CN101409319A

CN101409319A - Method for manufacturing LED using bonding technology

Info

Publication number: CN101409319A
Application number: CNA2007101822662A
Authority: CN
Inventors: 陈祖辉
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-10-12
Filing date: 2007-10-12
Publication date: 2009-04-15

Abstract

A manufacturing method of an LED is mainly characterized by adopting a heat sink substrate (e.g. aluminum nitride ceramics) with high heat conductivity and poor electrical conductivity when a bonding technology is used. After the heat sink is bonded, a P electrode and an N electrode are at the same side of the LED. The device structure provided by the invention is favorable for increasing the heat dissipation performance, and can effectively control the temperature of a chip when the chip is working, which improves the reliability of the chip, contributes to increasing injection current density and improves the brightness of the chip. The two electrodes are at the same side, which is also favorable for the work of a multi-chip module at constant current.

Description

A kind of method for manufacturing light-emitting that uses bonding techniques

Technical field

The present invention relates to a kind of light-emitting diode chip for backlight unit (LED) manufacture method of using bonding techniques, relate in particular to two electrodes making behind a kind of indigo plant, green glow epitaxial loayer and the thermal conductive substrate bonding method for manufacturing LED chip at the chip homonymy.This structure is by improving the heat-sinking capability of chip, and the temperature when reaching control chip work helps improving chip reliability, but also helps to increase injected current density, improves chip brightness.In addition, two electrodes help using the test of existing common LED chip, screening installation to realize test, sorting at the homonymy of chip, and this structure is very important for realize in the application process that multi-chip modules is worked under constant current conditions.

Background technology

Adopt indigo plant, green light LED (LED) manufacture method of bonding (bonding) technology that two kinds of schemes are arranged usually:

A kind of is to utilize hydride gas-phase epitaxy (HVPE) technology growth gallium nitride (GaN) substrate, blue, the green glow epitaxial layer of gallium nitride structure of growth on this basis again, then on epitaxial layer of gallium nitride, make the contact reflector layer, evaporation scolder then, with the silica-based version of conduction bonding, silica-based version goes up makes the P electrode, makes the N electrode on the gallium nitride substrate, as shown in Figure 1.1 is the N electrode among the figure; The 2nd, n type GaN; The 3rd, the multiple quantum well light emitting layer; The 4th, p type GaN; The 5th, contact, reflective metal layer; The 6th, solder layer; The 7th, silicon substrate; The 8th, back of the body gold layer.

Another kind of situation is a growing gallium nitride epitaxial loayer on Sapphire Substrate, plates earlier contact, reflector layer on epitaxial layer of gallium nitride, then by electroplating layer of copper as heat sink base; Or on epitaxial layer of gallium nitride, plate earlier the contact reflector layer, and cover scolder, then with the silicon substrate bonding, use silicon substrate as heat sink base.These two kinds of methods all are to adopt the method for laser lift-off that Sapphire Substrate is separated with epitaxial layer of gallium nitride after carrying out bonding.Such light emitting diode construction has all utilized the conductive characteristic of heat sink substrate, and electrode also has the people that this device architecture is called vertical stratification in the both sides up and down (as shown in Figure 1 and Figure 2) of chip.Among Fig. 29 is N electrodes; The 10th, n type GaN; The 11st, the multiple quantum well light emitting layer; The 12nd, p type GaN; The 13rd, contact, reflective metal layer; The 14th, the copper pedestal.

Although copper has good thermal conductivity, the heat that produces when LED works is very fast derives by the copper pedestal, can effectively overcome because of the excessive device performance decline that causes of temperature rising in the LED course of work.But the copper pedestal has a significant disadvantages: the thermal coefficient of expansion of copper is big more than the thermal coefficient of expansion of epitaxial layer of gallium nitride, and epitaxial loayer breaks because of the thermal stress that variations in temperature produces easily in following process and the use, thereby influences the reliability of device.

Silicon thermal conductivity ratio copper is little, and is bigger than sapphire, and thermal coefficient of expansion and epitaxial layer of gallium nitride are more approaching.Adopting the LED electrode that passes through laser lift-off behind silicon substrate and the gallium nitride epitaxial slice bonding again is up-down structure, and promptly electrode is respectively in the both sides of LED.Such device architecture is unfavorable for test, the classification after the scribing, is unfavorable for that also multi-chip modules works under constant current conditions.

In order to overcome the problem that above-mentioned two kinds of LED schemes exist, the present invention proposes a kind of new LED device architecture.

Summary of the invention

The present invention proposes a kind of new LED manufacture method, by improving the reliability that the chip cooling ability improves device, increase chip current injection density and improve brightness, by two electrodes being made in the same side of device, multi-chip modules is in the difficulty of constant current conditions work in solution encapsulation, the use.

For realizing above purpose, technical scheme of the present invention provides a kind of method that improves the chip cooling ability, earlier with epitaxial layer of gallium nitride and heat sink substrate bonding, by laser lift-off technique the Sapphire Substrate of growing gallium nitride epitaxial loayer is removed, heat sink substrate becomes the support substrates of epitaxial layer of gallium nitride again.It is characterized in that heat sink substrate has the characteristic of heat conduction non-conducting, typical material is the aluminium nitride ceramics substrate.Its method is: at first on the heat sink substrate of heat conduction non-conducting evaporation one layer thickness at 1～5um brazing metal (such as golden tin solder).Carry out metal reflective, contact layer at epitaxial layer of gallium nitride, evaporation 1～5um brazing metal (such as golden tin solder) again, then by photoetching, wet etching, dry etching, epitaxial loayer scribing road is carved thoroughly to Sapphire Substrate, become discrete tube core unit at epitaxial layer of gallium nitride, by bonding technology, make itself and heat sink substrate bonding then, by laser lift-off technique the Sapphire Substrate of epitaxial layer of gallium nitride is removed again.The epitaxial loayer n type GaN surface that to remove Sapphire Substrate makes rough surface by dry method or wet etching, reduces total reflection, improves and gets optical efficiency.On n type GaN, make the N electrode at last, on heat sink base version solder layer, make the P electrode.

Embodiment

Below be example with the light-emitting diode manufacture process that relates to laser lift-off, in conjunction with the accompanying drawings the invention process is described further.

1. evaporation one deck gold tin solder on the aluminium nitride ceramics substrate, thickness is at 1～5um, as shown in Figure 3.15 is golden tin solders among the figure; The 16th, the aluminium nitride ceramics substrate.

2. on the gallium nitride epitaxial slice that with the sapphire is substrate, do metal reflective, contact layer and golden tin solder, as shown in Figure 4.

3. by photoetching,, epitaxial loayer is carved thoroughly to Sapphire Substrate, made the epitaxial layer of gallium nitride on the Sapphire Substrate become discrete one by one tube core unit, as shown in Figure 5 at place, scribing road in conjunction with wet etching and dry etching.

4. the epitaxial wafer in the aluminium nitride ceramics base version and 3 in 1 is bonded together as shown in Figure 6.17 is golden tin solders among the figure; The 18th, contact, reflective metal layer; The 19th, p type GaN; The 20th, the multiple quantum well light emitting layer; The 21st, n type GaN; The 22nd, Sapphire Substrate.

5. utilize laser lift-off, remove Sapphire Substrate as shown in Figure 7.

6. make n type GaN surface become coarse by dry method or wet etching, as shown in Figure 8.

7. make P electrode, N electrode respectively, as shown in Figure 9.23 is N electrodes among the figure; The 24th, the P electrode.

8. the tube core after cutting apart, as shown in figure 10.

Though described example of the present invention by the example of above-mentioned employing laser lift-off technique, they are illustrative.In fact,, can also carry out various forms of modifications to it under the condition of the principle of the invention, such as, the basket of growing on the GaN substrate, green glow epitaxial loayer also can use above several key steps except that laser lift-off to implement.In addition, scope of the present invention is limited by appended claims.

Claims

1. this manufacturing method for LED, be primarily characterized in that, adopt when using bonding techniques that thermal conductivity is good, the heat sink substrate (such as aluminium nitride ceramics or similar material) of poorly conductive, or on thermal conductivity good metal material the very thin and nonconducting composite heat sink substrate of growth one deck.

2. the P electrode of LED and N electrode are at the device homonymy behind the heat sink bonding.

3. manufacture method of the present invention is not only applicable to the chip manufacturing of gallium nitride indigo plant, green light LED, also is applicable to the chip manufacturing of red yellow light LED.