CN102479891A - Light emitting diode epitaxial wafer, light emitting diode chip and manufacturing method thereof - Google Patents
Light emitting diode epitaxial wafer, light emitting diode chip and manufacturing method thereof Download PDFInfo
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- CN102479891A CN102479891A CN2010105714635A CN201010571463A CN102479891A CN 102479891 A CN102479891 A CN 102479891A CN 2010105714635 A CN2010105714635 A CN 2010105714635A CN 201010571463 A CN201010571463 A CN 201010571463A CN 102479891 A CN102479891 A CN 102479891A
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Abstract
The invention provides a light emitting diode epitaxial wafer, a light emitting diode chip and a manufacturing method thereof. The manufacturing method of the light emitting diode epitaxial wafer concretely comprises the following steps: firstly, providing a light emitting diode wafer; secondly, pasting a mask plate with a through hole at a surface of the wafer tightly, and forming a rough structure with an refractive index less than 1.5 at the surface of the wafer through a vacuum coating machine; thirdly, separating the mask plate to obtain the light emitting diode epitaxial wafer. According to the method, through the mask plate, the rough structure is formed at the surface of the wafer, the light emitting diode epitaxial wafer is formed, and luminous efficiency of the light emitting diode chip made of the light emitting diode epitaxial wafer is effectively raised.
Description
Technical field
The invention belongs to the semiconductor light emitting technical field, relate in particular to a kind of LED epitaxial slice, chip and preparation method thereof.
Background technology
Light-emitting diode (LED) is exactly that the semiconductor that will possess direct band gap is made the P/N diode; Under thermally equilibrated condition; Most electronics does not have enough energy to rise to cause conductive strips; When adding forward bias, the internal electric field intensity of P-N knot is weakened, and causes a large amount of electronics to be diffused into P type semiconductor from N type semiconductor.Under suitable bias voltage, electronics, the hole can combine in the P-N junction interface and luminous.The electric current of power supply can constantly replenish electronics and hole and give N type and P type semiconductor, makes luminous can continuing carry out.LED is luminous to be electronics and the combining of hole, and the energy of electron institute band is the form output with light.
The LED manufacture method is through MOCVD (Organometallic chemical vapor deposition) equipment epitaxial growth crystal material structure on substrate at present.Usually form minus semi-conducting material (N type semiconductor material, for example n type gallium nitride), luminescent layer and anodal semi-conducting material (P type semiconductor material, for example P type gallium nitride) at substrate successively, obtain the light-emitting diode wafer.LED in this light-emitting diode wafer is along with material and structure is different, send to such an extent that the color of light is different.
Fig. 1 is the structural representation of a kind of light-emitting diode wafer of the prior art.Please with reference to Fig. 1, the light-emitting diode wafer comprises P type gallium nitride layer 4, luminescent layer 3, n type gallium nitride 2 and Sapphire Substrate 1, and this P type gallium nitride layer 4, luminescent layer 3 and n type gallium nitride 2 stack gradually on this Sapphire Substrate 1.
Light-emitting diode is as the good light source of a new generation, but present brightness can't be satisfied people's demand preferably, so the luminous efficiency that how to improve light-emitting diode becomes scientific research personnel's research focus.Usually, the method for the luminous efficiency of raising light-emitting diode has the internal quantum efficiency of raising and improves external quantum efficiency.The inventor is through discoverys of concentrating on studies, and much easier and total reflection becomes the very important factor of LED external quantum efficiency that influences than the raising internal quantum efficiency to improve external quantum efficiency at present.The refractive index of the semi-conducting material of light-emitting diode is high a lot of with respect to air, and total reflection takes place in light-emitting diode chip for backlight unit the auroral poles that luminescent layer produces easily, and is not easy to penetrate, and causes external quantum efficiency low.
Summary of the invention
The present invention provides a kind of manufacture method of LED epitaxial slice for solving the low technical problem of luminous efficiency of light-emitting diode in the prior art.Concrete grammar is following:
A kind of manufacture method of LED epitaxial slice comprises the steps:
The present invention also provides a kind of LED epitaxial slice.This LED epitaxial slice is made by said method and is obtained.
Invention also provides a kind of light-emitting diode chip for backlight unit.This light-emitting diode chip for backlight unit by above-mentioned LED epitaxial slice via the preparation electrode, burst apart and obtain.
The manufacture method of LED epitaxial slice of the present invention forms coarse structure through mask plate on the surface of wafer and forms a kind of LED epitaxial slice; Reduce total reflection, make that the light extraction efficiency of making the light-emitting diode chip for backlight unit that obtains by this LED epitaxial slice is effectively promoted.
Description of drawings
Fig. 1 is the structural representation of a kind of light-emitting diode wafer of the prior art;
Fig. 2 A, Fig. 2 B are the mask plate vertical views that the embodiment of the invention provides;
Fig. 3 is the cross sectional representation of the mask plate of one embodiment of the invention;
Fig. 4 is the cross sectional representation of the mask plate of another embodiment of the present invention;
Fig. 5 is the structural representation of the vacuum coating equipment in the manufacturing process of the embodiment of the invention;
Fig. 6 is the structural representation of the LED epitaxial slice of the embodiment of the invention;
Fig. 7 is the structural representation of the light-emitting diode chip for backlight unit of the embodiment of the invention.
Embodiment
Clearer for technical problem, technical scheme and beneficial effect that the present invention is solved, below in conjunction with accompanying drawing 1-7 and embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
Core concept of the present invention is to obtain light emitting diode epitaxial structure through vacuum coating equipment and mask plate at the surface deposition coarse structure of light-emitting diode wafer; Reduce total reflection, thereby increase the light extraction efficiency of the light-emitting diode chip for backlight unit that makes by this LED epitaxial slice.
The said light-emitting diode wafer of the embodiment of the invention comprises the wafer of horizontal structure and the wafer of vertical stratification.
The wafer of so-called horizontal structure comprises matrix and is positioned at the ray structure on the matrix that this matrix is generally Sapphire Substrate, silicon substrate etc.
The wafer of so-called vertical stratification comprises conducting base and is positioned at the ray structure on the conducting base.This conducting base is generally copper substrate, aluminium substrate etc.
Above-mentioned ray structure, generally comprise and stack gradually (can be from top to down, also can down to down and on) n type semiconductor layer, active layer, p type semiconductor layer.This active layer is generally multiple quantum well layer.
A kind of special circumstances of the wafer of this vertical stratification are to have only ray structure.The surface of light-emitting diode wafer is the one side of the bright dipping of light-emitting diode wafer.In the wafer of horizontal structure, this surface is on the p type semiconductor layer or the face at its place, surface; In the wafer of vertical stratification, this surface is on the n type semiconductor layer or the face at its place, surface.
The wafer of horizontal structure generally forms through on matrix, grow successively n type semiconductor layer, active layer, p type semiconductor layer of the equipment of MOVCD.And the wafer of vertical stratification generally is to form through metal bonding and matrix lift-off technology on the basis of the wafer of horizontal structure.
The GAN type horizontal structure wafer (GAN wafer) that forms with growing GaN type epitaxial loayer on Sapphire Substrate below is an example; The present invention will be described; This GAN wafer comprises Sapphire Substrate and ray structure, and this ray structure comprises N type GAN semiconductor layer, INGAN multiple quantum well layer and the P type GAN semiconductor layer that is positioned at Sapphire Substrate successively.This GAN wafer prepares a plurality of GAN chips,
The manufacture method of the LED epitaxial slice of present embodiment comprises the steps:
S100 provides GAN wafer.
This GAN wafer can be bought through market and obtain, and also can obtain through above-mentioned preparation method's self-control; The surface of this GAN wafer is the surface of P type GAN semiconductor layer.
S200, provide one have some through holes mask plate.
This mask plate is preferably steel plate, and cost can reduce, and handling ease.
Downcut in a bigger steel plate through laser cutting technique, and form mask plate with some through holes through laser boring on the steel plate that downcuts.
S300, the mask plate that will have through hole is close to the surface of said GAN wafer, forms refractive index on the surface of said wafer less than 1.5 coarse structure through vacuum coating equipment.This mask plate and this GAN wafer be close to fixed form, preferably take the magnet fixed form, to reduce through of the influence of other geometrical clamps to plated film.This step, those skilled in the art can regulate parameter according to distinct device and can be easy to realize.
The material that this refractive index is lower than 1.5 coarse structure has silicon dioxide, calcirm-fluoride or magnesium fluoride etc., also can be the mixing of any two kinds or three kinds of these three kinds of materials.So evaporation source (in the evaporation coating technology) or target source (in the sputter coating process) comprise silica source, calcirm-fluoride source or magnesium fluoride source etc.This coating process also can use reaction magnetic sputtering technology to realize.
In order to obtain to have the coarse structure of regular shape, the inventor is through study and test discovery repeatedly: when this mask plate faced evaporation source or target source, when promptly the surface of GAN wafer faced evaporation source or target source, the coarse structure of formation was the most regular.
S400 separates said mask plate, obtains the GAN LED epitaxial slice.
Adopt mask plate and vacuum coating equipment to make and obtain sending out a GAN LED epitaxial slice, improved the light extraction efficiency that uses the luminescent device that this GAN LED epitaxial slice making obtains at the surface deposition coarse structure of GAN wafer.This process has that technology is simple, cost is low and is suitable for advantage such as large-scale production.And this process can not cause damage to the ray structure in the GAN wafer and influences its internal quantum efficiency in the manufacturing process of coarse structure.Another advantage of this process is to control the shape of coarse structure easily, obtains the shape of expectation easily, realizes the light extraction efficiency of expection.
Further, after step S400, also comprise:
Step S500 puts into the LED epitaxial slice that obtains in the annealing furnace, annealing in 500 degree.This step S500 is intended to increase coarse structure and the direct adhesion of GaN wafer.
What in the present embodiment formation of coarse structure is had the greatest impact is mask plate.The shape in the hole in this mask plate has determined the shape of coarse structure.Just this coarse structure is formed in the hole.
The size of general this mask plate can be identical with GAN wafer size, shown in Fig. 2 B, in a vacuum coating process, can use this mask plate of a lot of pieces, and this can increase process complexity.
The size of general this mask plate can be that the size with vacuum coating equipment adapts, and has several mask unit in this mask plate, and shown in Fig. 2 A, this mask plate only needs once fixing getting final product.Simultaneously, connect through steel plate between each mask unit, so in the vacuum coating process, the shape that obtaining near expection is made in its pollution of material atom pair around can reducing.
In order better to change the direction of propagation of light, increase the exitance of the light of ray structure, the coarse structure in the present embodiment preferably has the taper convexity of some separations.
This mask plate 20 comprises some through holes 23, and the surface that these through holes 23 are implemented in the GAN wafer forms the taper convexity of some separations.These taper convexities are that the GAN wafer that is limited in through through hole 23 forms in the vacuum coating process, and therefore, its arrangement mode is consistent with through hole 23.
In order to make the queueing discipline of taper protruding 500, increase bright dipping, preferably this through hole 23 is arranged as array arrangement.This array arrangement can adopt circular array to arrange, and also can adopt matrix array to arrange.
Fig. 3 is the cross sectional representation of the mask plate of one embodiment of the invention.Fig. 4 is the cross sectional representation of the mask plate of another embodiment of the present invention.
Said through hole 23 has first shape that is positioned at the mask plate upper surface and second shape that is positioned at the mask plate lower surface, and the spacing between said through hole first shape is the 2-3 micron, is preferably 2.5 microns.
The height of this mask plate 20 has determined the protruding height of taper, and preferably the height of this mask plate 20 is the 5-15 micron.
This mask plate 20 is a upper surface 21 towards the one side in evaporation source or target source, with upper surface 21 relative faces be lower surface 22.This through hole 23 can be cylindrical hole, promptly is arranged in size and second shape 232 that is arranged in lower surface big or small consistent, as shown in Figure 3 of first shape 231 of upper surface 21.This through hole 23 also can be round table-like through hole, and the size of this first shape 231 ' is less than the size of second shape 232 ', and is as shown in Figure 4.Can form coarse structure, obtain than high light-emitting efficiency with cone-shaped bulge.
When vacuum coating, the raw material molecule of coarse structure (perhaps atom or ion) is to be deposited on the mask plate 20 and to be deposited on the GAN wafer through through hole 23 simultaneously, in the process of deposition; The size that first shape 231 (231 ') of through hole 23 limits can slowly diminish owing to deposit the coarse structure material on first shape 231 (231 '), until filled up (be through hole 23 above be sealing by Coating Materials) fully by this material, therefore; At coating process; Because the current area of Coating Materials dwindling gradually, so it is just fewer and feweri to be deposited on the deposition materials of GAN wafer surface, under forming above big little taper protruding; Because the array arrangement of each through hole 23 and the spacing between the through hole; Thereby the surperficial formation rule taper bulge-structure at the GAN wafer reaches better bright dipping, has promoted light extraction efficiency.
Preferred round table-like through hole, during less than the thickness of mask plate, Coating Materials can fill up first shape at the protruding height of this taper.Therefore, the protruding tip of taper can contact with the Coating Materials in first shape, separate masks plate and GAN wafer, and understanding will be easily than cylindrical hole and can not destroy the tip shapes of taper convexity.The magnitude relationship of this second shape, first shape is by the parameter determining of the thickness and the vacuum coating equipment of mask plate.Can certainly be by the parameter of the thickness decision vacuum coating equipment of the size of this second shape, first shape and mask plate.
The size of general this second shape is more than or equal to the size of this first shape.This second shape can be circle or polygon, does not have special restriction.
As shown in Figure 6; The GAN LED epitaxial slice that this method forms; Comprise GAN wafer and the protruding coarse structure 500 of the taper that is positioned at this GAN wafer surface, this GAN wafer comprises Sapphire Substrate 100 and is positioned at N type GAN layer 200, luminescent layer 300 and the P type GAN layer 400 on this Sapphire Substrate 100 successively.Preferred this taper convexity is a conic convex, reaches than high light-emitting efficiency.
The bottom surface diameter of this conic convex is the 2.5-4.5 micron; Its bus and GAN wafer surface angulation are the 100-120 degree; And the spacing of conic convex is the 2-3 micron, and is best to the light taking-up of light-emitting diode, can be implemented in the light extraction efficiency that original base increases 10%-15%.
General 3 inches GAN LED epitaxial slice can obtain about 4500 GAN light-emitting diode chip for backlight unit.
As shown in Figure 7, the figure shows the structural representation of light-emitting diode chip for backlight unit.This GAN light-emitting diode chip for backlight unit is on the basis of above-mentioned GAN LED epitaxial slice, to form with bursting apart to separate that (this method is a technology well known to those skilled in the art, repeats no more at this through making electrode.), therefore, with regard to structure, this light-emitting diode chip for backlight unit is Duoed first electrode 60 and second electrode 70 than LED epitaxial slice, and this first electrode 60 is electrically connected with P type GAN, and this second electrode 70 is electrically connected with N type GAN.
Fig. 5 is the structural representation of vacuum coating equipment in the plated film of inventive embodiments.
At first, GAN wafer 30 is fixed on flap 130;
Secondly, mask plate 20 is close to is fixed on the GAN wafer 30; Adopt the magnet fixing means to fix, reduce the fixing influence of mask plate plated film.
In fact also can be earlier mask plate 20 is close to be fixed to and forms GAN wafer assembly on the GAN wafer 30, and then GAN wafer assembly is fixed on flap 130, this mask plate 20 be between source fixed part 140 and GAN wafer.This is close to and is meant that perfect condition is very close to each other between mask plate 20 and the GAN wafer 30, certainly, and in real technology, as long as this gap is also thought to be close to fixing in the reasonable scope.
The thickness of this mask plate is 10 microns, and this through hole is a cylindrical hole, and this arrays of openings is that circular array is arranged, and the size of first shape of this through hole is 3 microns, and spacing is 4 microns;
Then, open extract system, when the vacuum degree in the cavity 110 reached 0.001PA, the unlocking electronic rifle was transferred to the 3K volt with the electron gun high voltage, transfers big electron gun line fritting silicon dioxide coating materials, and this moment, vacuum degree descended.When vacuum degree reaches 0.001PA, open bias voltage, to slowly be increased to 200 volts when opening bias voltage.Open the baffle plate (not shown) and begin plated film, through the thickness of monitor control plated film, close baffle plate when thickness shows 3 microns, close air-extractor, the air inlet body boosts.Separate masks plate 20 and GAN wafer 30 obtain the GAN epitaxial wafer.
At last, the GAN epitaxial wafer is put in the annealing furnace annealing in 500 degree.Can increase the adhesion between this coarse structure and the GAN wafer.
The above is merely preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (13)
1. the manufacture method of a LED epitaxial slice is characterized in that, comprises the steps:
Step 1, the light-emitting diode wafer is provided;
Step 2, the mask plate that will have a through hole are close to the surface of said wafer, form refractive index on the surface of said wafer less than 1.5 coarse structure through vacuum coating equipment;
Step 3, separate said mask plate, obtain LED epitaxial slice.
2. the manufacture method of LED epitaxial slice according to claim 1 is characterized in that said mask plate is a steel plate.
3. the manufacture method of LED epitaxial slice according to claim 1 is characterized in that, said through hole has first shape that is positioned at the mask plate upper surface and second shape that is positioned at the mask plate lower surface, and said first is shaped as circle.
4. state the manufacture method of LED epitaxial slice like claim 3, it is characterized in that, the diameter of said first shape is the 2-5 micron.
5. state the manufacture method of LED epitaxial slice like claim 3, it is characterized in that the area of said first shape is less than the area of second shape.
6. like the manufacture method of the said LED epitaxial slice of claim 3, it is characterized in that said through hole is an array arrangement.
7. like the manufacture method of the said LED epitaxial slice of claim 6, it is characterized in that the spacing between said first shape is the 2-3 micron.
8. the manufacture method of LED epitaxial slice according to claim 1 is characterized in that the thickness of said mask plate is the 5-15 micron.
9. the manufacture method of LED epitaxial slice according to claim 1 is characterized in that the material of said coarse structure is silicon dioxide, calcirm-fluoride or magnesium fluoride.
10. like the manufacture method of the said LED epitaxial slice of claim 9, it is characterized in that, after the said step 3, also comprise LED epitaxial slice is put in the annealing furnace, the step of annealing in 500 degree.
11. the manufacture method of LED epitaxial slice is characterized in that according to claim 1, said mask plate faces evaporation source or target source.
12. a LED epitaxial slice is characterized in that, said LED epitaxial slice is made by each said manufacture method of claim 1-11 and is obtained.
13. a light-emitting diode chip for backlight unit is characterized in that, said light-emitting diode chip for backlight unit by the described LED epitaxial slice of claim 12 via the preparation electrode, burst apart and obtain.
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| US20050285132A1 (en) * | 2004-06-28 | 2005-12-29 | Matsushita Electric Industrial Co., Ltd. | Semiconductor light emitting element, semiconductor light emitting device, and method for fabricating semiconductor light emitting element |
| CN101351899A (en) * | 2005-12-29 | 2009-01-21 | 罗姆股份有限公司 | Semiconductor light emitting device and method for manufacturing the same |
| CN101395728A (en) * | 2006-03-10 | 2009-03-25 | 松下电工株式会社 | Light-emitting device |
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- 2010-11-30 CN CN2010105714635A patent/CN102479891A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1450197A (en) * | 2002-03-29 | 2003-10-22 | 三洋电机株式会社 | Deposition method and method for mfg display device |
| US20050285132A1 (en) * | 2004-06-28 | 2005-12-29 | Matsushita Electric Industrial Co., Ltd. | Semiconductor light emitting element, semiconductor light emitting device, and method for fabricating semiconductor light emitting element |
| CN1716655A (en) * | 2004-06-28 | 2006-01-04 | 松下电器产业株式会社 | Semiconductor light emitting element, semiconductor light emitting device, and method for fabricating semiconductor light emitting element |
| CN101351899A (en) * | 2005-12-29 | 2009-01-21 | 罗姆股份有限公司 | Semiconductor light emitting device and method for manufacturing the same |
| CN101395728A (en) * | 2006-03-10 | 2009-03-25 | 松下电工株式会社 | Light-emitting device |
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Application publication date: 20120530 |