© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Micro Fabrication Associate Professor Su-Jin KimSu-Jin Kim School of Mechanical Engineering Gyeongsang National University

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Index Micro fabrication of IC(Integrated Circuits) 반도체제조 1.Weiper( 웨이퍼 ) 2.Lithography( 노광 ) 3.Etching( 식각 ) 4.Doping( 확산 ) 5.Deposition( 증착 ) 6.Packaging( 포장 ) MEMS(Microelectromechanical system) 미소기전

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Micro-manufacturing Manufacturing on a microscopic scale IC: Integrated circuit MEMS: micro electro mechanical system Products 1.Sensors 2.Inkjet printing heads 3.Micro-actuators 4.Hard-drive heads 5.Computer processors 6.Memory chips

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Scale, mm / μm / nm

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Transistor to IC Transistors(1947)  IC (integrated circuits), MOS (metal- oxide-semiconductor)  VLSI (very large-scale integration) Moore’s Law : The number of transistors per chip doubles every 18 months. 1 st Transistor IC

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Clean Rooms Essential for the production of IC (integrated circuits). Cleanliness are defined by class of the clean rooms. Air is passed through a high-performance particulate air (HEPA) filter. Largest source of contaminants is people.

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes P B - -- Si Silicon (Semiconductors) Natural silicon dioxide SiO 2 is an excellent insulator. Single crystal silicon Si is semiconductor. Get n-type by doping P or p-type doping B. SiO 2 Insulator Single crystal siliconn-typep-type +phosphorus +boron

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Integrated Circuits; IC Process Wafers Deposition Film deposition Oxidation Lithography Coat photoresist Photolithography Remove exposed photoresist Etching Doping Wet etching Dry etching Diffusion Ion implantation Device Wire bonding Packaging Ingot Wafer 1967: (30min)

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Ingot & Wafer 1.natural SiO 2  purification  electric-grade silicon Si 2.Single-crystal silicon ingot is grown from the purified silicon melt. 3.The Ingot is cut into silicon wafers. The wafers are polished until they have mirror-smooth surfaces. Wafer:

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Lithography 1.Drop down photoresist on spinning wafer. 2.Photolithography : UV light passes through mask to wafer surface. 3.Exposed photoresist is dissolved by a solvent. Photolithography:

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Etching 식각 1.The photoresist protects material not be etched away in an acid solution. 2.After the etching the photoresist is removed and the desired shape becomes visible. scale: transistor level (~50-200nm) IC Process: Photoresist, Lithography, Etching, Doping, Deposition

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Doping 1.The photoresist (blue) will protect material that should not get ions implanted. 2.In Ion implantation, ions accelerate through a high-voltage beam and impact on the exposed areas (green) of the silicon wafer. 3.After the ion implantation the photo resist is removed 4.Operation of microelectronic devices depends on different doping types and concentrations.

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Deposition 증착 1.Three holes have been etched into the insulation layer (magenta color) above the transistor. 2.The wafers are put into a copper sulphate solution. The copper ions are deposited onto the transistor thru a process called electroplating. 3.On the wafer surface the copper ions settle as a thin layer of copper. 4.The excess material is polished off. Three holes are filled with copper which will make up the connections to other transistors. PVD: (30s)

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Metallization & Testing 1.Metallization: Devices are interconnected by multiple metal layers (Al, Cu). 2.Testing: Test each of the individual circuits with probe 3.The wafer is cut into pieces called dies.

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Wire Bonding and Packaging 1.Working dice is attached to a rugged foundation with epoxy or eutectic bond. 2.Chip is electrically connected to the package lead by thermo-sonic wire bonding. 3.Package: The green substrate, the die and the silver heat-spreader are put together to form a completed processor. Packaging m. p.:

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Printed Circuit Boards; PCB Packaged integrated circuits are combined with other ICs as building blocks for a larger system. Printed circuit board (PCB) is the substrate for the final interconnections.

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Equipment 공 정공 정주요 장비명기능 노광공정 (Photo/Litho) Stepper, Scanner, Track 빛을 사용하여 웨이퍼위에 회로의 모양을 그리는 장비 식각공정 (Etch) Poly-Si Etcher( 폴리실리콘 식각장비 ), Oxidation Etcher( 산화막 식각장비 ), Metal Etcher( 금속막 식각 ), Asher(PR 제거장치 ) 노광공정에서 그려진 대로 식각을 통하여 모양을 만드는 장비 세정공정 (Wetstation) Wetstation( 세정장비 ), Dryer( 건조장비 ) 제조공정상에서 웨이퍼위에 발생되는 이물질의 제거 평탄화공정 (CMP) CMP( 평탄화장비 ) 제조공정상에서 웨이퍼내의 소자간 위상차를 보 정해주기 위하여 평평하게 해주는 장비 원자층증착공정 (ALD)ALD( 원자층증착공정 ) 웨이퍼위에 미세하게 물질을 증착하는 장비 이온주입공정 (Ion Implant) 중전류 이온주입기, 고전류 이온주입기, 고에너지 이온주입기 웨이퍼내에 불순불을 주입하는 장비 증착공정 (CVD) APCVD( 상압증착장비 ), LPCVD( 감압증착장비 ), PECVD( 플라즈 마증착장비 ) 웨이퍼위에 산화막, 절연막 등을 증착하는 장비 메탈공정 (Metallization) Metal CVD( 금속막증착장비 ), Sputtering( 이온분사장비 ), Electro Platting( 금속막 전기도금장비 ) 웨이퍼위에 금속막을 증착하는 장비 열처리공정 (Diffusion)Furnace,TP(Annealer 포함 ), Epitaxial 성장장비 열을 이용하여 웨이퍼내 물질을 균질하게 하거나, 증착하는 장비 웨이퍼검사공정 (Micro Inspection) Wafer Inspection, Metrology( 물성분석장비 ) 웨이퍼내 물질의 특성을 분석하는 장비 기타공정 E-beam( 전자빔장비 ), Imprinter 노광을 하지 않고 웨이퍼위에 직접 패턴을 형성하 는 장비 Assembly 공정 Wafer Dicing, Die Attacher, TSV Etcher, Die Bonder, Wire Bonder, TAB Bonder, Wafer Marker 웨이퍼가공공정이 완료된 이후 절단하여 밀봉하 기 이전까지 진행하는 장비 Packaging 공정 Molding M/C, Singulator, Packaging Maker, Saw Sorter, Ball Attacher 전자제품에 장착하기 위하여 밀봉하는 장비 검사공정 (Test) Memory Tester, Logic Tester, Mixed Signal Tester, CIS Tester, Burn In Tester, Prober, 핸들러 제조공정을 완료한 이후 원하는 대로 만들어 졌는 지를 확인하는 장비

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes MEMS Devices The MEMS(Microelectromechanical systems) devices can be made through the IC Process: Bulk micromachining: Pressure sensor Surface micromachining: Accelerometer

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Bulk micromachining Mask pattern by SiO 2 or Si 3 N 4 Etching silicon substrate

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Acceleration and Pressure sensor

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Pressure Fabrication steps for pressure sensor

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Thermal Ink-jet printer

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Surface micromachining Micro-cantilever 1.Silicon substrate, Si 2.Deposit silicon nitride, Si 3 N 4 3.Grow silicon oxide, SiO 2 4.Pattern by Lithography 5.Deposit polysilicon 6.Remove SiO 2 by Etching

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Accelerometer for airbags Acceleration  Displacement of beam  Capacitive change  Turn on the airbag

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Micromirror Device

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Comb Drive / Capacitive Parallel Plate Capacitor C = ε A/d Electrostatic Force Fe = ½ ε (A/d 2 )V 2

© Pearson & GNU Su-Jin Kim MEMS Manufacturing Processes Nanoscale Manufacturing Parts are produced at nanometer(10 -9 ) length scales. Integrated circuits are at this length scale. Carbon nanotubes have high strength and electrical current-carrying capability. Carbon nanotubes: Nano tech: (10min)