Chapter 5.34
Rapid Thermal Annealing
With AG Heatpulse 610
RTA System (MOS Clean Silicidation or
Non-MOS Clean Silicidation)
(heatpulse4)
Heatpulse4, is the designated RTA system in the VLSI area used for siliciding MOSFET source, drain and gates (MOS clean chamber) or MEMS silicidation/Activation Anneal processes (Non-MOS chamber), all depending on which chamber is installed in the tool at a given time (Integrated device - MEMS fabrication). This tool is both 4" and 6" capable. A four-inch wafer can be processed on a six-inch pocket wafer (carrier wafer) in this tool.
This
manual chapter covers the general description of Heatpulse4 RTA system,
operation procedure, available processes, recipe set up/programming and some
trouble shooting guidelines at the end.
5.1 QDR Quick dump rinse (DI water)
5.2 SRD Spin rinse dry (DI water and N2 purge)
5.3 RTA Rapid Thermal annealing, high temperature short time anneal
6.1
In the event that user
smells ammonia (NH3) in the vicinity of heatpulse4, it is most
likely coming from the tool. She/he should immediately turn the gas flow knob to
off position (gas control panel on the wall behind the chamber), notify the
maintenance staff during business hours, and report the problem on wand.
6.2
Do not operate the tool
at temperatures above 1100oC (recommended maximum process temperature,
below 1050oC).
6.3
Do not touch chamber
wall or dummy/process wafers that have just been unloaded from the chamber, as
they will be at elevated temperatures.
The standby temperature is at around 200oC; hence dummy
wafers are hot and can burn you.
6.4
Do not use the system
if chamber wall temperature (default 15oC) is higher than set point.
Cooling water will have to be refilled before system can be used.
6.5
Do not use heatpulse4
when another user is operating heatpulse3 since the two RTA systems share the
same a common gas distribution system.
If you are using a gas other than N2, make sure that the
heatpulse3 knob is off and the heatpulse4 knob is on (found above the gas flow
knobs).
N/A
8.0
Available
Processes, Gases, Process Notes
8.1
There are two chambers
available for Heatpulse4 system, MOS Silicidation and Non-MOS
Silicidation/Activation Anneal chamber.
These chambers can be switch in and out of the tool, as per members'
request by e-mailing heatpulse4@silicon. Ask for proper chamber and dedicated
paddle to be installed for your specific MOS or Non-MOS application. Two
chambers are available:
8.1.1 MOS Silicidation chamber is used for siliciding MOSFET source, drain and gates.
8.1.2 Non-MOS Silicidation/Activation Anneal chamber is dedicated to silicidation of metal layer
on silicon or activation anneal of dopant species in the substrate plus any
other desired rapid thermal anneal
process for Non-MOS application.
8.2
Wafers need to received
proper cleaning before they can enter Heatpulse4 system, as per follows:
8.2.1
New Si, SOI and 100% quartz wafers need to
receive Sink6 clean.
8.2.2
MOS clean
wafers need to receive sink6 clean.
8.2.3
Non-MOS clean wafers (no metal layer) need to receive sink8 followed by sink6 clean.
8.2.4
Metal wafers
( wafers with metal layers on them)
need to get cleaned in sink5's metal cleaning bath (far right tank), Sink5 QDR
and sink5 SRD before entering heatpulse4.
8.2.5
NO Photoresist is allowed in Heatpulse 4 system, unless photoresit has completely been
removed by the ash process (Matrix) and/or wet clean (PR-300) followed by
proper sink cleaning required for a specific RTA chamber (MOS & Non-MOS
clean steps above).
8.3
Annealing at
temperatures up to 1100oC from 1sec to 1000 sec an be done in
heatpulse4 system.
8.4
Process gases available
– N2, NH3, O2, Ar, N2/H2.
8.5
Ammonia can be used
only with superuser and staff permission and training.
8.6
4" wafers can be
processed on 6" pocket wafers in heatpulse4.
9.1
Loading Your
Wafers
9.1.1
Make sure dedicated
chamber and paddle are installed for your specific application (see process
notes, above).
9.1.2
Clean your wafers in
the appropriate sink/s prior to RTA step, as per instructions outlined in the
process notes section.
9.1.3
Enable equipment on
WAND.
9.1.4
Make sure the system is
powered ON and the correct chamber is labeled on the tool, "MOS
silicidation" or Non-MOS Silicidation/Activation Anneal". If the wrong silicide chamber is in
heatpulse4, notify staff (David Lo) to change it. MOS-clean and Non-MOS-clean chambers are not to be interchanged
to avoid contamination.
9.1.5
Standby temperature
(indicator on upper left corner) should be in the neighborhood of 20.0oC.
The display is offset from the actual reading by a decimal point, i.e. 20.0oC
actually means 200oC.
9.1.6
Check the cooling water
temperature display, found below the heatpulse3 chamber (on top of the
computers). Make sure the chamber wall
temperature is 15oC. This is essential and must be checked before
use. If the wall temperature is high (25oC), the cooling water needs
to be refilled. This is a procedure that is generally restricted to staff
(David Lo) or superusers. Upon filling cooling water, the user should wait till
the temperature drops to 15oC.
9.1.7
Make sure PC is running
and is on main menu.
9.1.8
It is recommended that
users use a dedicated pair of clean Teflon tweezers when loading/unloading
wafers in Heatpulse4. It is advised to use 2 Teflon tweezers so not to drop the
wafers. DO NOT USE METAL TWEEZERS and
DO NOT USE TWEEZERS BELONGING TO HEATPULSE3!
9.1.9
Turn the knob to the
left of the door to show approximately 5 mm of N2 gas. This will purge the chamber while you load
your wafers.
9.1.10
It is recommended that
you run at least 2 dummy runs to test the recipe stabilization.
9.1.11
Carefully open the
chamber door by lowering the lever.
9.1.12
Pull lever towards user
to bring forward the wafer tray. There is always a dummy wafer in the chamber.
There are three prongs that are used to support the wafer in the. Carefully
remove the dummy wafer and place the process wafer over the 3 prongs and return
the door to the closed position. Users should minimize the time that the door
is kept open. Be sure not to touch the
thermocouple on the quartz holder.
9.1.13
Be careful not to touch
the quartz holder while loading your wafer.
Anything that touches the quartz may melt and contaminate the chamber.
9.1.14
Choose desired gas on
the gas control panel on the wall behind the chamber. Nitrogen (N2)
is the default gas, but oxygen and Argon are also available. NH3 is
available only with permission from the superuser. Turn gas flow knob on.
9.1.15
Let system purge for at
least 3 minutes (to lower background oxygen levels).
9.2
Creating and
Running Recipes
9.2.1
Press the Process for Engineer button on the Main
Menu.
9.2.2
Select the recipe to be
edited from the Recipe Files list
9.2.3
Press Recipe Edit to go to the Recipe Edit
Screen where recipes can be modified.
9.2.4
Users can create new
recipes by hitting the Recipe New or
F7 button.
9.2.5
Use the up, down arrows
or the mouse to select the desired step.
Begin with step 1 to define the recipe step by step. Commands can be seen on the bottom of the
screen for further clarification.
9.2.6
Move to the Step
Function column. Choose between Ramp
(R), Steady (S), Delay (D) and Finish (F) functions.
9.2.6.1
Ramp (R):
The ramp step occurs in the cycle when the temperature rises or falls from one
temperature to another temperature in a given time.
9.2.6.2
Steady (S):
The steady step occurs in the cycle when the temperature is kept at a
constant/steady-state temperature for a specified time
9.2.6.3
Delay (D):
The delay step occurs during the cycle when the lamps in the chamber are off
(no heating occurs) and the purge gas is flowing through the system. This step is most commonly used at the
beginning or the end of the cycle. The
initial delay purges any gases from the process chamber before heating the
wafer. The final delay cools down the
chamber before the user can remove the wafer.
9.2.6.4
Intensity (Intn): The step constant intensity step can be used instead of the steady
step. This indicates a constant
intensity of the lamp (between 0% to 80%) instead of a constant temperature.
9.2.6.5
Finish (F):
The fourth step is the last step of the process. The user can begin purging the process gases.
9.2.7
In each of the steps,
the user can specify the Time (s)
and Temperature (oC) or Intensity (%) columns. As well, a Steady Intensity Factor can be specified (between 0.01 to 20) to
compensate for undershooting or overshooting during temperature ramp. A larger Steady Intensity Factor will cause a larger overshoot and a smaller
one will cause an undershoot. In
annealing above 450oC, you should write a two-step process. The first should ramp to 450oC
and stay in the delay step for 30s; then ramp to the desired temperature.
9.2.8
Click the Recipe Validate or F10 button to check if the recipe is okay. Press OK
to validate the recipe.
9.2.9
Press Save to save the validated recipe
9.2.10
Press Exit to go to the Process Menu.
9.2.11
Press Start Process to run your process. The Recipe Graph window should pop up,
displaying the ideal and actual temperatures of your run.
9.3
Unloading Wafers
9.3.1
Turn off all the process gases except N2 by turning the gas
knob position off. Turn the N2
gas back on, if necessary.
9.3.2
Wait until the chamber cools down to at least 200oC before
unloading the sample.
9.3.3
Return the dummy wafer on the prongs and close the door
9.3.4
Exit out of the software to the Main Menu.
9.3.5
Return the heatpulse3 and heatpulse4 valves so that they both have N2
flowing in the chambers.
9.3.6
Disable the equipment on WAND.
9.4
Operational
Instructions for Ammonia Process in Heatpulse3
This process is only allowed during regular business
hours (8:00 AM - 5:00 PM, Monday - Friday). If ammonia odor is smelled,
immediately close the gas valve. Do not attempt to flow flammable (NH3,
H2/N2) and oxidizing (O2, N2O)
gases, simultaneously. Please keep it in mind that excess ammonia flow (> 2
liter/min.), could shut off the gas fuse at the cylinder cabinet, hence abort
other member's processes in Tystar9 and Tystar17.
9.4.1
Check ammonia source to
make sure gas fuse (red button) is down.
9.4.2
Turn valve in CV1, to
open.
9.4.3
Enable Heatpulse4 on
WAND, check standby temp, chamber wall temp.
9.4.4
Run recipe once on
dummy wafer, just using N2 gas.
9.4.5
Make sure that external
ammonia valve is off, then open chamber.
9.4.6
With clean Teflon
tweezers, unload dummy and load wafer, close chamber.
9.4.7
Put danger hang tag
on handle of heatpulse4.
9.4.8
Turn gas flow knob to
50 mm and let N2 flow for 2 minutes.
9.4.9
Turn gas flow knob to
15 mm, turn N2 off at external valve, and slowly turn ammonia on at
external valve. If ammonia odor is smelled, close the valve immediately.
Make sure gas flow is still at 15 mm.
9.4.10
Let ammonia flow for 2
minutes.
9.4.11
Run recipe.
9.4.12
During cool down, turn
ammonia off at external valve and turn N2 on at external
valve. Turn gas flow knob to 50 mm.
9.4.13
Let N2 flow for 5 minutes.
9.4.14
Visually check to make
sure that the ammonia external valve is really off, and
gently opening the chamber, by making sure that no smell of ammonia
is present.
9.4.15
Remove the wafer and
replace it with a dummy.
9.4.16
After final wafer, turn
off ammonia at valve in CV1.
9.4.17
Check that gas fuse
(red button) at ammonia source is still down.
10.0
Troubleshooting
Guidelines
10.1
Chamber wall
temperature > 15ºC. Please contact staff for refilling cooling water, after
which the wall temperature should gradually come down to 15ºC.
10.2
PC turned OFF. Turn PC
ON, at DOS prompt run PCAT, wait for PCAT main menu to be displayed.
10.3
System reboot – If a
system reboot is necessary, please turn power OFF on the unit, turn OFF PC,
then restart unit and then restart PC.
11.0 Figures & Schematics
Please refer vendor
supplied documentation is kept near system.
12.0 Appendix
Recipe
editing is generally explained to the user during qualification. Please contact
superuser before adding new recipes.