Chapter
5.14
Tystar
14
Boron+
Doping Furnace
(tystar14)
1.0
Title
Tystar14 Boron+ Doping Furnace
2.0
Purpose
Tystar14 is a Non-MOS clean atmospheric
pressure furnace that uses Boron+ solid source to dope process wafers. It
accommodates twenty-four 4” wafers in one run.
3.0
Scope
This chapter covers the general
furnace description of Tystar 14, process recipe loading, operation procedure,
which includes wafer loading/unloading, process status monitor, user level
problem diagnosis, and wafer cleaning requirements.
4.0
Applicable Documents
4.1
Tytan Diffusion Furnace System Instruction Manual (copy in
Office).
4.2
Tycom 9900 Microprocessor Control System Instruction Manual (copy
in Office)
4.3
Material Safety Data Sheet for Boron+ solid source, Oxygen, and
Nitrogen (copy in Lobby).
4.4
Boron+ solid source vendor web-site (TECHNEGLAS) at http://www.techneglas.com/dopantpages/boroncatalog.htm
5.0
Definitions & Process Terminology
5.1
MOS Furnace: This kind of furnaces is used to fabricate MOS devices (IC), whose
performance can be greatly impacted by trace contaminants. Wafers processed in
MOS clean furnaces should be MOS compatible (IC device). Absolutely no metal
film in any MOS Furnace, except the MOS sintering furnace, which allows only
Aluminum film.
5.2
Non-MOS Furnace: This kind of furnaces is used for Non-MOS
clean process (Non IC) such as MEMS or similar application. Wafers processed in
Non-MOS furnaces may contain materials that are not compatible with the MOS
processes, therefore are not allowed in any MOS furnace. Wafers with metal
films can be processed in some of the Non-MOS furnaces, as per defined in Chapter 1.7
(Material and Process Compatibility Policy) or with special permission from
Microlab’s management.
5.3
Boron Doping: A high temperature process that diffuses boron atoms into the
silicon wafer. Boron atoms provide extra electron hole to the silicon
substrate, which will make it more conductive.
5.4
Annealing: A high temperature process that uses nitrogen to keep wafers in
an inert atmosphere. Major applications include dopant diffusion and
activation, LTO/PSG/BSG/BPSG densification, film stress release, and etc.
PSG/BSG/BPSG different types of doped silicate glass (SiO2 glass).
6.0
Safety
Follow general safety guidelines in the lab as well as the
specific safety rules as per follow:
6.1
Electric Shock Hazard: Tystar furnaces utilize high electric
power (high amperages) to generate heat.
Do not open the side panels or touch the high power electrical parts in the
furnace cabinet.
6.2
Chemical Hazard: Boron+ solid source poses low health and
fire hazard. However, you should avoid inhalation of the dust or direct contact
to the skin or eye. Please refer to the MSDS for first aid information.
6.3
Burn Hazard. Cantilevers, boats, and wafers coming out of the furnace are
very hot. Wear face shield when
loading/unloading wafers. Proceed with caution. Avoid touching of any furnace
quartz ware to prevent burning of your hands and contamination of the furnace.
No flammable chemical, especially organic solvents, in the load station when
the tube is open.
6.4
The process staff must check all new recipes, before they can be
used on any Tystar furnaces. Customized recipes should be stored on the user’s
diskette, not the standard diskettes.
7.0
Statistical/Process Data
7.1 Problem and comments section under equipment
section of the wand.
7.2 Enable message for individual Tystar
furnace.
8.0
Available Process, Gases, Process Notes
Available Processes
8.1
14SB+O2A B+ doping process, which
uses O2 to prevent the wafer surface damage at process temperature
over 1000ºC.
8.2
14SB+N2A B+ doping process
without O2. It should only be used for process temperature below
1000ºC.
Available Gases
8.3
N2 (N2,
9999
sccm): Used to purge out room air and
keep the process tube in an inert atmosphere.
8.4
O2 (O2: 200 sccm): Used in the doping step of the
Boron+ process to prevent wafer surface damage.
8.5
N2/H2: (Forming Gas, 9999 sccm): Not connected.
Process Notes
8.6
The 4” Boron+ solid source used in Tystar14 are manufactured by
Techneglas, and are type GS-139 (see Section 4.4).
Recommended process temperature range for these types of solid sources are
between 975ºC to 1075ºC. Maximum process
temperature allowed in any of our furnaces, including Tystar14 is <
1100ºC.
8.7
TYSTAR14 uses two specially made 4” boats to hold Boron+ solid sources.
Process wafers are placed between two adjacent solid sources two at a time, and
back-to-back facing the solid sources (front side of the wafers face the solid
sources). This means each solid source will have two process wafers on both its
sides facing towards it.
8.8
Dummies wafers are used in TYSTAR14 to prevent the warping of the solid
sources during wafer loading/unloading.
8.9
Because the B+ solid source reacts with the moisture in the ambient air,
process tube door should not be open for long period of time
8.10
Standby temperature is kept at 600ºC to minimize out diffusion of dopant
material from solid sources, hence increasing their lifetime.
8.11
After the Boron+ diffusion process, a layer of boron rich film
will be formed on the wafers, which need to be removed. A wet oxidation
step (900ºC for 30 minutes) followed by a 5:1 BOE in
SINK8 is recommended for removing this boron rich film. For doping process
longer than 10 hours, wet-oxidation time should be doubled. Failure to perform
proper wet oxidation, post the diffusion step could make the film removal next
to impossible.
8.12 TYSTAR14 can be
used as a backup to non-MOS furnace for annealing. However, wafers with metal
film should not be processed in this furnace.
9.0
Furnace Operation
9.1
Wafer Cleaning Requirements Before Loading into Tystar14 Furnace
9.1.1
Photo-resist on the wafer surface must be stripped first in
PRS3000 bath of Sink5, Technics-c, or Matrix. Then cleaned in Sink8 (4”)
(Non-MOS) followed by sink6 (MOS) clean.
9.1.2
For additional information note general guidelines for cleaning in
Chapter 1.7
(Material and Process Compatibility) on the web.
9.2
Processing A Run
(Refer to Section 11.0,
for detail information on TYCOM and ROP)
Loading a Recipe
9.2.1
Enable the Tystar 14 furnace.
9.2.2
Check that no recipe is running in furnace and the ROP displays
READY. Check that the N2PRSAL is OFF.
9.2.3
Insert the recipe diskette for the furnace into floppy drive #2,
right hand side, of TYCOM CPU. Every furnace has its own standard recipe
diskette.
9.2.4
If you are not sure of the recipe name, enter DI DI at
TYCOM Terminal to display the recipe directory.
9.2.5
Enter LO recipe-name 14, and then press the [enter] key.
9.2.6
Enter the process parameters when prompted. You can use the
numeric keypads on the keyboard, but not the [enter] key on the right end of
the numeric keypad. TYCOM does not recognize this key, and will not load the
recipe.
9.2.7
TYCOM Terminal displays RECIPE LOADED SUCCESSFULLY if there
is no error in the recipe and parameter entries.
(Do not use TYCOM command RU # to
start the process, because someone may be loading/unloading wafers on another
furnace of the same bank. Besides, it is recommended that you check the ROP to
make sure the recipe is loaded into the furnace.)
Load Wafers and Run a Process Recipe
9.2.8
Go to the front of the load station module of the Tystar furnace.
Press [7/Status] button on the ROP to make sure the furnace is at READY
state and the recipe name is correct.
9.2.9
Put on the face shield. Then press [Recipe/Run] button. The
furnace door will open and the wafer boats come out. The door will close
automatically after 20 minutes. If the boats start moving in and you need more
time loading wafers, press [Alarm Ack] button on the ROP before the door
closes, the boats will move out again and you have another 20 minutes.
9.2.10
Transfer your wafers from Sink6 to the furnace in a BLUE wafer
box. Do not use the Teflon® cassette to avoid contamination. See Section 9.1 for wafer cleaning requirement.
9.2.11
Load wafers using the Non-MOS vacuum wand with black tubing. All
the wafers should be loaded with their flats up for better wafer support and
consistent run-to-run results.
9.2.12
Do not wear poly gloves over clean room gloves when
loading/unloading wafers. The poly gloves usually are too big and slippery. The
tips of the poly glove may melt on the hot quartz ware and cause contamination,
which is hard to notice, because it is colorless and transparent. The poly
gloves should be used at sinks and other room temperature operations only.
9.2.13
After loading wafers, press [Alarm Ack] button on the ROP. The
boat will start moving into the furnace. If you want to add/remove or
reposition wafers before the door closes, press [Alarm Ack] once, the boat will
move out again.
9.2.14
After the door closes completely, check DNTLK on the TYCOM
Terminal. If DNTLK is OFF, the process will continue automatically. You can
also monitor the status of the process run remotely (Section
12.6).
9.2.15
If the DNTLK keeps ON, the process will abort after a few minutes.
Press [Alarm Ack] button to silence the alarm. Check that the track and cable
of the boat loader is cleared of any obstacle. Press [Recipe/Run] button again.
If problem continues, report on WAND for boat loader problem.
9.2.16
You should monitor the process frequently during your run. You can
use either the TYCOM terminal (Section 12.4) or WAND (Section 12.6) to do so.
Unload Wafers After Process Ends
9.2.17
When the process reaches the last step, the ROP displays END
and the alarm beeps. Press [Alarm Ack] button to silence the alarm and reset
the furnace to READY state.
9.2.18
To unload your wafers, press [Recipe/Run] button again, and the
boats will move out. When the boats stop moving, wait a few minutes for wafers
to cool down. Then use the appropriate vacuum wand to unload your wafers to the
quartz boat on the cooling rack next to the furnace. The wafers may still be
too hot for the plastic wafer box.
9.2.19
Press [Alarm Ack] button to move in the boats. After the door closes completely, press
[Abort] button, then [Alarm Ack], and the furnace returns to READY
state. If you press [Abort] before the door closes, the boats will stop moving
and the door left open. Follow Section 9.3.3 to close the door manually.
9.2.20
Disable the Tystar furnace on the WAND. Unload wafers from the
cooling rack into wafer a box.
10.0
Troubleshooting Guidelines
TYCOM Terminal Problems
10.1
TYCOM Terminal is blank
Cause: The terminal is in sleep mode.
Solution: Press [Enter] key to activate the terminal.
Cause: The terminal needs reset.
Solution: Turn the terminal off, then on. Adjust
brightness/contrast if needed.
Cause: The power is off
Solution: Make sure the terminal is turned on and the
power cord in the back of the terminal is properly connected.
10.2
TYCOM Terminal displays the status of a tube continuously, and
does not respond to the keyboard input.
Cause: The previous user
set the display to the continuous mode.
Solution: Press [ctrl] and [c] keys at the same time to
kill the continuous mode.
10.3
TYCOM Terminal displays the status of a tube at a fixed interval
of time repeatedly.
Cause: Other user is checking the status of the
tube remotely.
Solution: If
too many users are doing so and you cannot perform the routine TYCOM operation,
contact staff to kill some of the remote checking.
10.4
TYCOM Terminal does not respond to any keyboard command at all
(CPU hangs).
Cause: TYCOM CPU needs reset.
Solution: Follow
the steps below to reset TYCOM:
Slide the TYCOM CPU out slowly.
Check that power cord and all the cables connected to the backside
of the CPU are secured.
On the backside (up left corner facing the CPU), there is a black
square power switch. Toggle the switch off then on.
Slide back the CPU slowly.
On TYCOM terminal, enter ACT PR, then [Enter].
Enter IN DA dd/mm/yy; enter IN TI hh:mm:ss to set
the date/time.
10.5
TYCOM Terminal displays a few lines of system messages every few
seconds that interferes with command inputs
Cause: TYCOM reset was
not properly finished
Solution: Enter ACT PR when TYCOM is not
displaying messages.
Check the system
date/time by entering DI DA.
If the date/time
is not correct, enter IN DA dd/mm/yy and IN TI hh:mm:ss.
10.6
TYCOM Terminal displays Tube I/O error message after a
command is entered.
Cause: The furnace I/O board needs to be replaced.
Solution: Report
on WAND. Equipment staff will replace the I/O board.
Process/Recipe Problems
10.7
The boat will not open or the boat loader stuck in the middle of
the track with process still running.
Cause: Something
physically blocks the movement of the boat loader.
Solution: Clear
the track and the boat loader path, then try again. If the problem repeats, the
boat loader needs to be reset. Report on WAND.
10.8
The process advances to the process-fail-hold step or ends without
ramping up the specified doping temperature.
Cause: The door did not close properly and DNTLK
is ON.
Solution: Abort
the recipe and run it again. Make sure there is nothing on the track to block
the door movement. If problem repeat, the door sensor needs to be checked.
Report on WAND.
10.9
The process advances to the process-fail-hold step before the
doping step is done.
Cause: One of the process gases, e.g., O2
or N2 has been used up.
Solution: Report
on WAND
10.10
The furnace temperature does not stabilize at the doping
temperature one hour after the wafer loading.
Cause: If all 3-temperature inputs are good, it is
the electronic noise.
Solution: Press [Alarm Ack], and the process will
continue to next step.
Cause: If one of the temperature inputs is 5ºC deviate from the set
point
then the furnace needs be re-calibrated.
Solution: Report on WAND.
General
/Additional Information on Furnace Operation
12.1
Tystar Furnace Modules
The Tystar Furnace consists of three basic modules: Load Station
Module, Furnace Module, and Source Cabinet Module. Microlab users can only
access to the Load Station Module in the clean room area. The other two are in
the Tylan service chase. Only Microlab staff with proper training has access to
these two modules due to potential hazards.
The Load Station Module houses a laminar flow unit with HEPA
filter for clean air distribution. A Boat Loader Unit opens/closes the furnace
door and pulls-out/pushes-in the cantilevers with wafer boats sitting on top.
The operation can be automatically controlled by a process recipe, or manually
using the ROP (see Section 9.3).
The Furnace Module consists of a quartz process tube, thermal
couples, and heating elements. It is divided into three zones: Load, Center,
and Source. The temperature is controlled through a PID electronic board (DTC).
All the control parameters can be set in the process recipe. The volume of the
quartz tube is approximately 45 liters. The process gas flows into the tube
from the Source end and vented through the holes on the Load end.
The Source Cabinet Module contains several
Mass Flow Controllers (MFC) that regulate the process gas flows, the DI water
vapor generator, and the TLC bubbler. A electronic gas control system MFS 460
coordinates all the MFC and interlocks for safe operation.
12.2
Tycom Terminal
The Tycom Terminal controls/monitors all the Tystar Furnace
operations. It consists of a CPU with two floppy disk drives, a CRT monitor and
a keyboard. Disk drive #2, on the right side, is used for viewing and loading
of recipes. The auxiliary drive is used for copying diskettes. The standard recipes for an individual
furnace are stored on a floppy diskette labeled with the furnace name, e.g.
TYSTAR1 STANDARD RECIPES. The floppy disk used has a special format. Please ask
staff if you need one to store your customized recipes.
12.3
TYCOM Commands – TYCOM CPU only recognizes CAPITAL letters.
|
Commands |
Function |
Example |
|
DI DI |
Displays the recipe directory of the diskette in Drive #2 |
|
|
DI RE recipe name |
Displays the content of a recipe on the diskette in Drive #2 |
DI RE 1SWETOXA |
|
LO recipe name # |
Load a recipe to a Tystar furnace |
LO 2SDRYOXA 2 |
|
DI ST # |
Displays current status of a Tystar furnace (see Section 9.2.2) |
DI ST 3 |
|
DI DE # |
Displays the system configuration of a Tystar furnace |
DI DE 3 |
|
DI AL # |
Displays previous process alarms of a Tystar furnace |
DI AL 4 |
12.4 Display Furnace
Status
- When you use DI ST commands, the CRT monitor displays the status of the
Tystar furnace. This information is very important, especially for equipment
diagnosis. The following example is used to explain the information users
should know. The furnace status to be displayed is Tystar2 with recipe 2SWETOXA
loaded but not running (Idle state).
|
05/05/02 |
16:30:32 |
|
|
|
|
|
|
|
|
|
|
*=DISABLED |
|
|
|
|
|
|
|
|
|
TUBE |
STATUS |
PROCID |
|
ET |
|
STEP |
TIME-TO-GO |
STEP ET |
|
|
002 |
READY |
2SWETOXA |
|
00:00:00 |
|
0000 |
00:00:00 |
00:00:00 |
|
|
|
|
|
|
|
|
|
|
|
|
|
OUTPUTS |
RELAYOUT |
RELAYIN |
INPUTS |
|
|
||||
|
N2 = |
0.0 |
N2 = |
ON |
DNTLK = |
OFF |
TEMPL = |
H |
752.3 |
1220 |
|
N2/H2 = |
3000.0 |
N2/H2 = |
ON |
CCIN2 = |
OFF |
TEMPC = |
G |
751.0 |
0840 |
|
O2 = |
.0 |
O2 = |
OFF |
CCIN3 = |
OFF |
TEMPS = |
L |
747.2 |
1031 |