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EV Backside alignment (BSA)


Electronic Visions 620

Function Overview: Optical lithography contact/proximity aligner-bonder

  • 4 exposure modes: contact, vacuum contact, hard contact and proximity
  • frontside and backside alignment
  • 10X objectives (100X total)
  • bonding chucks for anodic bonding, thermal compression bonding and fusion bonding.
  • minimum resolution in dark field 1.0  µm line and <1 µm contacts
  • minimum resolution in clear field = 2 µm line and 2 µm contacts
  • 4" wafers, 5" masks (tooling is available for 6" wafers)
  • lamp calibrated: CI1 at 15 mW/cm2 @365nm
  • max wafer thickness 4.6 mm

Special Notes or Restrictions:

  • This machine allows most materials
  • See Materials section of our website for details
  • Clean front and back of mask before use
  • Clean mask every one to ten wafers, depending on your process and resist thickness

Operating Procedures for Backside Alignment

Startup Procedure

Change from bonding chuck to wafer align chuck

Change from bond tool frame to mask holder

Loading Mask

Load wafer

Align wafer

Shutdown Procedure

Button Reference Information

Special Notes


  • Leave key ON
  • The Lamp Power Supply is always ON
  • PC Power is left on
  • Enable "evalign"
  • Do not lean on the system at any time.
  • You need to make sure that the chuck is centered as much as possible to the mask holder. You can start by putting the micrometers x, y, and theta to the mark we have made on the micrometers, Very critical.
  • Click icon ev620
  • OR if already there , click on login and enter "620" for name and enter "620" for password
  • Initialization begins.
  • If necessary change chucks (this should not be necessary, but check that the appropriate chuck and mask holder are in place).
    • Change from Bonding Chuck to Wafer Align Chuck
      • Use Clean gloves!
      • Remove vacuum line
      • Remove bonding chuck and replace with align chuck (octagonal shaped vacuum pattern on bonding chuck). Lift chuck out of frame from below.
      • Replace vacuum line
    • Change from Bond Tool Frame to Mask Holder
        • Use Clean gloves!
        • Bond Tool - use clean gloves, do not touch chuck part.
        • Remove Bond tool -
          • Hold by feet and lift out.
        • Lift bond tool frame out.
        • Lower mask holder in
  • Follow instructions on screen (arrow indicates a machine instruction)
  • ->Move <tray out>
  • Double click on the process you want. These processes are standard processes so only change exposure time, alignment gap and other necessary changes. Alignment gap 40 µm is recommended for standard processes.
    • Standard programs are: Top side align; bottom align; Si-Gl bond; Si-Si bond.


Process=Bottom Align Mask Holder=5" Wafer=4"
Process Mode=crosshair (overlay, normal) Side=bottom (top)
Exposure mode=continuous (interval) Exposure time=
Contact Mode=soft, hard, vac, vac/hard Delay time=
Proximity gap µm=0 Interval=
Separation µm=40 (gap during alignment)  
  • For Contact Alignment select one :
    • Selecting V-Cont (space between wafer and mask is evacuated)
    • NOTE: If you use vacuum contact, you must put the vacuum ring on the chuck.
    • Selecting H-Cont
  • Click "Run"
  • ->Save Changes? NO (use them for your process only, do not change the program permanently)

Load Mask

  • ->Insert Mask Holder (this should already be in place, make sure it is firmly pressed down)
  • press <CONTINUE>
  • ->Insert Mask with load frame and press <continue> (mask frame loaded with tab on right).
    • Load chrome side down and the wafer flat side to the right
    • (Note: If you are going to do backside alignment there is a limited area to view the targets, plan accordingly when you make masks for this machine).
  • ->Please Wait
  • ->Move tray in
  • ->Please Wait (long wait)
  • ->Adjust Mask
    • Press "Scan Optic" in the "Position-Menu" and you can move the microscopes with the joystick in x, y and z direction (small motions give slower responses). For x and y push forward back or right or left, for focus rotate clockwise or counter clockwise. L to adjust left, R for right side.
    • To adjust for rotation use the micrometer screw (since the mask is not yet attached by vacuum)
    • When targets have been found and focused press "CONTINUE" (to attach mask with vacuum).
  • ->Please Wait (long wait)
  • ->Move <TRAY OUT>
  • ->Remove loadframe and press <CONTINUE>
  • ->Move <TRAYIN> (without loadframe or substrates!!) *********
  • ->Please Wait
  • ->Adjust Mask and press <CONTINUE>
    • Note the screen will go out of focus because the mask was loaded, just adjust it .
    • Check that the targets are still where you wanted them, move if necessary.
  • ->Adjust Crosshair/Adjust Overlay and press <CONTINUE>
    • Move the crosshair with help of the Trackball.
    • Move the cursor with the trackball to a crosshair, then press the left button and you can move with the crosshair.
    • Crosshair size and color can be changed when "control button" is selected
    • For Overlay: You can freeze and store the picture of the adjusted marks of the mask. (adjust marks and press "continue")
    • Later when you want to adjust the substrate you see a shadow from the stored mask marks on the screen (you can change the intensity with the overlay regulator) and you can adjust the substrate to the shadow of the mask.
  • ->Please Wait
  • ->Move <TRAY OUT>
  • ->Insert substrate and press <CONTINUE> (to activate vacuum) (OR press EXIT to unload mask)
    • Load wafer (front side down)
    • During separation, is a good time to change menu selections (i.e. time and separation). Select "Recipe",make changes and click on "move to" .
    • Warning if you chose "Exit", you must unload mask (when asked "Do you ant to unload mask" - answer yes).
  • Check vacuum.
  • ->Move tray in
  • ->Please wait (wec is performed)
  • ->Adjust substrate using the 3 micrometer spindles (x axis, y axis and theta)
    • Press "Sep/Cont" button to go in and out of contact to check alignment and readjust (contact has the light off button and separate has the light on).
    • When satisfied with alignment you must remember to leave it in contact mode (if not poor exposure will result)
  • Press <CONTINUE> when wafer is aligned
  • ->Please Wait
    • If hard contact or vacuum contact is selected (0.5 bar is the correct setting) you will be given the option of pressing continue to expose OR pressing Undo if you want to do more alignment (view is of wafer in vacuum mode - last chance to back out before exposure)
  • Exposure time is announced and exposure begins.
  • ->Please Wait - after exposure lamp stays forward until all wafers are exposed
  • ->Move tray out
  • ->Change substrate and press CONTINUE.
    • During separation is a good time to check your crosshairs or overlay (between each alignment). After each wafer is exposed you should do a mask check to verify crosshairs are still where they should be.
  • Click on "Mask Check"
  • ->Move <TRAYIN> (without substrate!!)
  • ->Please Wait
  • ->Adjust Crosshair/Adjust Overlay and press <CONTINUE>
    • Check that the crosshairs are still in the correct position and adjust if necessary.
  • ->Move <TRAYOUT>
  • ->Insert substrate and press CONTINUE.
    • Now either load a new substrate or see below to unload the mask.
    • After each wafer you should go back to Mask Check above, alternating between mask check and wafer alignment.
  • Click "EXIT" or"UNDO" to unload mask.
  • >Insert load frame and move tray in
  • ->Please Wait
  • ->Move tray out
  • ->End of process - remove load frame
  • Click on EXIT
  • Select Park. Move tray in? Click on yes and move the tray in.
  • Click on Logout
  • Disable "evalign" (log resist type, thickness, exposure time,lamp setting, result)

Button Information


Button Description
Limits Choose Scan Optic
Scan Optic

To move with the split field microscope. In addition you see the minimum, maximum and actual value of the left and the right microscope in X, Y and Z direction. With "Store Optic Pos" you can store the actual optic position. With "Load Optic Pos" you can load a stored optic position.

Recipe To set process data during the process
Controls To change the cross data and overlay intensity (in case of topside alignment you do not have a cross.)
continue Usually acknowledges previous choice or that what is on screen is done. Also may push <ENTER> button for same result (button with arrow down and to the left)
enter Confirms data entry
Track Ball Used for PC control
Joystick Adjust split field microscope in X and Y (right and left, forward and back)and to focus (rotate clockwise or counterclockwise). Speed controlled by slow or fast movements.
L/R: To change between left and right objective
Sep/Cont: To change between separation and contact
Undo: If you have a problem press "Undo" to go one process step back, and follow instructions on screen.
Stop: To stop the process
Exit: To leave the process
Wec Force: Check pressure during WEC only, cover weight can be adjusted.(0.4 bar)
Exposure Force:

Check pressure during align phase (0.5 bar).

Chuck Weight: Is actual pressure during WEC (270 -300 mbar)
Hard Contact: When hard contact mode is selected you can adjust N2 pressure (0.5 bar)

Special Notes:

Lamp can not be restarted when key is turned on.

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