Plasma and Dry Micro/Nanotechnologies 6. Micro/Nanofabrications Lenka Zajíčková Faculty of Science, Masaryk University, Brno & Central European Institute of Technology - CEITEC lenkaz@physics.muni.cz spring semester 2023 Central European Institute of Technology BRNO I CZECH REPUBLIC Plasma & Dry Technologies Lenka Zajíčková 2 / 22 • 6. Micro/Nanofabrications 6.1 Approaches in Micro/Nanofabrications 6.2 Fabrication of Integrated Circuits 6.3 Fabrication of MEMS/NEMS 6.4 Biosensors 6.5 Examples of Bottom-Up Fabrication Plasma & Dry Technologies 6. Micro/Nanofabrications Lenka Zajíčková 3 / 22 Two principle approaches can be used for micro/nanofabrication: top-down approach: ► deposition of thin films ► doping ► etching/sputtering (lithography, i.e. through a mask, and nonlitographic fabrication) ► preparation of surfaces (cleaning, polishing, functionalization) bottom-up ► building using nanoobjects (atoms, molecules), self-assemply of structures Synthetic Chemistry, Genetic Engineering.... l Plasma & Dry Technologies 6. Micro/Nanofabrications Lenka Zajíčková 4/22 Fabrication of devices ► Microelectronics - requires fabrication of integrated circuits (ICs) ► MEMS/NEMS - borrows standard methods from ICs and adds other processes ► Sensors Plasma & Dry Technologies 6. Micro/Nanofabrications Lenka Zajíčková 5/22 6.2 Fabrication of Integrated Circuits Increase of integration: ► Small-Scale Integration (SSI) few transistors on chip, ► Medium-Scale Integr. (MSI) hundreds of transistors on chip (end of 60ties), ► Large-Scale Integration (LSI) 10 000 transistors on chip (70ties), ► Very Large-Scale Integr. (VLSI) 100 000 transistors on chip (begining of 80ties), 1 000 000 000 in 2007 AMD-AthJon *l AMD-Kti-2 ft3Sjl< 1,100,000) 0,15jlre5ufo5tičít>ř 2. Etch oxide for pMOSFET 1 J_ |í-ty|>e5ubitiďte 3. Diffuse n-well p-type-substičiite JZ 4. Etch oxidefornMOSFET Eí:_C p-type sub&tiíite -well J 5. Grow gate oxide ^1_I L p-type substrate J 6. Deposit pdysiicon p-type s u bstTBte J 7, Etch polysilioon and oxide p-type s u Initiate J 8, Implant sources and drains 1 •—i l~ p-typesubstrete 9. Grow nitride «1 pq I I f=i I p-type s u bstrote 10. Etch nitride p-type s u betrete 11. Deposit metal p-type s li b stifte 12. Etdi metal _ . t__. V n-weil_J |j-tyi>e substrate - Plasma & Dry Technologies 6 Micro/Nanofabrications Len ka Zajíčková 8 / 22 E acK-e ■ SEM view of three levels of copper interconnect metallization in IBM's CMOS integrated circuits (Photograph courtesy of IBM Corp., 1997) tructure Legend: Silicon (Si) □ n-Si Dp-Si Polysilicon (Poly-Si) Undoped silicon glass (USG, SiO)? Silicon dioxide (TE05 oxide, 5iO): Cobalt disilicide (CoSi), Spin-on dielectric (SOD) Phosphohsilicate glass (PSG) Ungsten (W) Copper (Cu) Silicon nitride (SiN) Silicon nitride (SiN) Silicon carbide (SiC) Plasma & Dry Technologies 6. Micro/Nanofabrications echnology Nodes in Microelectronics ka Zajíčková 9/22 Technology node - process sequence for manufacturing a chip Pitch Counts ■ Year Node Half pitch Gate length* 2009* 32 52 29 2007» 45 66 38 2005 b Ů5 90 32 2004" 90 90 37 2003 b 100 100 45 1 20.Olc I3D 1-SÖ 65 ISO 230 140 1997 0 250 250 200 1995 4 350 350 350 1992 d 500 500 5QO * Here. Mte width IS deEined as 11* phy&aL gate- l-?r.K.I It, '.vhit h it rccenL yeatt DMranw smaller than the printed gate lenslh aiTFtttfala MOB update n tfffiS data 2006 f URicfjfa Note Ihat each year skipped is Identified cn the ITR5 ai twtwew nodes. Marketing Takes Over Engineering Definitions Drawn gate length L^,, Actual gate length LKlual Effective gate length Effective gate length L^^^ « Width specified by layout engineer •* Actual physical width of gate material - Over etch shortens physical width of gate " Dopant migration shortens effective gate length Actual Gate Length Mm The device node - once equated to the half-pitch or spacing between the tightest metal lines then the minimum feature size in a chip and now a marketing term that continues to decrease linearly even if no feature on the chip can be found to match it. Plasma & Dry Technologies 6. Micro/Nanofabrications Len 6.3 Fabrication of MEMS/NEMS What are MEMS/NEMS? The acronym MEMS/NEMS (micro / nanoelectromechanical systems) originated in the USA. The term commonly used in Europe is microsystem technology (MST), and in Japan it is micro/nanomachines. Another term generally used is micro/nanodevices. ► MEMS - microscopic devices with characteristic length < 1 mm and > 100nm ► NEMS - nanoscopic devices with characteristic length < 100nm MEMS/NEMS terms are also now used in a broad sense and include electrical, mechanical, fluidic, optical, and/or biological functions. They are referred to as intelligent miniaturized systems comprising e.g. sensing, processing and/or actuating functions. MEMS/NEMS for ► optical applications -micro/nanooptoelectromechanical systems (MOEMS/NOEMS), ► electronic applications - radio-frequency-MEMS/NEMS or RF-MEMS/RF-NEMS. ► biological applications - BioMEMS/BioNEMS. Plasma & Dry Technologies 6. Micro/Nanofabrications Lenka Zajíčková 11/22 Dimensions of MEMS/NEMS in Perspective MEM5: CharacIetíe,lie ler^Lh less lhán 1 mm, larger Lhan 100 urn NEM5: Lest lhan 1 00 nm Human hair 50-100 fim DMD 12 um Molecular gear lQnrn-lOOnm L—™ SWCNT Lrari &i & Lor C abom O.lůnm DNA2.5nm i5nTri 0.1 1 10 1 00 1 000 10 000 1 00 000 5rae (nm.) MEMS/NEMS examples shown are of a vertical single-walled carbon nanotube (SWCNT) transistor (5 nm wide and 15 nm high), of molecular dynamic simulations of a carbon-nanotube-based gear, quantum-dot transistor, and digital micromirror device (DMD http://www. dip. com) Plasma & Dry Technologies 6. Micro/Nanofabrications Lenka Zajíčková 12/22 Examples of MEMS - gears/motors TYavE-l direction MEMS motor was developped in lates 1980s using polycrystalline silicon (polysilicon) technology left-top photo shows micro-gears fabricated in mid-1990s using a five-level polysilicon surface micromachining technology (J. J. Sniegowski et al. IEEE Solid-St. Sens. Actuat. Workshop, 178-182 (1996)) - one of the most advanced surface micromachining fabrication process developed to date left-bottom SEM photo - microengine output gear and two additional driven gears gear extreme diameter is approximately 50 micrometers and gear thickness is 2.5 micrometers (J. J. Sniegowski et al.) í E —s- I, Plasma & Dry Technologies Micro/Nanofabrications ka Zajíčková 13/22 6.4 Biosensors A biosensor is a transducer that incorporates a biological recognition component as the key functional element: ImpurltY Analyte Signal display/readout Analytical immunosensors are a subset of biosensors which utilize either antigen or antibody as the biospecific sensing element Need of antibody/antigen immobilization at the surface, preferentially by covalent binding ^^^^ Q>^> II II II II n n r r \ NH2 nh2 NH2 N I n I r r n I n I n n \ \ r r ' 1 substrate substrate substrate *-1 substrate Different principles/transducers but same material is needed - gold electrode coated with a functional film Quartz crystal microbalance Surface plasmon resonance Am mass change Angle Time change of resonance angle / reflectance at given angle Plasma & Dry Technologies Micro/Nanofabrications ka Zajíčková 15/22 .4 Applicatio [7 in immunosensing Human serum albumin (HSA) chosen for the demonstration of immunosensing application: ► Gold electrode of quartz crystal microbalance (QCM) coated by CPA plasma polymer replacement of thiol-based self-assembled monolayer ► Covalent attachment of antibody AL-01 by 3 coupling methods, the most robust being glutaraldehyde (GA): NH2NH2NH, —I—I—I— substrate gluteraltMiyde (GA) PBS *"* 1 h r.t. O O. U P K > J NN N substrate II NH2 antibody (AL-Ül^ PBS 12 h 5°C N l) ,N _N Ji _ N substrate USA antigen -> PBS 10 min r.t. N N N —t-1-1— substrate ► Detection of HSA by change of QCM frequency ► association phase: 15 min flow of HSA in PBS (50 mM phosphate buffer saline containing 150 mM NaCI, pH 7.0) ► dissociation phase: 5 min of PBS buffer flow A. Manakhov et al. Appl. Surf. Sci. 360(PartA) (2016)28. Plasma & Dry Technologies 6. Micro/Nanofabrications Lenka Zajíčková 16/22 Sensor performance a b sensor reactor W/F C N O thickn. loss [NH2] [at%] [at%] [at%] [%] [at.%] R3, floating 79.5 19.0 1.5 R2,RF driven 80.3 17.2 2.5 2 1.5 1.3 Response of both sensors to HSA (GA coupling of antibody AI-01): N < 10 ■ HSA/PBS in (for curves a, b) -10- -20- -30- -40 -50- whole time in flowing PBS 10 'TIS 20 25 time (min) i 30 E. Makhneva et al. Surf Coat. Technol. 290 (2016) 116 Better response for the sensor (a), i. e. for polymer with lower cross-linking degree. 3 coupling methods used for sensor (a), calibration curves: N X 240- 220 200 180 160 140 120 100 80 60 40 20 0 0.8 GA method -*--NaIO, method 4 sulfo-SMCC method —i— 1.0 —I— 1.2 —i-1-1— 1.4 1.6 —i-1-1— 1.8 2.0 log(C(HSA-antigen)) Plasma & Dry Technologies 6. Micro/Nanofabrications Lenka Zajíčková 17/22 0 5 1 0 1 5 2 0 25 1 05 1 06 1 07 1 0' /(min) c(CFU/ml_) Plasma & Dry Technologies 6. Micro/Nanofabrications ka Zajíčková 18/22 6.5 Examples of Bottom-Up Fabrication Plasma & Dry Technologies Micro/Nanofabrications ka Zajíčková 19/22 Carbon-Based Nanomaterials - formed by sp2C sp2-C bonding (one valence electron in pure p state and the other three in hybrid orbitals) enables synthesis of several interesting carbon nanomaterials due to planar bond structure Formation of 3 sp2 hybrid orbitals: combination of 1 /3s and 2/3p - trigonal planar bonding directions with angles of 120° unhybridized p orbital Potential energy 1 i i 1 2s 2Px 2Py 2P; sp2 hybridization mi sp2 sp2 sp2 P 5P' 9 0 sp~ orbitals graphite, sp2 bonded C Van der Waals bonds Carbon atoms Covalent bonds Ccpynght 19M by John Wiley and £ana. Ire. All rights Masai^sd. Plasma & Dry Technologies 6. Micro/Nanofabrications ka Zajíčková 20/22 Fullerene - hollow sphere, ellipsoid etc. Buckyballs -spherical fullerenes. C60- Buckminsterfuleren prepared in 1985 at Rice University Single-walled carbon nanotube (SWCNT) Multi-walled carbon nanotube (MWCNT) prepared 1991 by lijima 0) lij!2*S i li.ii i armchair Different chirality of SWNT: (a) armchair (b) zigzag (c) chiral (n,m) Plasma & Dry Technologies . Micro/Nanofabrications ka Zajíčková 21 /22 Widely-accepted growth mechanisms for CNTs: (a) tip-growth model, (b) base-growth model. (b) \CA/ ^CxHyŕ Hit / -, H2t Metal Substrate ■ (i) (ii) Growth stops eta]_ Substrate [i] CKHy In situ HRTEM image sequence of a growing carbon nanofiber - images (a-h) illustrate one cycle in the elongation/contraction process. □ J m 1 □ ] □ ^^^^ cm ľ=3 lj ( Drawings are included to guide the eye in locating the positions of mono-atomic Ni step-edges at the graphene-Ni interface. Scale bar = 5 nm. (Helveg et al., 2004. Nature 427, 426-429) TEM video of growing CNTs https://www.youtube.com/watch?v=TaNCWcumeyg Plasma & Dry Technologies 6. Micro/Nanofabrications Lenka Zajíčková 22/22 Mimicking Nature's 1 3ottom-up Processes Nature efficiently builds nanostructures by relying on chemical approaches: ► molecular building blocks: nucleic acids and proteins ► assembled in a variety of nanoscaled materials with defined shapes, properties, and functions. example of nucleic acids: ► nucleic acids are large biomolecules (linear polymers) composed of nucleotide repeating units (Fig. a) ► nucleotides have 3 components: 5-carbon sugar, phosphate group, nitrogenous base. ► Chemical bonds between the phosphate of one nucleotide and the sugar of the next ensures the propagation of a polynucleotide strand from the 5' to the 3' end. —■ main backbone of the polymeric strand ► Every nucleotide carries one of the four heterocyclic bases shown in Fig. b. A G C T