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MEMS Foundry


IMT offers the most complete wafer fabrication services, featuring the largest pure MEMS production fab and most extensive suite of tools of any independent manufacturer to meet our customers' high-volume production requirement and foundry services

•    30,000 ft2 class 100 cleanroom fab for manufacturing 6" wafers.
•    Technical staff with extensive experience in MEMS design, prototyping, and process development.
•    Complete analytical, metrology, and test capabilities for high-volume manufacturing with sqc/spc.
•    Volume foundry service for MEMS-specific or other wafer processing work.
•    Flexibility to develop and bring in new technologies.

Photolithography

  • Tight CD and overlay controls are critical to building complex MEMS. Many programs require 15 to 20 mask layers, some > 30.
    • Two Nikon I-line 5x reduction steppers with 0.3 µm resolution
    • Standard 1x contact aligner
    • CD control: +/- 0.1 µm on 5x stepper, +/- 0.3 µm on 1x aligner
    • Overlay: +/- 0.15 µm on 5x stepper, +/- 1 µm on 1x aligner
    • Positive and negative tone, liftoff stencil
    • Thick resists, including SU-8 (up to 80 µm), polyimide (including photo-imageable)
    • Front to backside alignment tolerance: +/- 1 µm

Deposition

  • IMT has 20 different targets constantly under vacuum in multiple production-class cluster tools, from RF and DC magnetron systems to LPCVD and PECVD, as well as thermal oxidation and annealing furnaces. A short list of deposition experience includes the following:
    • Metals: Au, Al, Cr, Ti, TiW, W, Mo, NiFe, Cu, Ta, CoFe, CoTaZr, NiMn
    • Dielectric: SiO2, Si3N4, Al2O3, TaO, TaN
    • Semiconductor: Si
    • 8 Angstroms to 1.5 µm for metals
    • Up to 60 µm deposition capability for dielectrics
    • Stress and uniformity controls

Electroplating/Wet Chemistry

  • Electroplating capability enables creating tall structural and functional features, such as molds, conductive coils, magnets, actuators, etc.
    • Some of the plating metals include the following: NiFe, Ni, NiCo, Au, Cu, and solder
    • Thickness: from 1 µm up to 50 µm
  • Having the ability to deposit or plate metals is only half the story. Wet chemistry capability complements our plating and deposition by allowing selective removal of materials
    • Wet etch experience includes the following: Au, Cu, Ni, Si, Al, Ti, TiW, Cr, NiFe, SiO2, Si3N4, Al2O3

Dry Etching (RIE, DRIE, ion milling)

  • Standard and key process technology in MEMS, IMT's deep reactive ion etching (DRIE) capability allows anisotropic etching of silicon
    • Up to 25:1 aspect ratio
    • 90 +/- 1 degree sidewall angle
    • Useful for etching of close-tolerance comb fingers, vias or holes, and trenches
  • In addition to DRIE, IMT's dry etch capability includes
    • RIE for dielectric etching
    • AOE (advanced oxide etcher) for high-rate anisotropic etching of oxide and glass etching
    • Ion mill for non-selective "micro-sandblasting" of various materials

Wafer Thinning/Grinding and CMP

  • Wafer thinning capability is a key tool for reducing the overall profile of a device or to expose materials that are embedded in the wafer.
    • Wafer grinding: +/- 1 µm thickness precision
  • Chemical Mechanical Polishing complements wafer thinning capability, which involves planarization and polishing to return the substrate surface to continue down the front end processing.
    • CMP:  Post-CMP surface roughness in the nm-range
    • Polished surface can be processed or bonded

Wafer Bonding

  • Over 50% of all wafers produced at IMT are wafer bonded. It is a key technology in MEMS, necessary for wafer-level packaging and encapsulation and for creating 3D microfluidics. IMT works closely with the customers' needs to determine the bonding method that includes the following:
    • Au-Au thermal compression
    • Glass frit
    • Anodic
    • Fusion
    • Metal alloy (low temperature)
    • Polymer
  • With the exception of polymer bonding, IMT's bonding allows hermetic wafer-level packaging to reduce the cost of post-process die-level packaging and to improve the performance and reliability of the MEMS. Depending on the bonding method and hermeticity requirements, capabilities include the following:
    • Sub-1 mTorr high vacuum bonding using getter
    • > 99% hermeticity yields in production – hermeticity verified by probing on-board thermistors
    • Vacuum, atmospheric, or partial pressure with unique gases
  • Although not hermetic, polymer bonding is useful for fabricating microfluidics, creating fluidic channels. Frequently, multiple bonding methods can be combined to achieve the desired final packaging. In addition to hermeticity requirements, other considerations include:
    • Design/device footprint
    • Temperature budget
    • Materials used
    • Final packaging and environmental requirements
  • After bonding, the wafers are protected from environment and fragile MEMS structures are protected. These wafers can continue on-ward, through die singulation and die-level packaging.

Automated Electrical Probing

  • In-process electrical testing of wafers includes various measurements, such as:
    • Capacitance
    • Resistance
    • Inductance
    • Isolation
    • High potential
  • Having this knowledge enables saving costs of producing devices. The end customer would only receive known-good-dies. IMT also offers reliability, environmental, and life testing, as well as other custom testing specific to individual customer's applications.

Assembly

  • In sampling quantities to modest volume, IMT offers die-level processing and assembly for packaging. IMT also has strategic partnerships to meet our customers' higher volume production assembly requirements:
    • Multiple qualified partners for standard and custom solutions
    • Wirebonding and bump bonding to PCB
    • Ceramic and injection molding

Metrology and Failure Analysis

  • The ability to obtain characteristics and measurements of devices and materials helps in verifying wafer processing and failure analysis. IMT's comprehensive metrology capability allows us to measure cross-section, CDs, thickness, width, optical, roughness, reflectivity, composition, etc. The following lists some of the capabilities at IMT:
    • FIB-SEM with EDX
    • Optical profiler/interferometer
    • Stylus profiler
    • Spectrophotometer
    • Automatic pattern recognition systems
    • AFM
    • FTIR
    • Ellipsometer
    • XRF
    • FE-SEM
    • Resmap
    • SurfScan particle detection

Design Capability

  • As a full turn-key foundry service provider, IMT also offers design and modeling services to complement the wafer foundry capabilities.
    • Design from customer specifications:  MEMS, packaging, circuit boards, systems
    • Design for manufacturability:  Monte Carlo analysis, design adaptation for wafer processing requirements
    • Engineering and modeling:  test structure design, multi-physics FEA, Computation Fluid Dynamics, magnetics, high-frequency analysis, Spice simulations
    • Full physics modeling software package


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How Does It Work?


Close collaboration and partnership are required for success. Starting from the initial design review, development and prototyping to product engineering and volume production.


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