Standard Operating Procedure (S.O.P) for JST Wet Bench
1. Check power status, if “sys” led is not light press “power on”. If “sys” is light,
then the power is already on.
To use the D.I. sink.
a. Press the “on” button under the “work sink drain” heading, just above the
sink, to activate the drain.
b. Press the “on” button the “cold DI Gooseneck” heading, just above the
sink, to start the DI Water flow.
To use the Quick Dump baths.
a. The Quick dump baths are programmed for 2 cycles, 1 cascade fill, 2
spray fills, and 2 dumps. These programs are not to be changed unless
done, by WSU supervision.
b. Choose the panel above the desired bath that reads, “rinse controller”.
c. Press start to begin the cycles, after samples are loaded in the bath.
d. When the cycles complete the water will shut off, and an alarm will sound
to signify completion of the cycles.
To use hot plates.
a. Check “Watlow” gauge above desired hotplate for temperature set point,
by pressing blue “Set ” button. If temperature is desirable proceed to step
b., if not hold “set” button, while pressing the up, or down arrows to set
point desired.
b. Turn hot plate on, by selecting hot plate controls above the desired hot
plate, the controls are yellow and read “Thermolyne Cimaree RC2” the
controls is mounted vertically. Select the desired range from 1 – 10, on
these controls.
c. When the “Watlow” gauge reads the set point for your process, start the
timer, for the desired length. The timers are located next to the hot plate
controllers. (See Timer for usage)
To use Timers.
a. Locate the timer labeled “timer”
b. Press “Start” button, the timer is set for a 15-minute countdown, if a
different interval is desired see support designated training person.
RCA Clean Process
INTRODUCTION:
Contaminants present on the surface of silicon wafers at the start of processing, or
accumulated during processing, have to be removed at specific processing steps in order
to obtain high performance and high reliability semiconductor devices, and to prevent
contamination of process equipment, especially the high temperature oxidation, diffusion,
and deposition tubes. The RCA clean is the industry standard for removing contaminants
from wafers. Werner Kern developed the basic procedure in 1965 while working for
RCA (Radio Corporation of America) - hence the name.
The RCA cleaning procedure has three major steps used sequentially:
I. Organic Clean: Removal of insoluble organic contaminants with a 5:1:1 H2O:
H2O2: NH4OH solution.
II. Oxide Strip: Removal of a thin silicon dioxide layer where metallic
contaminants may accumulated as a result of (I), using a diluted H2 O: HF
solution.
III. Ionic Clean: Removal of ionic and heavy metal atomic contaminants using a
solution of 6:1:1 H2O: H2O2: HCl.
SAFETY:
The chemicals used for RCA cleaning are all dangerous if you get in contact with them.
The MSDS sheets for all of these chemicals can be found outside of the clean room in the
yellow MSDS binder. HF acid is very dangerous; HF burns are particularly hazardous.
An insidious aspect of HF burns is that there may not be any discomfort until long after
exposure. These burns are extremely serious and may result in tissue damage. If you
contact HF, flush the area with cold water for fifteen minutes and be sure to work under
and around your fingernails. While rinsing yell for help (you should not be in the lab
alone!) Have your safety buddy get the Calcium Gluconate gel. The gel will be found on
top of the RCA clean bench and in the first aid box. Rub the gel on the exposed area. A
physician must look at all HF burns.
Acid protective gear MUST be worn when working at this station. Lab aprons, acid-proof
gloves (atop the normal clean room gloves), and an acid facemask (with the face shield
DOWN) worn over safety glasses, are all required. All “RCA CLEAN” acid gear should
be labeled and not used at any other wet bench.
ALWAYS know the location of the nearest eyewash and safety shower. Exposure of the
eyes requires flushing with water for at least 15 minutes. As a precaution, all exposures to
the eye will require a visit to an emergency room for a check up. Exposure of the skin
requires immediate removal of all contaminated clothing. Rinse under the shower for 15
minutes.
SOLUTION PREPARATION:
Each will be prepared a follows.
A. Organic Clean is a solution of DI H2O: NH4OH: H2O2 (5:1:1)
*** Always add reactive compounds (acid/base) to water ***
a.) 2500 ml DIH2O
b.) 500 ml NH4OH
c.) 500 ml H2O2
Pour DIH2O into Organic Clean beaker located on the Organic Clean hot plate. Heat
DIH2O to 90C. Remove temperature probe and rinse. Add H2O2 and NH4OH to heated
DIH2O. The addition of these chemicals will reduce the DIH2O temperature to 80C
(desired operating Organic Clean temperature.)
B. Oxide Strip is a solution of DIH2O: HF (50:1) or (100:1) This solution will be
prepared for you. The solution is located in the Buffered HF Bath between the Organic
Clean and Ionic Clean Baths.
C. Ionic Clean solution of DIH2O: HCl: H2O2 (6:1:1)
*** Always add reactive compounds (acid/base) to water ***
a.) 2600mL of DIH2O
b.) 450mL of HCl
c.) 450mL of H2O2
Pour DIH2O into Ionic Clean beaker located on the Ionic Clean hot plate. Heat DIH2O to
90C. Remove temperature probe and rinse. Add H2O2 and HCL to heated DIH2O. The
addition of these chemicals will reduce the DIH2O temperature to 80C (desired operating
Ionic Clean temperature.)
PROCEDURE:
1. Place wafer(s) on glass carriers (five at a time maximum.)
2. Submerge the carrier with wafer(s) in the Organic Clean solution for a minimum of
10 minutes and a maximum of 20 minutes.
3. Remove carrier from the bath and rinse wafer in the DI quick dump for 2 cycles.
4. Submerge the carrier with wafer in the Oxide Strip solution for 10 to 15 seconds
(when desired.)
5. Remove carrier from the bath and rinse wafer in the DI quick dump for 2 cycles.
6. Submerge the carrier with wafer in the Ionic Clean solution for a minimum of 10
minutes and a maximum of 20 minutes.
7. Remove carrier from the bath and rinse wafer in the DI water quick dump for 5 cycles.
8. Remove carrier from the DI water quick dump. Using (RCA only) Teflon tweezers
place the wafers into the dedicated (RCA clean only) wafer carrier and then (RCA clean
only) spin rinser/dryer. Press start.
9. Clean RCA bench with DI and clean room wipes.
10. Take wafer to next processing step.
CLEAN UP:
1. Turn off hotplates and allow solutions to cool
2. Dispose of Organic Clean in Wet Bench Bath marked 'organic clean waste'. Rinse
beaker twice with DI water. Do not cap or plug the container until you are sure the
Hydrogen peroxide has reacted completely. Check the waste container located behind the
bench in the chase to make sure there is room for waste. If ok, press the Organic Clean
Dump to dump the waste into the container.
3. Dispose the Ionic clean in the work sink labeled ionic clean waste. Rinse beaker twice
with DI water. Check the waste container located behind the bench in the chase to make
sure there is room for waste. If ok, press the Ionic Clean Dump to dump the waste into
the container.
4. Leave the oxide strip for a Wayne State employee to drain. Do not hit the dump
waste.
5. Manually rinse the work area with DI water, wipe it with Kim wipes, and rinse the
rubber gloves that you have been wearing.
6. Remove the protective clothing.