Chapter 6.29
(oxford2)
1.0
Title
2.0
Purpose
PlasmaLab 80plus® PECVD system, made by Oxford Instruments, is a multipurpose tool capable of depositing silicon oxide, silicon nitride, amorphous silicon, and other films (under staff permission). Machine is controlled by a PC that runs the PlasmaLab 800 software. The sample susceptor is 10 inches in diameter that can hold a 6” or 8” wafer or several 4” and smaller wafers for processing. Compound III-V semiconductor material can also be processed in this tool on a designated 8" wafer susceptor, available by the machine. No organic material and/or photoresist-covered wafers are allowed in this tool.
3.0
Scope
This document includes the system overview, operations, and user level trouble shootings.
4.0
Applicable Documents
4.1
Plasmalab80Plus
Compact Plasma System – PECVD – Installation Data
4.2
Plasmalab80Plus
System Manual - 5. Operating Instructions
4.3
PECVD
System 80/800 Cleaning Procedure Full Version with Explanations
4.4
CDs in Microlab Office
4.5
Material Safety Data Sheet for all the process gases listed
in Section 8.0 in the MSDS blue binders in both Office and Lobby.
5.0
Definitions & Process
Terminology
5.1
Non-MOS Tool: Non-MOS wafers, which may contain
materials not compatible with the MOS processes, are allowed in this kind of
tools. Even though all the process gases used are MOS-clean grade, the cross
contamination from the non-MOS wafers may impact the electrical/parametric
behavior of the fabricated IC/transistor devices. Oxford2 is considered a
non-MOS Tool. Please note, MOS clean runs processed in this tool cannot
continue in the MOS clean furnace path. Therefore, films deposited on MOS clean
runs in this machine changes the status of the run to non-MOS, thereafter.
5.2
PECVD: Plasma Enhanced Chemical Vapor Deposition. This kind of
process uses RF generated plasma to assist the deposition reaction to take
place at temperature lower than required by similar LPCVD process.
6.0
Safety
Follow
general safety guidelines in the lab as well as the following specific safety
rules.
6.1
Burn Hazard: The wafer susceptor is
heated up to over 300°C. Extreme care must be taken when loading/unloading
samples onto the susceptor.
6.2
RF, UV/Visible Radiation: Do not look into the plasma for
long period of time. Do not touch RF cables and all other electrical wires.
6.3
Chemical Hazard: If a process gas leak is suspected
or detected, press the red Emergency Off Button
on the lower left side of the chamber. Active the HAZMAT alarm, then
evacuate the lab.
7.0
Statistical/Process Data
7.1
Problem and comment section under equipment section of the
wand.
7.2
Enable message of Oxford2.
8.0
Available Processes, Gases, Process
Notes
Available
Processes
8.1
Silicon Oxide PECVD: uses N2O and 10%SiH4
in Ar, deposition rate >50 nm/min.
8.2
Silicon Nitride PECDV: uses NH3 and 10%SiH4
in Ar, deposition rate >20 nm/min.
8.3
Amorphous Silicon PECVD: uses 10%SiH4 in Ar, most recent dep rate listed
at the Oxford2 enable message.
8.4
Silicon Carbide PECVD: uses CH4 and 10%SiH4
in Ar, to be developed.
Available
Gases
8.5
N2O: used in the silicon oxide process
as the source of oxygen.
8.6
10%SiH4 in Ar: used in all processes as the source
of silicon.
8.7
NH3: used in the silicon nitride process
as the source of nitrogen.
8.8
Ar: used as a dilutant to
improve the uniformity of film deposition.
8.9
20%CF4 in O2: used for process chamber cleaning.
8.10
CH4: used in the silicon carbide process
as the source of carbon. Not connected yet.
8.11
BCl3: used in the silicon carbide process
as the source of boron dopant. Not connected yet.
Process
Notes
8.12
efore loading your samples into Oxford2,
make sure all the non-metal and non compound III-V wafers/samples are cleaned
in SINK8 followed by sink8, standard non-MOS furnace cleans for silicon based
processes (Microlab Manual Chapter 2.6). Samples with exposed metal film needs to be cleaned in
SINK5 (Microlab Manual Chapter 2.5) pre-furnace metal clean bath. Compound III-V material do
not need pre-furnace clean, however need to get loaded on their designated susceptor available at the machine.
8.13
Samples with photo-resist or any other organic film are not
allowed in the system.
8.14
When loading wafers/samples, make sure that there is no air
gap between the wafer/sample and the susceptor.
Otherwise, the wafer may move during the process, and the uniformity of the
film will be bad.
8.15
After deposition, the wafer/sample is very hot. Cool the
wafer on the heat sink provided at the site. Do not put the wafer back into the
wafer box before it is cooled down to room temperature.
8.16
The plasma chamber needs regular cleaning to prevent
particle build up. There are 5 clean recipes corresponding to various
deposition thicknesses, e.g. clean1.rcp for 1 μm
deposition. When finish using the tool, add up the total
deposition thickness and run a corresponding clean recipe. If you need
to deposit more than 5 μm of film, you have to
split the process and run clean recipe in between.
8.17
The chamber temperature for PECVD process can be set between
300 to 400°C. It is set to be 350°C for all the standard processes.
8.18
The maximum process pressure is 1 Torr
for the system.
9.0
Equipment Operation
Log On
Procedures
9.1
Enable the Oxford2 on the WAND.
9.2
Check the system LCD panel is on and displays that the
control is via the remote PC.
9.3
Double click the ‘PC Plus” icon on the PC. Wait until the Access
page shows up on the screen. Click the Access drop down menu, and a list
of User Name will show up. Select Oxford2 and enter the password, which
is given to the qualified users. Click the Proceed button, and the Master
Menu panel will show up on the screen.
The Master Menu panel has five buttons, which are described in
the following sections.
9.3.1
Manual: Reserved for equipment staff.
9.3.2
Display: It gives user three screen display options.
Status
Page: This page
displays all the current system information, e.g. pressure,
temperature, process gas flows, and etc. that are important to the user (see Section
11.1).
Vacuum
Page: This page
displays the information of the system hardware (see Section 11.2).
Process
(Recipe) Page: This
page displays the details information of a selected recipe (see Section 11.3).
9.3.3
Edit: Reserved for process staff and super-users to edit
recipes.
9.3.4
Select: Used to select process recipes to be executed. When this
button is clicked, a list of available recipes will be displayed. Double click
the recipe to select. When a recipe is selected, the text on this button
changes to Start. Click it to start running the selected recipe. When
the recipe is completed or aborted, the text on this button returns to Select.
9.3.5
Quit: Use this button to logout the system when the process is
finished/aborted and no new process is selected. When a process is running, the
text on this button changes to Abort. Click it to stop the process
manually.
Loading
and Unloading Wafers/Samples
9.4
Click the Select button, and then double click the [Vent]
recipe. Click Start button to start the venting process.
9.5
Click Display button on the Master Menu and
select Status option. Check the substrate temperature displayed on the
left bottom of the screen is at 350°C. If the temperature is not at 350°C, wait
until it reaches the set point. It takes about half an hour to heat up from
room temperature.
9.6
When the [Vent] recipe completes and the temperature
stabilizes at 350°C, turn the chamber switch on the front of the tool to OPEN.
Press and hold both HOIST buttons down at the same time. The top section
on the chamber will lifts up, then swings backward. When it stops moving,
release both HOIST buttons.
9.7
Check the chamber wall and susceptor.
It should be clean with a thin layer of pre-coated film on top. If not, see Section
10.1 for
troubleshooting.
9.8
Load/unload wafers/samples. Take cautions listed in Sections
8.12 to 8.16.
9.9
Turn the chamber switch to CLOSE. Press and hold both
HOIST buttons down at the same time. The top section of the chamber will
swing forward and then lower. When the chamber is completely closed, release
both HOIST buttons.
Running
a Process Recipe
9.10
Click the Select button, and then double click the
process recipe to be executed. Start button to start the process.
Available process recipes are listed in the Appendices Section 12.0.
9.11
Most of the process recipes are set up for 1, 2,
3, 4, and 5 μm film thicknesses. If more precise film thickness is needed,
use the Abort button to terminate the deposition step at target time.
9.12
Follow Sections 9.4 to 9.9 to unload and/or reload
wafers/samples.
Post Deposition Chamber Clean
9.13
After you are finished using the Oxford2, the chamber needs to
be plasma cleaned. Add up all the film thickness for the run, and then run the
corresponding clean recipe, e.g. [clean2] recipe for total deposition
thickness between 1 to 2 μm.
9.14
Disable Oxford2 on the WAND, once the plasma clean recipe
starts and the plasma ignites. There is no need to wait for the clean recipe to
finish.
10.0
Troubleshooting Guidelines
10.1 Problem: After enabling Oxford2, find that the clean
recipe is running or aborted.
Cause: The clean recipe needs more time to finish or the tool has gas/RF stabilization problems.
Solution: Wait for the cleaning recipe to finish.
Or abort the cleaning recipe.
Vent the chamber. If the chamber and the susceptor
look clean, you can process your wafers/samples. Add remaining time of the
previous clean recipe to the one you are going to use after you finish your
process.
10.2 Problem: After starting a recipe, the tool does not
respond and the actual process parameters remain zero.
Cause:
There is a communication problem between the main system and the PC.
Solution:
Check the system LCD panel is on and displays that the control is via the
remote PC. If not, report on WAND and the equip staff will reset the
system.
10.3 Problem: After starting a recipe, it takes long time
to pump down to base pressure. Then the pressure cannot stabilize when process
gases start flowing.
Cause:
The pump/blower may be overloaded and triggered off.
Solution: Report on WAND. Equipment staff will restart the pump/blower.
10.4 Problem: When running the [Nitride] recipe,
the NH3 fluctuates first, and then a gas stabilization re alarm
appears on the PC screen
Cause:
The NH3 delivery system needs to be replaced. (Equipment staff is
working on this problem)
Solution: Click the OK button
to the right of the alarm. The Process will continue without problem.
10.5 Problem:
When running a recipe, one of the process gases flows
starts to decrease, and then the process aborted.
Cause:
The gas cylinder is empty or a valve is shut off on the gas line.
Solution: Report on WAND.
11.1 Display Status Page
11.3
Display Process (recipe) Page
Diagram
1 - Typical Process
Recipe Page
12.1
Vent Recipe
|
Step |
Description |
Time |
NH3 |
Ar |
SiH4 |
HF RF |
Pressure |
Temp |
|
1 |
Pump1 |
0:01:00 |
- |
- |
- |
- |
- |
350 |
|
2 |
Purge1 |
0:01:00 |
- |
200 |
- |
- |
0.200 |