Chapter 6.02
Novellus m2i Sputtering System
(novellus)
1.0
Title
Novellus m2i Sputtering System
2.0
Purpose
This document provides specific operation and process information
for Novellus m2i sputtering system. This is a modular system (cluster tool)
capable of sputtering metals on both six-inch and four-inch wafers (specially
made six-inch pocket wafers are available at the station, which can be used for
4-inch wafer processing).
3.0
Scope
This chapter provides general machine description, operational
procedure, process recipes, and safety consideration for the Novellus m2i
Sputtering System. Physical Vapor Deposition (PVD) process is used to sputter
metal on to the target wafers (dielectric materials such as SiO2 are
allowed only with special permission or training by Joe Donnelly). Process
module/s in the system can be evacuated at very low pressures level (10 -8 torr), which provide a very clean environment for deposition of a
good quality/pure film (PVD process). It is very important to introduce clean
wafers into the system. Proper degas step (certain recipes) have to be applied
to prevent process/tool contamination. ABSOLUTELY NO PHOTORESIST, POLYIMIDE
and/or other organic coated wafers are in this system. Up to five different
layers of films can be deposited by each process recipe and by routing the
wafers through a set of desired process modules.
4.0
Applicable
Documents
Novellus advanced sputter process application book, available at
the station. This can be used as process
recipe guideline for superuser/ trained staff, only.
5.0
Definitions and
Process Terminology
5.1
Physical
Vapor Deposition (PVD) process: Solid
source material bombardment with energetic gaseous ions formed in a plasma
produces constituent atoms, which will go through a low-pressure gas phase, and
ultimately condense on the substrate (wafer).
5.2
Mean
free path: the distance that any particle can travel before colliding with
another one.
5.3
Sputter
etch (R.F.) prior to metallization: in-situ method of pre-cleaning/desorbing
the wafer surface just prior to metallization process, essential to metal
deposition over contacts / vias.
5.4
BSA:
Backside Argon pressure (default for this value is 0 –disabled).
5.5
DCM: Dual Cassette Module
5.6
TM: Transfer Module
5.7
PM: Process Module
5.8
WHC: Wafer Handling Chamber
6.0
Safety
6.1
Wear gloves while working at the station
to prevent process modules/wafer contamination.
6.2
Wear safety UV goggles (orange goggles in
the novellus room) when working with the UV lamp.
7.0
Statistical/Process
Data
N/A
8.0
System
Description, Process Notes and Available Processes
8.1
System Description
8.1.1
The Novellus m2i is a modular sputtering
tool with an Automation and Control Enhancement (ACE) component, which can
communicate with controllers of various process modules (PCs), as well as
transfer arms, and ultimately coordinates their actions. Wafers are loaded into the tool via a dual
cassette module (DCM). Two load locks (DCM), one wafer degas station, and a
cooling station are positioned in module A1. A small robot arm moves wafers
between these stations. Process modules PM1 through PM5 are designated in
modules A2-A6 of the machine. A transfer arm located in Transfer module (TM)
moves wafers in and out of the process modules, and the A1 module position for
desired processing sequence. See Figure 1 (Section 11.0)
for more details.
8.1.2
Module names and corresponding power
supplies are listed in Table 1. Different recipes may call for different power
settings, and sputter gas flow (argon). There is a Status board mounted
above the loadlocks indicating the material power supply setting and
status of module
|
Module Position |
Module Function |
Power Supply |
|
|
TM |
A0 |
Transfer module,
which housed the transfer arm |
N/A |
|
DCM |
A1 |
Dual Cassette
Module with Degas & Cool Stations |
N/A |
|
PM1 |
A2 |
Advanced
Magnetically Enhanced (sputter) etch |
1 KW AC (60 MHZ) |
|
PM2 |
A3 |
Deposition of
Al / 2% Si (or Al) |
12 KW DC |
|
PM3 |
A4 |
Deposition of
Ti/TiN |
6 KW DC |
|
PM4 |
A5 |
Deposition of
pure Al/ALN (or Al/2%Si) |
3 KW DC |
|
PM5 |
A6 |
Deposition of
various material (research module) |
3 KW DC |
Table 1 - Module
Configuration
8.2
Process Notes
8.2.1
Standard (Specific) recipes are available
and maintained by staff, as noted in Table 2 below. Do not alter standard
recipes, as they are set for a specific target thickness (fixed deposition
time). Special recipes can be defined by the user.
8.2.2
PVD system requires a low-pressure vacuum
environment void of unwanted reactive gases or moisture to produce a good film
quality. Appropriate DEGAS step is used to minimize wafer outgassing/moisture
from wafers’ surface prior to sputtering step. BPSG, PSG, and TEOS on a wafer
can absorb moisture from the ambient, hence require degas step prior to
deposition process.
8.2.3
Argon gas is used for target sputtering
(non reactive sputtering gas).
8.2.4
Reactive deposition can be used for deposition
of compound films such as aluminum nitride (AlN) and titanium nitride
(TiN). N2 (reactive gas) is
introduced into the sputtering chamber in addition to sputtering gas (argon
plasma), and the compound is formed by the N2 element combining with
the sputtered material (Al or Ti). Oxygen can also be used for specific
compound/target materials (Hafnium or Si), which are not part of the standard
processes offered at this time. Staff needs to be consulted for non-standard
(special application) processes.
8.2.5
PVD processes at elevated temperatures
above 400°C are not allowed
and could severely impact process module’s hardware (gaskets & seals).
8.2.6
Changing the target power supply can be
requested by sending an email to Joe Donnelly (donnelly@eecs). The target power
supplies can be changed from 3kW, 6kW to 12kW DC for process modules PM2 to
PM5.
8.3
Available Processes/Recipes
8.3.1
Degas
station: to reduce the water vapor on surface of the wafers, prior to moving
them into the etch module. This is highly recommended before any deposition
step.
8.3.2
Advanced ME Sputter Etch station: to
remove native oxide from the bottom of vias or contacts, so that the metal to
substrate ohmic contact can be achieved.
8.3.3
Process
Modules: to sputter target material/s on the wafers.
8.3.4
Cool
station: to cool finished wafers, before they get loaded back into the
cassette.
8.3.5
Standard process recipes with appropriate
degas, sputter process and cooling steps have been developed, which are listed
in Table 2 (Note: Standard recipes names have STD suffix).
|
Description |
|
|
AL7KSTD |
Standard 7000A
thick aluminum recipe with pre-metal sputter etch step |
|
AL10KSTD |
Standard 10000A
thick aluminum recipe with pre-metal sputter etch step |
|
TI300STD |
Standard 300A thick
titanium recipe with no pre-metal sputter etch step |
|
TI1KSTD |
Standard 1000A
thick titanium recipe with no pre-metal sputter etch step |
|
TiN1KSTD |
Standard 1000A
thick titanium nitride (TiN) recipe with no pre-metal sputter etch |
Table 2 -
Standard process recipes (Novellus m2i)
9.0
Equipment
Operation
ABSOLUTELY NO PHOTORESIST, POLYIMIDE AND/OR OTHER
TYPE ORGANIC WAFERS ARE ALLOWED IN THIS SYSTEM. Evaporation of
such material inside a PVD system can easily trash cryogenic pump/s, and critical
parts of the machine, extremely expensive to replace.
The Novellus m2i Sputtering System can be logged onto at four
different security levels. These are service, supervisor, lead operator and
operator levels. Qualified users are only allowed to operate the system in an
operator mode. This system utilizes two load stations; currently the left one
is not functional. Wafers get loaded/unloaded in and out of the system in
exactly the same cassette slot they started from in an automated mode (operator
mode).
9.1
Main screen (Touch Screen)
9.1.1
A simplified version of this screen is
shown in Figure 1, which has three parts; machine
status, bottom menu bars and operational buttons.
9.1.2
Menu options at the bottom of the main
screen can be used to toggle between Operations, Recipe, Service, Alarm and
Login screens.
9.2
Logging in
9.2.1
Enable the machine using machine name novellus.
Failure to enable the machine will not allow the load locks to pump up to
atmosphere.
9.2.2
You should not have to login to the
machine. Most users leave the machine on the Main Operation page, where you can
see an overview of all the modules. You can select Operations menu if you are not on this page.
9.2.3
Set your desired process module(s) to be
controlled by the front computer (remote). Click on the Service screen, and select the Set
Module Control button. The transfer module (TM), the dual cassette module
(DCM) and your process module(s) should be in remote. If it is not, select the
specific module(s) to change the local control to remote control.
9.2.4
Check the Alarm screen by touching the alarm button. You can always get back
to the main menu or previous screen by touching the Operations button.
If there are red alarms, report on faults. Experienced users may be able to
clear certain alarms, providing they know how to fix the problem. No operations
can be started without a clear alarm page.
9.2.5
If there are no red alarms displayed on
the screen, proceed with loading your wafers.
9.3
Wafer loading
9.3.1
Make sure that novellus is in
a good working order, and before selecting/running your recipe. Specific
information on different modules can be displayed from the Main Operations screen shown in Figure 1, top screen. Using the provided mouse, click the
desired machine component (module) displayed on the screen, and check the
screen for more detailed information. Select Operations button to go back at any time.
** Note: Left
load lock is not available for processing at this time. Do not use it
9.3.1.1 Make sure the Cryogenic pump
temperature is less than 20 Kelvin. Report it as fault if temperature if it is
above this value, and if machine does not allow you proceed with your run
(Cryogenic pumps may need to be regenerated by staff).
9.3.1.2 Make sure base pressure is
within specific rage defined by the recipe.
9.3.1.3 Before
loading wafers, put on latex gloves and use tweezers, provided for you near
novellus. If there are no gloves, check them out of the Microlab supply office.
9.3.1.4 To
load wafers, click Move Wafer from
the Main Operations screen. You should now be in the Operations Move Wafer submenu. Click Unload Right Cassette. OK
the box when it asks “Are you sure?”
Wait a few minutes and try opening the door (do not use too much force).
The door will easily open when the load lock is at atmospheric pressure.
9.3.1.5 Inspect the load lock for
particulates. Wipe clean, if necessary..
9.3.1.1 Load
the wafers in the cassette.
9.3.1.2 Load
the cassette back in the load lock (H-bar faces down). To reload the cassette,
click Load Right Cassette from the
Operations Move Wafer submenu. OK
the box when it asks “Are you sure?”
9.3.1.3 The
wafers will be loaded when you see them represented by orange lines in the
cassette on the screen (takes a few minutes).
9.4
Recipe editing, writing and loading
9.4.1
Click on the Recipes page. You should see the list of process modules on the
left and a list of recipes on the main page. If you see only one specific
recipe, click Recipes to return to
the main Recipe page.
9.4.2
Click on the process module that your
recipe will be used in. Pick a recipe that you can edit. Do not save over this
recipe. If you need to define your own recipe, save it under a different name.
9.4.3
Click whichever parameters you want to
alter. A number pad will pop up on the screen, and you can input variable
temperature, pressure, deposition time, pre-heat times, etc.
9.4.4
To save your recipe, press the Save As… button. A keyboard will pop up
on the computer screen, so you can enter your own recipe name.
The
following steps are needed to when running in automatic mode. You will need to
define a process recipe, wafer route and cassette route.
9.4.5
Click on the wafer module in the main Recipe page. Define a wafer route, by
clicking on the degas chuck and specifying a degas recipe. Then click on your process module(s) and
specify the process recipes. Lastly, click on the cool station and specify a
cool recipe.
9.4.6
To save your wafer route, press the Save As… button and name your wafer
route recipe name.
9.4.7
Click on the cassette module in the main Recipe page. Define whether to fill up
the cassette with wafer route or single cassette slots with wafer route by
choosing Single or Fill.
To save your cassette recipe, press the Save As… button and name your cassette recipe name.
9.5
Running a process in
manual mode
9.5.1
Return to the main Operations screen.
9.5.2
Click on the desired process module(s) and
select Startup Module. This starts
the Argon flow into the chamber. You can choose the recipe you will want to run
when the box pops up. Select Continue.
9.5.3
When the process module is ready, return
to the Operations screen. Select the
Operations Move Wafer screen.
9.5.4
Select Move Wafer. The screen will ask you to select the source of the
move. Select the wafer that you want to process.
9.5.5
The screen will then ask you to select the
destination of the move. Select the desired process module. Click OK
when it asks “Are You Sure?”
9.5.6
After the wafer has been moved to the
desired chamber, you can return to the main Operations screen. Click on the process module itself. Then click
the Run Process button. A box will pop
up, and you can select the desired recipe. Select View Recipe to double check that the correct recipe has been
chosen.
9.5.7
After the film has sputtered, return to
the Operations Move Wafer submenu.
Select Move Wafer, with the source
being the process module and the destination being the cool station. Select
[none] or a standard cool recipe in the popup box.
9.5.8
For films processed above 100oC,
you need to let the recipe cool for at least 1 minute. For processes above 300oC, you
should wait at least 5 minutes.
9.5.9
After the wafer has sufficiently cooled,
select Move Wafer and return the
wafer from the cool station to the desired wafer slot.
9.5.10 After
processing all your wafers, return to the process module page and Shutdown Module so you don’t waste
Argon gas.
9.6
Running a process in
auto mode
9.6.1
Return to the main Operations screen. Select Start Auto.
9.6.2
Select recipe from right load lock column
(L-LL) by selecting the desired recipe displayed on the list, followed by OK. It is highly recommended to check
recipe content, before running the process. Make sure that recipe has not been
altered in any way; to include deposition time (see Standard Recipes, 12.1 and
12.2, at the end of this chapter)
9.6.3
The machine will ask you if you want to
skip the vent of the load lock. Select yes.
The machine will then ask if you want continuous processing of the
cassette. Select no. There may several
minutes of delay time, before wafers actually start moving in. Machine will
need a little time to startup the module, and reach module temperature setting,
stabilize and perform the necessary pumping sequence.
9.6.4
Monitor your process/machine status
through the operation screen. If process halts, check the alarm status page,
and report problems as necessary. You may try to Resume Process if the alarms are cleared.
9.6.5
Remove your wafers from the load lock
through the Operations Move Wafer
page after the process is finished.
9.7
Removing wafers after the process in
manual mode
9.7.1
When your
process is done and all the wafers have been returned to the cassette slots,
you can return to the Operations Move Wafer screen. Select Unload
Right Cassette, and then the OK button.
9.7.2
Similar to
loading wafers, wait until the load lock has been vented to atmospheric
pressure. Unload your wafers, remembering to wear latex or nitrile gloves and
to use tweezers.
9.7.3
You can pump the
right load lock again by selecting Load Right Cassette, and then the OK
button.
9.7.4
After the load
lock has pumped down, return to the main Operations screen. Then click
on the process module(s) that you used. Select the Shutdown Module. Disable novellus.
9.8
Operation Procedure for
DUV-Oxidation in Novellus Machine
See Section 12.3
of the Appendix.
10.0 Troubleshooting
Guidelines
10.1 Load
Lock Vent problem
10.1.1 Make
sure you have enabled the machine. Report the problem, if it is still not
venting.
10.2 Sputtered
Film Quality (haze)
10.2.1 Presence
of moisture on the wafers or reactive gases in the process modules could result
in haze. Degas step and processing couple of dummy wafers ahead of the run can
get rid of the moisture and residual reactive gases in the chamber. Check the
recipe and make sure that it has not been altered/modified (skipping the degas
step). Check process temperature in the status screen for that particular process
module as well. These steps should alleviate the problem; if not, report as
fault. There may be other factors/issues involved for the staff to check.
10.3 Issues
Ti or Aluminum Film Quality
10.3.1 Make
sure to send a couple of dummies ahead of your process wafers for an aluminum
process run, which is following an aluminum nitride (AlN) run/step OR Ti
process following a TiN run/step (PM2
and PM3 modules, respectively). Presence of reactive gas such as N2 from a
previously run process can impact Al or Ti film quality.
10.4
Fault Recovery
10.4.1
Report all problems on FAULTS.
10.4.2
Do not delete an alarm if it occurs during wafer handling or
processing, and do not try to resume operation; your wafer might be shattered.
10.4.3
Alarms members can recover:
10.4.3.1
Chamber not in Remote: Go to service screen and set
module to remote.
10.4.3.2
Source out of Regulation: Try to restart process. If it
doesn’t restart, report on FAULTS.
10.4.3.3
Arm, Cassette, Iso valve need to be initialized: Go to Service screen and
initialize robot feature if needed. If it fails, report on FAULTS.