Prof. CR Yang, NTNU MT...

台灣師範大學機電科技學系

Prof. CR Yang, NTNU MT

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LEDLED製程與應用製程與應用技術技術LED fabrication process and application technology

楊啟榮博士

教授

國立台灣師範大學機電科技學系Department of Mechatronic Technology

National Taiwan Normal UniversityTel: 02-23583221 ext. 14E-mail:[email protected]



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綱綱要要

LED原理與應用

基礎LED製程模組技術

LED技術未來展望



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LEDLED原理與應用原理與應用



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愛迪生1847-1931

半導體發光元件1962

1880年所發明的電燈

LED (發光二極體)

LD (雷射二極體)



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What is What is GaNGaN LED?LED?

GaN LED means “gallium nitride light emitting diode.- GaN LED is a kind of blue LED.

Ref: N. Shibata, Phys. stat. sol., Vol.2 , pp.254-260, 2002

Cross-section of conventional GaN LED.

P-type Active region N-type

light

Theorem of LED.

(Mg doped )

(Si doped)

(Multi quantum well)

(AlN+undoped GaN)

(ITO glass)

(In1-xGax N)



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Light Emitting Diode (LED)Light Emitting Diode (LED)

p-electrode

n-electrode

transparentcontact layer

n-GaN

p-GaNMQWs

Sapphire substrate



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What is What is ““active region active region ““??

cladding layer (high bandgap material )

active region

light light

量子井發光層材料與結構： 1. 決定發光波長；2. 提升發光效率



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半導體發光元件材料半導體發光元件材料Nitride-based is the most suitable material



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半導體發光元件材料半導體發光元件材料



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光的三原色：光的三原色：RGBRGB

目前白光LED 的製作技術主要有以下五種：1. 以UV LED激發螢光物質，產生紅、藍、綠三種色光後再混合成白光。2. 利用綠色與紅色螢光物質塗抹在藍光LED 上，以發出白光。3. 運用黃色的螢光粉以及藍光LED，使黃光與藍光混合後發出白光。4. 混合紅、藍、綠三顆三原色LED 的發光，以得到白光。5.使用ZnSe 材料的白光LED，且不需螢光體。(發光效率較差)



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GaNGaN 與與ZnSeZnSe 白光白光LED LED 結構比較結構比較



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Advantages and defects of Advantages and defects of LEDsLEDs

Defects:Defects:The cost of high brightness is The cost of high brightness is higher.higher.

The efficiency of The efficiency of LEDsLEDs is not is not very well.very well.

Heat problem is serious.Heat problem is serious.

Advantages:Advantages:Color rendering and Color rendering and chromaticity is well.chromaticity is well.

ItIt’’s kind of luminescence s kind of luminescence

Long life time.Long life time.

DonDon’’t need mercury.t need mercury.

Response is fast.Response is fast.

Smart lighting.Smart lighting.

(冷光)

(顯色性)

(色度)



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發光效率、強韌設計、彈性、環保為其主要優勢發光效率、強韌設計、彈性、環保為其主要優勢



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LEDLED應用市場分類應用市場分類



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Applications of LEDApplications of LED

All kinds of LEDs.

Ref: N. Shibata, Phys. stat. sol., Vol.2 , pp.254-260, 2002



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LED照明燈 TOYOTA 汽車前燈

LED走廊裝飾燈（波士頓）LED 公園路燈



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藍光CD/ DVD讀寫頭 ● UV Curing 紫外光治療

醫療器材(手術燈) ● 鏡片黏著 (epoxy)

郵票與貨幣檢驗 ●刑式犯罪鑑識( 微物鑑識)

半導體紫外光元件應用半導體紫外光元件應用



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我國我國LEDLED產業結構產業結構



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我國白光我國白光LED LED 照明產業結構照明產業結構

光連 Optolink, 八十九年九月, 第29 期



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LED efficiencyLED efficiency

e/I)hv/(P

=secondper LED into injected electrons ofnumber

secondper region active from emitted photons of number=η intint

)hv/(P)hv/(P

=secondper region active from emitted photons of number

secondper space free into emitted photons of number=η

intextraction

extractionintext η×η=e/I)hv/(P

=secondper LED into injected electrons of number

secondper space free into emitted photons of number=η

Internal quantum efficiency (IQE):

Extraction efficiency:

External quantum efficiency (EQE):

IVP

=LED to providedpower electricalspace free into emittedpower total

=ηpower

Power efficiency:



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Loss due to critical angle Loss due to critical angle ( I )( I )

θ1 θ2

2air1GaN θsin•n=θSin•n

23.6=n

1sin=θ

90=θ critical, is θ When

GaN

1-c

21

o

o

total internal reflection

n-GaN

p-GaN

active layer

substrate

light



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)cos1(21

PP

r4)cos1(r2PP

)cos1(r2rdsinr2dAA

csource

ecape

2c

2

sourceecape

c2

0

c

θ−=

πθ−π

=

θ−π=θ⋅θπ== ∫ ∫θ

2c

2c

source

ecape

41)

21(-1

21

PP

θ=⎥⎦

⎤⎢⎣

⎡ θ−≅

GaN LEDs emits ratio of photon:

r·sinθ

dθ2πr sinθ · rdθ

r dθ

θ r θ

Area=2πr2 ( 1-cosθ )

r

Loss due to critical angle ( II )Loss due to critical angle ( II )



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TTruncatedruncated--invertedinverted--pyramidpyramid (TIP) (TIP) LEDsLEDs

Ref: M. R. Krames et al., Applied Physics Letters, 75 (2006) 2365-2367.

EQE can increase 1.4 times with TIP structure.



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Ref: I. Schnitzer et al., Applied physics letters, 63(16) (1993) 2174-2176.

GaAsGaAs LEDsLEDs with textured surfacewith textured surface



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Typical Process Steps of the ConventionalTypical Process Steps of the ConventionalLEDs on Sapphire LEDs on Sapphire

Sapphire

u-GaNn-GaNMQWp-GaN p-GaN

n-GaN

u-GaN

sapphire

Mesa Semitransparent metal或ITO導電玻璃

p-type contact Ni/Au n-type contact Ti/Al

sapphire

u-GaN

n-GaN

MQWp-GaN

MQW

(1) 磊晶結構 (2) 定義大小區塊

(4) P電極製作 (5) N電極製作

(3) 透明接觸層製作

(6) 熱處理

(7) 點燈測試



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LASER LIFTLASER LIFT--OFF (LLO) GaN LEDOFF (LLO) GaN LED

C. F. Chu et. al. JJAP, Vol.42, L147, 2003 and JAP, 95, pp. 3916, 2004

一般 p-side up GaN LED結構 P-side down GaN LED結構

＊基板不導電＊電極製作複雜＊需p型透明電極＊電流分佈不均勻＊基板導熱效果差＊無法耐高電流操作＊大面積發光製作困難

＊基板導電佳＊電極製作簡單＊無需透明電極＊電流分佈均勻＊基板導熱效果佳＊耐高電流操作，輸出功率與波長穩定＊可實現大面積及高功率發光

缺點：優點：

P-透明電極P-electrode

N-electrodeSapphire substrate sapphire

u-GaNn-GaN

MQWp-GaN

Cu substrate

N-electrode

P-electrode

Cu

Bonding metals

p-GaN

n-GaN

MQW

300μm 300μm

300μ

m

300μ

m



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Fabrication of Fabrication of InGaNInGaN LED membranes by laser liftLED membranes by laser lift--offoff

Ref: W. S. Wong et al., Applied physics letters, Vol.75 , pp.1360-1362, 1999

adhesive

Si

GaN

heat

Al2O3

Si

GaN

adhesive

Si

GaN

Process of LLO (laser lift-off ).



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LASER LIFTLASER LIFT--OFF (LLO) GaN LEDOFF (LLO) GaN LED

The process scheme for fabrication of the LLO undoped GaN.C. F. Chu et. al. JJAP, Vol.42, L147, 2003 and JAP, 95, pp. 3916, 2004



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Process steps of GaN chip:

(a) AlN deposition, (b) n-GaN deposition, (c) MQW deposition, (d) p-GaN deposition, (e) electroforming Cu, (f) bombarding the buffer layer through

sapphire by KrF laser, (g) sapphire departed from the whole

chip, (h) up-side down and n-face up, (i) surface roughing, (j) epoxy packaged (k) chip packaged.

次世代電鑄銅基板次世代電鑄銅基板LEDLED製程製程



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基礎基礎LEDLED製程模組技術製程模組技術

MQW

transparency electrode

n-face(0001)

substrate

buffer layer

n-GaNp-GaN

Ga-face(0001)



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基礎基礎ICIC製程技術製程技術 (LED(LED製程基礎製程基礎))



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LEDLED製程流程製程流程



-39-Ref. http://www.tdii.com/ganbulk.htm

藍寶石基板之長晶法藍寶石基板之長晶法Crystal Growth for Sapphire SubstrateCrystal Growth for Sapphire Substrate



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薄膜沉積薄膜沉積

Chemical Vapor Deposition (CVD)Chemical Vapor Deposition (CVD)

PECVDLPCVDAPCVDMOCVD(光電薄膜沉積)



-41-有機金屬氣相磊晶有機金屬氣相磊晶 (Metal(Metal--Organic CVD)Organic CVD)系統系統

GaNGaN磊晶成長系統與技術磊晶成長系統與技術 ( I )( I )



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SputteringSputtering

Physical Vapor Deposition (PVD)Physical Vapor Deposition (PVD)

Joule heat or Electron beamJoule heat or Electron beam



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分子束磊晶 (Molecular Beam Epitaxy, MBE)系統

GaNGaN磊晶成長系統與技術磊晶成長系統與技術 ( II )( II )



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分子束磊晶 (Molecular Beam Epitaxy, MBE)系統



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基板

光罩

光阻

紫外光曝光

薄膜

基板基板

薄膜

正光阻負光阻顯影

薄膜

基板

薄膜

蝕刻

薄膜

基板

基板

薄膜

光阻去除

薄膜

基板

正、負光阻微影製程示意圖

黃光微影製程黃光微影製程



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光阻的微影程序光阻的微影程序

Dehydration Bake

resistresist

VacuumSpin Coating

Soft Bake

Exposure

UV

Post Exposure Bake

VacuumSpin Drying

Hard Bake

10-15min @ 250℃

(optional)

? min @ ?℃

? dosage/?thickness

Development(agitation)

? min @ ? ℃

(Rinse)

(Priming)



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濕式蝕刻法乾式蝕刻法

溼式與乾式蝕刻溼式與乾式蝕刻

電漿蝕刻遮罩層

結構層



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反應性離子蝕刻(RIE)系統, NTNU MOEMS Lab.

濕式蝕刻槽

加熱與磁石攪拌器

蝕刻槽

溫控器

冷凝管



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HighHigh--aspectaspect--ratio, Anisotropic Silicon Etching ratio, Anisotropic Silicon Etching TechniquesTechniques by by Inductively Coupled Plasma Reactive Ion Etching (ICPInductively Coupled Plasma Reactive Ion Etching (ICP--RIE)RIE)

感應耦合電漿之高深寬比非等向性感應耦合電漿之高深寬比非等向性乾式乾式矽蝕刻技術矽蝕刻技術

Mask材料選擇的原則：高選擇比, 蝕刻深度, 非等向性…Etching maskSubstrate

Plasma

etch stop

感應耦合電漿蝕刻(ICP-RIE)系統, ITRC



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Deep Reactive Ion Etching (DRIE)Deep Reactive Ion Etching (DRIE)RimpleRimple現象現象

鏡面品質鏡面品質

垂直結構側壁放大圖

交替蝕刻與高分子鈍化過程 (C4F8/SF6)：

1. 矽壁沈積鈍化高分子C4F8被電漿分解成活性機，並進行高分子沈積反應，使壁上形成鈍化膜

2. 矽底部的高分子與矽被蝕刻SF6被電漿分解成F-，先蝕刻鈍化膜再蝕刻Si

3. 交替反覆，平衡鈍化沈積與蝕刻步驟選擇適當的反應氣體，以維持蝕刻與鈍化的平衡沈積膜必須具有良好的一致性，並足以保護側壁



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擴散法擴散法(diffusion)(diffusion) 離子植入(Ion implantation)

離子佈植是將所需的摻雜元素(如砷)電離成正離子，並施加高偏壓，使其獲得一定的動能，以高速射入矽晶圓的技術。

擴散時摻雜物質經由氣體帶入爐管中，藉

由一定時間的高溫擴散，擴散為所需的濃

度分佈曲線。

離子摻雜離子摻雜(doping)(doping)



-54-NMOS

PMOS

ICIC離子摻雜離子摻雜(doping)(doping)的目的的目的



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基板薄化製程基板薄化製程

( a ) 研磨法 (lapping) ( b ) 切削法 (grinding)

為了方便切割或減少元件的串聯電阻，通常將晶圓減薄到250μm

(一般半導體基板)或85μm (藍寶石基板)



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晶粒切割製程晶粒切割製程

( a ) ( a ) 輪刀式輪刀式

( b ) ( b ) 鑽石式鑽石式

( c ) ( c ) 雷射式雷射式



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Chip on the sapphire wafer Chip on the sapphire wafer 大半圓片大半圓片on the blue tapeon the blue tape

研磨、拋光、切割、崩裂研磨、拋光、切割、崩裂



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Schematic of an electrochemical cellSchematic of an electrochemical cell

Power supply

CathodeAnode

e- e-

Cu → Cu2+ → Cu2e- 2e-

2H2O + 2e-→ H2 + 2OH-↑

H2 ↑H2

↑

H2↑H2 Cu deposition

H2 evolutionCu dissolution

結合精密電鑄技術之結合精密電鑄技術之次次世代銅基板製程世代銅基板製程



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Principle of an Electroforming TechnologyPrinciple of an Electroforming Technology

PMMA微齒輪鎳金屬微齒輪



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氣泡所造成的缺陷後處理所造成的缺陷

一般常見之電鑄缺陷與解決之道一般常見之電鑄缺陷與解決之道

內應力導致電鑄層嚴重變形內應力已獲得控制之鑄層



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電鑄金屬電鑄起始層光阻

避免鑄層沈積厚度差異過大之製程示意避免鑄層沈積厚度差異過大之製程示意 (a) (a) 改良改良前；前；(b) (b) 改良後改良後

( a ) ( b )

電源供應器

陰陽極間電流密度分布陰陽極間電流密度分布

陰極

陽極



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Surface Surface roughingroughing

表面粗化以增加光萃取效率表面粗化以增加光萃取效率

● Solution: KOH, 40-50 wt%.● Temperature: 90~92 ℃● Etching time: 4 min for each piece● Various surfactant added



-63-

Special surface roughing technology Special surface roughing technology

by our surface by our surface roughing technologyroughing technology

The cone by surface roughing can increase photon escaping at The cone by surface roughing can increase photon escaping at side part, and it also should be better shape than hexagonal side part, and it also should be better shape than hexagonal cone.cone.



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LEDLED技術未來展望技術未來展望



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資料來源：日本綜合技術研究所/材料世界網整理

白光白光LEDLED發光效率成長趨勢發光效率成長趨勢



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白光白光LEDLED的課題與解決之道的課題與解決之道

‧Flip-chip構裝可靠性

‧降低晶片製造時的參差不一‧強化晶片的選別

輝度的均一性

‧晶片發光效率的提高成本

‧基板設計的改善(採用陶瓷基板或金屬基板)‧晶片發光效率的提高

散熱性

‧晶片的高功率化(功率超過2W的產品)‧多晶片化(構裝達20個以上的產品)‧晶片發光效率的提高

光通量

解決之道課題

材料世界網整理



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Our Earth at NightOur Earth at NightLED可讓落後地區有一盞明燈，使夜晚的地球更明亮

Keep on moving !By Dr. Yang, National Taiwan Normal University



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Thank you for your attention!Thank you for your attention!敬請批評與指教敬請批評與指教

Prof. CR Yang, NTNU MT...

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