Difference between revisions of "Acid Bench 02"

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Revision as of 14:43, 13 September 2016

Acid Bench 02
Equipment Details
Technology Wet bench
Materials Restriction CMOS Clean
Sample Size 4" and 6" wafers
Chemicals Used
Equipment Manual
Overview System Overview
Operating Procedure SOP
Supported Processes Supported Processes
User Processes User Processes
Maintenance Maintenance

Acid Bench 02 is used for acid processing on CMOS-clean wafers for a variety of purposes. The Buffered HF (BHF) tank and 1:1 HF tanks are generally used for wet etching of silicon dioxide selective to silicon. The hot phosphoric tank is generally used for selective wet etching of silicon nitride selective to silicon dioxide and/or silicon. The Nanostrip tank is generally used for wafer cleaning and/or removal of positive photoresist from silicon wafers.


  • Update this with announcements as necessary

System Overview

Chemicals Allowed


Proper PPE for this bench are apron, face shield, trionic gloves and safety glasses
Warning Warning: You must use the buddy system for all chemical processing. No processing if you are alone in the lab. If the yellow warning lights are on it means that there are 2 or 1 people in the lab.

Working with chemicals can be very dangerous. Chemicals used at this bench are some of the most hazardous in the lab. To minimize the chance of accident, make sure you always:

  • Know the properties and hazards of chemicals you are working with. If you don’t know, find out by reading about them or asking staff.
  • Plan the details of your process. Before you start working, plan what quantities of chemicals and sample carriers you will use. Plan how you will rinse your sample and what you will do with any waste generated. Make sure you know how the controllers work.
  • Only process 4” and 6” wafers.
  • Do not use this bench without proper training
  • Waste from this bench goes into the LNF's acid waste neutralization system and then to the city sewers. No solvents can be used or disposed of in this bench.

Hardware Details

Acid Bench 02 consists of:

  • Recirculating Buffered HF (BHF) tank
  • Heated bath for etching with hot phosphoric acid at 165 degrees Celsius
  • Heated bath for Nanostrip cleaning and photoresist removal
  • Unheated chemical bath for Hydrofluoric acid (HF) Etching
  • A Quick Dump Rinse ("QDR") for rinsing wafers
  • A Bottle wash station for rinsing empty acid bottles before disposal.

Substrate Requirements

  • 4 inch and 6 inch wafers
  • Silicon Substrates ONLY

Material Restrictions

The Acid Bench 02 is designated as a CMOS Clean class tool. Below is a list of approved materials for the tool. Approved means the material is allowed in the tool under normal circumstances. If a material is not listed, please create a helpdesk ticket or email info@lnf.umich.edu for any material requests or questions.

Supported Processes

LNF Standard Processes in this bench

  • Buffered HF (BHF) for etching silicon dioxide
  • Hydrofluoric acid (HF) for etching silicon dioxide
  • Hot Phosphoric Acid ("Hot Phos") for etching silicon nitride
  • Nanostrip for cleaning wafers and stripping approved positive photoresists
  • Piranha Etch for cleaning silicon wafers

Acid 02 Supported Processes Allowed

Standard Operating Procedure

Acid 02 Standard Operating Procedure

Checkout Procedure

  1. Take the General Wet Bench Training, if you haven't already.
  2. Read through this page and the Standard Operating Procedure above.
  3. Practice with your mentor or another authorized user until you are comfortable with tool operation.
  4. Open a Helpdesk ticket and request a checkout.
  5. A tool engineer will schedule a time for checkout.


  • This bench is cleaned and inspected twice a week during lab clean.
  • Buffered HF is changed on an as-needed basis when crystallization is observed or when etch rate changes considerably.
  • Hot Phosphoric, Nanostrip and HF are generally user-maintained baths. Please fill out helpdesk ticket if you need training or assistance.