Micro-fabrication Process

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Micro-fabrication Process. Clean Room. Clean room classifications and applications. Clear room classification. Class 1000: fewer than 1,000 particles (>0.5μm) in 1 cubic foot of air Class 100: fewer than 1,00 particles (>0.5μm) in 1 cubic foot of air. Micromachining Materials. - PowerPoint PPT Presentation

Transcript of Micro-fabrication Process

  • Micro-fabrication Process

  • Clean Room

  • Clean room classifications and applications

  • Clear room classificationClass 1000: fewer than 1,000 particles (>0.5m) in 1 cubic foot of airClass 100: fewer than 1,00 particles (>0.5m) in 1 cubic foot of air

  • Micromachining MaterialsSubstrates: Silicon GaAs Other elemental or compound semiconductors Metals (bulk and foils) Glasses Quartz Sapphire Ceramics Plastics, polymers and other organics

  • Micromachining MaterialsAdditive Materials: Silicon (amorphous, polycrystalline, epitaxial) Silicon compounds (oxides, nitrides, carbides, ) Metals and metal compounds Glass Ceramics Polymers and other organics Biomaterials

  • Silicon Crystallography

  • Cubic Lattices Simplest arrangements of atoms in three dimension in which the unit cell is a cubic volume Simple Cubic (sc) structure has an atom located at each corner of the unit cellBody Centered Cubic (bcc) has an additional atom at the center of the cube Face Centered Cubic (fcc) unit cell has atoms at the eight corners and on the six faces.

  • Cubic Lattices How is the arrangement of atoms in Silicon? Silicon has fcc + (1/4x, 1/4y, 1/4z) fcc structurea is lattice constant

  • Si crystal structureSi crystal= fcc +1/4(x,y,z)fcc

  • Planes and directionsLattice vector R= r*a+ s*b+ t*c, r, s & t are integersWe can define a plane in a crystal lattice with three integer, called Miller indices1. Find the intercepts of the plane in terms of integral multiples of the basis vectors [Fig2, 4, 1]Take the reciprocal of the integers and reduce to smallest set of integers h, k, l, in this case 2,1,4Label the plan (214) & direction is

  • Planes and directions

  • Czochralski MethodFor growing single-crystalline ingot

  • CZ

  • Floating Zone Method(FZ)

  • (FZ) CZFZ(RF) (dislocation) (thyristor) (rectifier)

  • (Czochralski) (300 mm in production) (FZ) () (150 mm)

  • ()(centerless grinder)-X(diffraction)(collimated)(off-orientation)

  • Silicon Wafer CutsMiller indices indicated by ground edges called flats. n-type and p-type refer to doping. N means negative (phosphorous) and P means positive (boron).

  • Photolithography

  • Lithography devices

  • Lithography process

  • Lithography process-cont.

  • Positive/negative resist

  • Positive/negative resist-cont.

  • Positive/negative resist-cont.

  • Masking and Exposure

  • Mask fabrication process

  • Lithographic masks

  • Lithographic light source

  • Exposure Light Source (UV)

  • Development

  • Developing the pattern (C)

  • Oven Baking

  • Lithographic processing: Repeat process

  • Etching

  • Etching MechanismEtching type Wet etching Dry etchingEtching steps Oxidation Reaction Remove products

  • Factors in Wet EtchingLimitedReaction limitedDiffusion limitedFactorsConcentrationTemperatureStirring

  • Anisotropic Wetting Etching

    HNA system

  • Anisotropic Etch

  • Anisotropic Etchants

  • Wet anisotropic etching

  • Etch the material

  • Dry EtchingIon bombardmentPlasma reactor

  • Bulk machining using dry etch

  • Lithographic processing: Final release

  • Micro device integration: Packaging

  • Commercial micro devices: sensors and actuators