Droop esd and heat dissipation of flip chip power leds
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Droop, ESD and Heat dissipation of Flip-Chip Power LEDs. Prof. Liann-Be Chang Vice Dean & Director Engineering College Green Technology Research Center (GTRC). Outline. Epitaxial technology LED process technology Flip Chip technology. MOCVD 磊晶設備. 1 set of MOCVD ( Aixtron).

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Droop, ESD and Heat dissipation of Flip-Chip Power LEDs

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Droop, ESD and Heat dissipation of Flip-Chip Power LEDs

Prof. Liann-Be Chang

Vice Dean & Director

Engineering College

Green Technology Research Center (GTRC)


Outline

  • Epitaxial technology

  • LED process technology

  • Flip Chip technology


MOCVD

1 set of MOCVD

( Aixtron)

2 sets of MOCVD

( Nippon Sanso)


MOCVD

JPC


MOCVD

X





LED

Flip-Chip Bonder

Wafer Bonding Bonder


Wire & Bump Bonder


LED

IS-250 (25cm) Keythley2420


SLM-20T (50cm)

Agilent E3634A (50V;4A)


LED

LED


SC620

:25um

:-40~1500o


LED

Operating Current (mA)

Tj-a (oC)

Forward Volt. (VF)


MOCVD

  • Apparatus(1F)3 sets of MOCVD ( Nippon Sanso + Aixtron)


Clean Room

  • Apparatus(9F) Measurement Equipments

    Device Process Equipments


Methodology used in GTRC to Improve LED Performance


MOCVD epitaxial technology


Low Temperature n-GaN LED Structure

Inserting LT n-GaN layer


Optical & Electrical Characteristic


Pattern Sapphire Substrate LEDs

(flat-top)

(pyramid)


Optical & Electrical Characteristic

74% up

2 times


LED structure

ZnO buffer (300 nm)

Sapphire

Epitaxial Growth : LED on ZnO Template


Improving the luminescence by selective activation or ion implantation


Reflectance and Contact Resistanceof Ni/Ag-Based Metal Contacts on p-Type GaN

Ni/Ag

Ni/Ag/Au

Ni/Ag/Ti/Au


Micro Channel LED


Electron confine (blocking) effect

  • For sample B, except an additional 20-nm-thick p-type Al0.25Ga0.75N EBL inserted between the active layer and the p-type AlGaN/GaN superlattice structure to enhance the electron-

  • blocking effect, the other growth conditions and structures were the same as those for sample A.

  • The light-output power of sample

  • B increases more rapidly and

  • becomes greater than that of

  • sample A in the measurement

  • range from 25 to 130 A/cm2.

Applied Physics Express 3 (2010)


Electron decelerating effect

Appl. Phys. Lett. (2010).


Efficiency droop research by double-hetero structure LED


Wafer Bonding Technology

At present, wafer bondingtechnology is used widely


The proposed Flip-Chip Structure on MOS submount

  • high reflect material

heat

  • use MOS heat sink & ESD protecting substrates

  • heat flow can through the submount with high thermal conductivity material


Core Technology : Pick/Place and U.S. Bonding


Top View of Flip-Chip Power LED


PN Junction & MOS Structure Submount

Conventional FCLED on PN Junction Submount

The Proposed FCLED on MOS Protective Submount


ESD Handling Capability

  • FC-LED on PN junction

  • Non flip-chipped LED


ESD Handling Capability

  • FC-LED on MOS

Zc = 1/jc is small for large capacitance submount


Output Power Intensity

  • Non Flip-chip LED luminance would be saturated at a large current injection

  • The best performance was flip-chip LED on AlN submount because AlN had higher thermal conductivity than Si


Flip-Chip AC-LED

  • We can easily design an 24 V AC-circuit directly on the submount through FC technology


Different LED chip on Si substrate thermal analysis

VLED

CLED

FCLED

CLED

VLED

FCLED (20 gold bumps)

69oC

78oC


Remote Phosphor


  • Researchers from Taiwans Chung-Gung University have determined the diffusion mechanism into GaAs.

  • Sep,2007


Thank you for your attention


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