CN102832302A

CN102832302A - Method for manufacturing N electrode of GaN-based light-emitting diode (LED)

Info

Publication number: CN102832302A
Application number: CN2012103151057A
Authority: CN
Inventors: 李璟; 詹腾; 张溢; 冯亚萍
Original assignee: YANGZHOU ZHONGKE SEMICONDUCTOR LIGHTING CO Ltd
Current assignee: YANGZHOU ZHONGKE SEMICONDUCTOR LIGHTING CO Ltd
Priority date: 2012-08-31
Filing date: 2012-08-31
Publication date: 2012-12-19

Abstract

The invention discloses a method for manufacturing the N electrode of a GaN-based light-emitting diode (LED), and relates to a method for manufacturing the N electrode in an LED manufacturing process. During inductively coupled plasma tabletop etching, only a part of a transverse P-GaN layer, a part of a transverse multi-quantum well luminous layer and a part of a longitudinal N-GaN layer on one side of a GaN epitaxial wafer are removed, a part of the transverse P-GaN layer, a part of the transverse multi-quantum well luminous layer and a part of the longitudinal N-GaN layer are reserved, and form an N tabletop, and the N tabletop, a sidewall on one side of the N tabletop and the N-GaN layer are evaporated by using the metal CrPtAu of the N electrode. A process is simple, stable and reliable, a new process step is not required to be added, routing is facilitated, and the luminous efficiency of the GaN-based LED can be effectively improved.

Description

The manufacture method of N electrode among a kind of GaN base LED

Technical field

The present invention relates to optoelectronic device manufacturing technology field, the manufacture method of N electrode in particularly a kind of gallium nitride (GaN) based light-emitting diode (LED) manufacture process.

Background technology

Along with the development of growth technology and multi-quantum pit structure, the internal quantum efficiency of GaN base LED has had very large raising, and the LED internal quantum efficiency of GaN base can reach more than 70% at present, but the external quantum efficiency of led chip has only about 40% usually.Influence GaN base the LED external quantum efficiency principal element except since GaN material and refringence with air cause more greatly light extraction efficiency low, metal electrode is also very serious for the absorption of light.As everyone knows, conventional led chip needs the positive and negative electrode access to make it luminous, and corresponding need make positive and negative routing dish on chip, normally golden material, and gold absorbs bigger for blue green light, influenced light extraction efficiency greatly.

Summary of the invention

The manufacture method that the purpose of this invention is to provide N electrode among a kind of GaN base LED, the absorption of the light that sends for active area with effective reduction N electrode.

The present invention adopts the method for metal organic chemical vapor deposition; Growing low temperature GaN resilient coating, the GaN layer that undopes, N-GaN layer, multiple quantum well light emitting layer and P-GaN layer successively on Semiconductor substrate; Form the GaN epitaxial wafer, GaN carries out the inductively coupled plasma mesa etch then; Make the method vapor deposition ito thin film of deposited by electron beam evaporation at the upper surface of GaN epitaxial wafer; Outside P-GaN layer, ITO layer and P table top, select for use negative photoresist L-300 to make P electrode and N electrode by lithography at last; When it is characterized in that carrying out said etching; Only remove the horizontal part P-GaN layer of GaN epitaxial wafer one side, multiple quantum well light emitting layer and part N-GaN layer longitudinally; Horizontal a part of P-GaN layer, multiple quantum well light emitting layer and part N-GaN layer have longitudinally been kept; This part that keeps is called the N table top, then with on the above-mentioned N table top of N electrode metal CrPtAu vapor deposition, the sidewall and the N-GaN layer of N table top one side.

Conventional LED manufacture method is: a side of GaN epitaxial wafer is carried out the ICP etching, remove laterally whole P-GaN layer, multiple quantum well light emitting layer and longitudinal component N-GaN layers of a side, form the N-GaN layer.And the present invention is through the N table top of above etching technics for forming; The degree of depth of institute's etching is the same with conventional LED, is 1000nm ~ 1600nm, and this process only need slightly be made an amendment on lithography layout; Need not to increase new processing step; And the N electrode metal is positioned at the main effect of these three positions: (1) N electrode metal is positioned at above the N table top, equates with P electrode height on the P table top, is convenient to packaging and routing.(2) the N electrode metal is positioned at N table top one side sidewall, short circuit PN junction.(3) the N electrode is positioned on the N-GaN layer, and N electrode metal ground floor is Cr, can form good Ohmic contact with the N-GaN layer, reduces N electrode touch voltage, thereby reduces the operating voltage of device.Another sidewall of N table top is not covered by the N electrode metal; Its effect is: because the GaN material absorbs light hardly; So the light that sends from LED SQW side is reflected by the N electrode metal Cr and the Pt of another side after getting into the N table top, goes out to shoot out from the N table top again.Improved the light extraction efficiency of LED device greatly.

Technology of the present invention is simple, and need not increases new processing step, and is reliable and stable, makes things convenient for routing, can effectively improve the light extraction efficiency of GaN base LED.

Description of drawings

Fig. 1 is the structure chart of conventional GaN base LED.

Fig. 2 is the structure chart of GaN base LED of the present invention.

Embodiment

The manufacture method of N electrode is as shown in Figure 2 among a kind of GaN base LED of the present invention, comprises the steps:

Step 1: make the GaN epitaxial wafer: the method that adopts metal organic chemical vapor deposition (MOCVD); Growth thickness is that low temperature GaN resilient coating 2, the thickness of 1 μ m is that the GaN layer 3 that undopes, the thickness of 2 μ m is the P-GaN layer 6 that the N-GaN layer 4 of 3 μ m, multiple quantum well light emitting layer 5 that thickness is 200nm and thickness are 700nm successively on Semiconductor substrate 1, forms the GaN epitaxial wafer.Wherein, Semiconductor substrate 1 can be any one of sapphire, silicon, carborundum or metal.

Step 2: GaN is carried out ICP (inductively coupled plasma) mesa etch:

Conventional LED carries out the ICP etching with a side of GaN epitaxial wafer, removes laterally whole P-GaN layer 6, multiple quantum well light emitting layer 5 and longitudinal component N-GaN layers 4 of a side, forms N-GaN 41, and is as shown in Figure 1.

And the present invention has only removed the horizontal part P-GaN layer 6 of a side, multiple quantum well light emitting layer 5 and part N-GaN layer 41 (as shown in Figure 2) longitudinally; The horizontal a part of P-GaN layer 6 of a side, multiple quantum well light emitting layer 5 and part N-GaN layer 4 have longitudinally been kept; This part that keeps is designated 10 in Fig. 2, be called the N table top.

The total depth of institute of the present invention etching is the same with conventional LED, is 1000nm～1600nm.This step process only need slightly be made an amendment on lithography layout, need not to increase new processing step.

Step 3: make the method vapor deposition ito thin film 7 of deposited by electron beam evaporation, thickness 2400: select AZ6130 photoresist and little chloroazotic acid (HCl and HNO for use at the upper surface of GaN epitaxial wafer ₃Volume ratio be 3 ︰ 1) photoetching corrosion goes out the ITO figure, removes part ito thin film and P type table top ito thin film outward on the P-GaN layer 6, on P type table top, forms ito transparent electrode.Ito transparent electrode and P-GaN can form good Ohmic contact, can reduce the touch voltage of P electrode, thereby reduce the operating voltage of device.

Step 4: outside P-GaN layer 6, ITO layer 7 and P table top, select negative photoresist L-300 photoetching P, N electrode for use: adopt electron-beam vapor deposition method evaporation metal CrPtAu (200/600/15000), peel off the back and form P electrode 8 and N electrode 9.

N electrode 9 among the present invention is positioned on top, the N table top 10 1 side sidewalls and N-GaN 41 of N table top 10.This step process only need slightly be made an amendment on lithography layout, need not to increase new processing step.

N electrode 9 is positioned at the main effect of these three positions: (1) N electrode 9 is positioned at above the N table top 10, equates with P electrode height on the P table top, is convenient to packaging and routing.(2) N electrode 9 is positioned at N table top 10 1 side sidewalls, short circuit PN junction.(3) N electrode 9 is positioned on the N-GaN layer 41, and N electrode metal ground floor is Cr, can form good Ohmic contact with N-GaN layer 41, reduces N electrode touch voltage, thereby reduces the operating voltage of device.Another sidewall of N table top 10 is not covered by N electrode metal 9; Its effect is: because the GaN material absorbs light hardly; So the light that sends from LED quantum well region 5 sides gets into N table top 10 backs and is reflected by the N electrode metal Cr and the Pt of another side, goes out to shoot out from N table top 10 again.Improved the light extraction efficiency of LED device greatly.

Claims

1. the manufacture method of N electrode among the GaN base LED; Adopt the method for metal organic chemical vapor deposition; Growing low temperature GaN resilient coating, the GaN layer that undopes, N-GaN layer, multiple quantum well light emitting layer and P-GaN layer successively on Semiconductor substrate; Form the GaN epitaxial wafer, GaN carries out the inductively coupled plasma mesa etch then; Make the method vapor deposition ito thin film of deposited by electron beam evaporation at the upper surface of GaN epitaxial wafer; Outside P-GaN layer, ITO layer and P table top, select for use negative photoresist L-300 to make P electrode and N electrode by lithography at last; When it is characterized in that carrying out said etching; Only remove the horizontal part P-GaN layer of GaN epitaxial wafer one side, multiple quantum well light emitting layer and part N-GaN layer longitudinally; Horizontal a part of P-GaN layer, multiple quantum well light emitting layer and part N-GaN layer have longitudinally been kept; This part that keeps is called the N table top, then with on the above-mentioned N table top of N electrode metal CrPtAu vapor deposition, the sidewall and the N-GaN layer of N table top one side.