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Center of MicroNanoTechnology CMi

Photolithographic cluster EVG150

 

EVG 150 - Automatic Resist Processing Cluster

General description

The individual processing stations are fed by a central robot arm. The EVG150 cluster at EPFL can process standard silicon wafers or transparent substrates from 100mm to 150mm. The machine is available for positive photoresist coating, softbake, PEB (post exposure bake), hardbake and development.

Specific Modules

Cassettes
Two stations for standard cassettes of 25 wafers. Default standard configuration is for 100mm cassettes only; separated for coating and development.
Per request, 150mm cassettes are available.


Status light

A light tower is installed behind the upper left corner of the front window:

  • Red blinking = Error is detected, process cannot continue
  • Middle Yellow Continuous = Automatic mode on
    Blinking = Process paused or stopped
  • Lower Green Continuous = Initialization complete, normal state
    Blinking = Initialization in progress

 

Robot with two arm options ("endeffector") and flip option
R-Theta robot with 3 vacuum sensors:

  • Large fork = 100 and 150mm wafer size

 

Flat aligner
Top optical edge detection for alginment and centering of wafers. Semi-transparent wafers are also detected.

Fully transparent wafers are not recommended (large sensitivity to edge defects).

 

Hotplates with programmable proximity and temperature setpoint
3 hotplates for high temperatures up to 350ºC (1x); and standard 150ºC (2x). N2 purge or evacuate mode is available.

 

Coater module features
Spinner chucks for 2-3'' or 4'-6'' wafers are available.
Main dispense arm with two permanent resist lines, 2 edge bead removal (EBR) lines and 3 motorized syringe lines.
Second dispense arm with spray coating head.
2 back side rinse nozzles.
Cover with nozzles for automatic bowl wash system.

 

Developer module features
Dual chemistry system (manual toggle).
Puddle and spray dispense of developers.
2 back side rinse nozzles.
DI water rinse.

 

Cool plate
Passive system for rapid cooling of substrates to room temperature.


 

Checklist before starting

A library of coating and development recipes is available for users by making a selection on the graphical user interface. Recipes are stored in databases, separated by photoresist type and substrate type. Thicknesses can be selected from within these databases.

 

1) Make a reservation

Reserve machine on the CMi website by specifying process parameters.

IMPORTANT: Configuration is prepared by staff in advance according to the reservation calendar. Proper selection of slots is required to ensure availability of the desired photoresist.


Booking of the equipment requires the declaration of the process. First select the substrate size, then the appropiate material from the remaining options:

  • Parameter 1 = Substrate size: 100 or 150 mm
  • Parameter 2 = Syringe options (nLOF, TI35ES, spray coat)
  • Parameter 3 = Development
  • Parameter 4 = Resist line 1, AZ1512 HS
  • Parameter 5 = Resist line 2, AZ9260

 

The syringe motor is connected to one of three different lines depending on configuration. The default syringe is LOR, paired with AZ1512.
When using a syringe configuration, verify the label on the left syringe, loaded in the motor unit, to ensure the correct resist is connected into the dispense arm.

Note: 150 mm substrates cannot be selected with spray coating.

 






Substrate size selection: 100 mm or 150 mm wafers

 








Syringe line selection:

  • N/A = LOR (default syringe selection)
  • Syr nLOF: image reversal photoresist, capable of liftoff and ebeam exposure; different dilutions available for 400-800 nm or 1.3-3.5 um thicknesses
  • Spray coat: for coating high topography substrates with the spraycoat head; two dilutions for standard or planar coating
  • TI and other: please contact staff for details

 

 

 

 

Example: selecting 100 mm substrate size and development.

2) Reservation rules and booking fee policy

1. Maximum reservable slots per person between 9h and 17h is 4 (or 2 hours). It is still possible to get 4 consecutive hours from 7h to 11h or from 15h to 19h.
2. Maximum reservable slots per person per week is 20 (or 10 hours).
3. Reservation name must correspond to operator.
4. To discourage overbooking and/or massive releasing of slots with short or no notice period, a booking fee policy is applied. The free cancellation limit is 24 open slots. The equipment login rate is 60.-/hour, and the booking fee is 20.-/slot.

3) Verify machine configuration

Note: four photoresist dispense lines are connected:

The two developer lines are adapted for all resists listed above.

4) Prepare wafers

Perform appropriate surface preparation steps (dehydration, HMDS coating, ...) based on process flow. Make sure to finish before reservation starts.

 

Operation

1) Login on the CAE terminal

Login is required to use the system. If system is not enabled, error message will show on display.

 

2) Login on equipment

  • Click on the “Login Here” button (bottom left corner of main window)
  • General user access parameters:
    ID=0000; PW=0000
  • After successful login the following sections will appear on display: Recipes, Jobs, Pumps, Tanks, Low IO Terminal.

 

3) Chose one application database

Several application databases are stored in the system. Each file is a unique set of recipes for use with a specific configuration and resist type. Databases are optimized for a specific photoresist type and substrate type combination. Thicknesses can be chosen within these databases.

  • Verify the name of database in the title of the software window
  • Application database directory tree is shown in the right picture
  • Recipes level (Standard library) is write protected
  • Library level (Advanced library) is write protected
  • Users level is free for read/write

For transparent wafers without any deposited layer use a "Glass Only" certified recipe (see also information note processing with transparent wafers).

Note: as long as the same database is selected, coating and development can be run in parallel.

 

Use the "Open" window from the top menu of the software, and start from the folder
C:/...EVG/EVG150/Recipe to find the default library.

4) Verify your recipe

The Recipes tab shows the actual recipes database with the complete hierarchy. Station recipes are grouped under corresponding station names in subfolders. The user executable recipes are at the top level (bottom of hierarchy tree).

Hierarchical tree:

  • Subprograms are in subfolders categorized by stations. These are called from the main programs by links.
  • Master recipes are executable (listed at bottom) describe the process flow for a wafer.

A master recipe is shown on the right.

 

Subprograms list step by step parameters related to an individual station.

 

5) Check for liquid levels

Chemicals can be monitored using the "Pumps" and "Tanks" tabs. If a low level is reached, the recipe will not run and the process will be stopped.

  • A warning message window will appear on all tab screens at 5% level.
  • An alarm shows at 0% level and will stop processes.

Note: the machine levels are verified on a daily basis. If levels are low, notify staff before proceeding.

 

6) Check for errors

Schematic under “Job” screen is shown on right.

  • Click with the left mouse button on each station to get a user menu
  • Status bar at top will turn red and indicate possible error conditions. Clicking on this bar with the mouse might clear the problem in some simple cases.

Terminal window (bottom) shows history of all high level user communication.

 

7) Start Batch Run

Load cassette on left dock station for coating (cassette 1) or right dock station for developing (cassette 2)

  • If necessary, tilt the station by right clicking on the corresponing cassette and select "Tilt cassette"
  • Center the wafer carrier sliding down the cassette

 

 

 

 

 

 

 

 

Initialize the system

  • Press "Start" on the top left of display
  • Start all the stations for production mode
    (yellow light will be turned on).

 

Status bar will change to “Load a cassette” when system is ready. Right click on cassette to get the load menu.

  • First, choose your master recipe to run.

 

  • Second, choose slots to be processed on the second tab.
  • Critical level for resist dispense is updated according to the number of wafers to be processed.

     

    IMPORTANT: have a look inside the equipment to check if wafersize adaptor rings are not inserted on top of loading pins on the robot arm.

     

    8) Atomatic processing is started

    • Hotplates temperature adjustment will start if necessary
    • Check of available liquids
    • Automatic dispense nozzle purge
    • Colors for slots are:
      Yellow = Waiting for process
      Red = In process
      Green = Process is finished

      Light blue = Wafer handling failure.

    It is possible to interrupt the process if necessary:

    The Pause and Stop buttons will pause or stop the main wafer flow in a safe way (recommended).
    Pause will stop loading wafers which are still waiting in the cassette.
    Stop will stop loading and force the end of run.

    In both cases, all wafers inside the flow will be processed according to the chosen recipe. Abort button will cause immediate abort of all current process in all station (not recommended).
    After aborting, a “Clean-up” is necessary to continue.

    DO NOT PRESS ABORT WHEN A WAFER IS ON THE ROBOT ARM OR ON THE PRE-ALIGNER UNIT. THIS CAN CAUSE DAMAGE TO THE ROBOT.

    Wait until the wafer is loaded into a station (coater, developer, HP, or CP) before clicking “Abort” if it is really necessary to abort the process.

     

    In case of a prealignment error:

    an error message with “RETRY” as option is proposed. BE CAREFUL, make sure the station is clean; otherwise a collision will happen with the next wafer. Remove manually the wafer from the alignment station before trying to continue.

    (See also information note processing with transparent wafers)

     

    In case a system clean-up is required, pay attention for each step and answer correctly to the questions asked by the system.

    Load an empty cassette to proceed, and select accordingly:
    Large Endeffector = 100 and 150mm wafer
    Small Endeffector = not installed

     

    9) Batch is finished

    • Main status bar turns green and cassete tilts for unloading
    • A new batch can be started from an idle cassette any time (simultaneous coating and development in parallel is possible)
    • Press "Stop" button in the top left if necessary, to access other menus or change recipe family

     

     

    10) Logout from equipment and access

    • Unload cassette and remove wafers. Return cassette on the loading station.
    • Clicking on the login icon key will end the session.
    • Log out on the CAE terminal.

    Note: under any circumstances, do not exit the application or the windows session. The system will not function if restarted.

     

     

    Notes

    There is a wafer countdown for the coater bowl shown on the "Jobs" screen. If value becomes low (orange) or red (zero), an automatic bowl wash is required.

    To clean the bowl, load a dummy wafer into the loading cassette, and right click on the bowl, then select "Bowlwash". The wafer will load and return automatically if the step is finished. The procedure takes only a few minutes. If not sure, call staff.

    If necessary, proceed as table shows:

    Process

    Action
    Frequency
    Spin coating with Cybor 1 or Cybor 2,
    nLoF or TI35ES from the positive syringe line


    Automatic bowl wash can be performed Done by the last user of the day,
    or when necessary
    Coating with LOR

     

    DO NOT START an Automatic bowl wash. LOR reacts with the cleaning agent. Call staff.
    Spray Coating

     

    Wash Spray Unit Immediately after batch is finished.