Chapter
6.31
Ion Beam Deposition System (4” and 6”)
Located in 188 Cory Hall
(iondep)
1.0
Title
Iondep – Ion Beam
Deposition System.
2.0
Purpose
Iondep is an
ion beam based deposition system. It
can be used in Ion Beam Sputtering (IBS) mode or Ion Beam Assisted Deposition
(IBAD) mode. This tool is specifically
designed to deposit thin Silicon Carbide or Carbon films at low temperatures
(below 450°C) by sputtering with or without assist. It is capable of depositing
on 4” and 6” wafers at various temperatures and tilt angles.
3.0
Scope
This document provides operational procedures for iondep, recipe selection, and user-level troubleshooting.
4.0
Applicable Documents
4.1
Operators Reference
Manual Binder (located by machine and also stored as .pdf files on iondep
computer)
4.2
MSDS information for
argon, 10% silane in argon, and 10% methane in argon
4.3
Vendor Information: Process
Materials, Inc.
http://www.processmaterials.com
5625 Brisa St. Suite A
Livermore, California 94550
Phone:
(925) 245-9626
5.0
Definitions & Process
Terminology
5.1
IBS (Ion Beam Sputtering) Mode: Sputter deposition process
that uses an ion beam to sputter a target.
5.2
IBAD (Ion Beam Assisted Deposition) Mode: Deposition process that uses
a separate, independent ion source (assist) with the sputtering ion source. The
assist source is used for ion bombardment during film growth which can alter
the properties of the thin film.
5.3
Angle of Incidence: The angle between the
substrate normal and the angle at which atoms arrive at the substrate. The deposition process has been optimized
for an angle of incidence of 50 degrees.
Please contact staff for modification of this angle.
5.4
PC Control Panel: Allows user
to pump, vent, select and monitor process.
5.5
Deposition Controller: Indicates crystal health,
deposition rate, and time remaining for 16 cm Ion Source deposition. The
controller also opens/closes the shutter.
5.6
Process
Chamber Components
5.6.1
Shutter: Prevents sputtering onto substrate when 16cm
Source is ramping up.
5.6.2
Heater Box: Contains four quartz heating lamps and is
capable of heating substrate surface to approximately 400 °C.
5.6.3
Substrate Holder: Secures wafer to heating/rotating chuck via
three spring clips. Maximum rotation is
5 rpm.
5.6.4
Target Carousel:
Holder for the target material and capable of
holding three targets. Currently
available target materials are silicon carbide (SiC), silicon, and carbon. Process Materials INC is the vendor for the
targets.
5.6.5
16 cm Ion Source: Ion beam used to sputter the
target material for deposition on to the wafer. Argon is the currently
available gas.
5.6.6
RF Neutralizer: Neutralizer for 16 cm source.
5.6.7
16 cm Ion Source Controller: Loads, saves, and stores programs
for the 16 cm ion source.
5.6.8
Mark II Ion Source: Secondary ion beam source for
etching (cleaning wafer surface) and ion bombardment (alter material
properties). Argon, 10% silane in
argon, and 10% methane in argon are the currently available gases.
5.6.9
Mark II HO Controller: PC system that updates Mark II
setpoints.
5.6.10 HCES
(Hollow Cathode Electron Source): Gas source attached to Mark II.
5.6.11
Crystal Health Indicator: Reads deposition rate and
crystal health.
6.0
Safety
6.1
Use nitrite gloves at all times when handling components that go in the chamber or when cleaning the
chamber. This protects you from the
particles in the chamber as well as the tool from body oils that can outgas or
damage the pumps.
6.2
High Voltage Hazard: Iondep utilizes a high
power source for the operation of its ion sources and heater. Do not touch the
high power electrical parts behind the service panels.
6.3
Strong
Light Hazard: The plasma emits strong light. Do not look
straight into the plasma for a long period of time.
6.4
Burn Hazard: The deposition chamber is usually quite warm
after a deposition process. In particular, the Heater Box, Mark II source,
HCES, and Target Holder are usually hot after deposition. Because the process
runs under vacuum, it takes a while for everything to cool down. Do not vent the chamber until the PC reads a
substrate temperature below 100oC.
There is an interlock for this but DO NOT try to bypass this step
to save time.
6.5
Do not leave the vacuum
system until you are certain the chamber is pumping down properly.
6.6
Do not use N2 gun to
clean the iondep. Use a vacuum hose to prevent particles from being blown
around.
6.7
Please contact the
Microlab staff if new gases or target materials need to be used.
DO NOT experiment with new materials without permission.
7.0
Statistical/Process
Data
7.1
16 cm
Source Recipes
7.1.1
Program #1
7.1.1.1
Beam (Current, Voltage):
500 mA, 1000 V
7.1.1.2
Accel. (Current,
Voltage): 17 mA, 175 V
7.1.1.3
RF Source (Forward
Power): 400 W
7.1.1.4
RF Neutral (Emission
Current): 625 mA
7.1.1.5
RF Neutral (Forward
Power): 64 W
Note: These settings are known to yield stoichiometric SiC. With an angle
of incidence of 50 degrees the deposition rate is approximately 0.4 um/hour.
7.2
Mark II
Assist Source Recipes
7.2.1
Program # 1
7.2.1.1
V_anode = 150 V
7.2.1.2
I_anode = 5 A
7.2.1.3
Gas 1 (Argon)
7.2.1.4
Start Source Gas Flow =
8.5 sccm
7.2.1.5
HCES Flow = 4 sccm
Note: This high energy recipe is
typically used to etching/cleaning the substrate surface.
7.2.2
Program # 2
7.2.2.1
V_anode = 60 V
7.2.2.2
I_anode = 1.5 A
7.2.2.3
Gas 1 (Argon)
7.2.2.4
Start Source Gas Flow = 6
sccm
7.2.2.5
HCES Flow = 3 sccm
Note: This recipe is used for
moderate ion bombardment.
8.0
Available Process, Gases, Process
Notes
Materials: The only materials allowed in
the chamber are silicon carbide (SiC), silicon (Si), silicon dioxide (SiO2),
and silicon nitride (Si3N4). No other materials are allowed.
Materials such as polymers may outgass and damage the pumps or
contaminate the chamber. DO NOT
put new materials into the chamber without permission from Microlab staff.
9.0
Operating Procedure
9.1
Enable iondep with WAND,
if software process screen does not show, double click on the “Welcome” icon on
the Windows Desktop.
9.2
From the process screen (Figure 11.3) vent chamber by pressing the “Vent” button in the
lower left of the monitor.
9.3
If the chamber is cool,
wearing gloves, use a Techni-cloth
with some isopropyl alcohol (IPA) and wipe the substrate holder, door seal,
heater box, and floor of the chamber to check for debris. Particulates in the chamber can degrade film
quality. If the chamber is clean and no
particulates or dust are wiped up, continue past 9.4 Cleaning Procedures.
9.4
Cleaning Procedures
9.4.1
If heater box and
substrate holder are cool, use a Techni-cloth with IPA and wipe down. Also,
wipe down the top of the shutter.
9.4.2
If there are a lot of particulates
use the vacuum cleaner located next to the iondep tool and vacuum the inside of
the chamber.
9.4.3
If aluminum foil on the
walls of the chamber is flaking, report a faults report notifying staff to
change out the foil.
9.5
Check if the Mark II is
appropriately covered or uncovered with foil.
9.5.1
If using the tool in IBS
mode, use aluminum foil to cover the Mark II opening as well as the HCES source
opening. Sputtering deposits can damage
these components if they are not in use and are left uncovered. If covering
Mark II & HCES, check to make sure shutter can close. This is done by pressing the shutter button
on the Mark II controller.
9.5.2
If using the tool in IBAD
mode, remove any foil that is covering the Mark II or the HCES opening.
9.6
If the desired process
requires the substrate holder to rotate, it is a good idea to also check
rotation before pumping down the system.
This is done by pressing the “rotate” button on the engineer
screen. Do not set the rotation above
5 rpm. If no rotation is observed,
refer to the troubleshooting guidelines.
9.7
Load wafer onto the
substrate holder and secure it in place with the spring clips.
9.8
Close the shutter by
pressing the shutter button on the deposition controller.
9.9
Close the chamber door
and lock by turning all three knobs.
9.10
Pump down the system
pressing “Pump” on the process screen.
9.11
Monitor the pumping and
ensure that the chamber crosses over to Hi-Vac and that the pressure is below
5.00E-6 Torr. Note: The cross over
chamber pressure for the roughing pump is 100 mTorr.
9.12
Once the system is in
Hi-Vac, turn on the 16 cm ion source controller. Otherwise, your process will not start.
9.13
From the recipe screen,
load the desired recipe.
9.14
Recipe Selection
9.14.1 Please speak with superuser or staff before creating/modifying a
recipe.
9.14.2 To load a recipe, press the “load recipe” button at the bottom of the
recipe screen.
9.14.3 To save a recipe, press the “save recipe” button at the bottom of the
recipe screen.
9.14.4 Overview Recipe Steps
9.14.4.1
Heat (Step
1) – Used as a heat ramping and hold step.
The maximum temperature allowed is 400oC.
9.14.4.2
Etch (Step
6) – Used to turn on Mark II for a cleaning/etching of substrate surface
9.14.4.3
Deposit (Step
8) – Used to turn on 16 cm ion source for deposition and Mark II for assist
bombardment
9.14.4.4
Delay (Step 9)
– Used as a hold step for purging of ion sources
9.14.4.5
Cool (Step
14) – Used to cool the substrate holder with high gas flows to 100oC
after deposition. This step is
optional.
9.14.4.6
End (Step
15) – Ends the deposition and is the last step of the recipe.
9.14.4.7
Skip – Skips
to the next process step.
9.14.4.8
NOTE:
Please keep the appropriate step numbers when creating recipes. Ex. Heat step is always step #1.
9.14.5 Changing The Deposition Time
9.14.5.1
On the deposition
controller press “program” button.
9.14.5.2
Scroll to the appropriate
program number
9.14.5.3
Press the “>” button
to access program
9.14.5.4
Modify the thickness to
change the time. Please note that 1 Angstroms = 1 seconds. For example: 3.6
kAngstroms = 3600 seconds.
9.14.5.5
Press the “<” button
2X to exit program.
9.15
Open the liquid nitrogen
(LN) valve for pump cooling.
9.15.1 Manually open valve on the LN dewar.
9.15.2 Press the “LN valve” icon on the vacuum screen.
9.16
From the process screen,
press the “Start” button to begin the process.
9.17
Should a major failure
occur or if the process needs to be halted immediately, press the Process Abort
button on the process screen. The abort will shut down all process related
equipment (vacuum equipment will remain running).
9.18
If there is a minor
error, pressing the “Hold” button will leave the process sequence at the
current step until the “Continue” button is pressed. If “Hold” is pressed
during the actual material deposition, it will be paused after the material is
deposited and the shutter is closed.
9.19
During the Deposit Step
(#8) of the recipe, there is a 15 minute purge delay for the 16 cm ion
source. Once the purge is complete, it
is a good idea to monitor the 16cm source controller settings and the Mark II
controller settings and ensure that the sources start up without problems.
9.19.1
Check that the 16 cm ion source
controller reads the correct beam current (default is 500 mA). If not, abort the recipe and report a
fault. This may mean that there is a
short in the discharge chamber.
9.19.2
Check that the plasma is
a purple or magenta color. If not, abort recipe and report a fault. Any discoloring of the plasma could mean
that the chamber is contaminated.
9.19.3
Check that the gas flow
rates are reaching the set points. If
not, abort recipe and report a fault.
9.19.4
In IBAD mode, if Mark II
source current reaches 15 A and stays there for more than three seconds,
immediately hit abort and refer to the troubleshooting guidelines.
9.20
After process is
complete, turn off the 16 cm ion beam controller, close the LN flow, vent the
chamber, and retrieve the wafer.
9.21
Use caution when retrieving
and loading samples. NOTE: Do
not vent the chamber until the PC reads a substrate temperature below 100oC. There is an interlock for this but do not
try to bypass this hold step to save time.
This could lead to severe burns or oxidation of the
chamber components.
9.22
When done using the
iondep, pump down the chamber for the next user. Do not leave until the chamber reaches Hi-Vac and pressure is
below 5.00E-6 Torr.
9.23
Disable the iondep with
WAND.
10.0
Troubleshooting Guidelines
10.1
Hi-Vac gate takes a long time to open or close when
either pumping down or venting system.
10.1.1
If trying to vent from
Hi-Vac, pump down the system again by pressing “Pump” on the process screen and
try again.
10.1.2
If trying to pump down
from a vented system, vent the system again by pressing “Vent” on the process
screen and try again.
10.1.3
If problem persists,
leave the system in its stable state (pumped or vented) and report a fault to
alert staff immediately.
10.2
Mark II Source current reaches 15 A limit and stays
there fore more than 3 seconds.
10.2.1
Abort process by pressing
the “Abort” button on the process screen and reset the alarms with the “Alarm
Reset” button located on the top right.
10.2.2
Refer to the flowchart (Figure 11.5) to select the appropriate Mark II start flow.
10.2.3
If problem persists,
report a fault to alert staff.
10.3
16 cm ion source reads a lower beam current
than the recipe setting.
10.3.1
Abort process by pressing
the “Abort” button on the process screen and reset the alarms with the “Alarm Reset”
button located on the top right.
10.3.2
Leave the system pumped
down
10.3.3
Report a fault for bead
blasting of the ceramic dome inside of the 16cm ion source.
10.4
16 cm ion source controller is not starting
and a beam is not visible
10.4.1
Abort process by pressing
the “Abort” button on the process screen and reset the alarms with the “Alarm
Reset” button located on the top right.
10.4.2
Do not attempt to run
recipe again
10.4.3
Report a fault for staff
to look at feedthrough connectors behind the 16 cm ion source.
10.5
The substrate heater is not reaching the setpoint
temperature.
10.5.1
Abort process by pressing
the “Abort” button on the process screen and reset the alarms with the “Alarm
Reset” button located on the top right.
10.5.2
Try to run the recipe
again.
10.5.3
If problem persists,
abort recipe and leave system pumped down.
10.5.4
Report a fault.
10.6
The substrate holder is not rotating when pressing
“rotate” on the engineering screen.
10.6.1
Report a fault.
11.0
Figures & Schematics
Figure
11.1 - Iondep Interior Overview
Figure 11.2
- Schematic of the Various Control Panels of the Iondep System
Figure
11.3 - Schematic of Process Screen
Figure
11.4 - Schematic of Vacuum Screen
Figure 11.5 - Process Flow For Selecting Appropriate Mark
II Recipe
(From Veeco’s
Mark II HO Contoller Technical Manual)
12.0
Appendices
12.1
System Shut Down Procedure for Staff Only:
Used only when total powering down of the system is needed.
12.1.1
From a Hi-Vac chamber
state press the “Pump” button to go into manual mode.
12.1.2
From the Vacuum Screen
press the following buttons in this order to start shut down of turbo pumps
12.1.2.1
IG-1 (Turns off ion
gauge)
12.1.2.2
Hi-Vac (closes valve)
12.1.2.3
Turbo (begins
deceleration of turbos)
12.1.3
Wait for approximately 15
minutes for both turbo pumps to turn off.
Confirm that turbos have spun down by looking at LEDs on the turbo
controllers.
12.1.4
From the Vacuum Screen
press the foreline valve to close it
12.1.5
Go to back of machine
(behind the deposition chamber) the vent the pumps by turning t-valve
12.1.6
Turn off the main breaker
located at the back of the machine near the gas cylinders
12.1.7
Shut down the PC
12.1.8
Turn off all power
switches of controllers (Deposition, Mark II, 16 cm Ion source, RF neutralizer)
except for the turbos.
12.1.9
Turn of all breakers on
the side of the controller panel.
12.1.10
To power up do the
reverse of this procedure.
12.2
Vacuum Setup Default Values (for Staff Only)
- DO NOT CHANGE THESE VALUES!
12.2.1
Atm. Setpoint = 760 Torr
12.2.2
Roughing Line Ready = 200
mTorr
12.2.3
High Vacuum Crossover
Setpoint = 110 mTorr
12.2.4
Heater Enable Setpoint =
5E-4 Torr
12.2.5
Heater Disable Setpoint =
5E-3 Torr
12.2.6
High Temperature Alarm Set = 500oC