CN2762356Y - Base structure of LED chips - Google Patents

Abstract

The utility model relates to a substrate structural body of an LED core. The substrate structural body of the utility model is provided with a backing, a cushioning layer and a reflective mirror layer, wherein the cushioning layer is arranged on the backing, and the reflective mirror layer is arranged on the cushioning layer; the reflective mirror layer is composed of a metal substrate layer provided with a micropore array and a metal reflective layer deposited on the surface of the metal substrate layer and in the micropore array. An LED made of substrate structural body of the utility model has little leakage loss and total reflection loss during operation, which results in the high light emitting efficiency of the LED.

Description

The underlying structure body of LED core

Technical field

The utility model belongs to technical field of semiconductors, particularly relates to a kind of underlying structure body of diode chip.

Background technology

The luminous component of light-emitting diode (also being LED, i.e. Light Emitting Diode) tube core is arranged on the mobile layer between p type semiconductor layer and the n type semiconductor layer.Non-equilibrium minority carrier and majority carrier compound tense when injecting mobile layer will discharge the form of unnecessary energy with luminous energy with the form of radiation photon.It is only nondirectional that but mobile layer is sent, and promptly to all directions identical emission probability arranged.General semi-conducting material and surrounding air or encapsulating material comparatively speaking have higher refraction coefficient (refraction coefficient n=2.2～3.8 of typical semi-conducting material).Therefore the emitting surface generation total reflection that part light will be in chip, and have the part total reflection light to continue in light-emitting diode, to reflect, the form that is converted to heat energy by crystal and other material absorbs, and this phenomenon is called the total reflection loss herein; There is part light to spill in addition, this phenomenon is called spills loss herein from other direction that is different from emitting surface.Because total reflection is lost and spilt loss, the light that produces in the mobile layer of light-emitting diode can all not send from emitting surface, has reduced luminous efficiency (Luminous Efficiency); And the problem of also having brought luminous diode temperature to increase when light is by the absorbed in the diode has increased the difficulty that improves lumination of light emitting diode efficient.

Spilling of LED core lost and the total reflection loss in order to reduce in the prior art, a kind of method is between substrate and mobile layer Bragg reflecting layer to be set, the advantage of Bragg reflecting layer is the reflectivity height, but because it is necessary for the multiple stratification structure, and generally all be 10～20 layers structure, caused its complex manufacturing technology, cost is higher.Another kind method is on the die surfaces of the opposite side relative with surface of emission light LED core, the layer of metal reflector is set, this metallic reflector also can reduce and spills loss and total reflection is lost, but poor effect, because mobile layer is sent shines metallic reflector and reflexed to the light of emitting surface by metallic reflector, experience the process that is absorbed by die material for twice.

Semiconductor photoelectric device technology mainly comprises technologies such as extension, photoetching, etching, sputter, alloy, deposit dielectric film and optical coating.

Semiconductor deposits on the substrate that lattice constant is mated substantially with crystal habit or the process of growing is called epitaxial growth.It is different with common optical coating, the atom of deposition can be in the growing surface auto arrangement neat and with below the substrate atoms bonding, be the direct continuity of single crystalline substrate atomic arrangement.Main epitaxy method has molecular beam epitaxy (MBE), metal-organic chemical vapor deposition equipment extension (MOCVD) and liquid phase epitaxy types such as (LPE).What grow up the earliest is liquid phase epitaxial technique, it utilizes supersaturated solution to separate out crystallization to carry out material growth, too fast because of its speed of growth, difficult control of material component and adjustment are replaced by metal-organic chemical vapor deposition equipment epitaxy method and molecular beam epitaxial method gradually; The metal-organic chemical vapor deposition equipment epitaxy method utilizes the chemical reaction of metallo-organic compound gas and corresponding alkanes gas to carry out extension, the precision of control growing thickness reaches 1 micron, exactly because the appearance of metal-organic chemical vapor deposition equipment epitaxy method, just make multiple quantum trap (Multi-Quantum Well, MQW) technical applicationization, and be widely used on the products such as semiconductor laser; Molecular beam epitaxial method is by molecular beam scanning carrying out epitaxial growth, compare with metal-organic chemical vapor deposition equipment epitaxy method technology, growth rate is slow, but thickness and component that can more accurate control epitaxial loayer, so the metal-organic chemical vapor deposition equipment epitaxy technology more is used for producing, molecular beam epitaxy technique then more is used for scientific research.

Photoetching process is that the geometric figure that designs is transferred to the technical process that the skim material to the illumination sensitivity (also being photoresist, photoresist) of semiconductor wafer surface gets on.

Etching is the technical process of going on the thin layers of semiconductor material of the figure transfer on the photoresist below photoresist.The etching technics of semi-conducting material mainly is divided into two kinds of wet etching and dry method.Wet etching uses liquid chemical reagent to corrode, and damage for a short time, but to environment sensitivity relatively, machining accuracy is low; Dry etching uses the chemical reagent of gaseous state under the acting in conjunction of microwave and plasma semi-conducting material to be carried out etching, major technology ion etching technology (RIE) and plasma microwave coupling lithographic technique (ICP) two kinds that respond, the advantage of dry etching is the control precision height, the large tracts of land etching homogeneity is good, utilizes all right etching perpendicularity of plasma microwave coupling lithographic technique and all extraordinary minute surface of fineness; In the actual processing, often two kinds of lithographic methods are used.

Also comprise technologies such as sputter, alloy, deposit dielectric film and optical coating in the semiconductor photoelectric device technology, these technologies are also extremely important.The major function of sputter and alloy is to make good metal to contact with semiconductor; The deposit dielectric film also can be described as mask layer, is mainly used to do the zone of etch mask and the injection of control device electric current, and common insulating material is SiO ₂And Si ₃N ₄, use the method deposit of plasma enhanced chemical vapor deposition technology (PECVD), the advantage of this method is the rete densification, refractive index and thickness can be controlled finely; Optically coated function is the photoelectric characteristic of trim, is one of main critical technological point in the making of semiconductor optical amplifier and super-radiance light emitting diode.

The utility model content

The purpose of this utility model provides a kind of underlying structure body of LED core, after the LED core that adopts this underlying structure body is used to make light-emitting diode, spill loss and total reflection loss raising luminous efficiency thereby can when work, reduce preferably.

Total technical conceive of the present utility model is: special metallic mirror layer is set on substrate layer and makes the underlying structure body of LED core, thereby after the LED core that adopts this underlying structure body is used to make light-emitting diode, this light-emitting diode can be emitted to the light of mirror layer by the mobile layer that this mirror layer reflects LED core in when work, thereby spills the luminous efficiency of loss and total reflection loss raising light-emitting diode with minimizing.

The technical scheme that realizes the utility model purpose is: this underlying structure body has substrate and the resilient coating that is arranged on the substrate; Its design feature is: also have mirror layer, mirror layer is arranged on the resilient coating; Mirror layer is by the metallic substrate layer with microwell array and be deposited on the surface of metallic substrate layer and the metallic reflector in the micropore of microwell array is formed.

Above-mentioned substrate is sapphire or silicon or carborundum; Resilient coating is a gallium nitride, and the thickness of resilient coating is 1.0～2.0 μ m.The metal of the metallic substrate layer of mirror layer is silver or copper, and the thickness of metallic substrate layer is 1.5 μ m～3 μ m.The metal of metallic reflector is silver or aluminium, and the thickness of metallic reflector is 0.05 μ m～0.08 μ m.

Micropore in the microwell array of above-mentioned metallic substrate layer is evenly arranged, and staggers between row and the row; The shape of each micropore is all identical in the microwell array, and is circle or regular polygon.Spacing between the adjacent micropore in the microwell array of metallic substrate layer is 2.8 μ m～3 μ m; The aperture of each micropore is 1.3 μ m～2.6 μ m, and the degree of depth of each micropore is 0.8 μ m～1.2 μ m.

The utlity model has positive effect: the underlying structure body of (1) LED core of the present utility model is after being used for light-emitting diode, wherein reflecting light is mirror layer, preferred aluminium of metal or silver that metallic reflector wherein adopts, in theory, the aluminum metal reflector of surface smoothing to wavelength at 400nm to the average reflectance of the light between the 800nm greater than 90%, the silver metal reflector of surface smoothing to wavelength at 400nm to the average reflectance of the light between the 20000nm then greater than 95%, so the mirror layer in the underlying structure body of the present utility model has good reflecting effect.(2) has microwell array in the metallic substrate layer of the mirror layer in the underlying structure body of the present utility model, deposit in this micropore thin metal layer be positioned at the lip-deep thin metal layer of metallic substrate layer and connect into an integral body, form a continuous metallic reflector; This metallic reflector with shrinkage pool shape orienting reflex mobile layer preferably is emitted to the light of mirror layer, and that can effectively reduce light in the LED core spills loss and total reflection loss, the luminous efficiency of raising light-emitting diode.(3) manufacturing process of the mirror layer in the underlying structure body of the present utility model is compared with the manufacturing process of Bragg reflecting layer, has better simply manufacturing process, lower manufacturing cost; Compare with the metallic reflector that is arranged on the die surfaces place, then spill on the performance that loss and total reflection lose and substantially exceed the latter in minimizing.

Description of drawings

Fig. 1 is a kind of structural representation of the underlying structure body of LED core of the present utility model.

Fig. 2 is the schematic diagram of the microwell array of the metallic substrate layer of mirror layer among Fig. 1.

Fig. 3 is a position view of making mask layer in the process of underlying structure body of LED core among the embodiment 1.

Fig. 4 is the schematic flow sheet that the utility model is made the underlying structure body of LED core.

Fig. 5 is the structural representation of traditional LED core.

Fig. 6 is the structural representation for the LED core of the underlying structure body that adopts structure shown in Figure 1.

Fig. 7 is the relative light intensity with light-emitting diode of Fig. 5 structure a---wavelength graph.

Fig. 8 is the relative light intensity with light-emitting diode of Fig. 6 structure a---wavelength graph.

Embodiment

(embodiment 1)

See Fig. 1, the underlying structure body of the LED core of present embodiment has substrate 1, resilient coating 2 and mirror layer 3; Resilient coating 2 is arranged on the substrate 1, and mirror layer 3 is by the metallic substrate layer 31 with microwell array and be deposited on the surface of metallic substrate layer 31 and the metallic reflector 32 among the micropore 31-1 is formed.

Wherein the material of substrate 1 employing is a sapphire; Resilient coating 2 is gallium nitride (GaN), and the thickness of resilient coating 2 is 1.85 μ m; The metal of metallic substrate layer 31 is a copper, and the thickness of metallic substrate layer 31 is 2.3 μ m; The metal of metallic reflector 32 is a silver, and the thickness of metallic reflector 32 is 0.08 μ m.

See Fig. 2, metallic substrate layer 31 has microwell array, and the micropore 31-1 in the microwell array is shaped as circle; Micropore is evenly distributed in the metallic substrate layer 31, and staggers between row and the row; Spacing between the adjacent micropore 31-1 (distance at the micropore center of two adjacent micropores) is 2.8 μ m; The aperture of each micropore 31-1 is (when micropore is shaped as regular polygon, be the external diameter of a circle of regular polygon, regular polygon herein can be square, regular pentagon or regular hexagon) be 1.3 μ m, the degree of depth of each micropore 31-1 is 0.8 μ m, metallic reflector 32 is arranged in the surface or the micropore 31-1 of metallic substrate layer 32, is continuous mirror surface.

See Fig. 3 and Fig. 4, the manufacture method of the underlying structure body of the LED core of present embodiment has following steps:

1. in metal organic chemical vapor deposition system (U.S. GS3200 of EMCORE company type), with sapphire as substrate 1 (Fig. 4 a), with homemade high-purity TMGa and NH ₃As source material, with H ₂As the gas that carries in MO (being metallo-organic compound, down together) source, with high-purity N ₂As the adjustments of gas of vitellarium, growth one deck gallium nitride (GaN) crystal is as resilient coating 2 on Sapphire Substrate 1; The relative growth technological parameter: growth temperature is 560 ℃, NH ₃Adding speed is 3.1L/min; It is 20 μ mol/min that TMGa adds speed; N ₂Adding speed is 3.8L/min; H ₂Adding speed is 2.0L/min; Growth time is 2min; Obtain the gallium nitride resilient coating 2 (Fig. 4 b) of thick 1.85 μ m at last.

2. in metal organic chemical vapor deposition system (U.S. GS3200 of EMCORE company type), with Cu-TMOD as source material, with H ₂As the gas that carries in MO source, with high-purity CO ₂As the adjustments of gas of vitellarium, growing metal dielectric layer 30 on resilient coating 2; The related process parameter: growth temperature is 380 ℃, CO ₂Adding speed is 2.8L/min; It is 65 μ mol/min that Cu-TMOD adds speed; H ₂Adding speed is 2.0L/min; Growth time is 10min; Obtain the copper metallic dielectric layer 30 (Fig. 4 c) of thick 2.3 μ m at last.

3. in plasma reinforced chemical vapor deposition system (the PECVD 1000C of Britain CEVP company), deposited silicon nitride is as mask layer 33 on metallic dielectric layer 30; Sedimentary condition: radio-frequency power is 80W; Depositing temperature is 280 ℃; The adding speed of He is 50sccm (ml/min, 20 ℃ of normal temperatures are under 1 standard atmosphere condition); SiH ₁Adding speed be 1sccm; NH ₃Adding speed be 30sccm; Sedimentation time is 20min; Obtain the silicon nitride mask layer 33 of thick 0.025 μ m at last.

4. coating thickness is the photoresist (model is Shipley 6112) of 0.8 μ m on mask layer 33, adopt the single face contact to aim at photolithographicallpatterned at etching system (the German Karl Suss MA6 of company) then and on photoresist layer, carve evenly distributed array of circular apertures figure, the part photoresist of flush away behind illumination reaction then through exposure, development; Then in ion etching system (the French Alcatel Nextral of company 100), with SF ₆And O ₂As etching gas, etching figure on the silicon nitride mask layer; The technological parameter of etching: chamber pressure is 1.0Pa; Radio-frequency power is 500W; Bias voltage is 80V; SF ₆Adding speed is 50cm ³/ s; O ₂Adding speed is 80cm ³/ s; Etch rate is 5nm/min; Etch period is 20min; After the microwell array etching is good, then peel off residual part photoresist, use the residual part silicon nitride mask 33 of KOH corrosive liquid flush away again, obtain having the metallic substrate layer 31 of microwell array with acetone.Micropore 31-1 in the microwell array evenly is arranged in the metallic substrate layer 31, and staggers between row and the row; Micropore 31-1 is circular, and the spacing between the adjacent micropore 31-1 is 2.8 μ m; The diameter of each micropore 31-1 is 1.3 μ m, and the degree of depth of each micropore 31-1 is 0.8 μ m.

5. in metal organic chemical vapor deposition system (U.S. GS3200 of EMCORE company type), with Ag-TMOD as source material, with H ₂As the gas that carries in MO source, with high-purity CO ₂As the adjustments of gas of vitellarium, plated metal silver is to form metallic reflector 32 on the microwell array of metallic substrate layer 31; Deposition process parameters: depositing temperature is 320 ℃, CO ₂Adding speed is 3.2L/min, H ₂Adding speed is 2.5L/min, and it is that 25 μ mol/min growth times are 10min that Ag-TMOD adds speed, and obtaining thickness at last is the silver metal reflector 32 of 0.08 μ m, thereby makes metallic substrate layer 31 and metallic reflector 32 form mirror layer 3 (Fig. 4 d).

(embodiment 2)

All the other are identical with embodiment 1, and difference is: the thickness of resilient coating 2 is 1.80 μ m; The thickness of metallic substrate layer 31 is 2.2 μ m.

The degree of depth of the circular micropore of microwell array is 1.0 μ m, and diameter is 2.6 μ m, and the spacing between the adjacent micropore 31-1 is 3 μ m.

The manufacture method of the underlying structure body of the LED core of present embodiment, all the other are identical with embodiment 2, difference is: step 1. in, growth temperature is 545 ℃, NH ₃Adding speed be 2.9L/min, N ₂Adding speed be 3.9L/min; The thickness of the gallium nitride resilient coating 2 that obtains at last is 1.80 μ m.Step 2. in, growth temperature is 390 ℃, CO ₂Adding speed be 2.9L/min; The thickness of the metallic dielectric layer 30 that obtains at last is 2.2 μ m.Step 3. in, depositing temperature is 270 ℃.Step 4. in, the diameter of controlling circular micropore 31-1 is 2.6 μ m, the degree of depth of micropore 31-1 is 1.2 μ m, the spacing between the adjacent micropore 31-1 is 3 μ m.Step 5. in, growth temperature is 300 ℃, CO ₂Adding speed is 3.0L/min.

(test example 1)

Figure 5 shows that a kind of tube core structure of traditional light-emitting diode, the substrate of its underlying structure body is a sapphire, and resilient coating is a gallium nitride.

Figure 6 shows that the tube core structure of the light-emitting diode of the underlying structure body that adopts embodiment 1, after obtaining the underlying structure body of embodiment 1, adopt metal-organic chemical vapor deposition equipment extension or molecular beam epitaxial method to generate Multiple Quantum Well active layer (MQW) as second resilient coating; On second resilient coating, adopt metal-organic chemical vapor deposition equipment extension or the molecular beam epitaxial method active layer and the P type gallium nitride semiconductor layers of extension generation n type gallium nitride semiconductor layer, InGaN/GaN multiple quantum trap successively; Then adopt the method for sputter on p type semiconductor layer, to generate P utmost point electrode, on P utmost point electrode layer, adopt metal-organic chemical vapor deposition equipment extension or molecular beam epitaxial method to generate mask layer then, then adopt etching method to remove mask layer, p type semiconductor layer, active layer and the n type semiconductor layer of part, n type semiconductor layer is come out, then on the part n type semiconductor layer that comes out, adopt the method for sputter on n type semiconductor layer, to generate N utmost point electrode, thereby obtain light-emitting diode chip for backlight unit; Along the cutting apart of light-emitting diode chip for backlight unit that designs chip is divided into singulated dies with patterning method or scribing method at last.

The tube core of these two kinds of light-emitting diodes is except underlying structure body difference, and other parts are identical.

The light-emitting diode that LED core shown in Figure 5 obtains is tested, and device therefor is the full spectrum photoelectric color of LED comprehensive performance testing system (a Taiwan Yi Jia scientific ﹠ technical corporation), and test voltage is 3.3V, and measuring current is 20mA; Obtain relative light intensity shown in Figure 7---wavelength graph.

The light-emitting diode that LED core shown in Figure 6 obtains is tested, and device therefor is the full spectrum photoelectric color of LED comprehensive performance testing system (a Taiwan Yi Jia scientific ﹠ technical corporation), and test voltage is 3.3V, and measuring current is 20mA; Obtain relative light intensity shown in Figure 8---wavelength graph.

Can learn light-emitting diode from Fig. 7 and Fig. 8 with underlying structure body of the present utility model, its luminous intensity obviously increases, thereby has proved that underlying structure body of the present utility model can reduce the luminous efficiency that spills loss and total reflection loss raising light-emitting diode preferably when work.

Claims (6)

1, a kind of underlying structure body of LED core has substrate (1) and is arranged on resilient coating (2) on the substrate (1); It is characterized in that: also have mirror layer (3), mirror layer (3) is arranged on the resilient coating (2); Mirror layer (3) is by the metallic substrate layer with microwell array (31) and be deposited on the surface of metallic substrate layer (31) and the metallic reflector (32) in the micropore (31-1) of microwell array is formed.

2, the underlying structure body of LED core according to claim 1 is characterized in that: substrate (1) is sapphire or silicon or carborundum; Resilient coating (2) material therefor is a gallium nitride, and the thickness of resilient coating (2) is 1.0～2.0 μ m.

3, the underlying structure body of LED core according to claim 1 is characterized in that: the metal of the metallic substrate layer (31) of mirror layer (3) is silver or copper, and the thickness of metallic substrate layer (31) is 1.5 μ m～3 μ m.

4, the underlying structure body of LED core according to claim 1 is characterized in that: the metal of metallic reflector (32) is silver or aluminium, and the thickness of metallic reflector (32) is 0.05 μ m～0.08 μ m.

5, the underlying structure body of LED core according to claim 1 is characterized in that: the micropore (31-1) in the microwell array of metallic substrate layer (31) is evenly arranged, and staggers between row and the row; The shape of each micropore (31-1) is all identical in the microwell array, and is circle or regular polygon.

6, the underlying structure body of LED core according to claim 5 is characterized in that: the spacing between the adjacent micropore (31-1) in the microwell array of metallic substrate layer (31) is 2.8 μ m～3 μ m; The aperture of each micropore (31-1) is 1.3 μ m～2.6 μ m, and the degree of depth of each micropore (31-1) is 0.8 μ m～1.2 μ m.

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