CN102903799B

CN102903799B - TCO (transparent conducting oxide) conducting DBR (distributed Bragg reflector) vertical blue-light LED (light-emitting diode) chip and manufacturing method thereof

Info

Publication number: CN102903799B
Application number: CN201110212605.3A
Authority: CN
Inventors: 林宇杰
Original assignee: SHANGHAI PN-STONE PHOTOELECTRIC CO LTD
Current assignee: SHANGHAI PN-STONE PHOTOELECTRIC CO LTD
Priority date: 2011-07-28
Filing date: 2011-07-28
Publication date: 2015-04-01
Anticipated expiration: 2031-07-28
Also published as: CN102903799A

Abstract

The invention provides a TCO (transparent conducting oxide) conducting DBR (distributed Bragg reflector) vertical blue-light LED (light-emitting diode) chip and a manufacturing method thereof. The method comprises the following steps: form a light-emitting epitaxial layer on a sapphire substrate; coating a TCO conducting DBR layer, which is composed of a first-type N-type TCO film and a second-type N-type TCO film and/or nth-type N-type TCO film alternately, on the upper surface of the light-emitting epitaxial layer by vaporization, thereby forming ohmic contact with the upper surface of the light-emitting epitaxial layer; bonding the conducting substrate onto the TCO conducting DBR layer to form a P electrode by a wafer bonding technique; peeling the sapphire substrate by a laser peeling technique; and finally, preparing an N electrode on the lower surface of the light-emitting epitaxial layer. The vertical blue-light LED solves the problems of difficulty in forming ohmic contact with P-GaN, weak reflector adhesiveness, lower reflection factor of the reflector at high temperature, overhigh preparation temperature of the conducting DBR, overhigh voltage of the blue-light LED chip using the conducting DBR as the P electrode, and the like in the vertical LED chip electrode material in the prior art.

Description

Rectilinear blue-light LED chip of TCO type conduction DBR and preparation method thereof

Technical field

The present invention relates to a kind of blue-light LED chip and preparation method thereof, particularly relate to rectilinear blue-light LED chip of a kind of TCO type conduction DBR and preparation method thereof.

Background technology

At present, common blue-light LED chip is divided into two kinds, the i.e. blue-light LED chip of transversary (Lateral) and the blue-light LED chip of vertical stratification (Vertical), wherein, its P of the blue-ray LED of described transversary, N electrode is in the same side, P, N electrode homonymy certainly will need to etch away part quantum well to prepare N district, thus waste sizable a part of light-emitting area, and P, it is uneven that N electrode homonymy has CURRENT DISTRIBUTION, the shortcomings such as poor radiation, and CURRENT DISTRIBUTION is uneven and then have influence on voltage and the brightness of chip, thermal diffusivity missionary society causes junction temperature to raise, degradation problem under internal quantum efficiency, have influence on the light efficiency of chip.

And its P of the blue-light LED chip of vertical stratification, N electrode are distributed in the both sides of quantum well, therefore do not need to etch quantum well, substantially increase the utilance of chip light emitting area, electric current is uniformly distributed perpendicular to chip, and the material that in rectilinear LED chip structure, each layer all can select thermal conductivity good as far as possible, therefore the heat dispersion of rectilinear LED chip is good, and greatly eliminate the junction temperature rising that heat accumulation brings, internal quantum efficiency declines.Just because of the advantage of these uniquenesses, rectilinear LED chip becomes the focus of LED research.

In the manufacturing process of rectilinear blue-light LED chip common at present, be generally reflective metal Ag or Al on direct plating on the surface of blue light emitting epitaxial loayer well known to those skilled in the art, but this kind of way but have following shortcoming: 1, Ag and Al is difficult to form ohmic contact with P-GaN to making the voltage of LED chip very high; 2, the reflectivity of Ag and Al sharply can reduce along with the rising of temperature, when LED chip internal heat gathers temperature rising, because the decline of metallic reflection specular reflectivity, cause chip external quantum efficiency to reduce, thus reduce brightness and the luminous efficiency of LED chip; 3, the adhesiveness of Ag, Al and GaN is very poor, be easy to come off, and Ag at high temperature easily reunites.

Also another kind of way is had in the manufacturing process of rectilinear blue-light LED chip, namely after plating transparency conducting layer (TCO), high-reflectivity metal Ag or Al is plated again on transparency conducting layer, but, this kind of way still has following shortcoming: 1, because the reflectivity of Ag and Al sharply can reduce along with the rising of temperature, when LED chip internal heat gathers temperature rising, because the decline of metallic reflection specular reflectivity, cause chip external quantum efficiency to reduce, thus reduce brightness and the luminous efficiency of LED chip;

2, the adhesiveness of Ag and Al and TCO thin film is very poor, easily comes off, and Ag at high temperature can reunite.

For this reason, for the ohmic contact how solving rectilinear LED chip P-GaN, the bad problem declined with reflectance of reflector under high temperature of speculum adhesiveness, current also have some scholars to use metallorganic chemical vapor deposition method (MOCVD with reference in red-light LED and yellow light LED, Metal-organic Chemical Vapor Deposition) growth conduction DBR experience, attempt on the surface of blue light emitting epitaxial loayer, use MOCVD to grow conduction DBR, because use MOCVD growth in indigo plant, growth temperature when having the conduction DBR of high permeability high conductivity film formation in green light band exceeds a lot than the growth temperature of the base in quantum well and trap, quantum well performance degradation and chip wavelength is directly caused to occur very huge drift, and the surface of blue light emitting epitaxial loayer is the doping of P type, in order to form good ohmic contact between P-GaN, generally select MOCVD at blue light emitting epitaxial loayer upper surface growing P-type conduction DBR, but the difficulty of Group III-V compound semiconductor ubiquity P type doping, and the carrier concentration of P type Group III-V compound semiconductor is not high, thus cause resistivity excessive, the problem of overtension is there is with the rectilinear blue-light LED chip that this P-type conduction DBR makes.

Therefore, the preparation temperature and the reduction that how to reduce conduction DBR use conduction DBR as the voltage of the blue-light LED chip of P electrode, and then prepare low-voltage, and the rectilinear blue-light LED chip of high axially output, has become practitioner's problem demanding prompt solution of this area.

Summary of the invention

The shortcoming of prior art in view of the above, the object of the present invention is to provide a kind of TCO type to conduct electricity DBR rectilinear blue-light LED chip and preparation method thereof, difficultly to form that ohmic contact, speculum adhesiveness are weak with P-GaN to solve above-mentioned rectilinear LED chip of the prior art, the reflectivity of speculum declines under high temperature, the preparation temperature of DBR of conducting electricity is too high and use the problem such as blue-light LED chip overtension of DBR as P electrode of conducting electricity.

For achieving the above object and other relevant objects, the invention provides the manufacture method of the rectilinear blue-light LED chip of a kind of TCO type conduction DBR, it is characterized in that, described manufacture method at least comprises the following steps: 1) provide a Sapphire Substrate, and forms light emitting epitaxial layer in the upper surface of described Sapphire Substrate; 2) in the upper surface evaporation one TCO type conductivity DBR layer of described light emitting epitaxial layer, described TCO type conductivity DBR layer is superimposed by the first N-type TCO thin film and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film and forms, and the upper surface of the first N-type TCO thin film described and described light emitting epitaxial layer forms ohmic contact; 3) conductivity substrate is provided, adopts wafer bond techniques described conductivity substrate to be bonded to the upper surface of described TCO type conductivity DBR layer to form P electrode; 4) laser lift-off technique is utilized to peel off described Sapphire Substrate, to be peeled off by the lower surface of described Sapphire Substrate from described light emitting epitaxial layer; And 5) prepare N electrode in the lower surface of described light emitting epitaxial layer.

In manufacture method of the present invention, the first N-type TCO thin film described and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film are that homotype is adulterated.The first N-type TCO thin film described is ITO material, and described the second N-type TCO thin film is AZO material, and described n-th kind of N-type TCO thin film is GZO material.

Step 3 in manufacture method of the present invention) in, be the upper surface that by a bonded layer, described conductivity substrate is bonded to described TCO type conductivity DBR layer; Described bonded layer is metal material, alloy material, non-metallic conducting material or organic conductive material, and described bonded layer is single layer structure or sandwich construction.

In manufacture method of the present invention, described conductivity substrate is metal material, alloy material or non-metallic conducting material, and described conductivity substrate is single layer structure or sandwich construction.

The present invention also provides the rectilinear blue-light LED chip of a kind of TCO type conduction DBR, it is characterized in that, comprising: light emitting epitaxial layer; TCO type conductivity DBR layer, be stacked and placed on the upper surface of described light emitting epitaxial layer, be superimposed by the first N-type TCO thin film and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film and form, and the upper surface of the first N-type TCO thin film described and described light emitting epitaxial layer forms ohmic contact; Conductivity substrate, is bonded to the upper surface of described TCO type conductivity DBR layer and forms P electrode; And N electrode, connect the lower surface being placed in described light emitting epitaxial layer.

In the rectilinear blue-light LED chip of TCO type of the present invention conduction DBR, the first N-type TCO thin film described and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film are that homotype is adulterated.The first N-type TCO thin film described is ITO material, and described the second N-type TCO thin film is AZO material, and described n-th kind of N-type TCO thin film is GZO material.

The rectilinear blue-light LED chip of TCO type conduction DBR of the present invention also includes bonded layer, between described conductivity substrate and described TCO type conductivity DBR layer, described bonded layer is metal material, alloy material, non-metallic conducting material or organic conductive material, and described bonded layer is single layer structure or sandwich construction.

In the rectilinear blue-light LED chip of TCO type conduction DBR of the present invention, described conductivity substrate is metal material, alloy material or non-metallic conducting material, and described conductivity substrate is single layer structure or sandwich construction.

As mentioned above, rectilinear blue-light LED chip of TCO type conduction DBR of the present invention and preparation method thereof has following beneficial effect:

1, the easy and P-GaN of the conductivity type DBR utilizing ITO or P type TCO and homotype TCO material that is another kind of or multiple different refractivity to form forms ohmic contact, thus significantly reduces the voltage of rectilinear LED die.

2, TCO type conduction DBR is because be made up of resistant to elevated temperatures transparent conductive semiconductor film, and and there is between P-GaN good adhesiveness, use Ag and Al non-refractory and the bad shortcoming of adhesiveness before efficiently solving.

3, TCO type conduction DBR can keep in wider wavelength band more than 99% straight to reflectivity, and this reflectivity not with temperature raise and reduce, efficiently solve Ag or AL reflectivity can with temperature decline shortcoming.

4, the composite type reflector of TCO type conduction DBR/metal reflector composition is at the reflectivity of blue green light wave band) 99% phase religion AL (91%) Ag (95%) has higher reflectivity, and compare simple metallic mirror there is better axial reflective, more be conducive to light to be reflected back chip front side, improve the axial intensity of LED chip and the luminous efficiency of chip.

5, TCO thin film has very excellent electric conductivity, and its conductive capability can match in excellence or beauty metal, and therefore TCO type conduction DBR also has very excellent conductive capability, bring extra voltage can not to rectilinear LED.

6, the conductivity type DBR that the conductivity type DBR that ITO or P type TCO and another kind of TCO material form compares other types has great price advantage, effectively can reduce the production cost of chip, easy large-scale production.

Accompanying drawing explanation

Fig. 1 to Fig. 5 is shown as in manufacture method of the present invention according to the LED chip cross section structure schematic diagram that each step presents.

Fig. 6 is shown as of the present invention rectilinear blue-light LED chip cross section structure schematic diagram in another embodiment.

Embodiment

By particular specific embodiment, embodiments of the present invention are described below, person skilled in the art scholar can understand other advantages of the present invention and effect easily by content disclosed in the present specification.

Notice, structure, ratio, size etc. that this specification institute accompanying drawings illustrates, content all only in order to coordinate specification to disclose, understand for person skilled in the art scholar and read, and be not used to limit the enforceable qualifications of the present invention, therefore the not technical essential meaning of tool, the adjustment of the modification of any structure, the change of proportionate relationship or size, do not affecting under effect that the present invention can produce and the object that can reach, still all should drop on disclosed technology contents and obtain in the scope that can contain.Simultaneously, the term as " upper surface ", " lower surface ", "left", "right", " centre ", " two " and " one " etc. quoted in this specification, also only for ease of understanding of describing, and be not used to limit the enforceable scope of the present invention, the change of its relativeness or adjustment, under changing technology contents without essence, when being also considered as the enforceable category of the present invention.

Refer to Fig. 1 to Fig. 5, be shown as the middle LED chip cross section structure schematic diagram presented according to each step of the present invention.As shown in the figure, the invention provides the manufacture method of the rectilinear blue-light LED chip of a kind of TCO type conduction DBR, described manufacture method at least comprises the following steps:

As shown in Figure 1, first perform step 1, a Sapphire Substrate 11 is provided, and form light emitting epitaxial layer 12 in the upper surface of described Sapphire Substrate 11.Then step 2 is performed.

As shown in Figure 2, in step 2, in upper surface evaporation one deck TCO type conductivity DBR layer 13 of described light emitting epitaxial layer 12,

In the upper surface evaporation one TCO type conductivity DBR layer 13 of described light emitting epitaxial layer 12, described TCO type conductivity DBR layer 13 is superimposed by the first N-type TCO thin film (diagram) and the second N-type TCO thin film (diagram) and/or n-th kind of N-type TCO thin film (diagram) and forms, and the upper surface of the first N-type TCO thin film described and described light emitting epitaxial layer 12 forms ohmic contact; In the present embodiment, the first N-type TCO thin film described and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film are that homotype is adulterated, to reduce the voltage of rectilinear blue-light LED chip.Such as the first N-type TCO thin film described and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film are all N-type and adulterate, or the doping of P type.

In the present embodiment, the first N-type TCO thin film described is different from the refractive index of second and/or n kind N-type TCO thin film.Particularly, the first N-type TCO thin film described is ITO (tin indium oxide, Indium-Tin Oxide) material, and described the second N-type TCO thin film is AZO (namely azo-compound is doped with the ZnO of 1-5%Al) material.Described n-th kind of N-type TCO thin film is GZO (zinc gallium oxide) material, so, is not limited thereto, and in other implementations, described n-th kind of N-type TCO thin film also can be the homotype TCO material of other multiple different refractivity.

As from the foregoing, the conductivity type DBR layer 13 utilizing ITO or P type TCO and homotype TCO material (above-mentioned AZO material) that is another kind of or multiple different refractivity to form easily and light emitting epitaxial layer 12 form ohmic contact, thus significantly reduce the voltage of rectilinear LED die, and, because described TCO type conduction DBR layer 13 is made up of resistant to elevated temperatures transparent conductive semiconductor film, and and between light emitting epitaxial layer 12, there is good adhesiveness, use Ag and Al non-refractory and the bad shortcoming of adhesiveness before efficiently solving.

Then step 3 is performed.

As shown in Figure 3, in step 3, provide a conductivity substrate 14, in the present embodiment, described conductivity substrate 14 is metal material, alloy material or non-metallic conducting material, and described conductivity substrate 14 is single layer structure or sandwich construction.Then, wafer bond techniques is adopted described conductivity substrate 14 to be bonded to the upper surface of described TCO type conductivity DBR layer 13 to form P electrode, in the present embodiment, by one deck bonded layer 15, described conductivity substrate 14 is bonded to the upper surface of described TCO type conductivity DBR layer 13, particularly, described bonded layer 15 is metal material (such as Au, Cu, Sn, Ag etc.), alloy material, non-metallic conducting material or organic conductive material, and described bonded layer 15 can be single layer structure also can be sandwich construction.Certainly, in other examples, also by the mode of Direct Bonding, described conductivity substrate 14 can be bonded to the upper surface of described TCO type conductivity DBR layer 13 to form P electrode (sign).Then step 4 is performed.

As shown in Figure 4, in step 4, laser lift-off technique is utilized to peel off described Sapphire Substrate 11, to be peeled off by the lower surface of described Sapphire Substrate 11 from described light emitting epitaxial layer 12.Then step 5 is performed.

As shown in Figure 5, in steps of 5, the lower surface in described light emitting epitaxial layer 12 prepares N electrode 16, so far, namely produces low-voltage, the high rectilinear blue-light LED chip of TCO type conduction DBR axially exported.

The present invention also provides the rectilinear blue-light LED chip of a kind of TCO type conduction DBR, comprising: light emitting epitaxial layer 12, TCO type conductivity DBR layer 13, conductivity substrate 14 and N electrode 16.

For ease of understanding, respect referring again to Fig. 1 to Fig. 5.Described TCO type conductivity DBR layer 13 is stacked and placed on the upper surface of described light emitting epitaxial layer 12,

Described TCO type conductivity DBR layer 13 is superimposed by the first N-type TCO thin film (diagram) and the second N-type TCO thin film (diagram) and/or n-th kind of N-type TCO thin film (diagram) and forms, and the upper surface of the first N-type TCO thin film described and described light emitting epitaxial layer 12 forms ohmic contact; In the present embodiment, the first N-type TCO thin film described and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film are that homotype is adulterated, to reduce the voltage of rectilinear blue-light LED chip.Such as the first N-type TCO thin film described and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film are all N-type and adulterate, or the doping of P type.

Described conductivity substrate 14 is bonded to the upper surface of described TCO type conductivity DBR layer 13 and forms P electrode, in the present embodiment, described conductivity substrate 14 is metal material, alloy material or non-metallic conducting material, and described conductivity substrate 14 is single layer structure or sandwich construction.

Rectilinear blue-light LED chip of the present invention also includes one deck bonded layer 15, between described conductivity substrate 14 and described TCO type conductivity DBR layer 13, described bonded layer 15 is metal material (being such as Au, Cu, Sn, Ag etc.), alloy material, non-metallic conducting material or organic conductive material, and described bonded layer 1515 is single layer structure or sandwich construction.

Described N electrode 16 connects the lower surface being placed in described light emitting epitaxial layer 12.

In another embodiment, rectilinear blue-light LED chip of the present invention also includes one deck scattered reflection type reflector 17, be arranged between described bonded layer 15 and described TCO type conductivity DBR layer 13, described scattered reflection type reflector 17 can be metal level or alloy-layer, also can be single or multiple lift structure, the composite type reflector formed to make TCO type conductivity DBR layer 13 and scattered reflection type reflector 17 the reflectivity > 99% of blue green light wave band compare reflectivity be 91% Al and reflectivity be 95% Ag there is higher reflectivity, and compare simple metallic mirror there is better axial reflective, light is more conducive to be reflected back chip front side, improve the axial intensity of LED chip and the luminous efficiency of chip.

In sum, easy and the light emitting epitaxial layer of the conductivity type DBR that rectilinear blue-light LED chip of TCO type of the present invention conduction DBR and preparation method thereof utilizes ITO or P type TCO and homotype TCO material that is another kind of or multiple different refractivity to form forms ohmic contact, thus significantly reduces the voltage of rectilinear LED die; And, described TCO type conduction DBR layer because be made up of resistant to elevated temperatures transparent conductive semiconductor film, and and there is between P-GaN good adhesiveness, use Ag and Al non-refractory and the bad shortcoming of adhesiveness before efficiently solving; Moreover, TCO type in the present invention conduction DBR can keep in wider wavelength band more than 99% straight to reflectivity, and this reflectivity does not raise with temperature and reduces, the shortcoming that the reflectivity efficiently solving Ag or AL can decline with temperature.

In addition, TCO thin film has very excellent electric conductivity, its conductive capability can match in excellence or beauty metal, therefore TCO type conduction DBR also has very excellent conductive capability, bring extra voltage can not to rectilinear LED, and the conductivity type DBR that the conductivity type DBR be made up of ITO or P type TCO and another kind of TCO material compares other types has great price advantage, effectively can reduce the production cost of chip, easy large-scale production.So the present invention effectively overcomes various shortcoming of the prior art and tool high industrial utilization.

Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all without prejudice under spirit of the present invention and category, can modify above-described embodiment or changes.Therefore, such as have in art usually know the knowledgeable do not depart from complete under disclosed spirit and technological thought all equivalence modify or change, must be contained by claim of the present invention.

Claims

1. a manufacture method for the rectilinear blue-light LED chip of TCO type conduction DBR, it is characterized in that, described manufacture method at least comprises the following steps:

1) Sapphire Substrate is provided, and forms light emitting epitaxial layer in the upper surface of described Sapphire Substrate;

2) in the upper surface evaporation one TCO type conductivity DBR layer of described light emitting epitaxial layer, described TCO type conductivity DBR layer is superimposed by the first N-type TCO thin film and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film and forms, and the upper surface of the first N-type TCO thin film described and described light emitting epitaxial layer forms ohmic contact;

3) conductivity substrate is provided, adopts wafer bond techniques described conductivity substrate to be bonded to the upper surface of described TCO type conductivity DBR layer to form P electrode;

4) laser lift-off technique is utilized to peel off described Sapphire Substrate, to be peeled off by the lower surface of described Sapphire Substrate from described light emitting epitaxial layer; And

5) lower surface in described light emitting epitaxial layer prepares N electrode.

2. the manufacture method of the rectilinear blue-light LED chip of TCO type according to claim 1 conduction DBR, is characterized in that: the first N-type TCO thin film described and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film are all N-type and adulterate.

3. the manufacture method of the rectilinear blue-light LED chip of TCO type conduction DBR according to claim 2, it is characterized in that: the first N-type TCO thin film described is ITO material, described the second N-type TCO thin film is AZO material, and described n-th kind of N-type TCO thin film is GZO material.

4. the manufacture method of the rectilinear blue-light LED chip of TCO type according to claim 1 conduction DBR, is characterized in that: in step 3) in, be the upper surface by a bonded layer, described conductivity substrate being bonded to described TCO type conductivity DBR layer; Described bonded layer is metal material or non-metallic conducting material, and described bonded layer is single layer structure or sandwich construction.

5. the manufacture method of the rectilinear blue-light LED chip of TCO type conduction DBR according to claim 1, it is characterized in that: described conductivity substrate is metal material or non-metallic conducting material, and described conductivity substrate is single layer structure or sandwich construction.

6. the rectilinear blue-light LED chip of TCO type conduction DBR, is characterized in that, comprising:

Light emitting epitaxial layer;

TCO type conductivity DBR layer, be stacked and placed on the upper surface of described light emitting epitaxial layer, be superimposed by the first N-type TCO thin film and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film and form, and the upper surface of the first N-type TCO thin film described and described light emitting epitaxial layer forms ohmic contact;

Conductivity substrate, is bonded to the upper surface of described TCO type conductivity DBR layer and forms P electrode; And

N electrode, connects the lower surface being placed in described light emitting epitaxial layer.

7. the rectilinear blue-light LED chip of TCO type according to claim 6 conduction DBR, is characterized in that: the first N-type TCO thin film described and the second N-type TCO thin film and/or n-th kind of N-type TCO thin film are all N-type and adulterate.

8. the rectilinear blue-light LED chip of TCO type conduction DBR according to claim 7, it is characterized in that: the first N-type TCO thin film described is ITO material, described the second N-type TCO thin film is AZO material, and described n-th kind of N-type TCO thin film is GZO material.

9. the rectilinear blue-light LED chip of TCO type conduction DBR according to claim 6, it is characterized in that: also include bonded layer, between described conductivity substrate and described TCO type conductivity DBR layer, described bonded layer is metal material or non-metallic conducting material, and described bonded layer is single layer structure or sandwich construction.

10. the rectilinear blue-light LED chip of TCO type conduction DBR according to claim 6, it is characterized in that: described conductivity substrate is metal material or non-metallic conducting material, and described conductivity substrate is single layer structure or sandwich construction.