June 27, 2007
• (A) plan and implement investigative
procedures including asking questions,
formulating testable hypotheses, and
selecting equipment and technology.
• (B) identify uses of electromagnetic waves in
various technological applications, such as
fiber optics, optical scanners, microwaves,
• (C) communicate valid conclusions.
Language (SIOP) Objectives
• Discuss their plan in groups.
• Write their plan and have it reviewed by
instructor prior to starting experiment.
• State and justify their conclusions.
• Design a CD label for your favorite
music artist using the UV
very small 3-D
features can be UV Light
• Involves a with design)
series of steps Positive
that creates (S-1813)
successive Substrate (CD)
Substrate – process
materials. photoresist is exposed to radiation
starts here. Silicon is
the preferred a the mask which contains a pattern
• Create a mask.
• Start with a
• Cover surface
• Soft bake
• Expose the
wafer to energy
• Develop the
Types of Lithography
Changing light source = type of lithography
Industrial Uses of Lithography
• Electronics and • Automobile
– Television, radio and
– Cars (microchips
printers trigger inflation of air
– Calculators and watches bag)
– Video cameras and – Traffic light (signals)
(microprocessor) • Pharmaceutical
– Cell phones and
waveguides – Lab on a chip
• Aviation and – Portable blood
Aerospace analyzers (microchip-
– Airplanes, meterology based sensing
equipment and devices)
Applications of Lithography
• Complex MEMS Ratchet • A truly amazing MEMS
Mechanism device. It is a sophisticated
MEMS Thermal Actuator
Incredible MEMS Clutch mechanism. This is actually a complex device
that required a working clutch mechanism. Gears are 50 microns across.
An early micromotor built in the SUMMiT technology.
For size comparison a microscopic dust mite is
shown on top.
Applications of X-ray Lithography
Micro motor core
• Work in pairs to Design a CD label for your
favorite music artist using the UV
• Each pair will design two CD labels
– One CD will be the control.
– The other CD will be varied (photoresist or exposure
• State and justify the impact your variation had
on the final product.
– Design must be drawn in black ink only.
– Design must be able to fit on a CD.
• Create a design
• Transfer the design to transparency
paper (inkjet or copy machine)
• Keep the transparency clean
1. Prepare Substrate
• Clean with
• Bake at 115°C
for 60 seconds
2. Apply Positive Photoresist
• Photoresist is spin
coated on to CD
• Students will dip CD
in S-1813 to get even
• Effective for λ 340 –
• 115°C for 60
• Complete when
hard to the touch. Post
• Temp. range:
5 – 550°C (41 - Develop
• Long wave UV mini
lamp (Intensity = 230
• Exposure time: 25
• Immerse wafer in solution
for 40 – 60 seconds.
• Quickly remove the wafer
from the developer bath
and rinse with deionized
water bath for 30 seconds
(using the wafer holder).
• Place the wafer on a
clean room wipe.
Dry the wafer holder.
6. Post Exposure Bake
• Bake at 115°C
for 60 seconds
• Set a hotplate to
• Place the wafer on
the hotplate, start
• When the time is
up, remove the
• Aprons, gloves and safety goggles
required at all times.
• UV goggles required during exposure.
• The more photoresist present, the
longer the bake time.
• Thorough Planning
• Mask Design
• Conclusions explained
Points (for Instructor) to Consider
• Give time limit on mask design. Students may
design on computer or by hand. Intricacy of
design may impact exposure quality.
• Thickness of photoresist impacts bake time
• Exposure time could impact image seen on
• Substrate surface must be very clean
• Students must wear UV goggles when
operating UV lamp
Three class periods (50 minutes each)
1. Day One – Background Info, Mask
Design, Substrate Preparation,
2. Day Two – Wafer Preparation, Apply
3. Day Three – Expose, Develop, State
• Dr. Kim
• Mr. Creary
• Dr. Conkey
• Dr. Srinivasa
• Mr. Derry
• Colleagues in the program