Chapter 6.28
P5000 TEOS PECVD & ThCVD System
1.0
Title
P5000 is a sub-atmospheric pressure, TEOS plasma enhanced/thermal
chemical vapor deposition system.
2.0
Purpose
Precision 5000 (P5000) is a single wafer, multi–chamber chemical vapor
deposition (CVD) system capable of depositing conformal TEOS oxide, and/or
etching back, oxide in a separate chamber. This system is a 6” processing tool,
however 4” wafers can be processed via carrier wafers in it. There are four
chambers available on this tool (Chamber A through D); Two oxide deposition
(TEOS) chambers, and two oxide etch chambers. One pair of oxide deposition /
etch chamber is designated to MOS clean processing, and another similar pair to
Non-MOS processes. Combination of oxide deposition and proper etch back steps
can be used to produce smooth dielectric layers for multi metal layer process
(es).
3.0
Scope
This chapter covers general P5000
description, available process recipes, general operational procedure to
include; loading/unloading wafers, and performing required chamber clean, after
depositing oxide in the TEOS chamber. Process status monitor, user level
problem diagnosis, and chamber/wafer cleaning requirement are also included in
this chapter.
4.0
Applicable Documents
4.1
Precision 5000 CVD by Applied Materials, December 1988 edition1
(copy in office).
4.2
SACVD hardware and process on Applied Materials P5000 (ThCVD copy
in the Office)
4.3
Material Safety Data Sheets (MSDS forms) for TEOS, TEB, TEPO, C2F6,
CF4, oxygen, ozone, argon, and helium are all available in the blue
binders (lobby).
5.0
Definitions & Process Terminology
5.1
MOS Clean process: This kind of process is used for
fabrication of MOS clean devices (IC), whose performance can be greatly
impacted by traces of contaminants. MOS clean wafers shall only be processed in
the MOS clean chambers of the P5000 machine.
5.2
Non-MOS clean process: This kind of process is used for the
fabrication of non-MOS or MEMS type of devices. Non-MOS clean wafers may
contain materials that are not compatible with MOS processes, should be
confined to the non-MOS clean chambers of the P5000 machine. Failure to do so
can result in cross contamination of the MOS clean chambers, hence severely
impacting the electrical/parametric behavior of fabricated IC/transistor devices.
5.3
PECVD: Plasma enhanced chemical vapor deposition, using oxygen (O2)
and plasma.
5.4
ThCVD: Thermal chemical vapor deposition, using ozone (O3).
5.5
USG: Undoped silicate glass, similar to undoped LTO from Tystar11 and
12.
5.6
PSG: Phosphosilicate glass, similar to phosphorous-doped LTO from
Tystar11 and 12.
5.7
BSG: Borosilicate (boron doped) glass is a boron doped oxide film.
5.8
BPSG: Phosphoborosilicate glass is a boron plus phosphorous-doped oxide
film.
5.9
Step Coverage: Ratio of the vertical
to the horizontal part of a deposited film over a step. A conformal film
deposition over step has step coverage equal to 1 (100%).
5.10
TEOS: Tetraethylorthosilicate (C8H20O4Si),
a liquid source for oxide deposition process.
6.0
Safety
Follow general safety guidelines in the lab as well as the
specific safety rules as per follow:
6.1
Electric Shock, RF, UV/Visible/IR Radiation, and Burn Hazards: A user, without
the supervision of Microlab staff, should not enter the backside mechanical
room of the P5000 machine to avoid electric shock, UV/IR radiation and burn
hazards.
6.2
Chemical Hazard: All the gases/liquid sources used in
P5000 are toxic and flammable. If there is a leak detected, evacuate the room
immediately. Refer to the MSDS for first aid procedures.
6.3
Pinch Hazard: The door and the wafer cassette handlers operate automatically.
Use caution when loading/unloading cassettes to avoid being pinched by them.
6.4
P5000 is a fully computerized tool. The system configuration is
complex. Users are not allowed to create new recipes, or modify existing ones
without the supervision of a Microlab staff.
7.0
Statistical/Process Data
7.1
Problem and comment section under equipment section of the wand.
7.2
Enable message for Applied P5000 machine.
8.0
Available Process, Gases, Notes
Available Processes:
Only Chamber B
(TEOS) and chamber D (etch back) are released at this time. Chambers A & C
have some hardware issues, are not released yet. We have undoped oxide, as well
as boron and phosphorous-doped oxide processes available in the TEOS chamber B.
There are total of six standard recipes available at this time for doped and
undoped oxide categories. These are half -micron, and one-micron recipes for
each type of recipe (undoped, phosphorous doped, and boron doped). Should you
need a different film thickness consult with Staff to set your up with special
application recipe/s.
8.1
B-PE-USGX.X: Undoped TEOS PECVD recipe, where X.X is film thickness in micron.
8.2
B-PE-BSGX.X: Boron doped TEOS PECVD recipe, where X.X is film thickness in
micron.
8.3
B-PE-PSGX.X: Phosphorous doped TEOS PECVD recipe, where X.X is film thickness
in micron.
8.4
B-CLNX.X: A clean/coat recipe used for cleaning/pre-coating the TEOS
chamber, after X.X micron of oxide film has been deposited in the TEOS chamber. A
properly timed etch/coat recipes is linked to all of our standard undoped/doped
oxide deposition processes (8.1, 8.2 and 8.3 above) to automatically
cleans/seasons the chamber for the next wafer to arrive. It is very important
that each time a deposition process is completed, excess film get entirely
removed from the chamber wall, and the area adjacent to susceptor (stage).
Failure to do so, will eventually form a thick layer of oxide film on the
chamber wall, which will be hard to remove, and can easily alter TEOS process
characteristic. Note, before etch/pre-coat steps begin, wafer is automatically
removed from the chamber, send on its way to load lock (receive cassette). Etch
step will then be performed to remove all deposited oxide film left behind by
the previous deposition step. Finally, a short deposition (pre-coat step) is
done to season the chamber, again to ensure good performance during the next
oxide deposition process (next wafer in line).
Available Gases/Chemicals:
8.5
TEOS (tetraethylorthosilicate, (C8H20O4Si):
A liquid chemical whose vapor is used to supply SiO2 for all TEOS
processes.
8.6
TEB (triethylborate, (C6H15BO3): A liquid
chemical whose vapor is used for in-situ boron doping.
8.7
TEPO (triethylphosphate, (C6H15O4P):
A liquid chemical whose vapor is used for in-situ phosphorus doping.
8.8
Helium (He): Used as a carrier gas for TEOS, TEB and
TEPO.
8.9
Oxygen (O2): Used in the PECVD processes to oxidize the
carbon/hydrogen attached to TEOS, TEB, and TEPO. Also used in the chamber
cleaning processes.
8.10
Ozone (O3): Used in the ThCVD processes. It oxidizes
carbon/hydrogen attached to TEOS, TEB, and TEPO without using plasma. The ozone
is generated from oxygen augmented by a small volume (~5%) of N2 via
an electrical discharge in the ozone generator cells, part of the P5000
hardware.
8.11
Hexafluoroethane (C2F6): Used in the
smoothing etch back process, and chamber cleaning.
8.12
Argon (Ar): Used for the sputter etching in the planarization
process.
8.13
Carbon Tetrafluoride (CF4): Also used for the sputter
etching in the planarization process.
Process Notes:
8.14
TEOS CVD oxide exhibit more conformal step coverage than
silane-based films, e.g. higher than the LTO film from Tystar11and 12, because of the higher mobility of the adsorbed
TEOS molecules used in the P5000 set up. Oxide film step coverage is
approximately 50% for the PECVD process, and 100% for ThCVD (better coverage),
according to P5000 equipment manufacturer (Applied Materials).
8.15
A CVD chamber etch (isotropic)/pre-coat recipe should be run after
each TEOS deposition to completely remove deposited oxide from the chamber, and
return it to a clean state, prior to introducing the next wafer. Each of our
standard TEOS deposition recipes includes such clean/coat sequence (proper etch
time used), after the oxide (TEOS) deposition step.
8.16
Planarization or smoothing etch process can be
performed on deposited TEOS film over high topography (steps) in etch chamber C
or D. This is anisotropic oxide etching process, which uses argon sputtering to
reduce the top step angle of the deposited oxide. Addition of low percentage of
CF4 (reactive sputter) reduces wafer temperature, and aids in
chamber cleanliness.
8.17
We have three PE TEOS processes: USG (undoped silicate
glass), PSG (phosphorous doped glass), and BSG (boron doped silicate glass)
available on this tool.
8.18
For special application recipes, make sure that each
time TEOS deposition is performed a PROPERLY TIMED clean/coat step will
follow. This is very important, as you may have different deposition
time/deposition rate, as compared to standard recipes, and that you cannot use
exact copy of clean/coat steps utilized in other recipes. You will most likely
need to make some modification. Finally, your recipes will need to be reviewed
by staff.
8.19
Six-inch pocket wafers can be used in P5000. Makes
sure to HF dip clean the pocket wafers, after few depositions, to ensure
uniform film thickness/ good film quality on your 4” wafers.
9.0
P5000 Operation
9.1
System Description
The P5000 (Applied Materials Precision 5000) is a fully automated,
single-wafer, multi-chamber system (see Figure 11.1). The automatic cassette-to-cassette loader and multiple
process chamber capability maximize system throughput. The automatic load lock
system minimizes operator wafer handling and reduces wafer contamination.
The cassette handler vertically aligns the cassette to
the load lock chamber load port. This allows wafers to be easily transferred
from the cassette to the load lock chamber and from the load lock to the
cassette. The handler can hold two cassettes: Cassette A on the left and
Cassette B on the right.
The load lock chamber isolates the process chambers
from atmosphere during wafer transfers. The robot is located inside the load
lock chamber. The robot transfers the wafer between the cassette handler,
storage elevator, and process chambers.
A metal wafer storage elevator is mounted inside the
load lock chamber. The storage elevator is the staging point for all wafer
transfers to and from the load lock chamber. The elevator holds the wafers in
position until the system allows the wafer access to the process chamber.
Processed wafers are returned to the storage elevator before they are returned
to the cassette.
The process chambers are where processing occurs.
There are four process chambers available on this tool. The chamber positions
are referred to as positions A, B, C, and D.
The operation is controlled by the pushing the buttons
on the mainframe front face (Figure 11.2) and
the pull-down commands on the touch screen CRT using a light pen (Figure 11.3).
9.2
Wafer Cleaning Requirements Before Loading Into P5000
9.2.1
Photo-resist on the wafer surface must be stripped first in PRS3000
bath of Sink5, Technics-c, or Matrix. Then cleaned in Sink8 (both 4” and 6”) piranha bath.
9.2.2
Wafers with aluminum films on them can only be processed in the
Non-MOS clean set of chambers.
9.2.3
All wafers will need sink6 clean, as their last cleaning step
prior to TEOS deposition (piranha and short HF dip). Non-MOS clean wafers will
need an additional sink8 clean (piranha and short HF dip) prior to sink6 clean,
before going into P5000 machine.
9.2.4
Wafers just unloaded from a MOS clean furnace can be processed
through MOS clean side of P5000 without any cleaning, provided that they have
been transferred in a dedicated MOS clean box (transfer box) from the lab.
Conversely wafers just unloaded from a non-MOS clean furnace can go straight
into the non-MOS chambers of P5000 without any cleaning.
9.3
Processing a Run in the P5000 Machine
Check System Availability
9.3.1
Enable the P5000 on the WAND.
9.3.2
Check on the top of the CRT; make sure the process chamber you are
planning to use is displayed as a blue rectangle on the computer screen
(automatic mode). All the other colors will indicate different status, which
prohibits members from using that particular chamber. See Figure
11.3 and color explanation in Section 12.4 in the
Appendix.
9.3.3
Click with light pen on the WAFER header on the screen.
Select Monitor Wafer command. The [Monitor Wafer Screen] will be
displayed (Figure 11.4).
Make sure that all the chambers are idle and there is no wafer in the system.
9.3.4
Touch the SYSTEM header and select Control System
command. The [System Control Screen] will be displayed (Figure
11.5). Make sure Vacuum Operation
and Normal Wafer Process are on the System State line and the Sequencer
State is in idle mode.
Load Recipe/Wafers
9.3.5
On the [System Control Screen] in Figure 11.5,
change the system state from Automatic to Manual by clicking on
this field and toggling its state o manual.
9.3.6
Touch the WAFER header on the CRT with light pen, and
select the Monitor Wafer command (Figure 11.4). On
the [Monitor Wafer Screen], Click the Open Door and the door to
the cassette handler will open.
9.3.7
Click Release A or Release B to unclamp the cassette
you plan to use. The option changes to Clamp A or Clamp B after
you click it.
9.3.8
Remove the cassette and load your wafers starting from slot one
and up. All the wafer flats should face toward the tool. If you used option 2
in Section 9.3.6, you must match the slots of the lot
name entered, with the corresponding wafer to be processed.
9.3.9
Put the cassette back into the cassette handler
chamber. Make sure the H bar of the cassette sits in the grove of the
cassette seat, and that no wafer extrudes out of the cassette. Wafers not sitting
all the way back in their cassette slots will cause wafers transfer
error/problems, may even break in the chamber. Should they make it to TEOS
process chamber, most likely will be placed off centered on the chuck, hence
get non-uniform film deposition. Avoid all these problems by making sure to
push back all the wafers in the cassette, and gently placing it back on
cassette seat. Repeat the process, if necessary.
9.3.10
Touch the SYSTEM header and select Enter Wafer Lot Name
command. The [Enter Lot Names for Presented Wafers] screen will be
displayed (Figure 11.6).
The lot name is linked to the chamber/recipe for the wafers to be processed.
You have two options to enter the lot name:
Option 1:
Use this method if you are going to
process all your wafers with the same recipe. Touch the For Whole Cassette
field of the cassette you plan to use with the light pen. Click on the field,
and a lot name window will pop up. Select the lot name you plan to use, and it
will show up in the For Whole Cassette field in blue rectangle. Click
the blue rectangle to confirm the selection.
Option 2:
This method allows you to enter different
lot names for different wafers to be processed. Touch the cassette slot number
field 1 – 25 of the wafer cassette you plan to use. Enter the lot name
for the wafer to be loaded in the slot using the method described in option1.
Repeat for different slots.
9.3.11
Click Clamp A or Clamp B. On the [Monitor Wafer
Screen]. Twenty-five vertical lines, which represent 25 wafers, will appear
for the cassette you just clamped down. You must delete the lines representing
the slots that do not contain wafers in them. Click a line, then select delete
a wafer command to delete them one at a time Or use the Start delete
Range, and Finish delete Range commands to do the job, by first
clicking on the beginning slot and end lines in your continuous range of
empty slots. This will leave behind the slots that have wafers in them.
9.3.12
Touch the SYSTEM header and select Enter Wafer Lot Name
command. On the [Enter Lot Names for Presented Wafers] screen, all the
lot names of the empty slots should be cleared. Double-check the slot number of
the lot name and the wafer to be processed. If you find mismatches, go back to
Section 9.3.7 and repeat the procedures again and
correct this problem.
Run The Process
9.3.13
Touch the SYSTEM header and select Control System
command. On the [System Control Screen], change the system state from Manual
to Automatic, Figure 11.5. The WAFER header
will turn green, and the message home all robot axes will be displayed
on the top of the screen. Wait until the robot homing operation is completed.
9.3.14
After the robot homing operation completes, touch the WAFER header
and select Run command. The system will start processing the wafers in
automatic mode.
9.3.15
Touch the WAFER header and select the Monitor Wafer
command. You can monitor the wafer movements on the [Monitor Wafer Screen].
9.3.16
When a wafer is transferred into a chamber, you can monitor the
process details by touching the corresponding CHAMBER header and select Monitor
Process command. [CVD Process Monitor Screen], and [Etch Process
Monitor Screen] are showed in Figure 11.7 and Figure 11.8.
Unload Wafers After The Process Ends
9.3.17
When the P5000 processed all the loaded wafers, it will display a
message - All wafers finishes processing, press RUN to unload wafers.
Press RUN button on the mainframe front face. All the wafers will be returned
to the cassette after the load lock has vented. Wafer handler door will open
and cassette unclamps.
9.3.18
Remove the cassette and unload all your wafers. Put the cassette
back into the wafer handler.
9.3.19
On the [Monitor Wafer Screen], Figure
11.4, click Close Door. The door will close. Disable P5000 on the
WAND.
10.0
Troubleshooting Guidelines
Because the P5000 is a complicate tool, please report all the problems
to on the WAND. User is not allowed to trouble shoot any problem encountered at
this point.
11.0
Figures & Schematics
Figure 11.1 -
P5000 Process Chambers and load lock (Top View)
Figure 11.2 -
Operator Controls (Mainframe Front Face)
See Appendix 12.3 for more details.
Figure 11.3 -
System Status Screen (Screen Configuration)
See Appendix 12.4 for more details.
Figure 11.4 -
Wafer Monitor Screen
See Appendix 12.5 for more details.
Figure 11.5 -
System Control Screen
See Appendix 12.6 for more details.
Figure 11.6 -
Enter Lot Names for Presented Wafers Screen
See Appendix 12.7 for more details.
Figure 11.7 -
Monitor CVD Process Screen
See Appendix 12.8 for more details.
Figure 11.8 -
Etch Monitor Screen
See Appendix 12.9 for more details.
12.0
Appendix
12.1
Typical TEOS Process Parameter Setup
|
|
Step 1 Initial Setup |
Step 2 Stabilization |
Step 3 Deposition |
Step 4 O2 purge |
Step 5 Lift |
Step 6 Pump |
|
Chamber
Selection |
A or B |
A or B |
A or B |
A or B |
A or B |
A or B |
|
Step End
Control |
By Time |
By Time |
By Time |
In
Position |
By Time |
By Time |
|
Max Step
Time |
5.0 secs |
20.0
secs |
Variable (60
secs) |
10 secs |
5.0 secs |
5.0 secs |
|
Endpoint
Selection |
No Endpoint |
No Endpoint |
No Endpoint |
No Endpoint |
No Endpoint |
No Endpoint |
|
Pressure |
Servo 9.0 Torr |
Servo 9.0 Torr |
Servo 9.0 Torr |
Servo 9.0 Torr |
Servo 9.0 Torr |