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SPTS uetch vapor etch system

The SPTS uetch vapor system uses anhydrous HF and ethanol at reduced pressure and 45C to etch isotropically sacrificial silicon oxide layers, primarily to release silicon microstructures in MEMS devices. The dry process avoids stiction of released moving parts and damage to delicate structures – common issues with conventional wet processing technology. This is a single wafer system for 4 inch to 8 inch wafers and dies on a carrier wafer.

Picture and Location

 SPTS uetch

The tool is located at A78 on the Lab Map.




The uEtch is a single-wafer system specifically designed for university and small research laboratories.


Process Capabilities

Cleanliness Standard

 The SPTS uetch appears in all three equipment groups (clean, semiclean, and gold).

Performance of the Tool

What the Tool CAN do

  • one 4”,6”, or 8” wafer, as well as one die on a carrier wafer
  • HF vapor and ethanol are used to isotropically etch SiO2 at 45C
  • recommended masking material is silicon
  • SiO2 Etch rate, for the latest etch rate check comments on Badger

    Oct 2013

    JAN 2014
     Feb 2015
      A/min   A/min    A/min  
    R1 224 1.7% 192 3.9%
     122  5.55%
    R2 570 6.6% 512 2.2%
    R3 1162 14.8% 1130 6.8%  1030  6.64%
    R4 1401 15.5% 1384 6.8%    
    R5 1581 5.4% 1505 4.1%  1403  3.28%


What the Tool CANNOT do

    Photoresist cannot be used as a masking material, it would contaminate the chamber with polymer.



    Contact List and How to Become a User

    1. Read all material on the SNF website concerning the SPTS uetch.
    2. Contact SNF training contact on the Equipment Summary page.


    Operating Procedures

    Wafer preparation:

    Masking material: Silicon is recommended, no resist/polymers.


    Bake your wafer and dies at 250C for 2 minutes to drive off any off-gassed polymer from storage containers. This step may be skipped if the wafer has not been stored for more than 2 hours since its last processing step. Alternatively, this step can be replaced by an O2 descum plasma.


    Make reservation.

    Enable uetch.

    Check exhaust gauge: 0.4

    Standby screen:

    SPTS uetch 01


    Select recipe:

    Press [Pump Valve] button (green to grey):

    SPTS uetch 02


    Press [Home] button:

     SPTS uetch 03


    Press [Recipes] button:

    SPTS uetch 04

    Use only recipes # 1 to 5. Press up or down arrow keys to switch recipes.

    Do not change recipe #6!

    You are only allowed to change the recipe #, number of cycles (up to 99), and etch time (240 to 600 sec).

    To change a value, click on number of cycles or etch time, enter in new value, press Enter.

    Press [Save] button:

    SPTS uetch 04


    Press [Process] button:

     SPTS uetch 07


    Load your wafer

    To open the chamber, press [Vent] button.

    SPTS uetch 06


    Wait for the preset 1min10sec for the chamber to vent:

    SPTS uetch 05

    Open the door; as you open the door from the left side, take care to hold the door up, as the single hinge on the right side is very fragile.
    Pull out wafer chuck and carefully load one wafer on the three pins. For pieces (one at a time): use carrier wafer! It is recommended to use your own carrier wafer to avoid cross contamination.

    Start the process

    Press the [Start] button.

    Caution: as you press the Start button to pump down the chamber, press and hold the middle of chamber door (as labeled on the door), until the chamber begins to pump down.

    The overhead time is 19 minutes, add your etch time for your total process time.
    Wait for the process to finish.

    At 00:01:10, 'Time Left' will stop. [vent] button changes to flashing blue. 

    Press [vent] button to finish venting the chamber.  When chamber is vented, open the door carefully and remove your sample.  If you want to run another sample, repeat the above steps.


    Press the [home] button.

    Press the [manual] button.

    Press the [pump valve] button, press and hold the door in the center before pressing [pump valve], the color of the button changes from grey to green.

    Disable uetch.

    Emergency stop:

    If you need to stop the process at any point, press [stop] button.
    If HF is in the chamber, you will need to go to the alarm screen and press "system Alarms" box. Press "ACK" then "ESC" to clear alarm.

    Press [Purge] button.

    Press [Vent] button.

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