CN112864293A - Deep ultraviolet LED chip with vertical structure and manufacturing method thereof - Google Patents
Deep ultraviolet LED chip with vertical structure and manufacturing method thereof Download PDFInfo
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- H01L33/20—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 bodies with a particular shape, e.g. curved or truncated substrate
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- H01L33/02—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 bodies
- H01L33/20—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 bodies with a particular shape, e.g. curved or truncated substrate
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Abstract
The invention belongs to the technical field of semiconductors, and particularly relates to a deep ultraviolet LED chip with a vertical structure and a manufacturing method thereof. The chip includes P electrode, conducting substrate, second welded layer, first welded layer, P type ohmic contact layer, P type AlGaN layer, AlGaN multiple quantum well layer, N type AlGaN layer and N electrode from supreme down in proper order, its characterized in that: the chip all around and the interior P type AlGaN layer, AlGaN multiple quantum well layer and N type AlGaN in situ contain the slot, the bottom surface and the side of slot have high reflectivity's composite reflection mirror, slot side and chip surface have reasonable contained angle, can take place to reflect and change the direction of propagation when the compound reflection mirror of slot side is touched along horizontal propagation to the deep ultraviolet ray of TM polarization mode, make the deep ultraviolet ray after the reflection mainly follow the chip surface outgoing along the vertical direction, thereby show promotion deep ultraviolet LED's light extraction efficiency, finally promote its external quantum efficiency.
Description
Technical Field
The invention belongs to the technical field of semiconductors, and particularly relates to an AlGaN-based vertical structure deep ultraviolet LED chip and a manufacturing method thereof.
Background
With the continuous progress of epitaxial growth, chip manufacturing and packaging technologies, the luminous efficiency of the deep ultraviolet LED based on the group III nitride material system is gradually improved, and the deep ultraviolet LED has a potential application value in the fields of photocuring, sterilization, water purification, light therapy, biomedical equipment, ultraviolet light communication, full spectrum illumination and the like, and has been widely applied in some fields. However, compared with the high efficiency of the visible light LED obtained from the same group III nitride material (the external quantum efficiency of InGaN-based blue light reaches more than 75%), the external quantum efficiency of AlGaN-based deep ultraviolet LED is still very low (for example, the external quantum efficiency of deep ultraviolet LED with wavelength of about 270nm is lower than 10% for a long time), which severely limits the wide-range popularization and application. The main reasons for the low External Quantum Efficiency (EQE) of AlGaN-based deep ultraviolet LEDs include the following aspects:
(1) the Internal Quantum Efficiency (IQE) of AlGaN based LEDs is more sensitive to Threading Dislocation Density (TDD) than InGaN based LEDs, high TDD resulting in low IQE;
(2) the hole concentration of P-type AlGaN is low (for P-type AlGaN having an Al composition of more than 60%, the hole concentration is only 1014/cm3Magnitude), resulting in low Electrical Injection Efficiency (EIE) of the LED;
(3) light Extraction Efficiency (LEE) is low, resulting in inefficient emission of internal luminescence.
In recent years, with the progress of material growth technology, TDD of AlGaN material is remarkably reduced (from 10)10/cm2Down to 5 x 108/cm2) And the IQE of the deep ultraviolet LED is improved from less than 1% to more than 60%. In the aspect of the electrical injection efficiency EIE, the electron leakage is inhibited through the reasonable design of the epitaxial structure, so that the EIE is improved to a higher level (about 80% for a 270nm deep ultraviolet LED). However, the light extraction efficiency LEE has not been effectively improved, only about 15% for a 270nm deep UV LED. Therefore, low LEE is a main factor for limiting the low external quantum efficiency of the deep ultraviolet LED.
The reasons for the low light extraction efficiency of the deep ultraviolet LED include two main reasons: the P-type GaN absorbs deep ultraviolet light; secondly, the light emitted by the deep ultraviolet band AlGaN-based LED is mainly in a transverse magnetic field (TM) polarization mode, which causes the light to be mainly transmitted in the transverse direction (the direction parallel to the chip surface), as shown in fig. 2-2, which causes a serious internal total reflection problem, and meanwhile, the transverse transmission path length is much longer than the vertical path length, which greatly increases the light absorption inside the LED, and these factors all cause the light not to be effectively emitted. In the existing AlGaN-based deep ultraviolet LED structure, the main purpose of P-type GaN is to improve the hole concentration, so that on one hand, the P-type ohmic contact can be improved, thereby reducing the operating voltage, and on the other hand, the electron leakage can be improved, and the EIE can be improved. The method for reducing the absorption problem of P-type GaN is to replace P-type GaN with P-type AlGaN with high Al component, but the problem of low hole concentration is not well solved and needs to be continuously improved. However, no feasible solution is provided for the problems caused by the fact that the light emission of the deep ultraviolet waveband AlGaN-based LED is mainly in a TM polarization mode in the prior art.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a deep ultraviolet LED chip with a vertical structure. According to the invention, on the basis of the traditional deep ultraviolet LED chip with a vertical structure, groove structures are introduced around and in the LED chip, as shown in figures 1-1 and 1-2, the bottom surface and the side surface of each groove are provided with high-reflectivity composite reflectors, the side surface of each groove and the surface of the chip are provided with reasonable included angles, when light in a TM polarization mode is transversely transmitted and collides with the composite reflectors on the side surfaces of the grooves, the light can be reflected, the transmission direction is changed, the reflected light can mainly exit from the surface of the chip in the vertical direction by adjusting the included angles between the side surfaces of the grooves and the surface of the chip, meanwhile, the arrangement shape of the reasonable grooves can greatly reduce the transverse transmission distance of the light in the TM polarization mode, and the absorption of the light in the chip is remarkably reduced, so that the light extraction efficiency of the AlGaN-based deep ultraviolet LED is remarkably improved, and.
The purpose of the invention is realized as follows:
the utility model provides a vertical construction deep ultraviolet LED chip, from supreme P electrode, conducting substrate, second welded layer, first welded layer, P type ohmic contact layer, P type AlGaN layer, AlGaN multiple quantum well layer, N type AlGaN layer and the N electrode of including in proper order down, its characterized in that: the chip comprises a chip body, a P-type AlGaN layer, an AlGaN multi-quantum well layer and an N-type AlGaN layer, wherein the periphery and the inside of the chip body are internally provided with grooves, the grooves start from the P-type AlGaN layer, upwards penetrate through the AlGaN multi-quantum well layer and deeply penetrate into the N-type AlGaN layer, each groove is provided with a groove bottom surface and a groove side surface, the groove bottom surface is positioned in the N-type AlGaN layer, the groove side surfaces penetrate through the P-type AlGaN layer, the AlGaN multi-quantum well layer and part of the N-type AlGaN layer and are intersected with the groove bottom surface, the included angle between the groove side surface and the chip surface ranges from 20 degrees to 70 degrees, composite reflectors are arranged on the groove bottom surface and the groove side surfaces and are formed by overlapping of a dielectric layer and a reflection metal layer, the dielectric layer is close to the groove bottom surface and the groove side surface. The existence of slot has set up the propagation obstacle for the deep ultraviolet ray along the TM polarization mode of horizontal propagation, will take place the reflection at the interface of slot lateral wall and compound speculum when light meets the slot lateral wall, thereby change the propagation direction, when the contained angle scope between slot side and the chip surface is 20 to 70, the direction of reverberation will be towards chip coarsening surface, the inside total reflection of suppression light that N type AlGaN layer coarsening surface can be very big, make the light energy that reaches the coarsening surface emergent smoothly, thereby promote the LEE of chip.
Furthermore, the light emitting wavelength of the AlGaN multi-quantum well layer is 220-360nm, the AlGaN multi-quantum well layer is a periodic structure consisting of an AlGaN quantum well and an AlGaN quantum barrier, the period number of the periodic structure is m, and the AlGaN quantum well is Al with the thickness of 1-5nmxGa1-xThe N, AlGaN quantum barrier is Al with the thickness of 5-20nmyGa1-yN, the N-type AlGaN layer is Al with the thickness of 1-5 mu mzGa1- zN, the P-type AlGaN layer is Al with the thickness of 30-300nmwGa1-wN, wherein m is more than or equal to 2 and less than or equal to 20, x is more than 0 and less than 0.9, y is more than 0 and less than or equal to 1, z is more than 0 and less than 1, w is more than or equal to 0 and less than 0.9, x is more than or equal to y, and x is more than or equal to z.
Furthermore, the dielectric layer is SiO2、MgF2、MgO、Al2O3And Na3AlF6The thickness of the dielectric layer is 20-200nm, the reflection metal layer is one of Al, Ni/Al, Cr/Al and Ti/Al, the total thickness of the reflection metal layer is 50-500nm, and the thickness of Ni, Cr and Ti is 0.1-2 nm. The composite reflector composed of the dielectric layer and the Al-based metal layer has very high reflectivity to deep ultraviolet light (wavelength of 220-360nm), the thickness of the dielectric layer and the thickness of the reflective metal layer can be adjusted to obtain the optimal reflectivity aiming at the deep ultraviolet light with different wavelengths, and the purpose of increasing Ni, Cr and Ti on the basis of Al is to increase the reflective metal layerThe adhesion force of Al and the dielectric layer is added, so that the reliability is improved, and the thickness of Ni, Cr and Ti is controlled to be 0.1-2nm, so that the reflectivity of the reflective metal layer is improved to the maximum extent and the absorption of deep ultraviolet light is reduced on the premise of ensuring better adhesion force.
Furthermore, the distribution shape of the grooves in the chip is a mutually connected net structure or a mutually separated independent structure, and when the grooves in the chip are mutually connected net structures, the grooves are connected with the grooves around the chip. The distributed groove shape is beneficial to enabling all the TM polarization mode deep ultraviolet light which is transmitted along the transverse direction to meet the side wall of the groove quickly, so that the transmission reverse direction is changed, the absorption of the inside of the chip to the deep ultraviolet light is reduced, and the deep ultraviolet light is beneficial to being emitted from the front surface of the chip.
Furthermore, the conductive substrate is made of one of silicon, copper, tungsten-copper alloy and molybdenum-copper alloy, the first welding layer is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti, the second welding layer is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti, the N electrode is one of Al, Cr/Au, Ti/Al, Ti/Au, Ni/Al, Ni/Au, Al/Ti/Au, Cr/Al/Ti/Au and Ti/Al/Ti/Au, and the P-type ohmic contact layer is one of Ni, Pt, Ag, NiAu, NiAg and ITO.
A manufacturing method of a deep ultraviolet LED chip with a vertical structure comprises the following steps:
(1) providing a substrate, growing a buffer layer, an N-type AlGaN layer, an AlGaN multi-quantum well layer and a P-type AlGaN layer on the substrate in sequence,
the buffer layer, the N-type AlGaN layer, the AlGaN multi-quantum well layer and the P-type AlGaN layer form a deep ultraviolet LED light-emitting film together, wherein the AlGaN multi-quantum well layer is of a periodic structure consisting of an AlGaN quantum well and an AlGaN quantum barrier, the period number of the periodic structure is m, and the AlGaN quantum well is Al with the thickness of 1-5nmxGa1-xThe N, AlGaN quantum barrier is Al with the thickness of 5-20nmyGa1-yThe N, N type AlGaN layer is Al with the thickness of 1-5 mu mzGa1-zThe N, P type AlGaN layer is Al with the thickness of 30-300nmwGa1-wN is whereinM is more than or equal to 2 and less than or equal to 20, x is more than 0 and less than 0.9, y is more than 0 and less than or equal to 1, z is more than 0 and less than 1, w is more than or equal to 0 and less than 0.9, x is more than y, and x is more than z;
(2) etching partial areas around and within the P-type AlGaN layer by utilizing a photoetching etching technology to form grooves,
the groove starts from the P-type AlGaN layer, penetrates through the AlGaN multi-quantum well layer and extends into the N-type AlGaN layer, the groove is provided with a groove bottom surface and a groove side surface, the groove bottom surface is positioned in the N-type AlGaN layer, the groove side surface penetrates through the P-type AlGaN layer, the AlGaN multi-quantum well layer and part of the N-type AlGaN layer and is intersected with the groove bottom surface, the included angle range between the groove side surface and the chip surface is 20-70 degrees, the distribution shape of the groove in the area within the periphery of the P-type AlGaN layer is a mutually connected net structure or a mutually separated independent structure, and when the groove in the area within the periphery of the P-type AlGaN layer is a mutually connected net structure, the groove can be connected with the;
(3) depositing a dielectric layer and a reflecting metal layer on the P-type AlGaN layer, the bottom surface of the groove and the side surface of the groove in sequence, forming a composite reflector layer by the dielectric layer and the reflecting metal layer,
the dielectric layer is SiO2、MgF2、MgO、Al2O3And Na3AlF6The thickness of the dielectric layer is 20-200nm, the total thickness of the reflection metal layer is 50-500nm, and the thickness of Ni, Cr and Ti is 0.1-2 nm;
(4) etching off the dielectric layer and the reflective metal layer at the position of the P-type AlGaN layer by utilizing a photoetching corrosion technology to expose the P-type AlGaN layer;
(5) a P-type ohmic contact layer is manufactured on the exposed P-type AlGaN layer by utilizing a photoetching stripping technology,
the P-type ohmic contact layer is one of Ni, Pt, Ag, NiAu, NiAl, NiAg and ITO;
(6) depositing a first welding layer on the P-type ohmic contact layer and the reflective metal layer,
the first welding layer is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti;
(7) providing a conductive substrate with a second welding layer on one side and a P electrode on the other side, welding the second welding layer and the first welding layer together by using a hot-pressing bonding technology,
in the hot-pressing bonding process, a gap formed by the composite reflector In the groove is filled by a first welding layer, the conductive substrate is made of one of silicon, copper, tungsten-copper alloy and molybdenum-copper alloy, and the second welding layer is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti;
(8) stripping off the substrate, and transferring the deep ultraviolet LED light-emitting film onto a conductive substrate;
(9) corroding the buffer layer, and roughening the surface of the N-type AlGaN layer;
(10) an N electrode is formed on the N-type AlGaN layer,
the N electrode is one of Al, Cr/Au, Ti/Al, Ti/Au, Ni/Al, Ni/Au, Al/Ti/Au, Cr/Al/Ti/Au and Ti/Al/Ti/Au.
Further, the substrate is Si substrate, Al2O3One of a substrate, a SiC substrate, a GaN substrate, and an AlN substrate.
Furthermore, the surface roughening process of the N-type AlGaN layer is to soak the N-type AlGaN layer in an alkaline solution of NaOH, KOH or TMAH to form a rough surface, or to perform dry etching on the surface of the N-type AlGaN layer by using a photoresist mask to form a rough surface.
Compared with the prior art, the invention has the following beneficial effects:
compared with the existing AlGaN-based deep ultraviolet LED, the invention introduces the groove structure around and in the AlGaN-based deep ultraviolet LED chip, the side surface of the groove penetrates through the P-type AlGaN layer and the AlGaN multi-quantum well layer and extends into the N-type AlGaN layer, the high-reflectivity composite reflector is manufactured on the bottom surface of the groove and the side surface of the groove, and the side surface of the groove and the surface of the chip have a reasonable included angle. The side surface of the groove arranged in the way can effectively block the light of the TM polarization mode emitted by the AlGaN multi-quantum well layer from a transverse propagation path, so that all the deep ultraviolet light of the TM polarization mode propagating along the transverse direction can be changed by chance in the direction beneficial to emergence. Can take place the reflection when the compound speculum of slot side is touch along horizontal propagation to the light of TM polarization mode, make the direction of propagation change, and the regulation of slot side and chip surface contained angle, can make the light after the reflection mainly follow the chip surface outgoing along the vertical direction, reasonable slot shape setting of arranging simultaneously can reduce TM polarization mode's light along horizontal propagation distance by a wide margin, show the absorption of reducing the chip inside to light, thereby show the light extraction efficiency who promotes AlGaN base deep ultraviolet LED, finally promote its external quantum efficiency. In a word, compared with the prior art, the method effectively solves the problem that the AlGaN-based deep ultraviolet LED emits light mainly in a TM polarization mode, and can greatly improve the light extraction efficiency LEE of the AlGaN-based deep ultraviolet LED.
Drawings
Fig. 1-1 is a schematic cross-sectional view of a deep ultraviolet LED chip with a vertical structure according to the present invention.
Fig. 1-2 are schematic diagrams of TM polarization mode deep ultraviolet light propagation paths in a vertical structure deep ultraviolet LED chip according to the present invention, in order to clearly show the TM polarization mode deep ultraviolet light propagation paths, filling patterns of individual layers in the diagrams are deleted, and layer name labels of the individual layers are deleted, and all layers in the diagrams are completely the same as those in fig. 1-1.
Fig. 2-1 is a schematic cross-sectional view of a deep ultraviolet LED chip with a vertical structure according to the prior art.
Fig. 2-2 is a schematic diagram of a TM polarization mode deep ultraviolet light propagation path in a deep ultraviolet LED chip with a vertical structure in the prior art, in order to clearly show the TM polarization mode deep ultraviolet light propagation path, filling patterns of individual layers in the diagram are deleted, and layer name labels of the individual layers are deleted, and all layers in the diagram are completely the same as those in fig. 2-1.
Fig. 3 is a schematic cross-sectional view of step 1 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 4-1 is a schematic cross-sectional view of step 2 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 4-2 is a schematic top view of one of the trench distribution shapes in step 2 of the method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1.
Fig. 4-3 are schematic top views of one of the trench distribution shapes in step 2 of the method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1.
Fig. 4-4 are schematic top views of one of the trench distribution shapes in step 2 of the method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1.
Fig. 4-5 are schematic top views of one of the trench distribution shapes in step 2 of the method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1.
Fig. 5 is a schematic cross-sectional view of step 3 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 6 is a schematic cross-sectional view of step 4 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 7 is a schematic cross-sectional view of step 5 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 8 is a schematic cross-sectional view of step 6 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 9 is a schematic cross-sectional view of step 7 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 10 is a schematic cross-sectional view of step 8 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 11 is a schematic cross-sectional view of step 9 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Fig. 12 is a schematic cross-sectional view of step 10 of a method for manufacturing a vertical deep ultraviolet LED chip in embodiment 1 of the present invention.
Illustration of the drawings: 101-substrate, 201-buffer layer, 301-N type AlGaN layer, 400-AlGaN multiple quantum well layer, 401-AlGaN quantum well layer, 402-AlGaN quantum barrier layer, 501-P type AlGaN layer, 600-groove, 601-groove bottom surface, 602-groove side surface, 700-composite reflector layer, 701 dielectric layer, 702-reflective metal layer, 801-P type ohmic contact layer, 901-first welding layer, 1001-second welding layer, 1101-conductive substrate, 1201-P electrode, 1301-N electrode, 1400-TM polarization mode deep ultraviolet light propagation path.
Detailed Description
The invention is further described below with reference to the figures and examples.
Example 1:
as shown in fig. 1-1, the deep ultraviolet LED chip with a vertical structure of the present invention sequentially includes, from bottom to top, a P electrode 1201, a conductive substrate 1101, a second solder layer 1001, a first solder layer 901, a P-type ohmic contact layer 801, a P-type AlGaN layer 501, an AlGaN multi-quantum well layer 400, an N-type AlGaN layer 301, and an N electrode 1301, and is characterized in that: the groove 600 is arranged in the P-type AlGaN layer 501, the AlGaN multi-quantum well layer 400 and the N-type AlGaN layer 301 at the periphery and inside of the chip, the groove 600 penetrates through the AlGaN multi-quantum well layer 400 from the P-type AlGaN layer 501 and penetrates into the N-type AlGaN layer 301, the groove 600 is provided with a groove bottom surface 601 and a groove side surface 602, the groove bottom surface 601 is positioned in the N-type AlGaN layer 301, the groove side surface 602 penetrates through the P-type AlGaN layer 501, the AlGaN multi-quantum well layer 400 and part of the N-type AlGaN layer 301, and intersects trench floor 601, with trench sides 602 at an angle in the range of 20 to 70 with the chip surface, the composite reflector 700 is arranged on the bottom surface 601 and the side surface 602 of the groove, the composite reflector 700 is formed by superposing a dielectric layer 701 and a reflecting metal layer 702, the dielectric layer 701 is close to the trench bottom 601 and the trench side 602, a gap formed by the composite mirror 700 in the trench 600 is filled with the first welding layer 901, and the upper surface of the N-type AlGaN layer 301 is a roughened surface. As shown in fig. 1-2, the existence of the trench 600 provides a propagation barrier for the TM polarization mode deep ultraviolet light propagating in the lateral direction, and when the light encounters the trench sidewall 602, the light is reflected at the interface between the trench sidewall 602 and the composite reflector 700, so as to change the propagation direction, and when the included angle between the trench sidewall 602 and the chip surface is 20 ° to 70 °, the direction of the reflected light faces the chip roughened surface, and the roughened surface of the N-type AlGaN layer 301 can greatly suppress the total internal reflection of the light, so that the light reaching the roughened surface can smoothly exit, thereby improving the LEE of the chip.
The AlGaN multi-quantum well layer 400 has the light-emitting wavelength of 220-360nm, the AlGaN multi-quantum well layer 400 is a periodic structure consisting of an AlGaN quantum well 401 and an AlGaN quantum barrier 402, the period number of the periodic structure is m, and the AlGaN quantum well 401 is Al with the thickness of 1-5nmxGa1-xThe N, AlGaN quantum barrier 402 is Al with the thickness of 5-20nmyGa1-yN, the N-type AlGaN layer 301 is Al with the thickness of 1-5 mu mzGa1-zN, the P-type AlGaN layer 501 is Al with the thickness of 30-300nmwGa1-wN, wherein m is more than or equal to 2 and less than or equal to 20, x is more than 0 and less than 0.9, y is more than 0 and less than or equal to 1, z is more than 0 and less than 1, w is more than or equal to 0 and less than 0.9, x is more than or equal to y, and x is more than or equal to z.
The dielectric layer 701 is SiO2、MgF2、MgO、Al2O3And Na3AlF6The thickness of the dielectric layer 701 is 20-200nm, the reflection metal layer 702 is one of Al, Ni/Al, Cr/Al and Ti/Al, the total thickness of the reflection metal layer 702 is 50-500nm, and the thickness of Ni, Cr and Ti is 0.1-2 nm. The composite reflector composed of the dielectric layer and the Al-based metal layer has high reflectivity to deep ultraviolet light (with the wavelength of 220-360nm), the thickness of the dielectric layer and the thickness of the reflective metal layer can be adjusted to obtain the optimal reflectivity aiming at the deep ultraviolet light with different wavelengths, the purpose of increasing Ni, Cr and Ti on the basis of Al of the reflective metal layer is to increase the adhesion between Al and the dielectric layer, so that the reliability is improved, and the purpose of controlling the thicknesses of Ni, Cr and Ti to be 0.1-2nm is to furthest improve the reflectivity of the reflective metal layer and reduce the absorption to the deep ultraviolet light on the premise of ensuring better adhesion.
As shown in fig. 4-2, 4-3, 4-4 and 4-5, the grooves 600 are distributed inside the chip in a mutually connected net structure or in a mutually separated independent structure, and when the grooves 600 inside the chip are in a mutually connected net structure, they are also connected with the grooves 600 around the chip. The distributed groove shape is beneficial to enabling all the TM polarization mode deep ultraviolet light which is transmitted along the transverse direction to meet the side wall of the groove quickly, so that the transmission reverse direction is changed, the absorption of the inside of the chip to the deep ultraviolet light is reduced, and the deep ultraviolet light is beneficial to being emitted from the front surface of the chip.
The conductive substrate 1101 is made of one of silicon, copper, tungsten-copper alloy and molybdenum-copper alloy, the first welding layer 901 is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti, the second welding layer 1001 is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti, the N electrode 1301 is one of Al, Cr/Au, Ti/Al, Ti/Au, Ni/Al, Ni/Au, Al/Ti/Au, Cr/Al/Ti/Au and Ti/Al/Ti/Au, and the P-type ohmic contact layer 801 is one of Ni, Pt, Ag, NiAu, NiAl, NiAg and ITO.
A manufacturing method of a deep ultraviolet LED chip with a vertical structure comprises the following steps:
(1) as shown in fig. 3, a substrate 101 is provided, a buffer layer 201, an N-type AlGaN layer 301, an AlGaN multi-quantum well layer 400 and a P-type AlGaN layer 501 are grown on the substrate 101 in this order,
the buffer layer 201, the N-type AlGaN layer 301, the AlGaN multi-quantum well layer 400 and the P-type AlGaN layer 501 commonly form a deep ultraviolet LED light-emitting film, wherein the AlGaN multi-quantum well layer 400 is a periodic structure consisting of an AlGaN quantum well 401 and an AlGaN quantum barrier 402, the period number of the periodic structure is m, and the AlGaN quantum well 401 is Al with the thickness of 1-5nmxGa1-xThe N, AlGaN quantum barrier 402 is Al with the thickness of 5-20nmyGa1-yThe N, N-type AlGaN layer 301 is Al with a thickness of 1-5 μmzGa1-zThe N, P type AlGaN layer 501 is Al with the thickness of 30-300nmwGa1-wN, wherein m is more than or equal to 2 and less than or equal to 20, x is more than 0 and less than 0.9, y is more than 0 and less than or equal to 1, z is more than 0 and less than 1, w is more than or equal to 0 and less than 0.9, x is more than or equal to y, and x is more than or equal to z;
(2) as shown in fig. 4-1, a trench 600 is etched in a local area around and within the periphery of the P-type AlGaN layer 501 by using a photolithography etching technique,
the trench 600 starts from the P-type AlGaN layer 501, penetrates through the AlGaN mqw layer 400 and penetrates into the N-type AlGaN layer 301, the trench 600 has a trench bottom 601 and a trench side 602, the trench bottom 601 is located in the N-type AlGaN layer 301, the trench side 602 penetrates through the P-type AlGaN layer 501, the AlGaN mqw layer 400 and a part of the N-type AlGaN layer 301 and intersects with the trench bottom 601, an included angle between the trench side 602 and the chip surface ranges from 20 ° to 70 °, as shown in fig. 4-2, 4-3, 4-4 and 4-5, a distribution shape of the trench 600 in a region within the periphery of the P-type AlGaN layer 501 is a mutually connected net structure or a mutually separated independent structure, and when the trench 600 in a region within the periphery of the P-type layer 501 is a mutually connected net structure, the trench 600 can be connected with the trench 600 in the periphery of the P-type AlGaN layer 501 at the same time, and it is required to point that fig. 4-2, and, The groove 600 profiles given in fig. 4-3, 4-4, and 4-5 are only specific examples of groove profiles and are not limited to the forms shown in the figures in order to meet the structural characteristics required by the present invention;
(3) as shown in fig. 5, a dielectric layer 701 and a reflective metal layer 702 are sequentially deposited on the P-type AlGaN layer 501, the trench bottom surface 601 and the trench side surface 602, the dielectric layer 701 and the reflective metal layer 702 together form a composite mirror layer 700,
(4) as shown in fig. 6, the dielectric layer 701 and the reflective metal layer 702 at the position of the P-type AlGaN layer 501 are etched by using a photolithography and etching technique, so as to expose the P-type AlGaN layer 501;
(5) as shown in fig. 7, a P-type ohmic contact layer 801 is formed on the exposed P-type AlGaN layer 501 by a photolithography lift-off technique,
the P-type ohmic contact layer 801 is one of Ni, Pt, Ag, NiAu, NiAl, NiAg and ITO;
(6) as shown in fig. 8, a first solder layer 901 is deposited on the P-type ohmic contact layer 801 and the reflective metal layer 702,
the first welding layer 901 is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti;
(7) as shown in fig. 9, a conductive substrate 1101 having a second bonding layer 1001 on one side and a P-electrode 1201 on the other side is provided, the second bonding layer 1001 and the first bonding layer 901 are bonded together using a thermocompression bonding technique,
in the thermocompression bonding process, a vacancy formed by the composite reflecting mirror 700 In the groove 600 is filled by the first welding layer 901, the conductive substrate 1101 is made of one of silicon, copper, tungsten-copper alloy and molybdenum-copper alloy, and the second welding layer 1001 is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti;
(8) as shown in fig. 10, the substrate 101 is peeled off, and the deep ultraviolet LED light-emitting thin film is transferred onto a conductive substrate 1101;
(9) as shown in fig. 11, the buffer layer 201 is etched away, and the surface of the N-type AlGaN layer 301 is roughened;
(10) as shown in fig. 12, an N electrode 1301 is formed on the N-type AlGaN layer 301,
the N electrode 1301 is one of Al, Cr/Au, Ti/Al, Ti/Au, Ni/Al, Ni/Au, Al/Ti/Au, Cr/Al/Ti/Au, and Ti/Al/Ti/Au.
The substrate 101 is Si substrate or Al substrate2O3One of a substrate, a SiC substrate, a GaN substrate, and an AlN substrate.
The surface roughening process of the N-type AlGaN layer 301 is to soak the N-type AlGaN layer 301 in an alkaline solution such as NaOH, KOH, TMAH, or the like to form a rough surface, or to perform dry etching on the surface of the N-type AlGaN layer 301 by using a photoresist mask to form a rough surface.
The foregoing merely represents preferred embodiments of the invention, which are described in some detail and detail, and therefore should not be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes, modifications and substitutions can be made without departing from the spirit of the present invention, and these are all within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. The utility model provides a vertical construction deep ultraviolet LED chip, from supreme P electrode, conducting substrate, second welded layer, first welded layer, P type ohmic contact layer, P type AlGaN layer, AlGaN multiple quantum well layer, N type AlGaN layer and the N electrode of including in proper order down, its characterized in that: the chip comprises a chip body, a P-type AlGaN layer, an AlGaN multi-quantum well layer and an N-type AlGaN layer, wherein the periphery and the inside of the chip body are internally provided with grooves, the grooves start from the P-type AlGaN layer, upwards penetrate through the AlGaN multi-quantum well layer and deeply penetrate into the N-type AlGaN layer, each groove is provided with a groove bottom surface and a groove side surface, the groove bottom surface is positioned in the N-type AlGaN layer, the groove side surfaces penetrate through the P-type AlGaN layer, the AlGaN multi-quantum well layer and part of the N-type AlGaN layer and are intersected with the groove bottom surface, the included angle between the groove side surface and the chip surface ranges from 20 degrees to 70 degrees, composite reflectors are arranged on the groove bottom surface and the groove side surfaces and are formed by overlapping of dielectric layers and reflecting metal layers, the dielectric layers are close to the groove bottom surface and the groove side surfaces, gaps.
2. The deep ultraviolet LED chip with vertical structure as claimed in claim 1, wherein: the AlGaN multi-quantum well layer has the light-emitting wavelength of 220-360nm, is of a periodic structure consisting of an AlGaN quantum well and an AlGaN quantum barrier, the period number of the periodic structure is m, and the AlGaN quantum well is Al with the thickness of 1-5nmxGa1-xThe N, AlGaN quantum barrier is Al with the thickness of 5-20nmyGa1-yN, the N-type AlGaN layer is Al with the thickness of 1-5 mu mzGa1-zN, the P-type AlGaN layer is Al with the thickness of 30-300nmwGa1-wN, wherein m is more than or equal to 2 and less than or equal to 20, x is more than 0 and less than 0.9, y is more than 0 and less than or equal to 1, z is more than 0 and less than 1, w is more than or equal to 0 and less than 0.9, x is more than or equal to y, and x is more than or equal to z.
3. The deep ultraviolet LED chip with vertical structure as claimed in claim 1, wherein: the dielectric layer is SiO2、MgF2、MgO、Al2O3And Na3AlF6The thickness of the dielectric layer is 20-200nm, the reflection metal layer is one of Al, Ni/Al, Cr/Al and Ti/Al, the total thickness of the reflection metal layer is 50-500nm, and the thickness of Ni, Cr and Ti is 0.1-2 nm.
4. The deep ultraviolet LED chip with vertical structure as claimed in claim 1, wherein: the grooves are distributed in the chip in a mutually connected net structure or mutually separated independent structures, and when the grooves in the chip are in the mutually connected net structure, the grooves can be connected with the grooves on the periphery of the chip.
5. The deep ultraviolet LED chip with vertical structure as claimed in claim 1, wherein: the conductive substrate is made of one of silicon, copper, tungsten-copper alloy and molybdenum-copper alloy, the first welding layer is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti, the second welding layer is one or a combination of more of Au, Ag, AuSn, In, Sn, Cu, Fe, Ni, Pt, Cr and Ti, the N electrode is one of Al, Cr/Au, Ti/Al, Ti/Au, Ni/Al, Ni/Au, Al/Ti/Au, Cr/Al/Ti/Au and Ti/Al/Ti/Au, and the P-type ohmic contact layer is one of Ni, Pt, Ag, NiAl and ITO.
6. The manufacturing method of the vertical structure deep ultraviolet LED chip according to any one of claims 1 to 5, characterized by comprising the following steps:
(1) providing a substrate, and growing a buffer layer, an N-type AlGaN layer, an AlGaN multi-quantum well layer and a P-type AlGaN layer on the substrate in sequence, wherein the buffer layer, the N-type AlGaN layer, the AlGaN multi-quantum well layer and the P-type AlGaN layer jointly form a deep ultraviolet LED light-emitting film;
(2) corroding partial areas around and within the periphery of the P-type AlGaN layer by utilizing a photoetching corrosion technology to form a groove, wherein the groove is provided with a groove bottom surface and a groove side surface;
(3) depositing a dielectric layer and a reflective metal layer on the P-type AlGaN layer, the bottom surface of the groove and the side surface of the groove in sequence, wherein the dielectric layer and the reflective metal layer jointly form a composite reflector layer;
(4) etching off the dielectric layer and the reflective metal layer at the position of the P-type AlGaN layer by utilizing a photoetching corrosion technology to expose the P-type AlGaN layer;
(5) manufacturing a P-type ohmic contact layer on the exposed P-type AlGaN layer by utilizing a photoetching stripping technology;
(6) depositing a first welding layer on the P-type ohmic contact layer and the reflecting metal layer;
(7) providing a conductive substrate with a second welding layer on one side and a P electrode on the other side, welding the second welding layer and the first welding layer together by utilizing a hot-press bonding technology, and filling a gap formed by the composite reflector in the groove by the first welding layer in the hot-press bonding process;
(8) stripping off the substrate, and transferring the deep ultraviolet LED light-emitting film onto a conductive substrate;
(9) corroding the buffer layer, and roughening the surface of the N-type AlGaN layer;
(10) and manufacturing an N electrode on the N-type AlGaN layer.
7. The method for manufacturing the vertical structure deep ultraviolet LED chip according to claim 6, wherein: the substrate is Si substrate or Al2O3One of a substrate, a SiC substrate, a GaN substrate, and an AlN substrate.
8. The method for manufacturing the deep ultraviolet LED chip with the vertical structure according to claim 6, wherein the surface roughening process of the N-type AlGaN layer comprises the following steps: soaking in NaOH, KOH or TMAH alkaline solution to form a rough surface, or performing dry etching on the surface of the N-type AlGaN layer by using a photoresist mask to form the rough surface.
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