Name: Frankie B. Reed
Mentor: Chris Kenney
Post-foundry integration of Nano-film
capacitors on integrated circuits
My project is to fabricate nano-film capacitors to be used in the sensors at LCLS. The problem
was that the old censors needed a larger capacitance so that it could hold more signal. In order to build
a nano-capacitor I will have to use an Atomic Layer Deposition machine. The machine I will be using is
named FIJI. This machine takes chemical gasses and blasts it at the substrate i.e. silicon wafer. Gas by
gas, chemical reactions occur to form new layers of metal or dielectric. For instance blasting Trimethyl
Aluminum (Al(CH3)3) at the Silicon (Si-O-H) which will produce some methane, then blasting water on
the plate will eventually form a layer of Aluminum Oxide (Al2O3) on to the wafer. A capacitor is an
electrical component used to hold charge or store energy in an electric field. Unlike a battery which
gives off a constant voltage, the charge held in a capacitor is given off at an exponential rate. The
applications of a capacitor can be used to smooth out input. This is done by methods of filtering. The
capacitor is formed by two electric plates or conductors separated by a material called the dielectric.
The capacitance is greatest when the separation between the two plates is narrow. So with a thin
dielectric strong enough to keep the plates apart you can create a large enough capacitance to satisfy
the censors’ needs. Different materials have different properties. Therefor with the numerous
chemicals I can produce numerous results but due to time my mentor has directed to use certain
material that will help optimize the performance of the capacitor.
So far using a program called Cadence I have designed
how the nano-film capacitor will look. The blue square
with the X represents the bottom medals pad (which
allows connection to the component). The bottom blue
squares are gold and they all have a layer of dielectric
glass on its surface, excluding the pad marked with an
“X”. The dielectric will be made of Aluminum Oxide and
Hafnium Oxide. The pinkish squares are the top metal
and pad. They are also gold. Each square is 100x100
μm in size.
The process for doing such things is as followed:
1) Start 12 wafers
6) Spin coat SPR3612 1.0 um
7) KS or EV
3) WBDIFF clean
4) Grow 4000A thermal oxide WET1000
9) Innotec Deposit Ti (50A) Au (200A)
10) Soak acetone overnight
11) Ultrasonic liftoff
12) Clean
18) Spin coat SPR3612 1.0 um
13) ALD 100 A of AlO3, HfO2
19) KS or EV
14) Spin coat SPR3612 1.0 um
21) Aluminum etch at WBGENERAL
16) Etch dielectric (PAD ETCH or DRYTEK2
22) Clean
17) Innotec 4000 A Aluminum
I was also given the task to make a nano-resistor. This resistor is as shown below. The calculated
resistance is said to be 1000 ohms. This resistor may also used in the censor as well.
The process for making the resistor is as
1) Start 4 wafers
3) WBDIFF clean
4) Grow 4000A thermal oxide WET1000
5) ALD Platinum 100A
6) Spin coat SPR3612 1.0 um
7) KS or EV
9) Platinum etch A.R.