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HF Vapor Etch, wbnitride

Tool uses HF vapor to etch thermal oxide, LTO and TEOS. Because the HF is in vapor phase, there is not a problem with stiction associated with wet etching. Condensation on the sample is reduced since it is at 45 degrees Celsius.

Picture and Location

 HF Vapor Etch

 

HF Vapor Etcher

 

HF Vapor Etcher water baths

The tool is located at FG56 on the Lab Map.

Background

 

Process Capabilities

Cleanliness Standard

 The HF Vapor Etch is in the Clean Equipment Group.

Performance of the Tool

What the Tool CAN do

  • Can etch 4" wafers that have been through diffusion clean at wbclean-1 or-2.

 

What the Tool CANNOT do

  • Cannot etch wafers that have any type of metal or have had any metal on them.
  • Cannot etch wafers that have photoresist on them.
  • Cannot etch small chips.
  • Cannot etch wafers that have devices that may come off during etching.

 

Process Monitoring
  • Etch rate on thermally grown oxide should be 300A - 600A per minute.

Contact List and How to Become a User

Contact List

The following people make up the Tool Quality Circle:

  • Process Staff:  Gary Yama
  • Maintenance:  Gary Yama
  • Super-Users:  Gary Yama

 

Training to Become a Tool User

 

  1. Read all material on the SNF website concerning the HF Vapor Etch.
  2. Become a qualified user at the Wet Bench Clean-1 or -2, contact SNF training contact on the Equipment Summary page.
  3. Contact SNF labmember Gary Yama, gyama@snf.stanford.edu.

Operating Procedures

 

Process Monitoring and Machine Qualification

Tool Qualification Run

 

Frequency

  • Do an etch rate check after fresh 38% HF has been poured or before using for the first time on your wafers.
  • After pouring HF, allow to stabilize for 48 hours.

 

Procedure

ETCH RATE CHECK

  • Check to see that the Julabo water baths under the bench are at 30C & 45C.
  • Use a thermally grown oxide wafer with 2.0um of thickness.
  • With the Nanospec, measure & record the thickness on 5 spots, Top, Center, Bottom, Left & Right. 
  • Measure ~ 2cm from the edge of the wafer.
  • Clean the wafer in wbclean-1 or -2 & skip the 50:1 HF dip.
  • Put the wbclean-1 or-2 cleaned wafer & Teflon cassette into the plastic wbclean-1 or-2 box & close the lid. 
  • Bring over to the HF vapor etcher.
  • Flip the left front etch head upside down & rest on the blank load position at the front right.
  • With clean non-metal plastic tweezers, load the wafer onto the left front etch head. 
  • Be sure to clip the wafer firmly under the Teflon clip. 
  • You need to use a freshly gloved hand to lift the clip slightly while pushing the wafer under it with the back side of your plastic clean non-metal tweezers.
  • Flip the etch head over back to the front left position.
  • Let the wafer sit for 10 minutes to let it reach 45C.
  • Remove the front right Teflon cover & place to the side.
  • Carefully move the back etch head to the front right position.
  • Move the front left etch head to the back position.
  • Try to do this as smoothly & quickly as possible to minimize the time the back etch position is left uncovered.
  • Start timer for desired etch time.
  • Reverse the procedure when time is up.
  • Let the etched wafer sit at the front left position for 5 minutes before removing & inspecting. 
  • Let the etch head rest on one of the 2 pins so that HF vapor may be exhausted.
  • With a freshly gloves hand, carefully lift the Teflon clip & push the wafer from under the clip with the back end of the plastic tweezers.
  • Remeasure the 5 spots with the Nanopsec & calculate the etch rate.

 

Responsibility

 

 

Recommendation to users with critical processes

 

Machine Status States

Red:

Yellow:

Green:

 

Process Monitoring Results

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