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Innotec ES26C E-Beam Evaporator, innotec

Innotec is an E-beam metal evaporation system, capable of depositing either single or multiple metallic thin films. Evaporation is a directional process and hence very good for lift-off applications. Innotec allows precisely controlled film thickness for films up to 1μm in thickness. Innotec is classified as gold contaminated. Many sources are available for film deposition including (but not limited to): Au, Cu, Cr, Pt, Ag, and Si (full list in Innotec Process Capabilities). Precious metals (Au, Pd, Pt) thickness must be below 200nm if using SNF metals. In general, evaporated films have worse adhesion to the substrate than sputtered films.

Picture and Location

 

Innotec

 

 The Innotec ES26C E-beam Evaporator

 

This tool is located at D56 on the Lab Map.

 

Background

Thin Film Evaporation

Evaporation and Vapor Pressure

In general evaporation systems heat a source to induce a vapor pressure greater than the pressure to which the deposition chamber has been pumped down. Typically this means creating a vapor of at least a few mTorr. Different materials will achieve the nominal vapor pressure a vastly different temperatures: for example the soft metal Al has a vapor pressure of 10 mTorr at 1250°C, while the refractory metal W has a vapor pressure of 10 mTorr at over 3000°C.

 

Deposition and Film Stress

The evaporated material is deposited on your substrate (and the rest of the chamber) at a rate dependent on the distance from the source, so typically wafers are arranged in a hemisphere to aid in wafer to wafer uniformity. The deposition of the desired film is essentially a vapor condensation process as the evaporated target particles stick to cooler surfaces in the chamber or on your substrate. The metal atoms stick as soon as they arrive at the surface, not allowing for much movement that can help with step coverage or limiting stress. The substrate temperatures has a great influence on the film stress by controlling the degree of “stuckness” for the metal particles when they hit the substrate. Hotter substrates will have less stress. Typically, metal films evaporated onto unheated Si substrates will be tensile. A rule of thumb is that the higher the melting temperature of a metal, the higher the stress of the film.

 

Adhesion

Quite in general, the adhesion of evaporated films to the substrate is worse than sputtering the same film/substrate combination. Adhesion depends on the film material, the substrate material, and the stress in the film. Certain applications require films such as Au and Ag may need a thin “adhesion layer” to be added first. Cr is the most commonly used adhesion layer for Au and Ag for Si and quartz substrates.

 

E-beam Evaporation

Different evaporation systems used different techniques to heat the source sample. Innotec is an e-beam evaporator meaning the source is heated very locally with a beam of high energy electrons. Because the beam can focus so much energy into such a small volume (<1mm3) temperatures in excess of 3000°C can be achieved.

 

Process Capabilities

Cleanliness Standard

The Innotec is operated in the GOLD EQUIPMENT GROUP.

 

Available Deposition Materials

The following sources are available in the SNF: Ag, Al, Au, Co, Cr, Cu, Fe, Ge, In, Mo, Ni, Pd, Pt, Si, Ti, Ta, and W.

The following sources are allowed in Innotec, but are not supplied:  Er, Hf, Ir, Ru, Tb, and Y

Please contact specmat about introducing a new source for the Innotec. NOTE: it is recommended you discuss you process with a member of the quality circle prior to contacting specmat.

 

Performance of the Innotec

What the Innotec CAN do

  • Innotec can provide thin films (<1um thick) of various metal and semi-conductors with precision measurement of film thickness via crystal monitoring.
  • Innotec provides very directional evaporation particularly useful for lift-off metal patterning.
  • For deposition on sidewalls, a 45° angle wafer holder is available.
  • Shadow mask deposition is possible. Currently only manually alignment is possible between the shadow mask and the substrate.
  • Deposition on up to 24 4" wafers at once.
  • Deposition on pieces, which are fixed to a 4” wafer via Kapton tape or via via baked photoresist.
  • Cross wafer uniformity is roughly 5% and Wafer to Wafer uniformity is roughly 5%.

 

What the Innotec CANNOT do

  • Innotec should not be used for depositing thick films due to time, wear on the system, expense of materials, and adhesion issues with your sample.
  • Uniformity values are only for wafers in the lowest row of the hemisphere.
  • Innotec should not be used to evaporate dielectrics.
  • Capture all the variability between users in terms of e-beam focusing, source condition (new sources will have a different deposition rate than a source that has been used many times).

 

Process Monitoring

At least once a month (and following any major repairs) a qualification process is run to ensure the machine is in basic working condition. The details and results of these qualifying runs are captured in the section on Process Monitoring and Machine Qualification.

 

How to Become a User

 

  1. Read all material on the SNF website concerning the Innotec.
  2. Contact SNF training contact on the Equipment Summary page to register for a training session.

Operating Procedures

System description

The Innotec is a non-load lock; six-pocket e-beam evaporator used for depositing Au, Ti, Ni, Al, Cr, Si, Ge, Pt, Ir, and other materials. Wafers are loaded on a rotating planetary and pumped to below 5e-7 Torr using a cryo pump. Pump time is typically two hours with overall turnaround time about three hours. Deposition thickness is controlled via a crystal monitor, verified by the user using the “GOLD CONTAMINATED” Dektak. The evaporator has three distinct sub-systems: the vacuum system, the deposition thickness control and monitoring, and electron-gun control. The Innotec has three control consoles:

  1. Master console - the Innotec Video Screen Control (VSC) on the right side, with a CRT screen.
  2. Maxtek Deposition Controller - on the left side, with a backlit LCD screen.
  3. Telemark TT10/15 control - power supply (above the Maxtek Controller).

 

Innotec VSC

Video Screen Controller

 

Innotec Maxtek and Telemark

Maxtek and Telemark

 

Safety warnings

This machine can cause injury if not used in a cautious manner.

  1. The chamber can crush hands if lowered onto them.
  2. Hot targets can cause burns.
  3. The operator can inhale particles while handling chamber parts and is advised to cover the mouth.
  4. Si or Ge sources can explode in an operator’s face or cause machine problems so additional training and special permission are required before using those materials.
  5. The system can also be easily damaged if the electron beam is misplaced or is allowed to drift out of position.
  6. While the amount of x-rays escaping the machine should be safe, we do not have current measurements of the level of exposure. Do not operate this machine if you could be pregnant.

 

For all these reasons:

The system must be monitored at all times during operation.

DO NOT ATTEMPT TO REPAIR THIS SYSTEM YOURSELF. Please contact maintenance. For certain issues (link to trouble shooting list), you may contact the super-user outside of staff hours.

 

Initial system checks

  1. Master console shows Pump Only Mode.
  2. Chamber ion gauge pressure reads less than 5 e-7 Torr on the master console, unless the system was recently used. (Chamber ion gauge reading is found on the Master console.)
  3. The green Start button is lit.
  4. The cryopump temperature is 15K or less.
  5. The chamber temperature is 40C or less on the “West” gauge. (Under the Maktek controller.)
  6. The crystal health is greater than 75%. (Readout on Maktek controller.)
  7. Telemark TT10/15 Control key switch is on and main power is off.

 

Status checks

  1. Check for an EMPTY sign attached to the machine. Do not use if an IN USE sign or MAINTENANCE sign is there. Check for problem notes. 
  2. Check the computer for reservations, problems, and to see if it is already enabled by another user.
  3. The system is available if the initial system and status checks are good. Enable the system on Coral. Place sign “IN USE” on the machine.

IMPORTANT! The sign is the official status of the machine. Don’t risk your wafers with an incorrect status card. If you don’t leave an IN USE sign on the machine and someone ruins your wafers, it is not their responsibility, regardless of whether the machine was enabled or reserved.

 

Venting the chamber (before loading wafers)

  1. Press the red STOP button next to the VSC. 
  2. Press Vent. F6 on the Master Console. 
  3. Wait until the “ATM” amber atmospheric pressure light is lit (about 4 minutes.)
  4. Wait one additional minute.
  5. Verify the main chamber seal has decompressed from the bell jar.
  6. Tap the UP button once or twice. If the chamber rises easily, continue raising it.

 

Inspecting the chamber before use

  1. Inspect the planetary for any “real” wafers belonging to other users. If any are found, keep them in a labeled box.
  2. Press Manual on the master console F3.
  3. Rotate the shutter away by stepping the cursor to Shutter 1 and then toggling it with the F2 key. It can be slow to move.
  4. Position Cursor at crucible select, toggle F2 to rotate the crucible to each position and inspect for splattering, contamination, cracking or other problems. Be sure the crucible assembly rotates freely. Don’t use crucibles in poor condition. Report any problems to staff.
  5. Inspect the chamber for peeling, particles, and material splatters. Vacuum and wipe if necessary. Thorough cleaning of the equipment every time will aid in reproducible results long term.
  6. Using the wafer mirror to inspect under shutter, view port and Crystal Holder for peeling, particles, splatters. When necessary vacuum area, change or clean the shutter.
  7. Load source into the correct crucible position posted on the front of the control panel. NOTE: some materials are allowed in multiple crucibles. Making sure they are clean and fit with the correct height and shape (snug not tight). Correct height would be 60% to 100% of the crucibles original Height or original weight.
  8. If more pellets are needed, be careful not to overfill. Pellets must not protrude above crucible or Hearth may get stuck or jam.
  9. Return the shutter to the closed position.
  10. If a new crystal monitor is needed (75% or less), change it now. Extras are kept in the drawer, in the Master console.

 

Source Material Correct Crucible
Ge, Si  C1
Al C2
Ir, W, Mo, Pt, Ni, Fe, Tb, Y, Er, Ti, Cr, Hf, Ru C3
Ti, Cr, Ni, Ag, Co, Cu, Pd, Ta  C4
Au C5
Sn C6

 

Load wafers

  1. Load samples on to wafer holders or wafers face down on the planetary. The top and bottom row of the planetary may give somewhat different deposition thickness. The outer circle of planetary is recommended for better uniformity and is the only rotary currently measured in the machine monitoring.
  2. To verify thickness load a bare Si wafer with a mask partially covering it for a step height thickness monitor. The mask can be a partial wafer or Kapton tape or a sharpie mark. Information on sharpie lift off can be found here.
  3. Wipe around the upper and lower part of the bell jar seal.
  4. Last chance to change crystal and to make sure the bar in front is aligned in front of holes.
  5. Lower the bell jar chamber by pressing both DOWN buttons, while insuring that no one’s hands are in the way.
  6. The lowered bell jar must be lying flat on the chamber edge. DON’T GET YOUR HANDS CAUGHT!
  7. Stepping the cursor to planetary, toggle F2 (ON) to test for proper alignment. If a loud grinding noise is heard or you can see rotation problems, stop the rotation, raise and lower the chamber, and try again. Always stop rotation before attempting to lift bell jar.
  8. Toggle F2 to stop planetary rotation.

 

Pumpdown

  1. Press Return to get out of manual mode (F1).
  2. Press the Vent key to stop venting (F6).
  3. Press Pump Only (F5) to start pumping. DON’T GO AWAY YET!
  4. Monitor the pump down to be sure the Bell Jar was correctly positioned:
    1. Verify that the amber ATM light goes out within 10 sec.
    2. Wait for the pressure to drop to the crossover pressure, i.e. for the cryopump to take over at about 150 mTorr.
  5. Typically less than one hour for the chamber to pump down to about 5e-7 Torr or below.

 

Deposition

On the master console VSC:

  1. Press the red Stop button.
  2. Wait until page changes to Runtime screen.
  3. Press the programmable key labeled Manual (F3).
  4. Cursor is next to Filament, pressing the Toggle F2 to turn ON.
  5. Check that the base pressure is about 5e-7 Torr or below. Record the pump time and pressure in the logbook.
  6. Moving the cursor to planetary, toggle F2 (ON), check that the pressure doesn’t rise.
  7. Select correct crucible, it may take a moment to rotate. See position/material list posted above video screen.
  8. Check that the gun filament 1 remains in the off position.

 

On Maxtek Deposition Controller console:

  1. Be sure that RESET is lit.
  2. Press ABORT.
  3. Press RESET.
  4. Press START to get material list.
  5. Select the right material using the up or down arrows.
  6. Press START.
  7. Check that the correct material is displayed at the top of the screen.
  8. Press ABORT.
  9. Press RESET.
  10. Press Manual.

 

On the master console VSC:

  1. Verify that the shutter 1 is closed.

 

On Telemark TT10/15 control console:

  1. Press Main Power button on.
  2. Wait 30 sec. for (cut back) fans to spin up and stop flashing.
  3. Press reset interlock on high voltage (all 7 green lights are lit).

 

On Telemark sweep power supply:

  1. Verify sweep controller power supply green light is on.
  2. Switch control/sweep select switch to control position.
  3. Joystick/sweep control box: spiral/triangle/manual, switch to manual.
  4. Precenter beam position using the joystick and the lat/long position readouts.

 

On Telemark TT10/15 control console:

  1. Place local/remote switch in loc position.
  2. Press source 1 button ON.
  3. Place local/remote switch in remote position.
  4. Press high voltage button ON.
  5. Be sure that the source, DC amps gauge does not show a sudden rise. If so, press ABORT, then RESET, and contact staff.
  6. Check that the Kilovolts meter reads -10.0 kV +/- 0.1 kV.
  7. Adjust the casing of the polarized glass window to get light through, and advance the window film if necessary to view the faint blue beam. This is located on the Bell jar.
  8. Using the remote control, (always keeping an eye on the e-beam):
    1. With a desired power in mind, slowly bring the power up 2% at a time for 20 sec. or more each time.
    2. Go slower for Si and Ge. (HOW SLOW?)
    3. Observe the electron beam each time the power is increased and adjust the position as necessary using the joystick.
  9. Verify that the e-beam is directed into the center of the crucible. IMPORTANT!
  10. Don’t let the e-beam go outside the source area and ruin the crucible!
  11. Open shutter 1 on the VSC.
  12. Check that the rate of deposition is normal for the power applied (log dep. rate). If not, turn down the power right away until the reason is known.
  13. When the desired thickness is reached, use the remote to turn down the power all the way. NOTE: Si and Ge will form peaks if cooled too quickly, which will interfere with the crucible rotation; you may want to close the shutter and turn down the power slowly before turning off.
  14. Close shutter 1 on the VSC.
  15. Press ABORT and record all information.
  16. Press RESET.
  17. Press High Voltage button OFF.
  18. Press Source 1 button OFF.
  19. To deposit another type of material let the crucible cool for several minutes.
  20. Rotate to the new crucible. Follow instructions starting at Step 9 in the “Deposition” section (some steps are still on.)
  21. If no more depositions are needed, move cursor to planetary and toggle off.
  22. Press Telemark power supply, Main Power button OFF.
  23. Press RETURN (F1) to get to the RUN TIME screen.
  24. Press PUMP ONLY (F5). Wait at least 10 minutes if Si or Ge, 5 minutes for all other materials. This cools the targets before venting, which prevents oxidizing them. WARNING! Si and Ge expand as they cool and have exploded when the chamber was vented too soon. DO NOT VENT UNTIL COOLED FOR 10 MINUTES.

 

Venting and unloading

  1. Press the red STOP button.
  2. Press Vent (F6).
  3. Wait until the “ATM” amber atmospheric pressure light is lit (about 4 minutes).
  4. Wait one additional minute.
  5. Verify the main chamber seal has decompressed.
  6. Tap the UP button once or twice. If the chamber rises easily, continue raising it.
  7. Remove wafers and inspect visually. You’ll be responsible if damage has occurred and you didn’t report it.
  8. Replace the dummy wafers, loading the polished side face up to distinguish them from “real” wafers.
  9. Perform the required crucible, shutter, and chamber inspections and clean as per previous instructions.
  10. Remove the source material if necessary.
  11. Press F1 to return to the Run Time Screen.
  12. Wipe around the upper and lower part of the bell jar seal.
  13. Press both DOWN buttons to lower the chamber as per previous instructions.


Pumpdown and shutdown

  1. Press the Vent key to stop venting (F6).
  2. Press Pump Only to start pumping (F5). WAIT, YOU”RE NOT FINISHED YET!
  3. Monitor the pump down to be sure the chamber was correctly positioned:
    1. Verify that the amber ATM light goes out with in 10 sec.
    2. Watch for the pressure to drop to the crossover point, i.e. for the cryopump to take over at about 150 millitorr. This will take 5 minutes
  4. While waiting for step 3B, pump crossover, use the Dektak profilometer to measure the total deposition if using a shadow mask test wafer.
  5. RECORD RESULTSin the logbook.
  6. Be sure the crossover pressure is met and that the cryopump valve opened.
  7. Clean up the area and return items to their proper locations.
  8. Place an EMPTY sign on the machine.
  9. Write down any problems or comments in the logbook.
  10. Record any problems on Coral.
  11. Disable the Innotec.

 

Process Monitoring and Machine Qualification

Innotec Qualification Run

To ensure continued machine performance the Innotec is regularly put through a qualification procedure meant to capture basic functionality and potential errors in the system.

 

Frequency

The machine qualification is run at least once per month under normal operation. This test is performed during the first training session of the month. Additionally a qualification run is performed after any major maintenance to the system. The resulting test data will be reported by the Friday following qualification run.

 

Procedure

A deposition of 100nm of Al is performed under the following conditions: 

  1. The qualification run is performed by the quality circle to eliminate the user-to-user variation inherent in the system as much as possible.
  2. Two diff clean 100 Si test wafers are used and are placed in the outer-most row of the planetary.
  3. A base pressure of at least 5.0 x 10-7 Torr is achieved (record the pump down time).
  4. The e-beam power is brought up in a consistent manner (what would be a good way to codify this?  Maybe increase 1 every 5 seconds.)
  5. The e-beam is focused in the center of the source.
  6. The crystal is used to determine the deposition of 100nm. NOTE:  this method may give an imprecise answer, but it should be consistently imprecise (see data).
  7. After deposition the 2 test wafers are tested for sheet resistance in the Prometrix, and that data is recorded here.
  8. If the sheet resistance is out of the specified acceptable operation range, the test wafers are patterned (the mask is available through the quality circle members) and wet etched in Al etch. NOTE: the wafer is gold-contaminated and should not be etched in wbmetal or P5000.
  9. The etched wafer is tested in the Gold Contaminated profilometer to determine thickness of the deposited metal.

 

Some notes:

  1. The sheet resistance measurement should capture either deposition rate inaccuracies or contamination.
  2. The follow up profilometer measurement determines if the layer deposited is of an appropriate thickness but of incorrect conductivity, to differentiate between errors in deposition rate and contamination.
  3. Al is used because of cost and historical reasons. The Innotec utilizes too many different sources to make it feasible to check each one. But if one material can be deposited correctly and accurately, the basic functionality of the tool has been demonstrated.

 

Responsibility

Performance of the qualification procedure is primarily the responsibility of the process members of the tool’s quality circle. The super-users are available to assist in times of need with running, testing, and reporting of the qualification procedure.

 

Recommendation to users with critical processes

If you have a critical deposition it may be in a user’s best interest to perform their own run of the qualification procedure before entrusting their precious process wafers to the Innotec. A run on the Innotec is time consuming and the schedule is often very full, so appropriate “cost-benefit analysis” should be considered.

 

Machine Status States

Red: the Innotec is in red-light condition and should not be used. It can be in this state for any of the following reasons:

  1. The machine failed to pass the qualification procedure within spec.
  2. The machine is currently under repair.
  3. The machine will not pump down to a base pressure below 1.0 x 10-6 Torr in a usable amount of time.
  4. The e-beam gun will not operate.

 

Yellow: the Innotec is in yellow-light condition and should only be used after careful consideration of posted comments and evaluation of likely effect to your process. NOTE: if the machine is in Yellow or Green it has successfully passed the qualification procedure in the most recent test.

  1. Problems with measured conductivity or thickness achieved for any deposited metal as compared to the crystal monitor.
  2. Excessive pump down times.
  3. User reported problems or issues.

 

Green: the Innotec is in green-light condition and is free of any known problems. NOTE: this does not mean that any specific ultra-critical process will work immediately without flaw, and users should take appropriate care with their wafers.

 

Process Monitoring Results

Below is profilometric thickness measurements of qualification runs for the first 3 months of 2008. Note that the crystal reading gave 1000Å but the measured results are consistently ~10% too large.

 

Innotec Qual Data

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