nano poster final submission
Published on: Mar 3, 2016
Transcripts - nano poster final submission
Manufacturing of Micromirrors used
in Projection Systems
BADI SAI NIHANTH REDDY
DEPARTMENT OF MECHANICAL
Nanosystems Principles Poster Session – Fall 2015
• Micromirror devices are devices based on microscopically small mirrors and
commonly known as Digital Micromirror Device (DMD).
• Micromirror arrays are spatial light modulators that can modulate incident
light’s phase or amplitude
• DMD chip consists of pressure sensors, accelerometers and micro actuators
DMD chip Micromirror array DMD pixels
• A film is fed on to the projector.
• A source light projects the image from the
film onto the screen.
•System has many mechanical components
and the system is very complicated.
• The film degrades over time producing
scratches and dirt.
• This system is a combination of
mechanical, optical and electronic
• It consists of a micromirror array that can
modulate incident light’s phase or
• Simple system with less components.
Film Projectors Digital Projectors
• Each micromirror in the array is considered as a pixel having bi-stable
operation of ±12o.
• When the mirror is tilted +12o the light is passed through the projector lens
and when it is tilted -12o, the light is tilted away from the projected lens on to
the light absorber.
Bi-stable operation of DMD pixel Torsion State of micromirror
1) Fabrication using membrane transfer bonding
• Thick silicon nitride is deposited and an
aluminum layer is sputtered.
• The electrodes and the probing pads are
patterned and wet etched.
• A sacrificial layer is bonded to the target using
low temperature adhesive wafer bonding.
• By DRIE and grinding the sacrificial layer is
removed to free the silicon micromirror.
Fabrication of micromirror by wafer
• Deposition of silicon nitride and
patterning of photoresist with KOH
• Etching to obtain the V grooves, back
nitride with RIE and silicon using DRIE.
• Pattern photoresist on the wafer backside
and etch Au and Cr on backside.
• Etch oxide on wafer backside to open
windows for DRIE.
• DRIE etch through wafer to form the
2) DRIE Fabrication
Schematic illustration of the micromirror array
• Galvanometric and Resonant optical
• Galvanometric type produces a steady-state
deflection and follows a control waveform
with considerable fidelity.
• Resonant type operates, only at, or near the
resonance of the system, where the system
Micromirror-based Zoom Lens
• Lens have different focal length and work same as
an optical zoom lens, also known as smart lens.
• Lenses are arranged in a polar grid array, i.e. in
Schematic layout of an integrated
Control of tilt angle of the
High-quality, real-time holographic displays
• Holography is based on light diffraction and
• Present technology has limited scaling limits
around 2-4 mm, by which the projection angle
is limited to 10 degrees.
• A high resolution display must have up to 8
million pixels, which is very insufficient for
visualization of a 3D scene.
• HoloDis system has 1 million submicron
diffractive devices on a single chip with a
diffracting angle of 30o and a 15 o projection
angle HoloDis System
SCOPE OF MICROMIRRORS
• Decorating 2D gold microplates with magnetic
nanoparticles for high contrast between on and off
• Optical colloid can be actuated with magnetic field.
• Laser head lights provides a glare-free high beam.
• The light is projected in the form of a user defined
image, only in the places without light, rejecting
the light from, by modulating the power of the
Bulk magnetic microplate solution
under an applied magnetic field
with various orientations (θ)
relative to the viewing direction