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PVD RF Sputterer
I. Introduction
The RF sputterer can be used to coat samples with dielectric materials. Metal coatings are usually performed with the DC 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.
The RF sputterer can be used to deposit many dielectrics. We have sputter targets for silicon dioxide, indium tin oxide, zinc oxide, silicon nitride and other materials.
RF sputterer coatings are performed by accelerating ions of argon or an argon oxygen mixture into the surface of a sputter target, which is made of the material to be applied to the sample. The gas ions cause atoms to be knocked off of the target and deposited on the sample being coated. Users desiring other materials need to provide their own target and show information that their target will not contaminate the system and other, later users' samples.
II. Machine Specifications
The materials used in the PVD75 are:
- ZnO
- ITO
- BST
- Silicon Dioxide
- Silicon Nitride
- Other materials*
*Please consult MiRC staff to process other materials.
III. System Components
- 3 3" Sputtering Guns
- Substrate Heater capable of heating to 600°C
- Cryopump
- 600W RF Power Supply
- Heat exchanger
IV. Operating Instructions
A. Loading the Sputterer
- Login to the machine.
- VENT the machine by touching the display screen. Wait until display screen says ‘Vent Completed.' Then open the chamber door.
- Visually inspect all the targets you plan to use. Make sure that they are the proper material and that they are not melted, destroyed, and/or cracked. If there is anything wrong with a target, please contact MiRC staff before attempting your run. See the “Changing a Target” section on how to change a target.
- Replace the SLIDES in the window of the door: have at least 2 slides in the door. If you do not do this, you will be unable to see your experiment.
- Remove the sample plate and load your samples. Note: Only remove the plate when the U-bracket is facing forward. Small samples must be clamped using small clip wires. These can be obtained from the MiRC staff. Also samples should be no thicker than 3/8".
- Check the crystal life by “ Xtal life ” on the crystal display found inside the right door. Note : Value must be greater than 85
- After your samples are loaded, turn ON the Rotostrate Control knob located near the bottom of the rack. Set the speed (red knob) to 2.5. Your samples should be rotating. Make sure that they stay pinned down and do not move. Note: the rotostrate speed should not be set greater than 5. Before cutting the power off, turn the rotostrate speed to 0.
- Wipe clean the door and area surrounding the o-ring with a dry text wipe.
B. Operating the Sputterer
- PUMPDOWN the machine by hitting the pumpdown button on the display. Note: Keep your hand on the door until the VAC turns green.
- Choose the appropriate source: source 1 is for the left gun, source 2 is for the right gun.
- Verify the parameters are correct for the type of target you are running.
- After pumpdown is complete, flow argon into the chamber to achieve 6 mTorr of pressure.
- On the display press GAS. (For a more detailed explanation of the Gas screen look below for Gas Flow Settings).
- Press the SP value for pressure and INCREASE or DECREASE until the appropriate value is reached.
- MFC1 is for ARGON .
- MFC2 is for OXYGEN .
- Change the MODE in either MFC1 or MFC2 to 2.
- Open gas valve by pressing Gas valve symbol. The symbol will turn green. Stay on the Gas screen while processing.
- Set the set point on the power supply to desired voltage (0-350W).
- Press the ON button. (light will turn red)
- Once the power is up to the desired wattage, zero the thickness by pressing the zero button (this will also zero the clock).
- Check the DC Bias level (should be consistant with the same process).
- The machine will continue running until you manually turn the power off.
- Manually ramp down the power supply if your target is brittle. Do so by lowering the setpoint in increments until the DC Bias is zero.
- Turn the power supply OFF .
- Set the set point power to 0 W.
Gas Flow Settings
Constant Pressure (Mode 2) will adjust the flow rate of this gas to maintain the SP pressure.
Example: If the process requires a 5 mTorr Argon environment, set The SP to 5 mTorr and MFC 1 to Mode 2
Ratio (Mode 1) will adjust the flow rate of this MFC according to the (CONT%) * (Mode 2 MFC flow rate).
Example: A 5 mTorr 75/25 Argon/Oxygen requires MFC 1 (Argon) to be set to Mode 2 since it is the larger component. MFC 2 (Oxygen) will be set to Mode 1 and CONT% is 33%. The pressure SP is 5 mTorr.
Constant Flow (Mode 0) will maintain a set point flow rate.
Example: In a 35% full scale Argon and a 50% full scale Oxygen recipe, MFC 1 is set to Mode 0 with SP FS set to 35%. MFC 2 is also set to Mode 0 but with a 50% SP FS.
C. Unloading the Sputterer
- When your run is finished and the power has been turned off. VENT the system.
- Remove your samples.
- Run PUMPDOWN .
- If there were any problems with this run, please report them to the MiRC Staff or submit a service request online.
*Please wait for atleast 15 min for the targets to cool down (or till the heater temperature is at 60 degrees) before venting the system.
V. Changing a Target
- VENT the system by pressing vent on the display.
- Once the screen says ‘Vent Completed' you may open the chamber door.
- Remove the shield by loosening the screws on the side.
- Remove the target.
- Wipe the conductive paste off of the back side of the target and off of the top of the sputter gun.
- Put the target in the appropriate box and store it in the drybox near the filament evaporator.
- 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 .
- Place the new target into the sputterer gun so that the copper backing plate side is facing down, and the sputtering side is facing up. This is because the samples are located above the targets, facing down.
- The target will CLICK into place when it is in the correct position. Target must be mounted properly or it will damage the gun. If you have any questions, contact a staff member.
- Place the shield over the target and tighten the screws.
- If you are using a CONDUCTIVE target, do a GROUND test. Measure resistance from the target to ground. Place the multimeter in diode check mode or resistance. Place one lead of the multimeter on the base of the chamber while the other lead is on the face of the target. If there is no contact (OL) or high resistance (>2M?), the target has been properly installed.
VI. Co-Deposition Instructions
- Load the targets in Gun 3 and either one of Gun 1 or 2 (selected by the source switch).
- Program the power controller like you usually do for Gun 1 or 2.
- Turn on both the Supplies for Gun 3 (power and tuner)
- Keep the Set-Point button pressed while turning the black knob on the power supply to the desired power levels.
- Turn on the power to Gun 1 or 2.
- Push the RF ON button on the power supply of Gun 3 when the power to Gun 1 or 2 has ramped up to the desired set point.
- At the end of your run turn off the power to Gun 1 or 2.
- Push RF OFF on the supply for Gun 3.
- Then turn off the power supplies for Gun 3 (Power and Tuner)
- Wait for 15 min. for the targets to cool down and follow the VENT procedure as usual.
VII. DOs and DON'Ts
DO
- Always check the target before using it to ensure that it is the correct target
- Always vacuum the inside of the chamber and the target surface to be sure that there are no loose particles present.
- Use the Online Service Request form available at http://grover.mirc.gatech.edu/pettit
- Email the list of users for the equipment for any advice on specific processing issues at pvd75rf-users@grover.mirc.gatech.edu
DO NOT
- Assume that the sign on the front of the sputterer identifies the target correctly.
- Attempt to do maintenance on the machine.
- Attempt to open the door whilst a process is running.
- Hesitate to pose any questions to MiRC Technical Staff and/or trainer of the equipment if you have any problems
- Continue using the machine when you encounter an unusual error. Contact the trainer and/or MiRC Technical Staff first.
VIII. Check-off Requirements
To be checked off, you must be able to demonstrate and/or answer questions asked by the trainer about the following procedures:
- Change the target.
- Know the materials that can be deposited at each station.
- Vent the chamber.
- Load a sample.
- Load a recipe.
- Run a sample.
- Unload a sample.
- Pump down the chamber.
- Know the DOs and DON'Ts
IX. Com Errors
If there is a COM Error on the touchscreen only:
- Open left rear door
- Find the SLT Adapter Board (top most PCB)
- Turn off Touchscreen mode switch (top left switch) (middle position)
- Turn off I/O Controller mode switch (I/O Controller switch) (middle position)
- Turn off I/O Controller mode switch (up position)
- Turn on the Touchscreen mode switch (up position)
If there is a COM Error on the touchscreen AND pressure reads on the -11 scale:
- Open left rear door
- Find the SLT Adapter Board (top most PCB)
- Turn off Touchscreen mode switch (top left switch) (middle position)
- Turn off I/O Controller mode switch (I/O Controller switch) (middle position)
- Find Analog Board (3rd from top PCB)
- Turn off switch next to WRG Cable (40CBL)
- Turn on I/O Controller mode switch (up position)
- Turn on the Touchscreen mode switch (up position)
- Turn on WRG switch