CN109244207A

CN109244207A - A kind of LED chip and preparation method thereof

Info

Publication number: CN109244207A
Application number: CN201810999625.1A
Authority: CN
Inventors: 崔永进; 庄家铭
Original assignee: Foshan Nationstar Semiconductor Co Ltd
Current assignee: Foshan Nationstar Semiconductor Co Ltd
Priority date: 2018-08-30
Filing date: 2018-08-30
Publication date: 2019-01-18

Abstract

The invention discloses a kind of LED chips, including substrate, epitaxial layer, N-type electrode and P-type electrode, the P-type electrode includes P pad and P current expansion item, and the P pad includes Cr layers, Al layers, Ti layers, Pt layers and Au layers, and the P current expansion item includes Al layers, Ti layers, Pt layers and Au layers.The present invention passes through the structure for changing P current expansion item, and the light that P current expansion item issues active layer reflects, and improves the light extraction efficiency of chip.Correspondingly, the present invention also provides a kind of production methods of LED chip.

Description

A kind of LED chip and preparation method thereof

Technical field

The present invention relates to LED technology fields more particularly to a kind of LED chip and preparation method thereof.

Background technique

LED (Light Emitting Diode, light emitting diode) be it is a kind of using Carrier recombination when release energy shape At luminous semiconductor devices, LED chip is with power consumption is low, coloration is pure, the service life is long, small in size, the response time is fast, energy conservation and environmental protection Equal many advantages.

The electrode of conventional LED chip includes N-type electrode and P-type electrode, and N/P type electrode includes electrode pad and current expansion Item (finger), wherein electrode pad is identical with the structure of current expansion item, including Cr layers, Al layers, Ti layers, Pt layers and Au layers, The metal of the two deposition is just as production method is identical, and the two is to be formed simultaneously.

Since the bottom of the current expansion item of existing P-type electrode is Cr layers, and Cr metal can be to the light that LED chip is issued It is absorbed, leads to luminance loss.As Cr thickness degree increases, Cr layers of extinction are more serious, the current expansion item pair of P-type electrode The intensity that the light that LED chip is issued is reflected is poorer.

Summary of the invention

Technical problem to be solved by the present invention lies in provide a kind of LED chip, p-type current extending can be to active The light that layer issues is reflected, and the light extraction efficiency of chip is improved.

Technical problem to be solved by the present invention lies in, a kind of production method of LED chip is provided, it is golden twice by depositing Belong to, the light that the p-type current extending of formation can issue active layer reflects, and improves the light extraction efficiency of chip.

In order to solve the above-mentioned technical problems, the present invention provides a kind of LED chips, including substrate, epitaxial layer, N-type electrode And P-type electrode, the P-type electrode include P pad and P current expansion item, the P pad includes Cr layers, Al layers, Ti layers, Pt layers With Au layers, the P current expansion item includes Al layers, Ti layers, Pt layers and Au layers.

As an improvement of the above scheme, Cr layers with a thickness ofAl layers with a thickness ofTi layers With a thickness ofPt layers with a thickness ofAu layers with a thickness of

As an improvement of the above scheme, the N-type electrode includes N pad and N current expansion item, the N pad and N electric current Extending item includes Cr layers, Al layers, Ti layers, Pt layers and Au layers.

As an improvement of the above scheme, the LED chip further includes electric current barrier and transparency conducting layer, the epitaxial layer Including n type gallium nitride layer, the active layer on n type gallium nitride layer and the p-type nitrogen on active layer being set on substrate Change gallium layer, the current barrier layer is set on p-type gallium nitride layer, and the transparency conducting layer is set on current barrier layer, the N-type Electrode is set on n type gallium nitride layer, and the P-type electrode is set on transparency conducting layer.

Correspondingly, the present invention also provides a kind of production methods of LED chip, comprising the following steps:

1, growing gallium nitride material on substrate forms epitaxial layer；

2, the deposited metal in N welding disking area, P welding disking area and P current expansion strip area forms Cr layers；

3, the deposited metal in N current expansion strip area and Cr layer, sequentially forms Al layers, Ti layers, Pt layers and Au layers, thus N pad is formed in N welding disking area, forms N current expansion item in N current expansion strip area, forms P pad in P welding disking area, P current expansion strip area forms P current expansion item.

As an improvement of the above scheme, the epitaxial layer includes the n type gallium nitride layer being set on substrate, is set to N-type nitridation Active layer on gallium layer and the p-type gallium nitride layer on active layer, before step 2, further includes:

Epitaxial layer is performed etching, formed through p-type gallium nitride layer, active layer and extends to the exposed of n type gallium nitride layer Region；

Current barrier layer and transparency conducting layer are sequentially formed on p-type gallium nitride layer, form LED wafer.

As an improvement of the above scheme, the N welding disking area is located on exposed n type gallium nitride layer, the N electric current Extension strip area, P welding disking area and P current expansion strip area are located on transparency conducting layer.

As an improvement of the above scheme, the N welding disking area and N current expansion strip area are located at exposed N-type nitrogen Change on gallium layer, the P welding disking area and P current expansion strip area are located on transparency conducting layer.

As an improvement of the above scheme, further comprising the steps of after step 3:

Deposition forms insulating layer in LED wafer, and performs etching to insulating layer, and N pad and P pad are exposed.

The invention has the following beneficial effects:

1, a kind of LED chip provided by the invention, including substrate, epitaxial layer, N-type electrode and P-type electrode, the p-type electricity Pole includes P pad and P current expansion item, and the P pad includes Cr layers, Al layers, Ti layers, Pt layers and Au layers, the P current expansion Item includes Al layers, Ti layers, Pt layers and Au layers.The present invention passes through the structure for changing P current expansion item, so that P current expansion item can To reflect the light that active layer issues, the light extraction efficiency of chip is improved, cost can also be reduced.

2, the production method of a kind of LED chip provided by the invention, by depositing two minor metals, so that P current expansion item Structure it is different from the structure of P pad, to change the structure of P current expansion item, allow P current expansion item to active layer The light of sending is reflected, and the light extraction efficiency of chip is improved, and can also reduce cost.

Detailed description of the invention

Fig. 1 is the structural schematic diagram of LED chip of the present invention；

Fig. 2 is the main view of LED chip of the present invention；

Fig. 3 is the structural schematic diagram of LED chip N pad of the present invention, P pad and N current expansion item；

Fig. 4 is the structural schematic diagram of LED chip P current expansion item of the present invention；

Fig. 5 is the production flow diagram of LED chip of the present invention.

Specific embodiment

To make the object, technical solutions and advantages of the present invention clearer, the present invention is made into one below in conjunction with attached drawing Step ground detailed description.

Referring to Fig. 1 to Fig. 4, a kind of LED chip provided by the invention, including substrate 10, epitaxial layer 20, N-type electrode and p-type Electrode, the P-type electrode include P pad 31 and P current expansion item 32, and the P pad 31 includes Cr layer 301, Al layer 302, Ti Layer 303, Pt layer 304 and Au layer 305, the P current expansion item 32 include Al layer 302, Ti layer 303, Pt layer 304 and Au layer 305.

The structure of P current expansion item of the present invention is different from the structure of P pad, wherein the bottom of P current expansion item is Al Layer, since the light reflectivity of Al metal is high, and the expanded range of P current expansion item is wide, therefore P current expansion item can be by active layer The light of sending more reflects, and then improves the brightness of LED chip.

The structure of existing LED chip P current expansion item is consistent with the structure of P pad, and bottom is all Cr layers, and Cr layers as viscous Attached layer, effect is to prevent power down pole in order to which other metal layers are preferably attached on chip.

Since P current expansion item of the invention links together with P pad, even if P current expansion item does not have Cr layers, not yet It is easy to happen and falls.

Specifically, the N-type electrode includes N pad 33 and N current expansion item 34.The N pad 33 and N current expansion item 34 include Cr layer 301, Al layer 302, Ti layer 303, Pt layer 304 and Au layer 305.

Preferably, Cr layers with a thickness ofAl layers with a thickness ofTi layers with a thickness ofPt layers with a thickness ofAu layers with a thickness of

Since Cr layers are used as bottom adhesion layer, thickness cannot be too thick, otherwise will affect the luminous suction of LED chip It receives, i.e. Al layers does not have reflex.Cr thickness degree existsWhen have preferable reflectivity, be lower thanWhen adhesion strength Poor and control difficulty is big.Wherein, when Al layers of the thickness is less thanWhen, it cannot preferably play Al layers of reflection Performance, chip brightness are lower；When Al layers of the thickness is greater thanWhen, because Al metal itself is relatively active easy to migrate, Al layers Protection difficulty increase.When Pt layers of thickness are respectively less thanWhen, Pt thickness degree is too thin can not to play the role of Al layers of protection, when Pt layers of thickness is all larger thanWhen, cost of manufacture is excessively high.The hardness of Au is preferable, to electrode when can effectively resist routing Active force, so that guard electrode, prevents fragmentation and falls off.Due to when routing, needing to electrode into strike, because This can generate an active force to electrode, so that electrode is easy to fall off and fragmentation.When Au thickness degree is less thanWhen, Au layers of protective effect of cannot get up, when Au thickness degree is greater thanWhen, cost of manufacture is excessively high.

The LED chip further includes electric current barrier 40 and transparency conducting layer 50, and the epitaxial layer 20 includes being set to substrate N type gallium nitride layer 21 on 10, the active layer 22 on n type gallium nitride layer 21 and the nitridation of the p-type on active layer 22 Gallium layer 23, the current barrier layer 40 are set on p-type gallium nitride layer 23, and the transparency conducting layer 50 is set to current barrier layer 40 On, the N-type electrode is set on n type gallium nitride layer 21, and the P-type electrode is set on transparency conducting layer 50.

Wherein, the material of substrate 10 can be sapphire, silicon carbide or silicon, or other semiconductor materials, this reality Applying the substrate 10 in example is preferably Sapphire Substrate.

In order to improve the yield of subsequent etching technics, the epitaxial layer 20 with a thickness of 4-10 μm.When epitaxial layer 20 Thickness is lower than 4 μm, and the brightness of LED chip can reduce, in subsequent etching, the case where LED chip is easy to appear sliver.But extension The thickness of layer 20 is greater than 10 μm, and the brightness of LED chip can reduce, and increase difficulty and the time of etching.

It should be noted that being equipped between the substrate 10 and the epitaxial layer 20 in the other embodiments of the application Caching rushes layer (not shown).

In order to protect chip, prevent chip from short circuit and electric leakage, 33 side wall of N pad, 31 side wall of P pad, N electric current occurs It extends 34 surface of item and 32 surface of P current expansion item and is equipped with insulating layer 60.Wherein, the insulating layer 60 can also extend To the surface of n type gallium nitride layer 21 and transparency conducting layer 50.

It is the production flow diagram of LED chip of the present invention referring to Fig. 5, Fig. 5, a kind of production of LED chip provided by the invention Method, comprising the following steps:

S101: growing gallium nitride material on substrate forms epitaxial layer.

The material of substrate of the invention can be sapphire, silicon carbide or silicon, or other semiconductor materials, this reality Applying the substrate in example is preferably Sapphire Substrate.

Growing gallium nitride material uses art methods, typical method are as follows: is deposited using Metallo-Organic Chemical Vapor (MOCVD) method grows n type gallium nitride layer, active layer and p-type gallium nitride layer, successively on substrate to form epitaxial layer.

In order to improve the yield of subsequent etching technics, the epitaxial layer with a thickness of 4-10 μm.When the thickness of epitaxial layer Lower than 4 μm, the brightness of LED chip can be reduced, in subsequent etching, the case where LED chip is easy to appear sliver.But epitaxial layer Thickness is greater than 10 μm, and the brightness of LED chip can reduce, and increase difficulty and the time of etching.

S102: performing etching epitaxial layer, is formed through p-type gallium nitride layer, active layer and extends to n type gallium nitride layer Exposed region.

Using photoresist or SiO₂As exposure mask, and use inductively coupled plasma etching technique or reactive ion etching Etching technics performs etching the epitaxial layer, is formed through the p-type gallium nitride layer and active layer and extends to n type gallium nitride The exposed region of layer.

Due to photoresist and SiO₂With high etching ratio, convenient for etching, so that the etching pattern needed for being formed, improves etching Precision.It, can also be using the substance of other high etching selection ratios as exposure mask in the other embodiments of the application.

In order to improve the light extraction efficiency of chip, the side light extraction efficiency of epitaxial layer, the side wall tool of the exposed region are improved There is certain tilt angle.

S103: sequentially forming current barrier layer and transparency conducting layer on p-type gallium nitride layer, forms LED wafer.

Using photoresist or SiO₂As exposure mask, it is deposited using electron beam evaporation process on p-type gallium nitride layer surface One layer of current barrier layer.Preferably, the material of the current barrier layer is SiO₂Or Si₃N₄。

Wherein, the area of current barrier layer is less than the area of p-type gallium nitride layer.

Using photoresist or SiO₂As exposure mask, one is deposited in the current blocking layer surface using electron beam evaporation process Layer transparency conducting layer.Preferably, the transparency conducting layer extends on p-type gallium nitride layer, and current barrier layer is wrapped up.This The vapor deposition temperature of invention transparency conducting layer is 0-300 DEG C, oxygen flow 5-30sccm, and vapor deposition chamber vacuum degree is 3.0- 10.0E-5, evaporation time 100-300min.When temperature is deposited lower than 0 DEG C, transparency conducting layer can not obtain enough energy It is migrated, the transparency conducting layer of formation is second-rate, and defect is more；When temperature is deposited higher than 300 DEG C, temperature is excessively high, film Energy is excessive to be not easy to deposit on light emitting structure, and deposition rate is slack-off, and efficiency reduces.When oxygen flow is less than 5sccm, oxygen Flow is too low, and transparency conducting layer oxidation is insufficient, and film quality is bad, and when oxygen flow is greater than 30sccm, oxygen flow is too big, Transparency conducting layer excessive oxidation, film layer defect concentration increase.When evaporation time is less than 100min, film needs higher deposition speed Rate can be only achieved required thickness, and deposition rate is too fast, and atom has little time to migrate, therefore film growth quality is poor, and defect is more.It is excellent Choosing, vapor deposition temperature is 290 DEG C, oxygen flow 10sccm, and vapor deposition chamber vacuum degree is 3.0*10^-5-10.0*10^-5。

Wherein, the material of the transparency conducting layer is indium tin oxide, but not limited to this.Indium and tin in indium tin oxide Ratio is 70-99:1-30.Preferably, the ratio of indium and tin is 95:5 in indium tin oxide.Transparency conducting layer is favorably improved in this way Conductive capability, prevent carrier from flocking together, also improve chip light extraction efficiency.

S104: the deposited metal in N welding disking area, P welding disking area and P current expansion strip area forms Cr layers.

Using electron beam evaporation plating, hot evaporation or magnetron sputtering technique in N welding disking area, P welding disking area and P current expansion item Cr metal is deposited on region, forms Cr layers.

S105: the deposited metal in N current expansion strip area and Cr layer sequentially forms Al layers, Ti layers, Pt layers and Au layers, To form N pad in N welding disking area, N current expansion item is formed in N current expansion strip area, forms P weldering in P welding disking area Disk forms P current expansion item in P current expansion strip area.

It is sequentially depositing in N current expansion strip area and Cr layers using electron beam evaporation plating, hot evaporation or magnetron sputtering technique Al, Ti, Pt and Au metal sequentially form Al layers, Ti layers, Pt layers and Au layers, so that N pad is formed in N welding disking area, in N electricity Stream extension strip area forms N current expansion item, forms P pad in P welding disking area, forms P electric current in P current expansion strip area and expand Open up item.

It should be noted that the N welding disking area and N current expansion strip area of the present embodiment are located at exposed N-type nitrogen Change on gallium layer, the P welding disking area and P current expansion strip area are located on transparency conducting layer.In the other embodiment of the present invention In, N welding disking area is located on exposed n type gallium nitride layer, N current expansion strip area, P welding disking area and P current expansion Strip area is located on transparency conducting layer.

S106: deposition forms insulating layer in LED wafer, and performs etching to insulating layer, and N pad and P pad is exposed Out.

With specific embodiment, the present invention is further explained below

Embodiment 1

A kind of LED chip including substrate, the epitaxial layer on substrate, the current barrier layer on epitaxial layer, is set to Transparency conducting layer, N-type electrode and P-type electrode on current barrier layer, the N-type electrode include N pad and N current expansion item, The P-type electrode includes P pad and P current expansion item, and the N pad, N current expansion item and P pad include Cr layers, Al Layer, Ti layers, Pt layers and Au layers, the P current expansion item include Al layers, Ti layers, Pt layers and Au layers, described Cr layers with a thickness ofAl layers with a thickness ofTi layers with a thickness ofPt layers with a thickness ofAu layers with a thickness of

Embodiment 2

Embodiment 3

Embodiment 4

Embodiment 5

Embodiment 6

Comparative example 1

A kind of LED chip including substrate, the epitaxial layer on substrate, the current barrier layer on epitaxial layer, is set to Transparency conducting layer, N-type electrode and P-type electrode on current barrier layer, the N-type electrode include N pad and N current expansion item, The P-type electrode includes P pad and P current expansion item, and the N pad, N current expansion item, P pad and P current expansion item are equal Including Cr layers, Al layers, Ti layers, Pt layers and Au layers, described Cr layers with a thickness ofAl layers with a thickness ofTi layers With a thickness ofPt layers with a thickness ofAu layers with a thickness of

Comparative example 2

The chip of above-described embodiment 1-6 and comparative example 1-2 are the chip of a size, and to chip progress photoelectric properties and always Change test, as a result as follows:

Group	Brightness (lm)	Voltage (v)	Power down pole rate (%)	Yields (%)
					Embodiment 1	18	3.1	2.5	93
Embodiment 2	18	3.1	3.1	93
					Embodiment 3	18	3.1	3.2	93
Embodiment 4	17	3.1	2.5	93
					Embodiment 5	18	3.2	2.0	93
Embodiment 6	18	3.1	2.3	93
					Comparative example 1	15	3.1	2.1	93
Comparative example 2	15	3.1	2.7	93

Can be seen that the chip of this hair compared with existing chip from above-mentioned test result, brightness is enhanced, But voltage is basically unchanged, and yield is also not much different, and serious power down pole will not occur.

Above disclosed is only a preferred embodiment of the present invention, cannot limit the power of the present invention with this certainly Sharp range, therefore equivalent changes made in accordance with the claims of the present invention, are still within the scope of the present invention.

Claims

1. an LED chip, is characterized in that, comprises substrate, epitaxial layer, N-type electrode and P-type electrode, and described P-type electrode comprises P-pad and P-current expansion bar, and described P-pad comprises Cr layer, Al layer, Ti layer, Pt layer and Au layer, the P current spreading bar includes Al layer, Ti layer, Pt layer and Au layer.

2. The LED chip according to claim 1, wherein the thickness of the Cr layer is The thickness of the Al layer is The thickness of the Ti layer is The thickness of the Pt layer is The thickness of the Au layer is

3 . The LED chip of claim 1 , wherein the N-type electrode comprises an N pad and an N current expansion strip, and the N pad and the N current expansion strip comprise a Cr layer, an Al layer, and a Ti layer. 4 . , Pt layer and Au layer.

4 . The LED chip according to claim 1 , wherein the LED chip further comprises a current blocking layer and a transparent conductive layer, and the epitaxial layer comprises an N-type gallium nitride layer, a An active layer on the N-type gallium nitride layer, and a P-type gallium nitride layer on the active layer, the current blocking layer on the P-type gallium nitride layer, and the transparent conductive layer on On the current blocking layer, the N-type electrode is arranged on the N-type gallium nitride layer, and the P-type electrode is arranged on the transparent conductive layer.

5. A method for making an LED chip, comprising the following steps:

1. Grow gallium nitride material on the substrate to form an epitaxial layer;

2. Deposit metal on the N pad area, the P pad area and the P current expansion strip area to form a Cr layer;

3. Deposit metal on the N current expansion strip area and the Cr layer, and form an Al layer, a Ti layer, a Pt layer and an Au layer in turn, so as to form an N pad in the N pad area, and form an N current expansion in the N current expansion strip area. bar, the P pad is formed in the P pad region, and the P current extension bar is formed in the P current extension bar region.

6. The method for manufacturing an LED chip according to claim 5, wherein the thickness of the Cr layer is The thickness of the Al layer is The thickness of the Ti layer is The thickness of the Pt layer is The thickness of the Au layer is

7 . The manufacturing method of an LED chip according to claim 5 , wherein the epitaxial layer comprises an N-type gallium nitride layer provided on the substrate, and an active layer provided on the N-type gallium nitride layer. 8 . , and the P-type gallium nitride layer disposed on the active layer, before step 2, further comprising:

Etching the epitaxial layer to form an exposed area that penetrates the P-type gallium nitride layer, the active layer and extends to the N-type gallium nitride layer;

A current blocking layer and a transparent conductive layer are sequentially formed on the P-type gallium nitride layer to form an LED wafer.

8 . The method for manufacturing an LED chip according to claim 7 , wherein the N-pad region is located on the exposed N-type gallium nitride layer, and the N-current expansion strip region, the P-pad region and the The P current spreading bar region is located on the transparent conductive layer.

9 . The method for manufacturing an LED chip according to claim 7 , wherein the N pad region and the N current expansion strip region are located on the exposed N-type gallium nitride layer, and the P pad region and the N-type gallium nitride layer are exposed. 10 . The P current spreading bar region is located on the transparent conductive layer.

10. The method for manufacturing an LED chip according to claim 7, wherein after step 3, the method further comprises the following steps:

An insulating layer is deposited on the LED wafer, and the insulating layer is etched to expose the N pad and the P pad.