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CVC Products DC Sputterer

Table of Contents:
I: Introduction
II: Machine Specifications
III: System Components
IV: System Theory
V: Operating Characteristics
VI: Operating Instructions
VII: Changing a 3" Target
VIII: Troubleshooting
IX: DO's and DON'Ts
X: Check-off requirements

I. Introduction

The DC sputterer is used to coat samples with metals. Metal coatings are usually performed with this sputterer or with the CVC E-Beam evaporator. Dielectric materials must be sputtered with the RF sputterer or deposited some other way, such as chemical vapor deposition (CVD) using a machine such as a PECVD. Sputterer depositions tend to coat all exposed surfaces, while evaporator depositions will coat surfaces facing the evaporation source, but will not coat the sides of features that are facing in directions parallel to the substrate surface.

The DC sputterer can be used to deposit virtually any metal. We have sputter targets for aluminum, copper, titanium, chrome, gold, platinum, nickel-chrome, and other materials. Sputter coatings are performed by accelerating argon ions into the surface of a sputter target, which is made of the material to be applied to the sample. The argon ions cause atoms to be knocked off of the target and deposited on the sample being coated.

For further information on the sputterer software, please refer to the Control Vision Software Manual.

II. Machine Specifications

Batch type deposition system
8" copper and aluminum/Si-1% targets for rapid sputtering
Two user exchangable 3" targets for sputtering of many different materials.
Optional substrate heating for metal depositions

III. System Components

The DC sputterer consists of an electronic stack and machine housing. The electronic stack contains most of the control devices for the sputterer while the bulk of the sputtering apparatus is contained within the machine housing.

A. The components of the electronics stack

ion gauge (top left) - indicates chamber pressure, when below 1 x 10^-4 Torr
signal conditioner (top right)
interlock controller (below ion gauge)
heater controller (third from top) - controls heater in station 1 and displays heater temperature when heater is active
hoist controller (above computer monitor) - buttons for raising and lowering the lid
computer (monitor and keyboard) - controls entire system
MDX1.5X power supply (below disk drive) - supplies power to stations 3 and 4
interlock control panel (below MDX1.5X power supply)
rotostrate control panel (below interlock panel) - controls rotation rate of the sample holder in the chamber
MDX Magnetron Drive power supply (at bottom) - supplies power to stations 1 and 2

B. The components of the machine housing:

Sputterer lid - in the lid are four deposition stations
Station 1 - 8" aluminum target
Station 2 - 8" copper target
Stations 3 and 4 - 3" chrome, nickel-chrome, gold, titanium, and other user-installed targets
Sputterer chamber base - under the chamber there is a heater
Lid hoist - for raising and lowering the lid
Rotostrate - rotating substrate holder with six sample holder trays - each can hold 1 150mm wafer or smaller
Viewport - to the right of the chamber itself, this window allows visual inspection of the sputtering process while in operation

C. Operating Software

Screens - There are four main screens that the user will find displayed. These screens are the PAL System screen, PUMPDOWN screen, LOGO screen and DEP.STATIONS screen. The PAL System screen offers menus for access to the batch and recipe information. The PUMPDOWN screen displays a schematic of the sputterer that includes information such as valve states, chamber pressure, pumpdown time, etc. The LOGO screen is used to run and stop batches. The DEP.STATIONS screen appears when the sputterer is depositing metal and displays station power readings, gas flows, chamber pressure, and other information. To toggle between screens, press any key and select the desired screen name from the list provided, or hit escape to reach the PAL System screen.

IV. System Theory

All of the process batches on the sputterer will cause the sputterer to perform these actions in this order:

The roughing valve is opened and the mechanical pump pumps the chamber to 300 milliTorr (mT).
The roughing valve is closed and the high vacuum valve is opened. The ion gauge is turned on. The cryo-pump pumps the chamber to 2 x 10^-5 torr.
The throttle valve is closed, partially obstructing the path from the chamber to the cryo-pump. Argon is injected into the chamber and the chamber pressure is raised to 6 mT where it stays for the duration of the process.
For each material being deposited:
- The shutter on the bottom of the chamber lid (under the sputtering guns) is moved to a station that is not currently being run.
- One of the power supplies on the instrument rack applies power to the sputtering gun that is being run. The plasma igniter filament is turned on.
- Once the plasma ignites, the igniter filament is turned off.
- The power supply gradually ramps the power to the setpoint set in the Sequencer.
- The shutter is turned to expose the running sputtering gun. The process timer begins counting down from the time set in the Sequencer.
- When the timer reaches zero, the power supply shuts off.
The argon is shut off. In most cases the high vacuum gauge is turned off, and the chamber is vented to atmospheric pressure with nitrogen. In some cases, the throttle valve will open and the cryo-pump will remain pumping on the chamber after the run; however, normally this does not happen.

V. Operating Characteristics

Operating Limits

Parameter	Operating Range	Notes
Sputtering Pressure	4-8 milliTorr	This is the gas pressure during deposition
Base Pressure	2 x 10^-5	The chamber is pumped to this pressure to remove impurities before starting
3" gun power	7% of max power supply rating	Exceeding this range will damage the power supply, cathode, and sputter target
8" (SiO₂) gun power	0-40% of max power supply rating	Exceeding this range will damage the power supply, cathode assembly, and sputter target

VI. Operating Instructions

A. Loading the Sputterer

Log on to the sputterer at the access control box.
Fill out the log book for this run before you start.
Check to make sure the target you want to use is installed. There will be a set of yellow signs on the front of the machine that the have the name of the target in each station written on them. Find the name of the material you want to use and note which station it is in.
Press escape until the machine displays the PAL System Options page. This page allows you to run batches (Operate), edit/view batches (Batch), and edit/view recipes (Recipe). To choose any options while using the sputterer, scroll through the names of the options using the cursor keys (Note: the left and right arrow keys scroll through the first row of options, and the up and down arrows display any additional rows of options). Press enter to select an option.
Choose Operate. The machine will display the last page viewed in Operate mode. To go to another page choose Select and choose the name of the page you wish to view. Go to the LOGO Page.
The LOGO Page displays the logo of CVC. Choose Direct Control. Choose RUN. Notice the commands under the RUN menu include PUMPDOWN, SHUDDER#N, VENT, and SEQ among others. The user will need to come back to this page for nearly every command they wish to execute. Remember OPERATE>>SELECT>>LOGO>>DIRECT CONTROL>>RUN. Now choose VENT to vent the chamber.
Wait till the screen says "****Chamber Vented Hoist Enabled****". Then press and hold the Hoist Up button located above the monitor. The top of the chamber will rise. Continue holding the Hoist Up button until you can look under the top of the chamber and see the targets. Then release the Hoist Up button.
Only one target is exposed at a time. To look at another target. Choose Select. Choose Logo. Choose Direct Control. Choose RUN. Choose the shutter you wish to view. For example to view the target in station 3 choose SHUTTER3.
Visually inspect all the targets you plan to use. Make sure that they are the proper material and that they are not melted or destroyed. If a target appears to be damaged, contact MiRC staff.
Load your samples into the chamber. Small samples need to be pinned down using the wires provided. Also samples should be no thicker than 3/8".
After your samples are loaded, turn ON the Rotostrate Control located near the bottom of the rack. Set the speed (red knob) to 6. Your samples should now be rotating. Make sure that they stay pinned and do not move.
Ensure that nothing has been placed underneath the chamber lid BEFORE lowering. This will damage the machine. Press and hold the Hoist Down button above the monitor. Release the button when the chamber lid stops moving.

B. Sequencer

A new batch and recipe pair have been created in order to replace all of the batches in the system. The batch name is Sequencer and the recipe is SEQ. You must use this program instead of any other batches. Instructions are listed below.

The sputterer uses a batch/recipe pair to select the desired sequence of steps and their duration. The batch is named 'SEQ' and the recipe is named 'Sequencer'.

Before a run, each user must program a sequence into the Sequencer recipe page. This recipe page is divided into 16 steps. From the PAL Options screen select RECIPE, then EDIT STEP to change the following options. Each step contains three options: Station, Step Time, and Power. The screen layout is shown below.

    Step # | Station | Step Time | Power % || Step # | Station | Step Time | Power %
    -------|---------|-----------|---------||--------|---------|-----------|--------
      1.   | [select]|       0.0 |     0.0 ||   9.   | [select]|       0.0 |     0.0
    -------|---------|-----------|---------||--------|---------|-----------|--------
      2.   | [select]|       0.0 |     0.0 ||  10.   | [select]|       0.0 |     0.0
    -------|---------|-----------|---------||--------|---------|-----------|--------
      3.   | [select]|       0.0 |     0.0 ||  11.   | [select]|       0.0 |     0.0
    -------|---------|-----------|---------||--------|---------|-----------|--------
      4.   | [select]|       0.0 |     0.0 ||  12.   | [select]|       0.0 |     0.0
    -------|---------|-----------|---------||--------|---------|-----------|--------
      5.   | [select]|       0.0 |     0.0 ||  13.   | [select]|       0.0 |     0.0
    -------|---------|-----------|---------||--------|---------|-----------|--------
      6.   | [select]|       0.0 |     0.0 ||  14.   | [select]|       0.0 |     0.0
    -------|---------|-----------|---------||--------|---------|-----------|--------
      7.   | [select]|       0.0 |     0.0 ||  15.   | [select]|       0.0 |     0.0
    -------|---------|-----------|---------||--------|---------|-----------|--------
      8.   | [select]|       0.0 |     0.0 ||  16.   | [select]|       0.0 |     0.0
    -------|---------|-----------|---------||--------|---------|-----------|--------
    Auto Vent?  Yes      Cycles:        0

The various sections of the screen include:

This is a selector that provides the user a choice about the action taken during that particular step. The choices available are:

Station selector: (shown as [select] above)

End: End of sequence. Any steps located after an 'End' step will be ignored. Note that the system adds an implicit 'End' after Step 16. For sequences that utilize all sixteen steps, a final 'End' is not necessary.
Delay: Delay execution. This is useful for operations such as cooling the chamber after a heating step.
Heat: Heat chamber. This activates the chamber heater (located in the Station 1 Base position) for the duration of this step. It is not possible to supply heat during the entire run.
Sta1, Sta2, Sta3, & Sta4: The sputter stations. This selects the respective sputter station for the deposition of metal

These settings will automatically be reset to the 'End' choice at the end of a a run.

Step Time

This is the duration of a step in seconds. A zero second Step Time will cause the system to skip the step. The End step ignores this value.

Power % (percent of full power)

This defines the amount of power applied to the station during operation. Each of the various actions in a step interpret this value differently.

The End and Delay steps ignore this value.
For the Heat step, this is the percent of maximum temperature which is 300 degrees Celsius. Thus, if the heat step requests 25% power, the heater will be set for 50 degrees.
For the four Sta[N] steps, this is the percent of maximum wattage applied to the station. However, there are internal limits set on the four sputter stations to prevent gun damage. The smaller guns are power limited to 350 Watts (7%) and the larger guns are power limited to 2500 Watts (40%). If you request a power higher than these limits, the system will silently reset to the programmed maximums for the stations. The main purpose for the power setpoints is to allow for lower power settings which can reduce sample heating and improve film quality.

Auto Vent?

This allows the user to prevent the system from venting at the completion of the run. The primary use for this option is for runs made overnight when the system will not be attended. It will keep the chamber pumped down until the user arrives to reclaim his or her samples. The default is Yes. This option will be reset to Yes at the end of the run automatically. If a user chooses to set this value to 'No', the system will need to be vented using the Vent batch.

Cycles

This allows the user to program a repeating sequence. The entire sequence visible on the screen will be repeated as many times as requested in this option. This option defaults to 1 (one) and is automatically reset to this value at the end of a run.

Edit this recipe using the Sequencer recipe editor:

Select the appropriate action for each step in your process (End, Delay, Heat, Sta1, Sta2, Sta3, or Sta4).
Remember to include the explict 'End' action if your process is less than 16 steps (most are).
Enter the desired step time in seconds.
Enter the desired power level in percent.
Optionally choose the Auto Vent method (default is Yes).
Optionally enter the number of cycles (default is 1).

Once the Sequencer recipe has been edited, samples are loaded, and the lid is down, go to the LOGO screen, choose Direct Control, choose Run, and then choose the SEQ. This will initiate the sputtering process following the recipe the user has just created. If AUTOVENT has been set to YES the machine will display ***Chamber Vented Hoist Enabled*** once the process is complete. Note:System pumpdowm may take more than 30 minutes.

C. Running the Sputterer

Press Esc. If you are not back at the PAL System Option Page, press Esc until you are.
A new batch and recipe pair have been created in order to replace all of the batches in the system. The batch name is Sequencer and the recipe is SEQ. You must use this program instead of any other batches.
Now that your samples are loaded you need to setup the batch you are going to run. A batch is set of one or more recipes that the machine will run together. There is separate recipe for each target. Choose Batch from the PAL System Option Page. Choose Select. Choose 'SEQ' for Sequencer.
The screen now displays a list of the recipes that the batch runs. Choose Sequencer and enter your information as illustrated in section B, which discusses the sequencer. Press Esc.
Esc back to the PAL System Option Page.
If you have multiple samples, turn on the rotostrate to a setting of 6. Since each sample holder spends the same amount of time beneath the gun, the rotostrate speed does not influence deposition rate. If you are sputtering a precious metal target, do not run the rotostrate unless you need to deposit on all six sample holders. Precious metal targets are very expensive and need to be conserved. Please note: make sure if you are using a precious metal target to center the rotostrate under your target to assure uniform deposition.
The screen now displays the parameters of the recipe you chose. To change one of the parameters. Choose Edit Step. Highlight the name of the parameter you wish to change using the cursor keys. Press Enter. Type in the new value and press Enter. Press Esc to save.
When you have set the parameters you want, Esc back to the Pal System Option Page.
If you are using Stations 3 or 4, turn on the red MDX-1.5K power supply. If you are using heat in your batch, turn on the Work Heater. Make sure the DC Power Interlock (under rotostrate control) is on.
Choose Operate. Go the Logo Page. Go to Select. Choose Direct Control. Choose RUN. Choose SEQ for Sequencer. The sputterer will perform the process now. Some stages of the process will take a while. The screen will display "****Chamber Vented Hoist Enabled***" when the process is complete.

See the section System Theory below for a step by step description of what the sputterer does after you start the batch.

D. Unloading Sputterer

When your batch is done running, the screen will say "****Chamber Vented Hoist Enabled****". Press and hold the Hoist Up button. Once the top of the chamber is up, release the button and remove your samples.
Press and hold the Hoist Down button until the top of the chamber stops.
Go to the Logo page. Choose Direct Control. Choose RUN. Choose PUMPDOWN.
When the HI VAC valve opens and the ionization gauge at the top of the rack reads pressure, Esc back to the PAL System Option Page.
If there were any problems with this run, please note them in the log book and submit a Pettit Service Request detailing the problem.
Log out of the sputterer at the access controller box.

VII. Changing a 3" Target

Press ESC until the main menu is displayed. Press "O" for Operate.
If the chamber is not open, check to see if "***CHAMBER VENTED HOIST ENABLED***" appears at the bottom of the screen. If this message does not appear, you will need to vent the chamber by doing the following:
1. Using the arrow keys, choose SELECT, then choose LOGO.
2. Choose DIRECT CONTROL, then select RUN and select VENT.
3. Wait for the message "***CHAMBER VENTER HOIST ENABLED***" to appear at the bottom of the screen.
Make sure the the chamber vented message is displayed at the bottom of the screen, then press and hold the HOIST UP button over the monitor to raise the hoist. You need to get the hoist high enough that you can reach the target. You can adjust its height later using the HOIST UP and HOIST DOWN buttons, so do not worry about the exact height at this time.
Using the arrow keys, choose SELECT, then select LOGO and press enter.
Select DIRECT CONTROL and press enter.
Select RUN and press enter.
Select SHUTTERN, where N is the number of the station where you are changing the target and press enter.
At this point you should be able to see the target and shield from the bottom, through the hole in the shutter.
You may lower the gun by loosening the hex screws atop the chamber lid. Carefully lower the gun by supporting it from below. Do not pull up on the Blue Box. This will damage the equipment and you will lose your access to the system.
The shield has no screws. It is removed by turning counter-clockwise (when looking at the target). Hold the shaft of the gun while unscrewing the shield. This will prevent damage to the internal components of the gun.
Wipe the conductive paste off of the back side of the target and off of the bottom of the sputter gun.
Put the target in the appropriate box and store it in the drybox.
Get the new target out of the box.
Coat the back side of the new target with conductive paste. Use only a very small amount of paste. You only need a very thin layer of paste on the target. Avoid getting paste on the front of the target.
Put the target in the clamp and hold the clamp in position under the sputter gun. Look under the lid directly at the gun or on the magnetic keeper on the back of the target. The shield should screw on easily. If you are having difficulty you must take the shield and target out and try screwing it in again until it screws on easily. If it screws on easily screw it on until the target just touches the gun.
Once the target touches the gun move it around until it is in between the ridges of the gun and then tighten it completely. (you will feel the resistance decrease dramatically as the keeper is no longer forcing the threads together). Turn one or two additional rotations until the shield stops turning. DO NOT tighten at this point, you may in fact back the shield off by 1/4 turn to prevent it from getting jammed on the gun.
Look at the target from the side, through the space between the shutter and the lid. The target should be flat against the gun. If it is not, you need to take it off and reinstall it.
Using a multimeter, check to be sure that the target and shield are not electrically connected. The easiest way to do this is to use the meters diode check function. Put one probe on the target and one on the shield. The meter should not beep. If the meter does beep, there is a problem. If this occurs, contact MiRC staff. Do not operate the sputterer if the target is electrically connected to the shield.

VIII. Troubleshooting

Q:Nothing was deposited on my sample during the run. What happened?

A: Make sure that all of the equipment on the instrument rack is turned on during the run. Even though you do not need to do anything to this equipment directly, it needs to be on so that the computer can control it. Make sure that the rotostrate knob was turned up to about 6. If the knob is set near zero, the sample holder will not rotate and your samples may not be exposed to the sputtering gun. If you checked those, and the system still did not deposit, contact MiRC staff and submit a Pettit Service Request

Q:The system never starts sputtering. Why?

A: Read the System Theory section above. If the sputterer is following the process outlined there, then it is working properly. Some of the steps can take a long time. If it gets stuck on one step, report the problem to MiRC staff and submit a Pettit Service Request.

IX. DO's and DON'Ts

DO NOT

attempt to open the chamber while a process is running.
put a target away without cleaning it - including getting the thermal paste off the back
try to run the sputterer without checking the target for conductivity
proceed with processing the in face of an unknown error. Contact the maintenance staff and/or the trainer first
use the machine if another user has placed a 'machine down' sign on it; ask the technical staff to verify that it is working
sputter over an open heater
waste precious metal targets
attempt to hoist the chamber without first seeing the "Chamber vented; Hoist enabled" message on the screen

DO

ask the trainer, cleanroom / technical staff, and other users about anything that is not clear to you or that you do not understand
ask other users of the equipment that work with the material that you are using for advice on specific processing issues with that material.
check to make sure that the area under the chamber lid is clear before lowering the hoist
practice on the equipment with a certified user before being checked-off

X. Check-off requirements

To be checked off, you must demonstrate a level of proficiency with this equipment. IT IS NOT ENOUGH TO SIMPLY AVOID DAMAGING THE EQUIPMENT. You must demonstrate a level of knowledge sufficient to handle the equipment with confidence. Do not ask to be checked off until you have practiced with this equipment with another user.

You must be able to:

Locate the relevant components of the system (Targets, heater, etc.)
Know the materials that can be deposited.
Know the specific materials and processes for which you will be using the sputterer.
Be familiar with the other materials that can be deposited in the system.
Set up, edit and run a batch.
Load a sample.
Change the target.
Understand how the sputterer works.