KJLesker Sputtering System

KJLesker Sputtering System


Description

The Lesker sputtering system is a large vacuum chamber where an inert (or reactive) gas atmosphere is introduced along with the generation of a plasma across a target material and substrate. Sputtering occurs when these gas particles are ionized in an electric field (producing a gas plasma) and then directing them toward the source or target, where the energy of these gas particles physically dislodges, or "sputters off," atoms of the source material.

A sputtering system provides thin film deposition of various metals and insulators using DC or RF plasmas across a substrate. The Lesker sputtering system contains four 2-inch sputtering guns and has the capability to sputter 15 different metals as well as insulators and semiconductors such as ceramics, silicon, and piezoelectric material. The system takes approximately 6-8 hours to pump down before a chamber pressure of 4E-7 Torr is reached, adequate for subsequent deposition.

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Usage Policy

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Contact

Name Office Extension Email
Suresh Santhanam ReH 301 Link Link

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Qualified Users List

Name Office Extension Email
       
       
etc.      

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Standard Operating Procedures

Updated Instructions

(detailed specifications for all components of the sputtering system can be found in the large black binder on the stainless steel shelves adjacent to the sputtering system.)

* observation items
- action items

General Operating Safety
The sputtering system is a very complicated and expensive piece of machinery. There are many safety features built in to protect you from it and vice versa. It is to be used only by properly trained personnel. The primary dangers include but are not limited to:
* mechanical injury from raising/lowering of chamber lid controlled by motorized hoist.
* electrical shock injury from exposed energized surfaces, cables, etc.
* mechanical injury from explosion/implosion generated from high/low pressures within the vacuum system.

Use this system only if you are authorized to do so and only when you are fully awake/aware, etc.

**- If the system malfunctions due to either a user error or random machine error please contact the appropriate personell listed on this page.

- DO NOT attempt to fix the problem yourself unless you have the proper training/knowledge.

STANDARD OPERATING PROCEDURES:

Sign In
  - occurs on the door between the cloak room and main bay of HH1216.
  - must include: NAME, ADVISOR'S NAME, ACCOUNT NUMBER, # OF TIMES SYSTEM WAS USED. The number of times the system was used refers to the number of pumpdown cycles (ie. if you sputter 4 wafers in a single pumpdown cycle, this is 1 run, likewise, 0 wafers sputtered because you forgot to load the target is also 1 run).

Sample Loading and Removal
  * you MUST be wearing clean gloves and long-sleave shirt (preferably a lab coat) when performing any action involving the inside of the chamber (sample loading, target mounting, etc.)
  * the system is normally in a high vacuum state
  * need to vent it to bring it up to atmosphere so chamber can be opened
  - make sure ion gauge 1 is OFF, it is for measuring P ~< 10e-5 Torr only
  - open mechanical regulator valve on nitrogen cylinders (the sputtering system line is the right-hand one as you face the cylinders)
  - turn key on main control panel to MANUAL
  - wait for cryopump gate valve to close
  * gate valve closing must make a popping noise (do NOT proceed if this does not occur!)
  - turn CHAMBER VENT VALVE to ON
  * chamber is now venting (takes approx. 1 min)
  - wait for green ATM light to go on
  * chamber is now at ATMosphere
  - turn CHAMBER VENT VALVE to OFF
  - close mechanical valve on nitrogen cylinders
  -use hoist button to lift chamber lid
  -change targets if needed
  - for PZT or other thick targets, use ohmeter to check for electrical short (check at coax lead on sputter gun under the sputter chamber)
  - load sample or remove sample
  - close lid with hoist
  - if loading samples, put SYSTEM IN USE up
  - if removing samples, put SYSTEM FREE up

Starting pumpdown procedure
  - turn key to AUTO mode
  - hit START button (pumping begins)
  * pump down takes ~ 2 hours

Deposition procedure
  * determine that system is ready to operate:
  - check inlet/outlet cooling water temperature/pressure
  - record on log sheet, determining that system is operational
    ** notify appropriate personnel if values are not within specs.
  - check to see that water is flowing to sputtering guns and cryo
    * valves should be ON if wheels spinning
      if you were looking down from the top of the system the gun orientation would be the following:
            gun 3
          gun2 gun4
            gun 1
  * base pressure of system must be low enough to insure high quality sputtered films (listed on check sheet)
  - turn on ion gauge 1
  - degas (approx. 30s) if necessary (this removes gas from ion gauge, allowing it to measure accurately)
  - turn off degas
  * P must be <= 4.0e-7 Torr
  - enter pressure value in log
  -turn throttle to open setting
  * P must be <= 2.0e-6 Torr in throttled position (this pressure gives you an idea of how much sample and chamber are outgassing
  - enter pressure value in log
  - return throttle to auto
  - turn off ion gauge 1


  * now ready to turn on processing gases
  - zero all pressure and flow rate modules
  - set pressure controller knob to desired pressure
  - if doing reactive sputtering (ie using an auxillary gas - either N2 or O2) check regulator valves to see that desired gas is selected
  * to change auxillary gases
       - close both regulator valves
       - set auxillary flow module to FLOW
       - open MAIN and N2 valves (square green buttons)
       - pump out lines until flow goes to zero
       - open regulator valve and let a little gas into line
       - close regulator valve
       - open MAIN and N2 valves (square green buttons)
       - pump out lines until flow goes to zero
       - open regulator valve
       * gas line switch now complete
  - set auxillary flow module to desired setting (FLOW or RATIO)
  - set gas ratio or flow to desired level
  * the mass flow calibration factors are the following (should not need changing unless a new gas is being used)
     1.00 for N2 or O2
     1.17 for 50/50 Ar/O2
     1.45 for Ar
  - turn on MAIN, AR, and(if using reactive gas) N2 valves(green buttons)
  * pressure and flows should reach set values within 20 sec


  * ready to sputter now
  - check pressure and temperature of cooling water P~ 30 PSI, T~ 70 F
  - enter values in log book
  - check cryo-pump Temp (blue readout) - contains liquid He ~ 11-12 K
  - enter value in log book


  - set shutter switch to timed
  - set sputter time
  - set table position to the station you are using

DC sputtering
   - connect DC cable to desired sputter gun
  - turn on the DC power module
  - turn to STANDBY
  - power to minimum
  - turn to WATTS
  - increase power to desired level at desired rate
  - check plasma
     *if no plasma:
       - hit Plasma Ignite button
       - increase Pressure temporarily if necessary
  - turn to VOLTS
  - enter DC voltage in log
  - turn back to WATTS
  - hit START button on timer module
  - when finished, ramp down power
  - turn to STANDBY
  - turn off power to DC module

RF sputtering
  - connect RF cable to desired sputter gun
  - turn on the RF power module
  - turn on the RF tuner module
  - set RF OFF
  - depress SETPOINT button, simultaneously turn power level to desired starting plasma power (40 W)
  - set tuner mode to AUTO if not already
  - set RF ON
  - check plasma
     *if no plasma:
       - hit Plasma Ignite button
       - increase Pressure temporarily if necessary
     * non-zero DC bias voltage will indicate that plasma has started: do NOT rely on reflected power to indicate whether plasma has started
  - ramp up power 10 W/min for non-metallic targets to avoid large temperature gradients in target and potential cracking
  * if for some reason you are using MANUAL tuning: - adjust two tuner knobs at bottom to achieve 0 reflected power
  - enter DC target bias voltage in log
  - hit START button on timer module
  - when finished, ramp down power
  - set RF ON
  - turn OFF RF power module
  - turn OFF RF tuner module


  * sputtering is now complete, you are now ready to turn off gases and vent the chamber to remove samples


  - close valves N2, Ar, MAIN


  * follow same procedure as given in Sample Loading above to remove samples

Back Sputter (substrate milling)
  - attach sample to backsputter chuck.
  - place chuck holder on desired table position.
  - attach chuck to holder inside chamber.
  - close chamber.
  - pump down chamber.
  - Using either Advanced Energy RF supply or K.J. Lesker supply, attach RF cable to upper bias cable using adaptor.(cable just reaches)
  - take down settings.
  - set pressure with Ar flow.
  - turn on power to RF supply and controller.
  - adjust set point to about desired power level (do not exceed 60 W)
  - turn on DC bias.
  - turn on RF supply.
  - adjust power, foreward power tune position, and reflected power shunt position to start plasma. if this fails turn up pressure. Note: the foreward power will be less than normal and the reflected power often cannot be reduced to zero.
  - once plasma is started adjust power, tune and shunt positions until the desired bias voltage is achieved.
  - start timing the process.
  - once time is up reduce power to zero.
  - turn off RF supply.
  - turn off DC bias.
  - turn off power supply to RF supply and controller.
  - turn off Ar and main valve.
  - disconnect RF cable!!!!!!! (if you are using Advanced Energy supply you will tear the cable when you vent the system and raise the hoist)
  - Continue with process.

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Application Notes

Sputtering Calibration Tip
Typically when sputtering with the Lesker or Indel you'll want to double check the sputtering rate and an easy way to do this is with lift-off. Although lift off with Kapton Tape is quite common, a simpler, more elegant solution was taught to me by Matt Moneck:
  1. Simply draw a line on the wafer with a Sharpe marker (or photoresist pen).
  2. Sputter the wafer as intended.
  3. Put the wafer in an acetone ultrasonic bath for 5 minutes to lift off the sputtered metal over the drawn line. If any of the metal hasn't lifted off, simply rub it away with an acetone soaked Q-tip.
Since the Sharpe comes off with acetone, there's no adhesive residue on the wafer. Even better, since the Sharpe line is so low, the "bunny ears" effect seen from lifting the Kapton tape doesn't occur.
by Michael Vladimer
Feb. 11th, 2004

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Useful Links

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Miscellaneous

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