(tystar20)
1.0 Title
Tystar20 Non-MOS Clean Si/Ge LPCVD Furnace (4” and 6”)
2.0 Purpose
This document has specific operation and process information about
the Tystar20 furnace. It can process both 4” and 6” wafers, and is used mostly
for MEMS applications.
3.0 Scope
Tystar20 is currently set up to deposit silicon (Si) (in relative
small quantity), Germanium (Ge), or a mixture of the two at specific ratios,
defined by process recipes. The deposited film can also be in-situ doped
(p-type) There is no Tycom monitor as compared to the furnaces in the VLSI
area. All commands are initiated from a menu-driven display located in front of
the furnace.
4.0 Applicable
Documents
4.1
Please
note that there is a specialty gas charge for Germane and for
Disilane. These gases are very
expensive; thus, gas charges are calculated based on the amount of gas used
during deposition, germane at 4 cents/cc and disilane at 1 cent/cc. This
translates into $432 for a 1 hour run at 180 sccm for germane (180 cc/min x 60
min x 0.04 $/cc), and $108 for a 1-hour run of disilane at 180 sccm. Gas charge
is considered as material cost and it is not subject to the monthly cap of
equipment fee.
4.2
Chapter 5.0 of
the lab manual (Tystar/Tylan Furnaces Overview)
4.3
The hazardous gas booklet at the
station, which explains the safety concerns for the specific gases used in
Tystar20 (includes MSDS).
5.0 Definitions
and Process Terminology
5.1
Non-MOS Furnace: The wafers
processed in the furnace may contain materials that are not compatible to the CMOS
processes. If you process CMOS devices in a Non-MOS furnace, the electrical
performance of the devices may be changed. Tystar20 has specifically been
developed to enable deposition of poly-Ge and poly-SiGe films upon CMOS wafers.
Thus, metals allowed in Tystar20 include Al, Al2%Si, Ti, and W.
Gold is NOT
allowed in Tystar20 under any circumstance
Requests to process metals other than the aforementioned in
Tystar20 must be approved by the lab managers. Also, note that the maximum
temperature for any process in Tystar20, regardless of substrate, is 450ºC.
5.2
LPCVD: Low Pressure
Chemical Vapor Deposition
5.3
Silicon/Germanium
(Si/Ge): Mixture of Silicon and Germanium (Si1-xGex)
5.4
Nucleation: Deposition of a thin
layer of poly/amorphous silicon. It is used to ensure uniformity of the
following main deposition. Poly Ge has been found to not grow well on certain
materials such as LTO, and therefore requires a nucleation layer.
Furnace Description (see Figures
& Schematics)
5.5
General: Tystar20 is a
hot-wall horizontal LPCVD reactor.
5.6
Temperature: Typical
operation temperature is 300°C - 450°C
5.7
Pressure: Process pressure can be controlled in the range of 100 – 1000 mTorr
5.8
Precursor gases: Pure SiH4 or Si2H6
and GeH4
5.9
Dopant gas: 1% BCl3 diluted in He
5.10 Gas
Ring: A device that connects the process gas lines to the main process
quartz tube. The main process gases, e.g. Silane, Disilane, and Germane, all
flow into the process tube through the Gas Ring.
5.11 Injector: A thin quartz
tube with small lateral ports that distributes dopant gas evenly in the main
process quartz tube.
5.12 MFC: Mass flow
controller that controls individual gas flow rate
5.13 MFM: Mass flow meter that
monitors the actual output of each MFC. All deposition recipes bypass the MFM
path. The MFM is only triggered on for monitoring recipes.
Front Panel
Keypad Description (see Figures & Schematics)
5.14 MENU: Display the main
menu
5.15 NEXT
PAGE: Used when prompted and for certain functions.
5.16 CMD: Used when
prompted and for certain functions.
5.17 RUN: Run a recipe by
pressing this key.
5.18 HOLD: Hold during a
recipe step (stops the recipe).
5.19 EVENT:
Acknowledge
event in recipe.
5.20 BOAT
IN: Manual boat in key.
5.21 BOAT
OUT: Manual boat out key.
Note: BOAT IN and BOAT OUT keys are
toggle switches. If you have either one activated, the IN or OUT action will continue until it is
turned off. However, if both functions/keys are ON at the same time, Tystar20 will be confused and will do nothing!
Therefore, if you wish to manually move the boat out, press BOAT OUT to
start the action, and then press BOAT
OUT once more (to turn if off) when
the boat reaches the open position.
5.22 ALARM
ACK: Silence alarm. This will only silence one alarm condition at a
time. If there is more than one alarm condition, you will have to press the
ALARM ACK key more than once. Alarm
conditions are displayed on the bottom line of the screen.
5.23 ABORT: Aborts the
recipe.
Note: This ABORT key is not the same as on
the Tystar furnaces. DO NOT PRESS THE ABORT KEY TO LOAD THE STANDBY
RECIPE. Excluding a dire emergency (e.g. toxic gas flowing into lab),
there is no need to use the ABORT key. The recipes itself incorporates
the loading/unloading of the boats.
5.0
CLEAR: Clear data input
(i.e., backspace).
6.0 Safety
Follow general safety guidelines in the lab as well as the
specific following safety rules:
6.1
Tystar20 utilizes high electric power
(high amperage) to heat its elements.
Users are not allowed entry in the service chase behind the furnace.
Likewise, Users are not permitted to touch/open any of the side panels on the
furnace that contain dangerous high power components.
6.2
Tystar20 uses several potentially hazardous
gases. Refer to the MSDS for the details of the hazardous gases used
in the furnace.
6.3
Note: Special care must be taken when the process
is aborted and while in deposition step. In some special circumstances, the
process may go into SPECIAL HOLD. In either case, the User should inform
process staff immediately. The process staff will decide whether the process
can be continued and take proper actions to remedy the situation. DO NOT try to open the tube in this circumstance; doing so may result in
exposure to toxic gas !!!
6.4
All furnace recipes
are written by process staff.
6.5
Burn Hazard: Furnace
cantilevers, boats, and wafers come out of the furnace at a very hot
temperature. Users are required to wear
a face shield when loading/unloading wafers. Proceed with caution.
7.0 Statistical/Process
Data
7.1 Microlab network folder C:\homes\equipment\tystar20 has lots of old characterization data.
7.2 Problem and comment section under equipment
section of the wand has a record of process history.
7.3 Jon Goldman computer captures the furnace
data every 30 seconds. Detailed process record can be navigated in its file
folder.
8.0 Available
Process, Gases, Process Notes
Available Processes
8.1
Low temperature (< 450ºC) Si/Ge deposition
(with nucleation step).
8.2
Low temperature (< 450ºC) Si/Ge
deposition (without nucleation step).
8.3
Tube conditioning process using
disilane coating.
8.4
MFC output monitoring process.
8.5
Please contact process staff for other
customized processes.
Available Gases
8.6
Silane (SiH4):
Used for Si/Ge film deposition.
8.7
Disilane (Si2H6):
Used for silicon film deposition in the nucleation step.
8.8
Germane (GeH4):
Used for Si/Ge or germanium film deposition.
8.9
Boron Trichloride (BCl3):
Used for in-situ doping of the deposited film (1% BCl3 + 99% He
used).
8.10 Nitrogen (N2):
Used for pressure control, tube purging, and venting the tube back to
atmospheric pressure.
Process Notes
8.11
Under normal circumstances, wafers that
are to be processed in Tystar20 should be run through the standard pre-furnace
clean procedure (Process
Module 1, Chapter 1.3). However, there are special cleaning procedures when
dealing with metalized wafers (i.e.
wafers that contain any kind of metal). DO
NOT attempt to clean wafers with metal in the piranha baths! Metals are
attacked aggressively by piranha, and furthermore will contaminate the baths in
sink6, sink8, or sink9. Use either of the following procedures for pre-furnace
(Tystar20) cleaning for wafers with metals:
8.11.1 i-line
or g-line resist: Microposit 1165 will strip both i-line and g-line resists that
coat wafers containing metals. A fresh clean bath should be used for each batch
of wafers being cleaned. A DI-water spin rinse and dry is necessary after the
strip clean.
8.11.2 DUV
resist: SVC-14 will strip DUV resists that coat wafers containing metals.
A fresh clean bath should be used for each batch of wafers being cleaned. A DI-water
spin rinse and dry is necessary after the strip clean.
8.12 All
available recipes have a temperature check in the deposition step. If the
deposition temperature is above 450ºC, the process will abort.
8.13 N-type
dopant gas phosphine (PH3) is no longer available in Tystar20.
Phosphine doping requires high temperature annealing for dopant activation and
it also slows down deposition rates significantly.
8.14 P-type
dopant gas diborane (B2H6) is no longer available in
Tystar20 due to injector clogging problem.
8.15 EXPINJ
and EXPGS are gas channels reserved for advanced development. Please consult
supper user if you want to try out new dopant or precursor gases.
8.16 In
order to accommodate more recipes in the furnace computer, the vent and boat in/out
sections have been separated from the process recipe. The BTOUTA.020
recipe will vent and move the boat out and in.
8.17 If
the process locks up unexpectedly at any given step, the User should
contact process staff (or superuser) as soon as possible.
Note: Before venting the tube, it is
recommended that the process step APP1 be initiated and the tube pumped
and purged 3 consecutive times.
8.18 All
the new recipes use 4-letter step ID’s instead of 4-digit numbers. The commonly
used ID’s are:
IDLE IDLE state STRT process STaRT
BPP# Before nucleation PumP # BPG# Before nucleation PurGe #
NTEQ Nucleation Temp stabilization BNPP Before nucleation pump
NGEQ Nucleation Gas EQuilibrium NUCL NUCLeation
ANPP After Nucleation PumP
DTEQ Deposition Temp EQuilibrium BDPP Before Deposition PumP
DGEQ Deposition Gas EQuilibrium DEPO DEPOsition
APP# After deposition PumP # APG# After deposition PurG #
WAIT WAITing for user’s action (event)
ABRT ABoRT sequence SHLD Special HoLD
9.0 Overall
Furnace Operation
9.1 General
Information and Menu Key Pad Explanation
The Tystar20 furnace operates as a
stand-alone unit. The menu driven display in front of the furnace can be used
to initiate command sequences for recipe load, run, and view operations. The EVENT
key replaces the old ACK key (Tystar furnaces) to bypass a particular
process step. Load and unload functions are built into the body of recipes.
Therefore, do not use the ABORT key to load and unload boats. The ABORT key will abort the process and
should only be used in emergency cases. The large red and green buttons located
under the console should not be used. These buttons control the off/on power to
the cabinet.
9.1.1
Recipes can be selected and initiated
through the main menu. The main menu can be brought up from any screen by
pressing the MENU key.
9.1.2
The following lists the main menu
selections:
D - display
R - recipe
G - graphics
H - host computer
C - configuration
X - diagnostics
TI - time, date
PW - password
9.1.3
Press the desired letter, then press ENTER.
A sub-menu will be displayed on the screen.
9.1.4
Press firmly on the front panel keys, and
then confirm your action by viewing the display screen before pressing other
keys. The only relevant sub-menus to the User are D (display), R
(recipe), and G (graphics).
Do not attempt to use any other sub-menus or commands. They are not
relevant, and may cause the system’s computer to lock up.
9.2 Available
Recipes
There are several process recipes available on this furnace.
Process staff should be consulted whenever a new recipe is needed. The Jon
Goldman computer is used for setting up new recipes. Users should NEVER upload a recipe from the menu
driven terminal to the Jon Goldman computer.
Note: Each of the low temperature recipes will
abort if the temperature exceeds 450ºC.
Note: Printouts of recipes are
located in the Tystar20 drawer in the cabinet near the furnace
9.2.1
BTOUTB.020: To vent and
open/close the tube.
9.2.2
SIGESTNC.020: Standby recipe to
keep the tube under low pressure and constant temperature. A tube conditioning silicon coating process, with duration
of 5 minutes, is built into this recipe. Furthermore, An optional 20-minute
silicon coating is also available in this recipe.
9.2.3
SIGEBCL3.020: Low temperature Si/Ge process. All parameters,
including temperature, time, pressure, and gas flows, are variable inputs for
both the nucleation and deposition steps.
9.2.4
SIGENONU.020: Same as SIGEBCL3.020
except no nucleation step.
9.2.5
MULLA.020: Same as SIGEBCl3.020,
but with the option of depositing 12 different layers.
9.2.6
MONVAR.020: MFC monitor
process with variable gas flow input. For process with critical Si to Ge ratio
control, users are advised to run the monitor recipe and keep a record of
actual MFC output for future reference.
MFC output of individual recipe is measured with a mass flow meter
(MFM). If the MFC drifts over time, the deposition recipe can be corrected
based on the MFM data for better repeatability.
9.2.7
MONCON.020: MFC monitor
process with fixed gas flow input. Super user will run this recipe weekly for
statistical control.
9.3 Processing
a Run (Loading recipe and wafers)
Venting the tube and Run a Process
Recipe
Note: When
there is no deposition being processed in Tystar20, SIGESTNC.020 is the default
standby recipe that is required to be run by all Users. There is a specific WAIT step at the end of this standby
recipe, and it is important that all Users observe parameters within this step
before loading their recipe.
9.3.1
When SIGESTNC.020 is in the WAIT step Users are required to record
several parameters: (1) The measured injector pressure (red LED panel located
below the Tystar20 display screen); (2) the parameter PRCPR (process chamber pressure); (3) N2DOPE (Nitrogen flow through injector), and (4) TEMPS (measured temperature at source
end of tube). Each user is responsible for reporting standby conditions in the
problems/comments section in the Microlab data base upon disabling the furnace.
This data is used for injector monitoring.
9.3.2
After recording the parameters required
from the SIGESTNC.020 WAIT step,
press EVENT to advance to IDLE state.
9.3.3
Skip to 9.3.10 if wafer loading is not
necessary.
9.3.4
Press MENU then RL. Use the arrow keys to highlight the BTOUTB
recipe and press ENTER twice to load
it. It does not require any parameter input.
9.3.5
Press MENU, then DS, then ENTER to show the status page. Make sure the BTOUTB recipe
is loaded and is at IDLE state.
9.3.6
Press RUN to start the venting
process. The tube requires 10 minutes to vent to atmosphere pressure. When the
venting process is completed, the recipe advances to the WAIT step and
the alarm will sound. The Alarm
Ack key will silence the alarm.
9.3.7
CAUTION: Before wafers
are to be loaded into Tystar20, they must have been properly cleaned. Refer to Section 8.11
for instructions on cleaning wafers.
Failure to follow proper cleaning procedures can cause severe contamination
problems within the furnace. Users that fail to follow the proper pre-furnace
cleaning procedures for Tystar20 will be promptly disqualified.
9.3.8
Press the EVENT key. The door will open, and remain
open for 20 minutes for the User to load/unload wafers. The door will
automatically begin to close after 20 minutes. If the wafers cannot be
loaded/unloaded within the 20 minute time frame, press the EVENT key
while the door is closing. The door will then reopen for another 20 minutes.
9.3.9
After loading/unloading the wafers, press
the EVENT key to close the door. Wait until the door closes completely
and the process advances to IDLE state.
9.3.10 Press
MEMU and RL and the screen
will show a list of the available recipes. Use the arrow keys to highlight the
recipe you want to load, then press ENTER twice.
9.3.11 Depending
upon the recipe selected, the User may be prompted by the computer to enter
specific process parameters (temperature, pressure, flow, etc.) Enter the
desired values if prompted, even if they are already shown as the default
parameters in the display.
9.3.12 Use
the Clear key to erase a wrong value entered.
DO NOT USE THE ARROW KEY TO MOVE THE CURSOR! This will cause the
software to crash and all programs will be lost.
9.3.13 Time
is entered in the format HH.MM.SS. Press ENTER
after typing each process variable value. Do not enter 00.00.00 since this will
hold the process at the respective step indefinitely.
9.3.14 Once
finished entering all of the required values, press MENU, then DS
to check that the recipe loaded properly. Press RUN to start the
process.
9.3.15 If
the process completes successfully, it will hold at the WAIT step. The
tube is then automatically purged with Nitrogen and held at low pressure and
350ºC. Press EVENT to end the recipe.
9.3.16 Refer
to Sections 9.3.4 through 9 to unload wafers.
Note: All slots of each boat should always contain
either a dummy wafer or a process wafer. Users are required to reload all dummy
wafers into the boats when finished processing.
9.3.17 Load
and run the SIGESTNC recipe.
9.3.18 MANDATORY: When disabling
the furnace on the Microlab WAND, enter into the comment section the following
previously recorded parameters during the SIGESTNC.020
WAIT step (see Section 9.3.1):
The measured injector pressure, PRCPR,
TEMPS, and N2DOPE. Also, make sure to enter process gas flow, pressure,
temperature, and duration of the deposition step. Finally, enter comments on
the resultant film – i.e. color, resistivity, anything unusual etc.
Troubleshooting
9.3.19 The
process will advance to the WAIT step if an equipment problem occurs
before the flow of process gases can begin. Always use DH (Display
History) to check whether your process completed successfully. If not, follow Sections
9.3.4 through 9 (Venting and Loading/Unloading
Wafers) to unload your wafers (and reload dummy wafers back into the boats).
Lastly, report a fault on the WAND.
9.3.20 If
the some of the process parameters exceed the tolerance set by the recipe, the
process will advance to the ABRT or ABPG step. Call process staff
to see whether the process can be continued.
9.3.21 If
there is an equipment problem, e.g. pump is not working, the process will
advance to the SHLD step. Inform process/equipment staff immediately,
since there may be hazardous gases in the furnace.
9.4 Viewing
the Content of Available Recipes on the Menu-Driven Display
9.4.1
Refer to the recipe book for the process
details. Recipes are also displayed by typing DR from the main
menu.
9.4.2
The desired recipe can be chosen from a
menu by using the arrow keys and pressing ENTER twice.
9.4.3
All the recipe steps are composed of a
4-letter identification, instead of a 4-digits number, to better describe the
step. For example: BPG1 stands for before deposition purge #1. For details of
the step identification, check the comment of the step in the recipe.
An example of the DS process status display is shown in the
appendix. Use this display to monitor your runs. The display will update automatically. There
is no Tycom monitor connection for automatic and/or remote monitoring. One
cannot display the process status through the (E) equipment Communication
option on the WAND.
The following is a description of the process status display (for
a complete display of a typical recipe status, refer to the appendix):
9.5.1
The top line gives the present recipe, i.e.,
SIGESTNC.020 in this example.
9.5.2
MODE can be RUN,
HOLD, IDLE, END, or ABORT. In particular, make sure you check the screen
before pressing the EVENT key twice, since there will be a small time
delay.
9.5.3
END gives the time remaining
in the recipe, assuming no looping occurs.
9.5.4
STEP gives the
present recipe step. You can display
recipes for descriptions of each step.
9.5.5
ST_TTG gives the time
remaining in the present step.
9.5.7