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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 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) 2 sets of MOCVD ( Nippon Sanso)
MOCVD附屬設備 層流台&防潮櫃 廢氣處理塔 特殊氣體房 氫氣儲存房 JPC廢氣處理塔 氮氣儲存房
MOCVD附屬量測設備 金相顯微鏡 可對磊晶片做 初步的表面分析 高解析度X光繞射儀 可快速對成長完之磊晶片做精確 的晶格結構分析
LED晶粒製程設備 Flip-Chip Bonder Wafer Bonding Bonder
LED標準亮度量測系統 IS-250 (直徑25cm) Keythley2420
積分球燈具量測系統 SLM-20T (直徑50cm) Agilent E3634A (50V;4A)
LED光學量測系統 穿透反射量測儀 LED遠場角量測儀
紅外線熱影像量測儀 SC620 顯微鏡頭:25um 測溫範圍:-40~1500o
LED熱阻量測分析儀 Operating Current (mA) ΔTj-a (oC) Forward Volt. (VF)
MOCVD • Apparatus(1F)3 sets of MOCVD ( Nippon Sanso + Aixtron)
Clean Room • Apparatus(9F) Measurement Equipments Device Process Equipments
Low Temperature n-GaN LED Structure Inserting LT n-GaN layer
Pattern Sapphire Substrate LEDs 平台 (flat-top) 三角形 (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
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).
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
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/jωc 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
Researchers from Taiwan’s Chung-Gung University have determined the diffusion mechanism into GaAs…. • Sep,2007