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IC 工艺技术系列讲座 第二讲. PHOTOLITHOGRAPHY 光刻. 讲座提要. 1. General 2. Facility ( 动力环境 ) 3. Mask ( 掩膜版 ) 4. Process step highlight ( 光刻工艺概述 ) 5. BCD 正胶工艺 6. History and 未来的光刻工艺. 1. General. MASKING Process ( 光刻工艺 ) Photolithography ( 光学光刻 ) ----Transfer a temporary pattern (resist)
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IC工艺技术系列讲座第二讲 PHOTOLITHOGRAPHY 光刻
讲座提要 1. General 2. Facility (动力环境) 3. Mask (掩膜版) 4. Process step highlight (光刻工艺概述) 5. BCD 正胶工艺 6. History and 未来的光刻工艺
1. General MASKING Process (光刻工艺) • Photolithography (光学光刻) ----Transfer a temporary pattern (resist) Defect control Critical dimension control Alignment accuracy Cross section profile • Etch (腐蚀) ----Transfer a permanent pattern (Oxide, Nitride, Metal…)
2.0 Facility requirement • Temperature (温度) 70 oF • Humidity (湿度) 45% • Positive pressure (正压) >0.02in/H2O • Particle control (微粒) Class 100 • Vibration (震动) • Yellow light environment (黄光区) • DI water (去离子水) 17mhom • Compress air and Nitrogen (加压空气,氮气) • In house vacuum(真空管道)
3.0 Mask (掩膜版) • Design • PG tape • Mask making • Plate --- quartz, LE glass, Soda line glass • Coating --- Chrome, Ion oxide, Emulsion • Equipment --- E-beam, Pattern generator • Mask storage ---Anti static Box
4.0 光刻工艺概述 • Prebake and HMDS (前烘) • Resist coating (涂胶) EBR (去胶边), soft bake, 3. Exposure (曝光) Alignment (校正) 4. Develop (显影) Post e-bake, Hard bake, backside rinse 5. Develop inspection (显检)
4.1 Prebake and HMDS treatment Purpose of Pre-bake and HMDS treatment is to improve the resist adhesion on oxide wafer. HMDS is adhesion promoter especially designed for positive resist. HMDS (Hexamethyldisilane) can be applied on the wafers by 1. Vapor in a bucket 2. vapor in a vacuum box 3. Directly dispense on wafer 4. YES system --- in a hot vacuum system 5. Vapor in a hot plate (with exhaust) Too much HMDS will cause poor spin, vice versa will cause resist lifting
4.2 Resist Coating (涂胶) Resist coating specification (指标) • Thickness(厚度)0.7u – 2.0u (3.0以上for Pad layer) • Uniformity(均匀度)+ 50A –+200A • Size of EBR (去胶边尺寸) • Particle(颗粒)<20 per wafer • Backside contamination(背后污染) 三个主要因数影响涂胶的结果 • Resist Product (产品) Viscosity (粘度) • Spinner Dispense method (涂胶方法) Spinner speed (RPM) (转速) Exhaust (排气) Soft bake temperature (烘温) • Facility Temperature (室温) Humility (湿度)
4.2.1 Coater (涂胶机) Equipment module and special feature • Pre-bake and HMDS --- Hot/Cold plate • Resist dispense --- Resist pump • RPM accuracy --- Motor • EBR --- Top/bottom • Hot plate --- soft bake temperature accuracy • Exhaust • Waste collection • Temperature/Humidity control hood • Transfer system --- Particle and reliability • Process step and process program --- Flexible
4.2.2 Coater (涂胶机)combination 升降机 涂胶 热板 升降机 SVG 8800 升降机 涂胶 热板 热板 升降机 升降机 HMDS 冷板 涂胶 热板 冷板 升降机 升降机 HMDS 冷板 涂胶 热板 热板 冷板 升降机 升降机 热板 冷板 显影 热板 热板 冷板 升降机
4.2.3 Coater (涂胶机) Resist dispense methods • Static • Dynamic • Radial • Reverse radial Resist pump (Volume control --- 2cc/wafer and dripping) • Barrel pump ---Tritek • Diaphragm pump --- Millipore • N2 pressure control pump --- IDL • Step motor control pump --- Cybot • size of dispense head
4.2.4 Coater (涂胶机) rpm (转速)and acceleration (加速) • Maximum speed --- Up to 10000 rpm • Stability --- day to day • Acceleration --- controllable number of steps • Reliability --- time to replacement EBR (Edge bead removal)(清边) • Method --- Top EBR or Bottom EBR or Top and bottom EBR • Problem --- Dripping • Chemical ---- Acetone, EGMEA, PGMEA, ETHLY-LACTATE
Resist Type • Negative resist • Positive resist G-line i –line reverse image TAC --- top anti-reflective coating BARLI --- bottom anti-reflective coating • Chemical amplification resist • X ray resist
4.3 .1 Exposure (曝光) Transfer a pattern from the mask (reticle) to resist Goal 1. Critical Dimension control (CD)条宽 2. Alignment 校准--- Mis-alignment, run in/out 3. Pattern distortion 图样变形--- Astigmatism 4. Cross section profile 侧面形貌--- side wall angle 5. Defect free无缺陷 Equipment/mask/resist selection 1. Resolution 分辨率--- Expose character, Light source (wavelength), N/A, 2. Auto-alignment skill 自动校准技术--- Light field, dark field, laser 3. Mask掩膜版--- e-beam master, sub-master, spot size, quartz plate, defect density, CD requirement 4. Resist selection 胶选择
4.3.2 Exposure (曝光) Aligner Technology 1. Contact print (接触) Soft contact, hard contact, proximity 2. Scanner (扫描) 3. Stepper (重复) 1X, 2X , 4X, 5X, 10X 4. Step – Scan (重复扫描) 4X --- reticle move, wafer move, reticle/wafer move 5. X ray (X光) 1:1 6. E-beam (电子束)--- Direct write
4.3.3 Exposure (曝光) Contact print (接触) 1. Most of use for negative resist process --- for 5u process and can be push to 3u. 2. Positive resist can print smaller than 3u, and deepUV can push to 1u, but very high defect 3. Equipment: --- Canon PLA 501 --- Cobilt --- Kasper --- K&S
4.3.4 Exposure (曝光) Scanner (扫描) 1. Most of use for G –line Positive resist process --- for 3u process and can be push to 2u. 2. Negative resist can print smaller than 4u 3. Equipment: --- Canon MPA 500, 600 --- Perkin Elmer 100, 200, 300, 600, 700, 900
4.3.5 Exposure (曝光) Stepper (重复) 1. G line positive resist --- for <0.8u process 2. i line positive resist --- <0.5u process 3. i line resist plus phase-shift mask --- can be pushed to 0.35 4. deepUV resist process --- 0.35u and below 5. Equipment: --- Ultratech --- Canon --- Nikon --- ASML
4.3.6 Exposure (曝光) 6 ASML Stepper list Model Wavelength Resolution ASML 2500 g 0.8 ASML 5000 ASML 5500 – 20,22,25,60,60B,80,80B i 0.55 ASML 5500 – 100,100C,100D,150 i 0.45 ASML 5000 – 200,200B,250,250B UV 0.35 ASML 5500 – 300,300B,C,D,TFH UV 0.25 ASML 5500-900 Step-Scan UV
4.4.1 Develop (显影) Develop process 1. Post expose bake 2. Resist Develop 3. DI water rinse 4. Hard Bake Develop equipment 1. Batch develop 2. Track develop Develop chemical 1.KOH 2. Metal free (TMAH) --- Tetramethylamoniahydroxide 3. Wetting agent --- with/without 4. Concentration --- 2.38%TMAH Track develop method 1.Spray 2. Steam 3. Signal-Paddle 4. Double-Paddle
4.4.2 Develop (显影) Develop Track 1. Temperature control water jacket for Develop line 2. Develop pump/develop pressure canister 3. Exhaust 4. Hot plate temperature control 5. Pre-wet --- process program
4.4.3 Develop (显影) CD control in developing 1. Post bake process 2. Develop Time 3. Concentration of developer chemical (Higher fast) 4. Developer temperature (lower faster ~ 1o C/0.1u) 5. Develop recipe --- pre-wet, paddle, rotation 6. Age of the develop chemical 7. Rinse --- DI water pressure 8. Hard bake temperature
4.5.1 Develop Inspection Tool for inspection 1. Microscope Manually loading Automatic loading 2. UV lamp Manually loading Automatic loading 3. CD measurement equipment Manually measuring system --- Vicker, Automatic measuring system --- Nanoline CD SEM
4.5.2 Develop Inspection Inspection items 1. Layer name 2. Alignment 3. Run in/out 4. Pattern distortion 5. Pattern integrity 6. Defects lifting, particle, discoloration, scumming, bridging, excess resist, scratch 7. CD (critical dimension)
Equipment SSI, SVG8800, SVG 90 Process step pre-bake/HMDS/cold plate spin (<5000rpm) ---dynamic dispense ---top (bottom) side EBR(2mm) soft bake (100oC)/cold/palte Resist/spec Shipley 6112 (1.2u) 1818 (1.8u 1st metal) 6818 (2.4u 2nd metal) 6118 (2.9u Pad) 6124 (3.6u-4.5u ST) Everlight 533(1.2) Uniformity ---+ 300A Resist coating 5.0 BCD 正胶工艺 升降机 HMDS 冷板 涂胶 热板 冷板 升降机
5.1.1 Positive Resist (正胶) Component (成分) • Resin (树脂) Diazonaphthoquinone(DNQ)/novolak • Photo-sensitizer (感光剂) • Solvent (溶剂) • Dye (染料) Manufacturing (制造商) • Kodak – Hunt – Ash chemical (USA) • TOK (Japan) • JSR (Japan) • Shipley (USA) • AZ (USA, Germany) • Sumitomo (Japan) • Everlight (Taiwan)
5.1.2 Positive Resist (正胶) Product Name and feature (产品称与特性) 以everlight (永光)正胶为例 Product Series EPG 510 Series Expose wavelength G-Line (435nm) Thickness Name 2000rpm 5000rpm Viscosity (粘度) EPG 510 --- 12 cp 1.25u 0.80u EPG 512 --- 21.5 cp 2.00u 1.25u EPG 516 --- 50 cp 3.25u 2.00u EPG 518 --- 105 cp 4.50u 2.75u EPG 519 --- 460 cp 9.00u 5.5u Resolution (分辨率) 0.8u (0.55u --- the smallest) Depth of Focus (聚焦深度)+ 1.4u (1.0u line/space) Sensitivity (感光度) Eth = 60 mj/cm2 Eop = 90 mj/cm2
5.1.4 Positive Resist (正胶) Select a positive resist 1. Resolution (分辨率) 2. Resist thickness --- Spin curve (厚度) 3. Photo speed (曝光速度) 4. Expose latitude (曝光宽容度) 5. Adhesion (粘附性) 6. Reflective notch (反射缺口) 6. Metallic content (金属含量) 7. Thermal stability (热稳定性) 8. Plasma resistance (抗腐蚀能力) 9. How easy to be removed (清除能力) 10. Price (價格)
5.2 Expose Equipment Ultratech stepper 1100 – (6”) Ultratech stepper 1500 – (6”) Canon 600 – (6”) Perkin Elmer 240 – (4”)
5.2.1 Ultratech Stepper Ultratech stepper • G-line • N/A --- 0.24 and 0.31 • 1:1 print ratio • 3 X 5 inch reticle --- 3, 4, 5, 7 field • 4u depth of focus • Blind step can be push to <5u (no spec) • Center of array < + 50u • Dark field alignment • Site by Site alignment • Alignment target *oat --- 4mm X 4mm *K/T --- 200u X 200u
UTS---Reticle and Job file Fiducials Guide