Data Sheet

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206. IC Packaging
Build the circuit shown on the left, connect the switch (62), and the
three LEDs will be turned on all at the same time. Circuits like this (and
much more complicated than this) often get put into ICs, which are then
packaged in many different ways, but typically have pins of pads coming
out of the packaging to connect the circuit to power and to provide
inputs and outputs.
207. Making ICs – Step 1
Replace the switch (62) with the press switch (61) in project #206,
then press the press switch (61) and you will see the three LEDs will
be turned on. To make ICs to support circuits like the one here and
more complicated circuits, recall the discussions on how LEDs and
transistors are made. The key is the semiconductor material that is
doped to have either an excess of electrons or a depletion of electrons
(excess of holes). By placing two different types of doped material next
to each other we created the LED (which is a diode). By placing three
different types of doped materials in layers we created the transistor.
And by placing lots of different doped materials at various layers you can
create all different types of circuits in an IC. The rst step in making an
IC is to make the wafers, or thin pieces of silicon.
208. Making ICs – Step 2
Replace the bi-directional LED (71) with the colorful LED (72) in project
#206 and turn on the switch (62). Press the switch (62) and you
will see the three LEDs will be turned on. The second step in making
an IC for a circuit like this or more complicated circuits is to perform
masking. This is the process of heating the wafers to coat them in
silicon dioxide and then add a hard, protective layer called photoresist.
209. Making ICs – Step 3
Replace the switch (62) with the press switch (61) in project #208,
then press the press switch (61) and you will see the three LEDs will
be turned on. The third step in making an IC for a circuit like this or
more complicated circuits is to perform etching. Etching is the process
of removing the photoresist from step 2 in a specic way to create a
blueprint of where p-type areas (areas with an excess of holes) and
n-type areas (areas with an excess of electrons) will be placed. The
blueprint created is specic to the circuit function desired.
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1st level