Microsoft PowerPoint - LED製程與其應用技術

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1 LED 製程與應用技術 LED fabrication process and application technology 綱要 LED 原理與應用基礎 LED 製程模組技術楊啟榮博士 LED 技術未來展望教授國立 Department of Mechatronic Technology National Taiwan Normal University Tel: ext 半導體發光元件 1962 LED 原理與應用愛迪生 LED ( 發光二極體 ) 1880 年所發明的電燈 LD ( 雷射二極體 )

electrod transparency electrode p-type GaN (Mg doped ) MQW(In

sapphire Cross-section of conventional GaN LED. Ref: N.

254-260, 2002 p-electrode Sapphire substrate transparent

2 What is GaN LED? GaN LED means gallium nitride light emitting diode. - GaN LED is a kind of blue LED. Light Emitting Diode (LED) light n- electrod p- (ITO glass) electrod transparency electrode p-type GaN (Mg doped ) MQW(In 1-x Ga x N) (Multi quantum well) P-type Active region Theorem of LED. N-type n-type GaN(Si doped) buffer layer (AlN+undoped GaN) sapphire Cross-section of conventional GaN LED. Ref: N. Shibata, Phys. stat. sol., Vol.2, pp , 2002 p-electrode Sapphire substrate transparent contact layer p-gan MQWs n-gan n-electrode light What is active region? light 半導體發光元件材料 Nitride-based is the most suitable material active region cladding layer (high bandgap material ) 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

3 半導體發光元件材料光的三原色 :RGB: GaN 與 ZnSe 白光 LED 結構比較目前白光 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 )

Advantages and defects of LEDs 發光效率強韌設計彈性

time. Don t t need mercury. Response is fast.

( 冷光 ) Defects: The cost of high brightness is

4 Advantages and defects of LEDs 發光效率強韌設計彈性環保為其主要優勢 Advantages: ( 顯色性 ) Color rendering and chromaticity is well. ( 色度 ) It s s kind of luminescence Long life time. Don t t need mercury. Response is fast. Smart lighting. ( 冷光 ) Defects: The cost of high brightness is higher. The efficiency of LEDs is not very well. Heat problem is serious LED 應用市場分類 Applications of LED Ref: N. Shibata, Phys. stat. sol., Vol.2, pp , 2002 All kinds of LEDs

5 半導體紫外光元件應用藍光 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 ) LED 照明燈 TOYOTA 汽車前燈 LED 走廊裝飾燈 ( 波士頓 ) LED 公園路燈

6 我國 LED 產業結構 -21- 我國白光 LED 照明產業結構光連 Optolink, 八十九年九月, 第 29 期

LED efficiency Loss due to critical angle ( I ) Internal quantum efficiency (IQE): η int = number of photons emitted from active region per second number of electrons injected into LED per second

7 LED efficiency Loss due to critical angle ( I ) Internal quantum efficiency (IQE): η int = number of photons emitted from active region per second number of electrons injected into LED per second Extraction efficiency: number ηextraction = number of photons emitted into free space per second = of photons emitted from active region per second Pint /(hv) = I / e External quantum efficiency (EQE): number of photons emitted into free space per second P /(hv) ηext = = = η number of electrons injected into LED per second I / e P /(hv) P /(hv) int int η extraction p-gan n-gan light substrate total internal reflection active layer n GaN θ 1 θ 2 Sinθ 1 = n air sinθ 2 n air n GaN boundary Power efficiency: η power total power emitted into free space = = electrical power provided to LED P IV o When θ is critical, θ = 90 θ c = sin n GaN 2 o = Loss due to critical angle ( II ) Truncated-inverted-pyramid (TIP) LEDs r sinθ r dθ Area=2πr 2 ( 1-cosθ ) 2πr sinθ rdθ θ dθ r θ r A P P P ecape ecape source da = 2 2πr sin θ rdθ = 2πr (1 cosθ ) c = θ 2 0 c Pecape 1 θc (1 ) = θc Psource πr (1 cosθc ) = Psource 2 4πr 1 = (1 cosθc ) 2 GaN LEDs emits ratio of photon: EQE can increase 1.4 times with TIP structure. Ref: M. R. Krames et al., Applied Physics Letters, 75 (2006)

300μm 300μm GaAs LEDs with textured surface Typical Process Steps of the Conventional LEDs on Sapphire (1) 磊晶結構 p-gan MQW n-gan u-gan Sapphire (4) P 電極製作 (5) N 電極製作 p-gan n-gan u-gan

, Applied physics letters, 63(16) (1993) 2174-2176.

P-electrode P- 透明電極 N-electrode Si Si Si N-electrode Sapphire substrate p-gan MQW n-gan u-gan sapphire 300μm * 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缺點 : 優點

8 300μm 300μm GaAs LEDs with textured surface Typical Process Steps of the Conventional LEDs on Sapphire (1) 磊晶結構 p-gan MQW n-gan u-gan Sapphire (4) P 電極製作 (5) N 電極製作 p-gan n-gan u-gan sapphire (2) 定義大小區塊 p-gan MQW n-gan u-gan sapphire MQW Mesa (6) 熱處理 (7) 點燈測試 (3) 透明接觸層製作 Semitransparent metal 或 ITO 導電玻璃 Ref: I. Schnitzer et al., Applied physics letters, 63(16) (1993) p-type contact Ni/Au n-type contact Ti/Al LASER LIFT-OFF (LLO) GaN LED 一般 p-side up GaN LED 結構 P-side down GaN LED 結構 Fabrication of InGaN LED membranes by laser lift-off heat P-electrode P- 透明電極 N-electrode Si Si Si N-electrode Sapphire substrate p-gan MQW n-gan u-gan sapphire 300μm * 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缺點 : 優點 : 300μm n-gan MQW p-gan Bonding metals Cu P-electrode Cu substrate * 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 adhesive GaN Al 2O 3 adhesive GaN Al 2O 3 Process of LLO (laser lift-off ). GaN C. F. Chu et. al. JJAP, Vol.42, L147, 2003 and JAP, 95, pp. 3916, 2004 Ref: W. S. Wong et al., Applied physics letters, Vol.75, pp ,

LASER LIFT-OFF (LLO) GaN LED The process scheme for

JJAP, Vol.42, L147, 2003 and JAP, 95, pp.

GaN chip: (a) AlN deposition, (b) n-gan deposition,

electroforming Cu, (f) bombarding the buffer layer

from the whole chip, (h) up-side down and n-face up,

9 LASER LIFT-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, 次世代電鑄銅基板 LED 製程 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. p-gan n-gan Ga-face(0001) n-face(0001) 基礎 LED 製程模組技術 substrate transparency electrode MQW buffer layer

10 基礎 IC 製程技術製程技術 (LED 製程基礎 ) LED 製程流程藍寶石基板之長晶法 Crystal Growth for Sapphire Substrate 薄膜沉積 Chemical Vapor Deposition (CVD) PECVD LPCVD APCVD MOCVD ( 光電薄膜沉積 ) Ref

11 GaN 磊晶成長系統與技術 ( I ) 有機金屬氣相磊晶 (Metal-Organic CVD) 系統 Physical Vapor Deposition (PVD) Joule heat or Electron beam Sputtering

GaN 磊晶成長系統與技術 ( II ) 分子束磊晶 (Molecular Beam Epitaxy, MBE) 系統分子束磊晶

(Priming) resist 正光阻顯影薄膜基板光阻負光阻 Dehydration Bake 10-15min @ 250

薄膜薄膜 UV 基板薄膜基板蝕刻光阻去除薄膜基板基板 Development (agitation) (Rinse) Post

12 GaN 磊晶成長系統與技術 ( II ) 分子束磊晶 (Molecular Beam Epitaxy, MBE) 系統分子束磊晶 (Molecular Beam Epitaxy, MBE) 系統黃光微影製程紫外光曝光光罩光阻的微影程序 (Priming) resist 正光阻顯影薄膜基板光阻負光阻 Dehydration Bake 250 Vacuum Spin Coating Soft Bake? 薄膜薄膜 UV 基板薄膜基板蝕刻光阻去除薄膜基板基板 Development (agitation) (Rinse) Post Exposure Bake (optional) Exposure? dosage/?thickness 薄膜薄膜基板基板正負光阻微影製程示意圖 Vacuum Spin Drying Hard Bake?

13 溼式與乾式蝕刻蝕刻遮罩層結構層電漿冷凝管濕式蝕刻法乾式蝕刻法蝕刻槽溫控器加熱與磁石攪拌器濕式蝕刻槽反應性離子蝕刻 (RIE) 系統, NTNU MOEMS Lab 感應耦合電漿之高深寬比非等向性乾式乾式矽蝕刻技術 Plasma etch stop High-aspect aspect-ratio, Anisotropic Silicon Etching Techniques by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE) Substrate Etching mask Mask 材料選擇的原則 : 高選擇比, 蝕刻深度, 非等向性感應耦合電漿蝕刻 (ICP-RIE) 系統, ITRC Deep Reactive Ion Etching (DRIE) 交替蝕刻與高分子鈍化過程 (C 4 F 8 /SF 6 ): 1. 矽壁沈積鈍化高分子 C 4 F 8 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 SF 6 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 Rimple 現象鏡面品質垂直結構側壁放大圖

14 擴散法 (diffusion) 離子摻雜 (doping) 離子植入 (Ion implantation) IC 離子摻雜 (doping) 的目的 PMOS 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 NMOS 基板薄化製程晶粒切割製程 ( a ) 輪刀式 ( a ) 研磨法 (lapping) ( b ) 切削法 (grinding) ( b ) 鑽石式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 ) ( c ) 雷射式

15 Chip on the sapphire wafer 大半圓片 on the blue tape Power supply 結合精密電鑄技術之次世代銅基板製程 e - e - 2e - 2e - Anode Cu Cu dissolution Cu 2+ Cu H 2 H 2 Cathode Cu deposition H 2 evolution 研磨拋光切割崩裂 H 2 H 2 2H 2 O + 2e - H 2 +2OH - Schematic of an electrochemical cell Principle of an Electroforming Technology 一般常見之電鑄缺陷與解決之道後處理所造成的缺陷氣泡所造成的缺陷 PMMA 微齒輪鎳金屬微齒輪內應力導致電鑄層嚴重變形內應力已獲得控制之鑄層

光阻電鑄金屬電鑄起始層表面粗化以增加光萃取效率電源供應器極陰陽極間電流密度分布陰陰陽極間電流密度分布陽極( a ) ( b )

wt%. Temperature: 90~92 Etching time: 4 min for each piece Various

our surface roughing technology The cone by surface roughing can increase

16 光阻電鑄金屬電鑄起始層表面粗化以增加光萃取效率電源供應器極陰陽極間電流密度分布陰陰陽極間電流密度分布陽極( a ) ( b ) 避免鑄層沈積厚度差異過大之製程示意 (a) 改良前 ;(b); 改良後 Surface roughing Solution: KOH, wt%. Temperature: 90~92 Etching time: 4 min for each piece Various surfactant added Special surface roughing technology LED 技術未來展望 by our surface roughing technology The cone by surface roughing can increase photon escaping at side part, and it also should be better shape than hexagonal cone

白光 LED 的課題與解決之道課題光通量散熱性成本晶片發光效率的提高解決之道晶片的高功率化 ( 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白光 LED 發光效率成長趨勢資料來源 : 日本綜合技術研究所 / 材料世界網整理輝度的均一性可靠性

17 白光 LED 的課題與解決之道課題光通量散熱性成本晶片發光效率的提高解決之道晶片的高功率化 ( 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白光 LED 發光效率成長趨勢資料來源 : 日本綜合技術研究所 / 材料世界網整理輝度的均一性可靠性降低晶片製造時的參差不一強化晶片的選別 Flip-chip 構裝材料世界網整理 Our Earth at Night LED 可讓落後地區有一盞明燈, 使夜晚的地球更明亮敬請批評與指教 Keep on moving! By Dr. Yang, National Taiwan Normal University Thank you for your attention!

<4D F736F F F696E74202D204C4544BB73B57BBB50A8E4C0B3A5CEA7DEB34E2DA578AE76A46ABEF7B971A874B7A8B1D2BA61>

<4D F736F F F696E74202D204C4544BB73B57BBB50A8E4C0B3A5CEA7DEB34E2DA578AE76A46ABEF7B971A874B7A8B1D2BA61> LED 製程與應用技術 LED fabrication process and application technology 楊啟榮博士教授國立 Department of Mechatronic Technology National Taiwan Normal University Tel: 02-23583221 ext. 14 E-mail:ycr@ntnu.edu.tw 綱要 LED