CN102034925B

CN102034925B - Flat FCB (Flip Chip Bonding) GaN-based LED (Light-Emitting Diode) chip structure

Info

Publication number: CN102034925B
Application number: CN2010105220762A
Authority: CN
Inventors: 沈燕; 徐现刚; 徐化勇; 郑鹏
Original assignee: Shandong Huaguang Optoelectronics Co Ltd
Current assignee: Changshu intellectual property operation center Co.,Ltd.
Priority date: 2010-10-28
Filing date: 2010-10-28
Publication date: 2013-04-03
Anticipated expiration: 2030-10-28
Also published as: CN102034925A

Abstract

The invention provides a flat FCB (Flip Chip Bonding) GaN-based LED (Light-Emitting Diode) chip structure comprising a substrate. An N-type GaN layer, a QW (Quantum Well) active area, a P-type GaN layer, a current extension level and a light-reflecting layer are sequentially arranged below the substrate from top to bottom, a stepped surface to the N-type GaN layer is etched on the light-reflecting layer, an N electrode is made on the N-type GaN layer of the stepped surface, a P electrode is made on the light-reflecting layer and arranged on the same plane with the outer end of the P electrode, a transparent insulated medium film is coated on the plane of the P electrode bonding pad and the N electrode bonding pad except the regions of P electrode bonding pad and the N electrode bonding pad, a P bonding board is made at the outer end of the P electrode bonding spot, an N bonding board is made at the outer end of the bonding point of the N electrode, and the P bonding board and the N bonding board are bonded on a P electrode area and an N electrode area of a conductive Si or SiC substrate by cocrystallization or alloy. The insulated medium film is coated outside the PN bonding pads to prevent PN from being subjected to short circuits and a limit N-area electrode conductive flat is spliced to the P area desk.

Description

Flat-plate inverted welding equipment GaN based LED chip structure

Technical field

The present invention relates to the structure of a kind of GaN base blue-ray LED (light-emitting diode), belong to the light emitting diode construction technical field.

Background technology

The structure of traditional Sapphire Substrate GaN base LED (light-emitting diode) chip as shown in Figure 1, on substrate 1, be provided with successively from the bottom to top N-type GaN layer 2, quantum well QW active area 3, P type GaN layer 4 and current extending 5, be provided with N electrode 7 at N-type GaN layer 2.Electrode just is positioned at the exiting surface of chip.In this structure, fraction P type GaN layer 4 and " luminous " layer are etched, and electrically contact in order to form with following N-type GaN layer 2.Light takes out from top P type GaN layer 4.P type GaN layer 4 limited conductivity require to precipitate one deck current-diffusion layer 5 on its surface again.The light splitting of the too thick meeting of this current-diffusion layer 5 absorbent portion, thus light extraction efficiency reduced, cross thin meeting Limited Current at the surface uniform and the ability that spreads large electric current of P type GaN layer 4.This structural constraint the operating power of led chip, the heat of this structure pn knot is derived by Sapphire Substrate and is gone, thermally conductive pathways is long, and sapphire thermal conductivity coefficient low than metal (be 35W/m? K), the led chip thermal resistance of this structure is large.Simultaneously, the p electrode of this structure and lead-in wire block part light.Device power, light extraction efficiency and the hot property of this packed LED chip all can not be optimum.

In order to overcome these deficiencies of above-mentioned traditional die, flip-chip (Flipchip) has been invented by Lumileds Lighting company, its structure as shown in Figure 2, substrate 1 is in the top, below substrate 1, be provided with successively from top to bottom N-type GaN layer 2, quantum well QW active area 3, P type GaN layer 4, transparent current expansion 5 and reflection layer 6, be etched with on the reflection layer 6 to the step surface of N-type GaN layer 2, be manufactured with N electrode 7 at the N-type GaN of this step surface layer, N electrode 7 and P electrode 8 welds with lower end heat conduction Si substrate 11 by metal salient point welding plate 9,10.In this structure, light takes out from Sapphire Substrate 1, needn't pass through current-diffusion layer 5 outgoing, and current-diffusion layer can be thickeied like this, increases the current density of Flipchip.This structure can also directly be led the heat of pn knot to the high backing material of thermal conductivity coefficient by metal salient point simultaneously, and radiating effect calibration assembling structure has greater advantage.

The heat that the pn knot produces in this inverted structure chip mainly passes to backing material or the external world by metal salient point, and the common metal salient point only has the area of two pad sizes of chip, generally about 100um, concentrate density very large at metal salient point place heat, the some temperature of this position is quite high.If metal salient point is excessive, chip PN electrode easily causes the metal salient point adhesion and short circuit.The led chip increased power, producing heat can't timely and effectively shed, and luminous efficiency is descended, the spectral red shift that temperature rise is launched chip, the colour temperature Quality Down, the LED life-span reduces.

Chinese patent literature CN1967883 discloses a kind of " high power LED flip-chip and preparation method thereof ", is to pass through evaporation metal speculum on silicon on the basis of traditional inverted structure, to improve bright dipping, still still adopts traditional metal salient point heat conduction.Chinese patent literature patent CN1901189 discloses a kind of " plane flip-chip LED integrated chip and manufacture method ", but chip still is connected by solder-ball flip with silicon substrate.If the heat that chip pn knot produces can not well be derived, the target in led chip 100 ℃ of 100,000 hours life-spans of working temperature will be difficult to realize.

Summary of the invention

The present invention is directed to that limited, the excessive salient point of heat-conducting metal salient point easily causes again this difficult problem of chip PN short circuit in the flip chip structure, propose the flat-plate inverted welding equipment GaN based LED chip structure of a kind of good heat dissipation effect, metal pad panelized.

Flat-plate inverted welding equipment GaN based LED chip structure of the present invention adopts following technical solution:

This flat-plate inverted welding equipment GaN based LED chip structure comprises substrate, is provided with successively from top to bottom N-type GaN layer, quantum well QW active area, P type GaN layer, current extending and reflection layer below substrate; Be etched with on the reflection layer to the step surface of N-type GaN layer, be manufactured with the N electrode at the N-type GaN of this step surface layer, be manufactured with the P electrode at reflection layer, the outer end of N electrode and P electrode is in same level; Other zone except P electrode pad and N electrode pad at P electrode pad and N electrode pad place face is coated with the layer of transparent dielectric insulating film, P electrode pads outer end is manufactured with the P welding plate, N electrode pads outer end is manufactured with the N welding plate, and P welding plate and N welding plate eutectic or gold alloy solder are received on the P electrode district and N electrode district of heat conduction Si substrate.

The present invention is coated with dielectric insulating film at PN pad exterior domain, prevented that PN is communicated with short circuit, derive two PN welding electrodes by the PN pad area, novelty is taken limited N region electrode heat conduction flat board to P district table top, has substituted the inverted structure that traditional PN solder joint is derived two metal salient points.This structure, metal salient point are converted into the sheet metal electrode, and the heat energy that its pn knot produces enough better leaves, simultaneously before two plate electrode welding disking areas with the deielectric-coating isolation, can be not bonded to one another and short circuit, this structure LED radiating effect is more excellent, technique is simple and easy to realize, is fit in batches large-scale production.

Description of drawings

Fig. 1 is the structural representation of common packed LED chip.

Fig. 2 is the structural representation of common flip LED chips.

Fig. 3 is the end view of flat-plate inverted welding equipment GaN base LED chip of the present invention.

Fig. 4 is the vertical view of flat-plate inverted welding equipment GaN base LED chip of the present invention.

Wherein: 1, substrate, 2, N-type GaN layer, 3, quantum well QW active area, 4, P type GaN layer, 5, current extending, 6, reflection layer, 7, the N electrode, 8, dielectric insulating film, 9, the P welding plate, 10, the N welding plate, 11, heat conduction Si or SiC substrate.

Embodiment

The structure of flat-plate inverted welding equipment GaN base LED of the present invention is to improve on the basis of flip chip structure shown in Figure 2, as shown in Figure 3 and Figure 4, be etched with on the reflection layer 6 to the step surface of N-type GaN layer 4, be manufactured with N electrode 7 at the N-type GaN of this step surface layer 4, be manufactured with P electrode 8 at reflection layer 6, N electrode 7 is in same level with the outer end of P electrode 8.Other zone except P electrode pad and N electrode pad at P electrode pad and N electrode pad place face is coated with layer of transparent dielectric insulating film 12.P electrode pads outer end is manufactured with P welding plate 9, and N electrode pads outer end is manufactured with N welding plate 10, and P welding plate 9 and N welding plate 10 are welded on the P electrode district and N electrode district of heat conduction Si or SiC substrate 11.

This structure mainly is flip-chip metal salient point welding passage of heat is extended to the metal flat welding, and one deck protective insulating film that passes through of novelty is taken the dull and stereotyped expansion of limited N region electrode heat conduction to P district table top.N welding plate 10 is not taken to P district table top by the size restrictions expansion of N district can.

Claims

1. a flat-plate inverted welding equipment GaN based LED chip structure comprises substrate, is provided with successively from top to bottom N-type GaN layer, quantum well QW active area, P type GaN layer, current extending and reflection layer below substrate; Be etched with on the reflection layer to the step surface of N-type GaN layer, be manufactured with the N electrode at the N-type GaN of this step surface layer, be manufactured with the P electrode at reflection layer, it is characterized in that: other zones except P electrode pad and N electrode pad at P electrode pad and N electrode pad place face are coated with the layer of transparent dielectric insulating film, P electrode pads outer end is manufactured with the P welding plate, N electrode pads outer end is manufactured with the N welding plate, the outer end of N electrode and P electrode is in same level, the N welding plate is not taken to P district table top by N district size restrictions, and P welding plate and N welding plate eutectic or gold alloy solder are received on the P electrode district and N electrode district of heat conduction Si or SiC substrate.