Electronic Vision 501 Bonder, evbond

The Electronic Visions system is comprised of the precision optical 620 Aligner and the 501 Wafer Bonder. The Bonder module includes a Megasonic Clean station for ultrasonic cleaning of wafers before alignment. Using the specially provided bond tool, wafers to be bonded are aligned on the 620 Aligner and then placed in the 501 Bonder for processing. Although primarily used for anodic bonding, the 501 Bonder is compatible with several other bonding modes, including: compression, direct Si-Si, low temperature eutectic/frit bonding. Our current configuration accommodates 100 mm round wafers and pieces.

Picture and Location

Process Capabilities

Cleanliness Standard

Performance of the Tool

How to Become a User

Operating Procedures

1. Function: Optical lithography contact/proximity aligner-bonder
2. Overview
3. Special Notes or Restrictions
4. Type of bond possible
5. Operating Procedures:Bonding Si/Glass
6. Computer Menu Setup (getting started)
7. SHUTDOWN PROCEDURE (automatic mode)
8. Shutdown Procedure (manual mode)
9. Cleaning Procedures

Picture and Location

Process Capabilities

Cleanliness Standard

The evbond system is in the Flexible (Gold contaminated) Equipment Group.

Performance of the Tool

What the Tool CAN do

• Universal vacuum bond chamber design allows for control of voltage, contact pressure, and temperature.
• Independent control of upper and lower plate temperatures allows for differences in thermal expansion coefficients in different substrate materials.
• Software allows full automation of the bonding process, with process control capability.
• (Please note that there is a five-hour limit on reservation length on this tool during prime time.)

What the Tool CANNOT do

• No resist or polymer allowed.

How to Become a User

1.   Read all material on the SNF website concerning the EV Bonder.
2. Contact SNF staff in charge for training.

Operating Procedures

Function: Optical lithography contact/proximity aligner-bonder

Overview:

• Overview (specifications, facts and tips, part names).
• Bonding chucks for anodic bonding and thermal compression bonding.
• 4" wafers, 4" glass
• For Electronic Visions 620 Aligner (evalign) operating procedures, click <here>.
• The bonder is "gold" and sodium contaminated.
• Please be very cautious, the graphite is sodium contaminated and will contaminate the table.
• Please wipe the table with Isopropyl Alcohol and change your gloves frequently

Special Notes or Restrictions:

• This machine allows most materials, but samples will be gold and Na contaminated after use.
• No resist or polymer  allowed.

Type of bond possible

• Anodic bonding

• Temperature and voltage and pressure
• Glass to glass or Si to glass or SiO2 to glass (maybe Si3N4 to glass)
• Pyrex 7740 is standard glass for anodic bonding
• Borosilicate Glass will work, but has wrong coefficient of expansion (bowing or breaking will occur)

• Eutectic bonding

• Temperature and pressure bond only
• Metal to metal (typically gold)

• Fusion bonding

• Temperature and pressure bond only
• Not possible with the evbond system (requires ~900°C)

Operating Procedures:Bonding Si/Glass

Pre-start up

• By request only: Quartz plate (anodic bonding. low force not more than 500NF) or steel plate (eutectic bonding).
• If anodic vs eutectic become problematic,  staff will make the schedule, heat is an issue the plate needs hours to cool off before staff attempt to change them.
• If different plate needs to be installed, it is your responsibility to email SNF staff.
• If you damage or break any parts in the system,  You will be responsible for replacing the bondglass, quartz presser plate or graphite if broken due to negligence or improper use!! Please  check with staff before doing nonstandard procedure.
• It is a good idea to pump the system--go to manual and hit pump.
• Measure the thickness of your wafers  before cleaning them for bonding (thickness is important!).

• Both glass and si wafer must be less than 4mm thick (total stack thickness, because of limitations of the aligner)
• If they are manually aligned the total stack can be 10 mm thick (actual thickness of the whole stack, including graphite, flags and the bond tool glass -- wafers alone, no thicker than 7 mm), but you must talk to SNF staff before attempting to bond anything thicker than 3mm).

• Be sure your wafers are really clean (i.e. H2SO4:H2O2 followed by DI rinse and spin dry if possible). Hydroxylated surfaces help in anodic bonding.
• MEASURE your wafer thicknesses!

• Note: The thickness of the graphite disk plus flags = 2.10 mm for anodic bond.
• Solid graphite is 3.0 mm used for Si bonding and eutectic.
• Add wafer and glass thickness (or two wafers if Si/Si bonding) to the above thickness. For example, if the wafer is 0.5mm and the glass is 0.7mm the total would be:
• 0.5 + 0.7 + 2.1 = 3.3 mm
• If you use solid graphite, the total would be:
• 0.5 + 0.7 + 3.0 = 4.2 mm
• NOTE: Once program is started do not adjust stack height!
• The dial up micrometer on top of the bonder should not exceed 6 mm.

• Use Megasonic Cleaner (see below for instructions)

Megasonic Cleaner (Sonicated DI Water)

Note: If system is locked up, press the red reset button behind the door on the left.

• If your wafers have holes, you need to use the blue wafer saw tape before using the megasonic cleaner.
• Press Align (arm moves down)
• Place wafer on chuck
• Press Align (arm moves back up)
• Dial to preset (only #1 is set up)
• Press Start
• Press Enter
• The white marker should read 5 on the top and 4 on the bottom. Adjust this carefully because this is sensitive.
• When it beeps Press Enter
• Remove your wafer

• Align and clamp wafers together

• with the evalign system (see instructions with evalign)
• or manually

• If you have used the blue wafer saw tape please make sure to remove it! This tape is not allowed inside the bonder. The tape will melt and damage the system.
• Make sure flags are out.
• Clean Si wafer and place on bonding chuck face up
• Carefully move flags in (lift if necessary)
• Clean Pyrex wafer and place on top of wafer face down

• must be Pyrex or glass (not quartz)

• Place Bond Tool Glass on top of samples with word "Top" near wafer flat and facing down. Bond glass without words should be used for manual alignment.
• Carefully rotate two clamps simultaneously in place to hold samples, careful, you can easily break the glass frame.....
• Place field electrode (graphite) onto the bond tool. You have two choices of graphite-- solid or steel with a flexible center. Use the solid graphite for pieces and eutectic, and use the steel graphite with flexible center  for anodic only.
• Place field electrode (graphite) onto bond tool glass(side with metal strips should be up, and wafer flat should match flat on electrode).  Pay extra attention.

Computer Menu Setup (getting started)

1. Enable "evbond"
2. System Check

• Check cabinet for warning lights

• yellow on top left
• green on right side
• red on bottom

• Check for readout (~22°C is good)

• If not on or if system does not heat up when latter attempted, press red reset button.

3. Select your run mode

• Start control software if not running.
• Select "Bonder" on desktop or select "Shortcut to 501' from list ???

• AUTOMATIC MODE (using an existing program or write your own program)

• Select program from existing .aba routines

• Enlarge AUTOMATIC SETUP window
• Click on File (top left) and drag to open and release.
• Select existing .aba file (click once on file you want)

• (Use standard.aba program or newstd.aba - setup for Si to Pyrex anodic bonding) Do not make any changes to this program.

• Click on "OK" to load.

• OR --Write recipe (see below for instructions)

• Clear Custom programs with SNF staff before running it.
• Writing an Automatic file

• Edit an existing file or initiating a new automatic file

• Activate AUTOMATIC SETUP window
• Drag "file" menu to "open", select prototype .aba file and click on "OK".
• Immediately drag "file" menu to "write to...." and save file as your own unique .aba filename ( a name that I recognize) Click "OK" and you may now edit the file.
• To insert a step

• select row before which steps will be entered and click "Insert"
• click on inserted row and click "Edit" to further select EV501 commands
• click "END" when complete

• To delete a step

• Select a row and click "Delete"

• To start a sequence from scratch, click "New"
• Save file when completed by dragging "file" menu to "write to", selecting your own unique .aba filename and click "OK".

• Note: Ensure all appropriate steps are included, as manual mode cannot be used while executing an automatic program.

• MANUAL MODE

• Clear your Manual programs or Custom programs with SNF staff before running it in MANUAL MODE.
• See below for Manual Mode instructions

4. Auto mode selected (newstantard.aba or standard.aba)

• System should be pumped down when not in use.
• Unselect Auto Mode and select manual mode to check status of system
• Check that vent button is off (button appears to be out)
• Check that pump button is on (button appears to be in)
• Return to Auto Mode

5. Load clamped bonding unit into chamber.

• Place field electrode (graphite) onto bond tool glass(side with metal strips should be up, and wafer flat should match flat on electrode).
• Click on EXTENDED BOND MONITOR window (option keys appear for manual operation)

• CAUTION!!! Check that voltage is off before opening chamber!!!
• Click on the Pump button to turn it off (button appears to be OUT)
• Click on the Vent button to turn the vent on (button appears to be IN)

• Push and HOLD down 2 green "Cover Open" buttons simultaneously to lift the lid.
• Place the bond tool on the two alignment pegs with  FLAT toward the system.

• If you are using FLAGS, make sure the flag mover pieces are in the IN position before you load the tool. The screen will indicate "Flags IN". If this is not done the screen will indicate "Flags OUT" and will not be able to access the flags to pull them out and the wafer will bond with the flags still in (possibly breaking the wafers).
•  Flat away from you,         Word "Top" (flat) goes toward back in bond tool

• Press both green "Cover Open" buttons simultaneously to CLOSE the lid.
• Set large Micrometer dial to the correct thickness.
• Start Auto program (or Manually do the bonding process, see Manual Information below).

• Auto Mode Monitoring

• Click on ENTENDED BOND MONITOR

• Manual operation can be monitored with this window.

• Make AUTOMATIC SETUP as active window
• Click on "RUN" button
• Enlarge PROCESS MONITOR window to view current step

• CAUTION: Click "Next" button ONLY if sequencing to next step is desired!

• Enlarge RECORDER window

• Drag filename to "write to" and insert your own unique .aba filename
• Recording options are:

• I (current)
• U (voltage)
• T top (top temperature)
• T chuck (chuck temperature)
• P (chamber pressure)
• A1 (arbitrary units 1-10)

• Monitor Chamber Pressure, Temperature, Voltage and Current.

• Pressure should get to e-4 or e-5 range

• Select PRESSURE CONVERTER to change units
• NOTE: Recorder does not compensate for changes of scale

• Temperature ramps up (first chuck then top)
• Voltage ramps up slowly (according to program instructions)

• Watch for arcing or shorting (lines shoot up)
• If the system arcs or hits the current limit - PUSH STOP!!! SHUT DOWN the system!!
• You must vent and inspect and contact maintenance or shut the system down.

• Current starts climbing when bonding starts

• Current climbs and peaks and then drops off after bonding is complete (it typically falls off exponentially).
• Either wait till auto program is complete (will end based on time in auto program) OR you can push NEXT on PROCESS MONITOR window to advance to next step.

6. To end the program early push STOP.

• Click on EXTENDED BOND MONITOR

• Manual operation can be monitored with this window.

• You could end the program after the bond is complete and it is in the cool down step.

• Takes about 1.5 hour for bonding unit to cool (program time)
• You could pull it out sooner (~200°C or lower) using the grabbing tool and leave it on the rack to cool (takes about 20 minutes).
• If you do this, leave a CAUTION HOT!! note by it.
• Remove the field electrode with your Teflon tweezers if you want to put it on the other bonding tool.
• Graphite needs to cool off on the system's metal surface before being returned to the Pyrex dish.
• Use your judgment, things are hot and many damages come to the tools when good judgment are not used.
• You could swap in the other tool while the first one is cooling.

• If you stop earlier in the program, check the following (push button to change if necessary):

• Check that the voltage is off (click on Voltage if not, button should appear out)
• Check that the heat is off (button should appear out)
• Check that the Pump is off (click on button - it should appear out)
• Check that the Vent is on (click on vent and button should appear in)
• Start the cool step (click on cool and button should appear in)
• Check status in Extended Bond Mode (click on refresh window if needed)

7. When program is finished go into Manual mode (push stop to end program and go into manual mode)

• Open MANUAL SET UP window
• Verify voltage is off, before opening the chamber
• Verify pump is OFF
• Verify vent is ON
• Press both green COVER OPEN buttons simultaneously to open the lid.
• Remove Bonding tool (CAUTION if it is still HOT)
• If no more bonding to do follow shutdown procedure.

SHUTDOWN PROCEDURE (automatic mode):

• Check that flags are in
• Press both green COVER OPEN buttons to close the lid
• Using MANUAL SET UP

• Click VENT to turn off vent
• Click PUMP to turn on pump (leave system pumped down)

• Disable "evbond"

• MANUAL MODE
• Manual Notes: (When in MANUAL SET UP window is opened, all functions are active)

• Open - pump/vent (Press once to vent, button appears out when venting)
• New Program set-up
• Bonder (enter time, will do ramp otherwise)
• Bonding: time (how long Voltage is switched on)

• pulse (?)
• start (Voltage on after temp reached or before)

• Manual Mode

• Click on ENTENDED BOND MONITOR

• Manual operation can be monitored with this window.

• Click on RECORDER

• NOTE: Recorder does not compensate for changes of scale
• Recording options are:

• I (current)
• U (voltage)
• T top (top temperature)
• T chuck (chuck temperature)
• P (chamber pressure)
• A1 (arbitrary units 1-10)

• Click on MANUAL SET UP (option keys appear for manual operation)

• Click VENT to turn OFF VENT (button looks out when OFF)
• Click PUMP to turn ON PUMP (button looks IN)
• Enter a TEMP and click ^ (up arrow button). This will give temp entered plus 20°C. Every click on up arrow will increase it another 20°C. See tip sheet.
• OR Click on HEAT (symbol is H with a down arrow), when temperature entered is reached the HEAT button appears to be out. Enter a new temp and Click on HEAT again.

• Could be ramped at a certain rate or just keep raising the temp and waiting for it to stabilize and raise it again.

• Enter CONTACT FORCE/newtons (1000 N/75X10e-4 = 1.33 X10e5 pascal) Max is 3340 newtons
• Click on BOW (symbol is W over a bending wafer) for force in center --After temp is stabilized (lower than bonding temp)
• Click on FLAGS (symbol is F with 3 flags and wafer) to move FLAGS OUT (check to verify status is "flags out".
• Click on ELECTRODE DOWN (symbol is E with a down arrow under it) to apply force.
• Monitor Chamber Pressure, Temperature
• Pressure should get to e-4 or e-5 range

• Select PRESSURE CONVERTER to change units

• Increase TEMP to bonding temp i.e. 400°C (Max is 500°C)
• If doing ANODIC BONDING ... Click on VOLTAGE (symbol is V with bolt of lightning) to apply voltage.

• Enter a low voltage (i.e. 100V) on MANUAL SETUP.

• Click on VOLTAGE (symbol is V with lightning bolt).
• Click on ^ (up arrow symbol) and voltage comes on.
• ^ Up arrow increases the voltage 20 volts at a time.
• Increase to desired voltage (watch for shorting or arcing). Typical range is 400 to 1000 Volts. Max is 1200 Volts Internal.>

• Could be ramped up to desired voltage or set and then increased by clicking on the ^ (up arrow button).
• Monitor the VOLTAGE and CURRENT ( I )

• Monitor the (recorder) voltage. Watch for arcing or shorting (line shoots up)
• Check Charge in EXTENDED BOND MONITOR. Range:
• When current starts (~5 mA range), bonding is taking place.
• When it starts dropping off, the bond is complete (typical machine takes 1 - 2 hours, this one ~30 minutes).

• Monitor Chamber Pressure, Temperature, Voltage and Current

Shutdown Procedure (manual mode):

• When bond is complete:

• Click on VOLTAGE to turn off voltage (buttons looks out)
• Click on ELECTRODE up symbol (force goes off)
• Wafer BOW symbol goes off automatically.
• Click on PUMP to turn off pump and start VENT
• Enter Temp to cool down to.
• Click on COOL (thermometer symbol) to start cooling).

• NOTE: COOL and HEAT are interlocked so that only one can be on at a time.

• Note contact force reads ~5004 (appears when wafer bow is off and sometimes during bond???)
• WAIT for chamber to cool before opening it.
• Press both green COVER OPEN buttons simultaneously to lift the lid.
• Remove the bond tool from the two alignment pegs

• CAUTION!!! If you unload it before it is completely cool, you can use the tool (grab 2 side bars and lift it out and set it on the back of the stainless steel counter.

• Press Flag button to move flags out (verify they area out)
• Press both green "Cover Open" buttons simultaneously to CLOSE the lid.
• Click on VENT to turn off vent (button appears out)
• Click on PUMP to turn on pump (button appears in)
• Always leave the system in pumped down condition when not in use.
• Disable "evbond

Cleaning Procedures:

Anodic Bonding:

Silicon Wafers:

Standard RCA clean (RCA1 then RCA2):

• RCA1 (SC-1)
  NH4OH (29%): H2O2 (30%): H2O in a volume ratio of 1:1:5 at 70C for 5 minutes
• HF: 1% HF dip for 15 seconds
• DI water rinse
• RCA2 (SC-2)
  HCL (37%): H2O2 (30%): H2O in a volume ratio of 1:1:6 at 70C for 5 minutes
• DI water rinse

Glass Wafers:

Piranha Clean:

• H2SO4 (98%): H2O2 (30%) in a volume ratio of 2:1 at 100C for 20 minutes
• DI water rinse

Silicon Direct Wafer Bonding:

Silicon Wafers:
Reverse RCA clean (RCA2 then RCA1 and no HF dip):

• RCA2 (SC-2):
  HCL (37%): H2O2 (30%): H2O in a volume ratio of 1:1:6 at 70C for 5 minutes
• DI water rinse
• RCA1 (SC-1):
  NH4OH (29%): H2O2 (30%): H2O in a volume ratio of 1:1:5 at 70C for 5 minutes
• DI water rinse

Reference: "Handbook of Semiconductor Wafer Cleaning Technology, "Werner Kern, 1993, Noyes Publications