CN102104233A

CN102104233A - High-reflectivity light-emitting diode chip with vertical structure and preparation method thereof

Info

Publication number: CN102104233A
Application number: CN2010106212693A
Authority: CN
Inventors: 黄辉; 徐瑾
Original assignee: HC Semitek Corp
Current assignee: HC Semitek Corp
Priority date: 2010-12-31
Filing date: 2010-12-31
Publication date: 2011-06-22

Abstract

The invention provides a high-reflectivity light-emitting diode chip with a vertical structure. The chip has a single-electrode structure, comprises a distributed Bragg reflector (DBR), an ohmic contact layer and a low-thermal resistance radiating substrate, greatly improves luminous efficiency, and improves the radiating capacity of devices. The preparation method comprises the following steps of: growing an epitaxial layer on a substrate, wherein the epitaxial layer comprises a buffer layer, an N-type layer, a multi-quantum well layer and a P-type layer; manufacturing graphics of the P-type layer; manufacturing the reflector and the ohmic contact layer; manufacturing a bonding layer of the radiating substrate; bonding the radiating substrate to the P-type layer; removing a sapphire substrate; manufacturing an N electrode; thinning the substrate; evaporating a metal layer to form a P electrode; and testing, scribing and sorting wafers. The chip manufactured by the method can effectively increase light output, improve the radiating capacity of the chip, provide stable light output power, and realize the application of high luminous efficiency.

Description

Light emitting diode with vertical structure chip of a kind of high reflectance and preparation method thereof

Technical field

The present invention relates to chip, especially light emitting diode with vertical structure chip of high reflectance and preparation method thereof.

Background technology

Light-emitting diode is a kind ofly high efficiency electric energy to be converted into the light emitting semiconductor device of luminous energy, is 21 century one of the most promising light source.Light-emitting diode generally is luminous by the charge carrier intrinsic transition of direct gap semiconductor, has high photoelectric conversion efficiency, promptly high internal quantum efficiency, and the internal quantum efficiency of blue chip can be accomplished more than 90% at present.In order to realize high efficiency illumination, current key is to improve light extraction efficiency, promptly improves external quantum efficiency.Traditional bipolar electrode light-emitting diode be the P/N electrode all with one side, dwindled the luminous zone area, and the heat-sinking capability of chip is poor, be difficult to obtain use widely.

Industrial circle has realized the chip production of vertical stratification, goes up at carborundum (SiC) as CREE company and makes unipolar chip application in lighting field.For the light emitting diode with vertical structure chip that Sapphire Substrate is made, key is the making with P type layer reflector layer of removing of Sapphire Substrate.Under the existing situation, can remove sapphire in conjunction with etching, use nickeline (NiAg), but in fact reflecting effect does not have so high in the ideal as P type layer metal reflective layer by laser lift-off Sapphire Substrate or mechanical lapping.Its reason is that silver (Ag) is very easily oxidized, to wavelength is the light of 460nm, and the reflecting effect of silver oxide (AgO) has only 70% of silver (Ag), like this by the nickeline reflector, the actual light extraction efficiency of device is not significantly improved, and final light extraction efficiency promotes also unsatisfactory.

Summary of the invention

The object of the present invention is to provide a kind of light emitting diode with vertical structure chip of high reflectance, this chip proposes to realize high light-emitting efficiency in conjunction with distributed Bragg reflecting layer (DBR) and metal contact layer that another object of the present invention provides the light emitting diode with vertical structure chip production method of this high reflectance.

Technical scheme of the present invention is: a kind of light emitting diode with vertical structure chip of high reflectance, this chip comprises heat-radiating substrate and welds epitaxial loayer on it, this epitaxial loayer comprises resilient coating, N type layer, multiple quantum well layer, P type layer, on the P type layer metallic reflector is arranged, the heat-radiating substrate bottom makes metal level as the P electrode, makes the N electrode on the N type layer, chip structure is a single electrode, comprises the heat-radiating substrate of low thermal resistance; The P type is the film-distribution bragg emission layer of folded high reflectance layer by layer, can form Ohm contact electrode simultaneously.Comprise on the P type layer distributed Bragg reflecting layer (DBR) and ohmic contact metal layer (as Ni/Ag/Ti/Au, Ni/Ag/Mo/Au, PdTiAu).The material of epitaxial loayer is a gallium nitride, comprises resilient coating, N type layer, multiple quantum well layer and P type layer.Heat-radiating substrate can use metallic copper, silicon, perhaps pottery (as aluminium nitride).Its substrate weld layer can use Au/Sn or Ti/Au or Ti/Al/Au.

A kind of light emitting diode with vertical structure chip production method of high reflectance, its step: at first be that wherein epitaxial loayer comprises resilient coating at the substrate growing epitaxial layers, N type conductive layer, multiple quantum well layer, P-type conduction layer; Wear the quarter of epitaxial loayer, passivation layer deposition, reflection layer (DBR) evaporation of P type layer, P type layer photoetching, corrosion, P type layer ohmic contact layer evaporation, the metal level evaporation of heat-radiating substrate, binding substrate and P type layer, substrate is removed, and the N electrode is made, substrate attenuation, the P electrode is made, and it is characterized in that: the making of P type metallic reflector, the binding of P type layer and substrate, the removing of substrate, the N electrode is made, substrate attenuation, the P electrode is made, and forms unipolar chip; Disk is tested scribing, sorting.

The invention has the advantages that: the reflector layer of the high reflectance of making based on the present invention, can realize high light reflection efficiency, device can be realized high luminous efficiency.

The manufacture craft of the light-emitting diode chip for backlight unit that the present invention proposes; under the condition of traditional manufacturing technique; increased the GaN epitaxial loayer carved and worn; and to the protection of etching sidewall making passivation layer; by P type layer reflector (DBR) and metal contact layer reflection, increased the light reflection efficiency, reduced the loss of light in device; heat-radiating substrate provides heat sink passage, makes the light output that can provide stable under the big electric current.

Description of drawings

Fig. 1 passes through the wafer profile of epitaxial loayer etching and P type layer reflector layer and ohmic contact layer on epitaxial wafer for the light emitting diode with vertical structure chip of high reflectance of the present invention;

Fig. 2 is the light emitting diode with vertical structure chip epitaxial wafer of high reflectance of the present invention and the profile after the heat-radiating substrate binding;

Fig. 3 finishes chip manufacturing, the wafer figure that cuts for the light emitting diode with vertical structure chip of high reflectance of the present invention.

Embodiment

The light-emitting diode chip for backlight unit preparation method of embodiment of the invention vertical stratification is as follows:

1, extension on substrate 1, grown buffer layer 2 successively, N type layer 3, multiple quantum well layer 4, P type layer 5;

2, by photoetching, dry etching is up to Sapphire Substrate (etching depth is about 7um);

3, deposit passivation layer (silicon dioxide) protection etching sidewall;

4, evaporation DBR reflector layer 6

5, DBR layer photoetching, corrosion (forming the aperture of 30 diameters), evaporation ohmic contact layer 7 (Ni/Ag/Ti/Au) at 3～5um;

6, evaporation binding metal level 9 (TiAlTiAu) on the heat-radiating substrate 8;

7, binding substrate and LED disk;

8, the way that combines with dry etching of chemico-mechanical polishing removes Sapphire Substrate, exposes N type layer;

9, with the heat-radiating substrate attenuate, and evaporation metal forms electrode 10 to substrate;

10, diamond blade cutting heat-radiating substrate, wafer test, sorting.

The present invention is described further below in conjunction with drawings and Examples.

Grown buffer layer 2, gallium nitride N type layer 3, multiple quantum well layer 4 and gallium nitride P type layer 5 on Sapphire Substrate 1.Photoetching forms figure, and dry etching arrives Sapphire Substrate, etching side deposit passivation layer, evaporation DBR reflector layer 6, photoetching, corrosion DBR reflector layer 6, evaporation ohmic contact Ni/Ag/Ti/Au layer 7.Simultaneously, the making of the silicon substrate 8 that dispels the heat, AM aluminum metallization/titanium/gold layer 9 is to silicon substrate, the metal covering and the P type gallium-nitride metal face of silicon substrate are bound (280 ℃ of heating and pressurizing), after the binding, adopt chemico-mechanical polishing (CMP), remove Sapphire Substrate 1 in conjunction with etching, expose N type layer 3, evaporated metal layer 10 is made the N electrode, again silicon substrate is thinned to 100um, and substrate back is evaporated metal layer 11 again, form electrode, at last disk is carried out scribing, test, sorting.

Claims

1. the light emitting diode with vertical structure chip of a high reflectance, this chip comprises heat-radiating substrate and welds epitaxial loayer on it, this epitaxial loayer comprises resilient coating, N type layer, multiple quantum well layer, P type layer, on the P type layer metallic reflector is arranged, the heat-radiating substrate bottom makes metal level as the P electrode, makes the N electrode on the N type layer, it is characterized in that: chip structure is a single electrode, comprises the heat-radiating substrate of low thermal resistance; The P type is the film-distributed Bragg reflecting layer of folded high reflectance layer by layer, can form Ohm contact electrode simultaneously.

2. according to the light emitting diode with vertical structure chip of claims 1 described high reflectance, it is characterized in that: comprise distributed Bragg reflecting layer and ohmic contact metal layer on the P type layer.

3. according to the light emitting diode with vertical structure chip of claims 1 described high reflectance, it is characterized in that: the material of epitaxial loayer is a gallium nitride.

4. according to the light emitting diode with vertical structure chip of claims 1 described high reflectance, it is characterized in that: heat-radiating substrate can use metallic copper, silicon, perhaps pottery.

5. according to the light emitting diode with vertical structure chip of claims 1 described high reflectance, it is characterized in that: the substrate weld layer can use Au/Sn or Ti/Au or Ti/Al/Au.

6. the light emitting diode with vertical structure chip production method of a high reflectance, its step: at first be that wherein epitaxial loayer comprises resilient coating at the substrate growing epitaxial layers, N type conductive layer, multiple quantum well layer, P-type conduction layer; Wear the quarter of epitaxial loayer, passivation layer deposition, the reflection layer evaporation of P type layer, P type layer photoetching, corrosion, P type layer ohmic contact layer evaporation, the metal level evaporation of heat-radiating substrate, binding substrate and P type layer, substrate is removed, and the N electrode is made, substrate attenuation, the P electrode is made, the making of P type metallic reflector, the binding of P type layer and substrate, the removing of substrate, the N electrode is made, substrate attenuation, the P electrode is made, and forms unipolar chip; Disk is tested scribing, sorting.