃, and the optimal doping concentration is 1 multiplied by 10 19 cm -3 。
And S205, growing a first InGaN/GaN multi-quantum well structure on the surface of the first n-type GaN layer 103 to serve as a first active layer 104. Referring to fig. 3, fig. 3 is a schematic structural diagram of an InGaN/GaN multiple quantum well structure in a blue light structure of a dual-color LED chip according to an embodiment of the present invention. Wherein the growth temperature of the first InGaN quantum well layer 104b is 650-750 ℃, and the growth temperature of the first GaN barrier layer 104a is 750-850 ℃; the period of the first quantum well is 8-30, the thickness of the first InGaN quantum well layer 104b is 1.5-3.5 nm, the content of In is 10% -20%, the content is determined according to the wavelength of light, and the higher the content is, the longer the wavelength of light is; the thickness of the first GaN barrier layer 104a is 5-10 nm. The experimental demonstration proves that the preferable growth temperature of the first InGaN quantum well layer 104b is 750 ℃, and the preferable thickness is 2.8 nm; the first GaN barrier layer 104a is preferably grown at 850 ℃ and preferably 5nm thick. The first quantum well period is preferably 20.
S206, growing a first Si-doped p-type AlGaN barrier layer 105 with the thickness of 10-40 nm on the surface of the first active layer 104, wherein the growth temperature is 850-950 ℃. Experiments prove that the thickness of the first p-type AlGaN barrier layer 105 is preferably 20nm, and the optimal growth temperature is 900 ℃;
and S207, growing a first p-type GaN layer 106 with the thickness of 100-300 nm on the surface of the first p-type AlGaN barrier layer 105 for contact. Among them, it is experimentally demonstrated that the first p-type GaN layer 106 is preferably 200nm thick with an optimal growth temperature of 900 ℃.
S21, preparing a plurality of green light lamp core grooves on the blue light material, wherein the blue light material forms a plurality of blue light structures. Referring to fig. 4, fig. 4 is a schematic structural diagram of a green light wick groove of a dual-color LED chip according to an embodiment of the present invention.
S211, depositing a first oxide layer on the surface of the first P-type GaN layer 106, wherein the first oxide layer is preferably SiO 2 The thickness is 300-800 nm. The experiment proves that the optimal value of the thickness of the first oxide layer is 500 nm.
S212, etching a rectangular window with the length being more than 50 microns, less than 300 microns, the width being more than 50 microns and less than 300 microns on the first oxide layer by utilizing a wet etching process; the length, the width and the length of the rectangular window are proved to be 100 mu m by experiments.
And S213, etching the layer material of the rectangular window by using a dry etching process until the sapphire substrate layer 11 is formed to form a groove body.
S214, removing the first oxide layer on the surface, and forming the first P-type GaN layer 106And depositing a second oxide layer. Preferably, the second oxide layer material is SiO 2 The thickness is 20 to 100 nm. The experiment proves that the optimal value of the thickness of the second oxide layer is 50 nm.
And S215, etching the second oxide layer on the surface of the first P-type GaN layer 106 by using a dry method. An oxidation isolation layer 12 is formed around the tank body.
And S22, growing a green light material in the green light lamp wick groove, wherein the green light material forms a plurality of green light structures. Referring to fig. 5, fig. 5 is a schematic structural diagram of a blue light structure and a green light structure of a dual-color LED chip according to an embodiment of the present invention.
S221, growing a second GaN buffer layer 201 with the thickness of 3000-5000 nm in the green light lamp core groove at the growth temperature of 400-500 ℃. The second GaN buffer layer 201 preferably has a thickness of 4000nm, and the optimal growth temperature is 500 ℃.
S222, growing a second GaN stabilizing layer 202 with the thickness of 500-1500 nm on the surface of the second GaN buffer layer 201, wherein the growing temperature is 900-1050 ℃, and experiments prove that the second GaN stabilizing layer 202 is preferably 1000nm in thickness, and the optimal growing temperature is 1000 ℃.
S223, keeping the temperature unchanged, growing a second n-type GaN layer 203 doped with Si with the thickness of 200-1000 nm on the surface of the second GaN stable layer 202, wherein the doping concentration is 1 multiplied by 10 18 cm -3 ～5×10 19 cm -3 . The experiment proves that the second n-type GaN layer 203 preferably grows to the thickness of 400nm, the optimal growth temperature is 1000 ℃, and the optimal doping concentration is 1 multiplied by 10 19 cm -3 。
And S224, growing a second InGaN/AlGaN multi-quantum well structure on the surface of the second n-type GaN layer 203 to serve as a second active layer 204. Referring to fig. 6, fig. 6 is a schematic structural diagram of a quantum well structure in a green light structure of a dual-color LED chip according to an embodiment of the present invention; the green LED may change the quantum well structure. Wherein the growth temperature of the second InGaN quantum well layer 204b is 650-750 ℃, and the growth temperature of the second AlGaN barrier layer 204a is 850-950 ℃; the period of the second quantum well is 8-30, the thickness of the second InGaN quantum well layer 204b is 1.5-3.5 nm, the content of In is 20% -30%, the content is determined according to the wavelength of light, and the higher the content is, the longer the wavelength of light is; the content of Al is 5-15%; the thickness of the second AlGaN barrier layer 204a is 5-10 nm. The experiment proves that the preferable growth temperature of the second InGaN quantum well layer 204b is 750 ℃, and the preferable thickness is 2.8 nm; the second AlGaN barrier layer 204a is preferably grown at 900 ℃ and preferably 5nm thick. The second quantum well period is preferably 20. The content of Al is preferably 10%.
S225, growing a second p-type AlGaN barrier layer 205 doped with Mg with the thickness of 10-40 nm on the surface of the second active layer, wherein the growth temperature is 850-950 ℃. The experiment proves that the thickness of the second p-type AlGaN barrier layer 205 is preferably 20nm, and the optimal growth temperature is 900 ℃.
S226, growing a second p-type GaN layer 206 with the thickness of 100-300 nm on the surface of the second p-type AlGaN barrier layer 205 for contact. Among them, the second p-type GaN layer 206 is preferably 200nm thick as experimentally demonstrated, and has an optimal growth temperature of 900 ℃.
And S23, manufacturing an electrode.
S231, depositing a third oxide layer on the surface of the whole chip by utilizing a PECVD process, preferably, the third oxide layer is made of SiO 2 The thickness is 300-800 nm. The experiment proves that the optimal value of the thickness of the third oxide layer is 500 nm.
And S232, etching a lower electrode window on the third oxide layer by using a dry etching process, wherein the lower electrode window is positioned on the first GaN stable layer 102. S233, removing the third oxide layer, and depositing a fourth oxide layer 107, preferably, the fourth oxide layer 107 is made of SiO 2 A lower electrode contact window is formed on the first GaN stable layer 102 by etching through a dry etching process, and an upper electrode contact window is formed on the first p-type GaN layer 106 and the second p-type GaN layer 206 by etching.
S234, evaporating a metal Cr/Pt/Au electrode, wherein the thickness of Cr is 20-40 nm, the thickness of Pt is 20-40 nm, and the thickness of Au is 800-1500 nm; experiments prove that the optimal thickness value of Cr is 30nm, the optimal thickness value of Pt is 30nm, and the optimal thickness value of Au is 1200 nm. Then annealing treatment is carried out at the temperature of 300-500 ℃ to form a metal compound, and redundant metal is removed to form the upper electrode 21 and the lower electrode 22. Referring to fig. 7 and fig. 8, fig. 7 is a schematic top sectional structure view of a dual-color LED chip according to an embodiment of the present invention; fig. 8 is a schematic side-view cross-sectional structure diagram of a dual-color LED chip according to an embodiment of the present invention. The annealing optimal value is 350 ℃ through experimental demonstration.
S235, depositing metal, photoetching a lead, and depositing a passivation layer by adopting a PECVD (plasma enhanced chemical vapor deposition) process, wherein the material of the passivation layer is preferably SiO 2 . And pattern photoetching is carried out to expose the area where the electrode pad is positioned so as to lead a gold wire in the following process.
After the above steps, the sapphire substrate 11 is thinned to 150 μm or less on the back side, and a reflective layer such as metal Al, Ni, Ti, or the like is plated on the back side. And then scribing to form the LED chip.
The preparation method and the structure of the double-color LED chip can achieve the following beneficial effects:
1. the bicolor LED chip prepared by the invention can generate light with two colors, so that the using amount of fluorescent powder can be reduced when a white light LED is produced, and the problem of weakened light caused by a large amount of discretely distributed fluorescent powder particles is solved;
2. the preparation process improves the integration level of the LED chip and reduces the cost of the LED chip;
3. the color temperature of the prepared two-color LED chip can be adjusted more flexibly.
Example 4
The two-color LED chip manufactured by the embodiment of the invention needs to be matched with red fluorescent powder to emit white light. Referring to fig. 9 and fig. 10 simultaneously, fig. 9 is a schematic top view structure diagram of another dual-color LED chip according to an embodiment of the present invention, and fig. 10 is a schematic side view structure diagram of another dual-color LED chip according to an embodiment of the present invention. This example prepares a white chip with a fluorescent thin film on the basis of the above examples.
S301, repeating the steps S10-S126 or S20-S226 of the above embodiment, and preparing the blue light-transmitting film 1001 on the surface of the prepared bicolor LED chip in the steps S20-S226. The light extraction efficiency is improved by reducing the Fresnel effect between the LED chip and the air interface. The LED light source comprises a light source, a light source module and a control module, wherein the light source module is arranged on the light source module, the light source module is arranged on the light source module, and the light source module, the light source module is arranged on the light source module, the light source module, the light source module.
S302, preparing a red light fluorescent film 1002 on the surface of the blue light transmitting film 1001. A layer of red fluorescent film with the thickness of 50 nm-2000 nm is formed on the surface of the chip by a sol-gel method.
S303, depositing a third oxide layer on the red light fluorescent film 1002 by utilizing a PECVD process, preferably, the third oxide layer is made of SiO 2 。
And S304, etching a lower electrode window on the third oxide layer by using a dry etching process, wherein the lower electrode window is positioned on the first GaN stable layer 102.
S305, removing the third oxide layer, and depositing a fourth oxide layer 107, wherein preferably, the fourth oxide layer 107 is made of SiO 2 By using a dry etching process, a lower electrode contact window is formed on the first GaN stable layer 102, and an upper electrode contact window is formed on the red light fluorescent film 1002.
S306, repeating the steps S134 to S135 to form the LED chip.
In the embodiment, the antireflection film and the red fluorescent film are formed on the surface of the LED chip, red fluorescent powder is not needed, so that the LED chip has a better white light emitting effect and a better heat dissipation effect, and the color temperature can be flexibly adjusted by changing the thickness of the red fluorescent film.
In addition, the sapphire substrate of the present invention can be replaced with a Si substrate, a SiC substrate. The substrate layer, the stabilizing layer and the N-type layer can be grown into an N-type layer, and the N pole can be directly connected out of the substrate, so that the area can be saved.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (6)
1. A preparation method of a double-color LED chip is characterized by comprising the following steps: the method comprises the following steps:
(a) growing a blue light material on a substrate;
(b) preparing a plurality of green light lamp core grooves on the blue light material, wherein the blue light material forms a plurality of blue light structures;
(c) growing a green light material in the green light lamp wick groove, wherein the green light material forms a plurality of green light structures;
(d) manufacturing an electrode;
wherein step (a) comprises:
(a1) selecting a sapphire substrate;
(a2) growing a first GaN buffer layer on the surface of the sapphire substrate;
(a3) growing a first GaN stable layer on the surface of the first GaN buffer layer;
(a4) growing a first n-type GaN layer on the surface of the first GaN stabilizing layer;
(a5) preparing a first InGaN/GaN multi-quantum well structure on the surface of the first n-type GaN layer to serve as a first active layer; the content of In the first InGaN/GaN multi-quantum well structure is 10-20%;
(a6) growing a first p-type AlGaN barrier layer on the surface of the first active layer;
(a7) growing a first p-type GaN layer on the surface of the first p-type AlGaN barrier layer;
the step (b) includes:
(b1) depositing a first oxide layer on the surface of the first p-type GaN layer;
(b2) etching a rectangular window on the first oxide layer by using a wet etching process;
(b3) etching the layer material below the rectangular window by using a dry etching process until the layer material reaches the inside of the first GaN buffer layer to form a groove body;
(b4) removing the first oxide layer, and depositing a second oxide layer;
(b5) etching the second oxide layer on the surface by using a dry etching process, and forming an oxidation isolation layer on the periphery of the tank body;
the step (c) includes:
(c1) growing a second GaN buffer layer in the green light lamp core groove;
(c2) growing a second GaN stable layer on the surface of the second GaN buffer layer;
(c3) growing a second n-type GaN layer on the surface of the second GaN stabilizing layer;
(c4) preparing a second InGaN/GaN multi-quantum well structure on the surface of the second n-type GaN layer to serve as a second active layer; the content of In the first InGaN/GaN multi-quantum well structure is 20-30%;
(c5) growing a second p-type AlGaN barrier layer on the surface of the second active layer;
(c6) and growing a second p-type GaN layer on the surface of the second p-type AlGaN barrier layer.
2. The method of claim 1, wherein: the length of the rectangular window is larger than 50 μm and smaller than 300 μm, and the width of the rectangular window is larger than 50 μm and smaller than 300 μm.
3. The method of claim 1, wherein: the thickness of the second oxide layer is 20-100 nm.
4. The method of claim 1, wherein: the material of the second oxide layer is SiO 2 。
5. The method of claim 1, wherein: the step (d) includes:
(d1) forming a lower electrode contact window on the first GaN stabilizing layer and forming upper electrode contact windows on the first p-type GaN layer and the second p-type GaN layer respectively;
(d2) evaporating a metal oxide electrode;
(d3) metal is deposited and the leads are lithographically etched to complete the preparation of the electrodes.
6. A bi-color LED chip structure, wherein the LED chip structure is prepared by the method of any one of claims 1-5.
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