CN101162748A

CN101162748A - Method for improving luminance brightness of chip at the axial direction

Info

Publication number: CN101162748A
Application number: CNA2006101170946A
Authority: CN
Inventors: 陈立人
Original assignee: Hangzhou Silan Azure Co Ltd
Current assignee: Hangzhou Silan Azure Co Ltd
Priority date: 2006-10-13
Filing date: 2006-10-13
Publication date: 2008-04-16
Anticipated expiration: 2026-10-13
Also published as: CN100464437C

Abstract

The present invention discloses a method for improving axial brightness of chip, and is characterized in that the method further comprises the following procedures: step 1, a layer of nickel metal with the thickness between 1 nanometer and 50 nanometer is coated on the surface of a sapphire substrate by vapor deposition; step 2: the nickel metal is rapidly annealed for 30 seconds to 300 seconds with the temperature of 600 DEG C to 900 DEG C, then the nickel metal forms a globular shape with the diameter between 200 nanometers and 400 nanometers, and is used as a mask; step 3, the surface of the sapphire substrate is etched selectively and the depth is between 100 nanometers and 500 nanometers; step 4, the nickel metal on the sapphire substrate is cleaned; step 5, indium gallium nitride epitaxial layer grows from the sapphire substrate. The technical proposal of the invention can reduce the full reflection of emergent light and improve axial brightness.

Description

A kind of method that improves the axial emitting brightness of chip

Technical field

The present invention relates to a kind of method that improves the axial emitting brightness of chip, relate in particular to a kind of method chip substrate and epitaxial layer interface formation nanoscale roughened textures.

Background technology

The LED manufacture method of general blue green light is an epitaxial growth InGaN monocrystal material structure on smooth smooth Sapphire Substrate, realize that by adding silicon and magnesium elements (N) minus reaches (P) eurymeric semi-conducting material respectively, and in active layer, adjust luminous wavelength by the ratio of adjusting the indium gallium, also will be behind the epitaxial manufacture process through the photoetching and the cleaning of chip surface, the making of electrode, the etching in negative pole zone, the detection of the characteristics of luminescence, attenuate cuts into discrete chip, so a traditional blue green light chip structure as shown in Figure 1, can be divided into anodal pressure welding point 11, transparency electrode 12, eurymeric gallium nitride 13, luminescent layer 14, minus gallium nitride 15, Sapphire Substrate 16, negative pole pressure welding point 17 is formed, in addition because P type transparency electrode light transmittance is limited, add that conductivity is not so good as general electrode, cause current crowding to cause luminous efficiency to descend, therefore another kind of general structure adopts flip chip bonding as shown in Figure 2, on P type gallium nitride contact layer 21, directly plate the ohmic contact and the high metallic reflector 22 of reflective of conduction, make the light that sends after these reflector 22 reflections, see through n type gallium nitride 23 and penetrate to extraneous by Sapphire Substrate 24.

Though electro-optical efficiency can reach about more than 75% at present, incide the process of hanging down the refraction coefficient medium and can produce total reflection phenomenon at the interface because of the medium of light, thereby limited the probability of photon effusion luminescence medium greatly from high index of refraction.As shown in Figure 3, light incides the medium 16 of low refraction coefficient from the light-emitting semiconducting material 15 of high index of refraction, only in the beam angle that theta=Sin-1 (n2/n1) constitutes, could overflow, shown in light path 1, total reflection (as light path 2) will take place in medium the beam angle UV light makes last luminous electro-optical efficiency to reach about 20%.If can form roughened textures at the interface, to make the light outside beam angle be reflected back in the beam angle, the probability that forms emergent light increases, the angle of bright dipping will more concentrate on axially in addition, improve axial brightness, no matter therefore be that formal dress or flip-chip all will so be planted structure and increased and luminous intensity.

Summary of the invention

The objective of the invention is to propose a kind of method that improves the chip exterior luminous efficiency.

For realizing above purpose, technical scheme of the present invention provides a kind of method that improves the axial luminous exitance of chip, it is characterized in that,

A kind of method that improves chip brightness, the electrode of upside-down mounting welding core and silicon are heat sink, and chip is fitted, it is characterized in that, the substrate of upside-down mounting welding core is produced the InGaN epitaxial loayer of growing up again behind the roughening of nano-scale, described method further comprises: step 1, at nickel (Ni) metal of Sapphire Substrate surface evaporation last layer thickness between 1 ~ 50 nanometer; Step 2 was carried out short annealing 30 ~ 300 seconds with 600 ~ 900 degrees centigrade temperature, and the nickel metal will form the coccoid of about 200 ~ 400 nanometers of diameter this moment, with this as mask; Step 3, etching Sapphire Substrate surface optionally, the degree of depth is in 100 ~ 500 nanometer range; Step 4 is cleaned the described nickel metal on the described Sapphire Substrate; Step 5 is with described substrate growing indium nitride gallium epitaxial loayer.

Reasonable is in the described step 3, to adopt the method for inductance coupling type reactive ion etching machine that etching is carried out on the Sapphire Substrate surface.The zone that the utility model can be controlled the big or small of mask and then control etching by the thickness and the annealing temperature of control nickel metal, etching depth is then controlled by the time or the power of ICP etching, with control Scattering of Vector size as shown in Figure 5.The advantage of this kind method be can be stable the control Sapphire Substrate and the roughness between the InGaN epitaxial layer interface make light extraction efficiency be promoted.

Description of drawings

Below, with reference to accompanying drawing, for those skilled in the art that, from the detailed description to the inventive method, above-mentioned and other purposes of the present invention, feature and advantage will be apparent.

The blue green light chip structure schematic diagram that Fig. 1 is traditional;

Fig. 2 flip welding LED structural representation;

Fig. 3 has illustrated not roughed interface light path schematic diagram;

Fig. 4 provides the implementation step schematic diagram of the inventive method;

Fig. 5 has illustrated roughed interface light path schematic diagram.

Embodiment

See also shown in (a)～(e) of accompanying drawing 4, the invention will be further described below in conjunction with drawings and Examples.

At first with reference to figure 4 (a), at nickel (Ni) metal 42 of Sapphire Substrate 41 surperficial evaporation last layer thickness between 1 ~ 50 nanometer;

Secondly as Fig. 4 (b), carried out short annealing 30 ~ 300 seconds with 600 ~ 900 degrees centigrade temperature, nickel metal 42 will form the coccoid of about 200 ~ 400 nanometers of diameter at this moment, with this as mask;

In Fig. 4 (c), utilize inductance coupling type reactive ion etching machine (ICP-RIE) with reacting gas (as chlorine, boron chloride and methane etc.) etching Sapphire Substrate surface optionally, reach the effect of surface roughening, the degree of depth of etching is generally about 100 ~ 500 nanometers

Fig. 4 (d) is clean with the corrosion of nickel metal 42 usefulness chemical solutions;

Fig. 4 (e), this substrate 41 is put into MOCVD stove upwards grow successively n type gallium nitride layer 43, luminescent layer 44 and P type gallium nitride layer 45 shapes or extension the most at last.

Fig. 5 provides the light path schematic diagram at the roughening interface of Fig. 4 extension, because the alligatoring effect at interface, light significantly promotes from Sapphire Substrate 41 probabilities that the epitaxial layer of gallium nitride 43 of high index of refraction incides low refraction coefficient.Therefore will help being lifted out optical efficiency in the nano level roughened textures of this interface manufacture.

In the above-mentioned steps of the present invention, high-temperature annealing step on the Sapphire Substrate 41 forms the nickel metal 42 of even spherical distribution as mask, selective etch Sapphire Substrate 41 surfaces then, thereby reach surperficial small grain size and uniform roughen effect, then nickel metal 42 is cleaned back growing indium nitride gallium epitaxial loayers.The advantage of this method be can be stable the control Sapphire Substrate and the roughness between the InGaN epitaxial layer interface make light extraction efficiency be controlled.

The front provides the description to preferred embodiment, so that any technical staff in this area can use or utilize the present invention.Various modifications to these embodiment are conspicuous to those skilled in the art, can be applied to other embodiment to total principle described here and not use creativeness.Thereby, the embodiment shown in the present invention will be not limited to here, and the wide region of principle that should disclose and new feature according to meeting here.

Claims

1. a method that improves the axial luminous exitance of chip is characterized in that, described method further comprises:

Step 1 is at the nickel metal of Sapphire Substrate surface evaporation last layer thickness between 1 ~ 50 nanometer;

Step 2 was carried out short annealing 30 ~ 300 seconds with 600 ~ 900 degrees centigrade temperature, and the nickel metal will form the coccoid of about 200 ~ 400 nanometers of diameter this moment, with this as mask;

Step 3, etching Sapphire Substrate surface optionally, the degree of depth is in 100 ~ 500 nanometer range;

Step 4 is cleaned the described nickel metal on the described Sapphire Substrate;

Step 5 is with described substrate growing indium nitride gallium epitaxial loayer.

2. a kind of method that improves the axial luminous exitance of chip according to claim 1 is characterized in that,

In the described step 3, adopt the method for inductance coupling type reactive ion etching machine that selective etch is carried out on the Sapphire Substrate surface.