國立台灣師範大學機電科技學系

(1)

台灣師範大學機電科技學系 -1-

LED LED 製程與應用技術製程與應用技術

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 University

Tel: 02-23583221 ext. 14 E-mail:ycr@ntnu.edu.tw

Prof. CR Yang, NTNU MT

綱綱要要

z LED原理與應用

z 基礎LED製程模組技術

z LED技術未來展望

(2)

LED原理與應用 LED 原理與應用

-4-

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)

(3)

What is

What is GaN GaN LED? LED?

z 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 z

Cross-section of conventional GaN LED.

P-type Active region N-type light

z

Theorem of LED.

(Mg doped )

(Si doped) (Multi quantum well)

(AlN+undoped GaN) (ITO glass)

(In_1-xGa_xN)

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

p-electrode

n-electrode transparent contact layer

n-GaN p-GaN

MQWs

Sapphire substrate

(4)

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

-8-

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

(5)

半導體發光元件材料半導體發光元件材料

(6)

光的三原色：

光的三原色： RGB RGB

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)

-12-

GaN GaN 與與 ZnSe ZnSe 白光白光 LED 結構比較 LED 結構比較

(7)

Advantages and defects of

Advantages and defects of LEDs LEDs

Defects:

z z The cost of high brightness is The cost of high brightness is higher.

higher.

z

z The efficiency of The efficiency of LEDs LEDs is not is not very well.

very well.

z

z Heat problem is serious. Heat problem is serious.

Advantages:

z z Color rendering and Color rendering and chromaticity is well.

chromaticity is well.

z

z It’ It ’s kind of luminescence s kind of luminescence

z

z Long life time. Long life time.

z z Don’ Don ’t need mercury. t need mercury.

z z Response is fast. Response is fast.

z

z Smart lighting. Smart lighting.

(冷光) (顯色性)

(色度)

發光效率、強韌設計、彈性、環保為其主要優勢

(8)

LED應用市場分類 LED 應用市場分類

-16-

Applications of LED Applications of LED

z All kinds of LEDs.

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

(9)

(10)

LED照明燈 TOYOTA 汽車前燈

LED走廊裝飾燈（波士頓）

LED 公園路燈

-20-

z 藍光CD/ DVD讀寫頭

^●

UV Curing 紫外光治療

z 醫療器材(手術燈)

^●

鏡片黏著 (epoxy)

z 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

(11)

我國我國 LED LED 產業結構產業結構

(12)

-24-

我國白光LED 我國白光 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

(13)

LED efficiency LED efficiency

e / I

) hv /(

= P second per LED into injected electrons

of number

second per region active from emitted photons

of number

=

η

_int ^int

) hv /(

P ) hv /(

= P second per region active from emitted photons of

number

second per space free into emitted photons of

number

= η

int extraction

extraction int

ext

= η × η

e / I

) hv /(

= P second per LED into injected electrons of

number

second per space free into emitted photons of

number

= η

z Internal quantum efficiency (IQE):

z Extraction efficiency:

z External quantum efficiency (EQE):

IV

= P LED to provided power

electrical

space free into emitted power total

= η

_power

z Power efficiency:

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

θ

₁

θ

₂

2 air 1

GaN

• Sin θ = n • sin θ n

23.6 n =

sin 1

= θ

90 = θ critical, is θ When

GaN 1 - c

2 1

o o

total internal reflection

n-GaN p-GaN

active layer

substrate

light

(14)

) cos 1 2 ( 1 P

P

r 4

) cos 1 ( r P 2

P

) cos 1 ( r 2 rd sin r 2 dA A

c source

ecape

2 c 2

source ecape

c 2

0 c

θ

−

=

π θ

−

= π

θ

− π

= θ

⋅ θ π

=

= ∫ ∫

^θ ²

c 2

c source

ecape

4 ) 1 1 2 ( - 2 1 1 P

P ⎥ = θ

⎦

⎢ ⎤

⎣

⎡ − θ

≅

z GaN LEDs emits ratio of photon:

r·sinθ

2πr sinθ · rdθ dθ

r dθ

θ r θ

Area=2πr²( 1-cosθ ) r

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

-28-

Truncated T runcated- -inverted inverted -pyramid - pyramid (TIP) LEDs (TIP) LEDs

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

z

EQE can increase 1.4 times with

TIP structure.

(15)

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

GaAs GaAs LEDs LEDs with textured surface with textured surface

Typical Process Steps of the Conventional Typical Process Steps of the Conventional

LEDs on Sapphire LEDs on Sapphire

Sapphire u-GaN n-GaN MQW

p-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

MQW p-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

(16)

LASER LIFT

LASER LIFT- -OFF (LLO) GaN LED OFF (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-electrode Sapphire

substrate ^sapphire

u-GaN n-GaN MQW p-GaN

Cu substrate N-electrode

P-electrode

Cu Bonding metals

p-GaN n-GaN MQW

300μm 300μm

-32-

Fabrication of

Fabrication of InGaN InGaN LED membranes by laser lift- LED membranes by laser lift -off off

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

Si

GaN

heat

Al

₂

O

₃

Si

GaN

adhesive

Si

GaN

z Process of LLO (laser lift-off ).

(17)

LASER LIFT

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

(18)

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LED LED製程製程

-36-

基礎基礎 LED製程模組技術 LED 製程模組技術

MQW transparency

electrode

n-face(0001)

substrate

buffer layer n-GaN

p-GaN

Ga-face(0001)

(19)

基礎基礎 IC製程技術 IC 製程技術 (LED (LED製程基礎製程基礎) )

LED製程流程 LED 製程流程

(20)

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 Substrate Crystal Growth for Sapphire Substrate

-40-

薄膜沉積薄膜沉積

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

z

PECVD

z

LPCVD

z

APCVD

z

MOCVD

(光電薄膜沉積)

(21)

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

GaN磊晶成長系統與技術 GaN 磊晶成長系統與技術 ( I ) ( I )

(22)

-44-

Sputtering Sputtering

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

Joule heat or Electron beam

(23)

分子束磊晶 ( Molecular Beam Epitaxy, MBE) 系統

GaN磊晶成長系統與技術 GaN 磊晶成長系統與技術 ( II ) ( II )

分子束磊晶 ( Molecular Beam Epitaxy, MBE) 系統

(24)

基板

光罩光阻紫外光曝光

薄膜

基板基板

薄膜

正光阻顯影負光阻

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

-48-

光阻的微影程序光阻的微影程序

Dehydration Bake

resist resist

Vacuum Spin Coating

Soft Bake

Exposure UV Post Exposure Bake

Vacuum Spin Drying

Hard Bake 10-15min @ 250℃

(optional)

? min @ ?℃

? dosage/?thickness Development

(agitation)

? min @ ? ℃

(Rinse)

(Priming)

(25)

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

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

(26)

High

High- -aspect aspect- -ratio, Anisotropic Silicon Etching ratio, Anisotropic Silicon Etching Techniques Techniques by by Inductively Coupled Plasma Reactive Ion Etching (ICP Inductively 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 mask Substrate

Plasma

etch stop

感應耦合電漿蝕刻(ICP-RIE)系統, ITRC

-52-

Deep Reactive Ion Etching (DRIE) Deep Reactive Ion Etching (DRIE)

Rimple

Rimple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

(27)

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)

NMOS PMOS

IC離子摻雜 IC 離子摻雜(doping) (doping)的目的的目的

(28)

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)

-56-

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

(29)

Chip on the sapphire wafer

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

研磨、拋光、切割、崩裂研磨、拋光、切割、崩裂

Schematic of an electrochemical cell Schematic of an electrochemical cell

Power supply

Cathode Anode

e

^-

e

^-

Cu → Cu

²⁺

→ Cu 2e

^-

2e

^-

2H

₂

O + 2e

^-

→ H

₂

+ 2OH

^-

↑

H2 ↑

H₂

↑ H₂

↑

H2 Cu deposition H₂evolution Cu 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

(30)

Principle of an Electroforming Technology Principle of an Electroforming Technology

PMMA微齒輪 鎳金屬微齒輪

-60-

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

(31)

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

(a) (a) 改良

改良前；前；

(b) 改良後 (b)

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

Surface Surface roughing roughing

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

(32)

Special surface roughing technology Special surface roughing technology

by our surface by our surface roughing technology roughing technology

國立台灣師範大學 機電科技學系

LED LED 製程與應用技術 製程與應用 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 University

Tel: 02-23583221 ext. 14 E-mail:ycr@ntnu.edu.tw

綱 綱 要 要

z LED原理與應用

z 基礎LED製程模組技術

z LED技術未來展望

LED原理與應用 LED 原理與應用

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)

What is

What is GaN GaN LED? LED?

z GaN LED means “gallium nitride light emitting diode.

- GaN LED is a kind of blue LED.

Cross-section of conventional GaN LED.

P-type Active region N-type light

Theorem of LED.

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

What is

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

cladding layer (high bandgap material ) active region

light light

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

半導體發光元件材料 半導體發光元件材料

光的三原色：

光的三原色： RGB RGB

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)

GaN GaN 與 與 ZnSe ZnSe 白光 白光 LED 結構比較 LED 結構比較

Advantages and defects of

Advantages and defects of LEDs LEDs

Defects:

Defects:

z z The cost of high brightness is The cost of high brightness is higher.

higher.

z

z The efficiency of The efficiency of LEDs LEDs is not is not very well.

very well.

z

z Heat problem is serious. Heat problem is serious.

Advantages:

Advantages:

z z Color rendering and Color rendering and chromaticity is well.

chromaticity is well.

z

z It’ It ’s kind of luminescence s kind of luminescence

z

z Long life time. Long life time.

z z Don’ Don ’t need mercury. t need mercury.

z z Response is fast. Response is fast.

z

z Smart lighting. Smart lighting.

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

LED應用市場分類 LED 應用市場分類

Applications of LED Applications of LED

z All kinds of LEDs.

LED 公園路燈

z 藍光CD/ DVD讀寫頭

UV Curing 紫外光治療

z 醫療器材(手術燈)

鏡片黏著 (epoxy)

z 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

我國 我國 LED LED 產業結構 產業結構

我國白光LED 我國白光 LED 照明產業結構 照明產業結構

LED efficiency LED efficiency

國立台灣師範大學機電科技學系

LED LED 製程與應用技術製程與應用技術

楊啟榮博士

教授

國立台灣師範大學機電科技學系

綱綱要要

半導體發光元件材料半導體發光元件材料

半導體發光元件材料半導體發光元件材料

GaN GaN 與與 ZnSe ZnSe 白光白光 LED 結構比較 LED 結構比較

我國我國 LED LED 產業結構產業結構

我國白光LED 我國白光 LED 照明產業結構照明產業結構