PFC Bench 01
| PFC Bench 01 | |
|---|---|
 PFC 01 | |
| Equipment Details | |
| Technology | Wet bench |
| Materials Restriction | CMOS Clean |
| Material Processed | 1 |
| Sample Size | 4" and 6" diam. standard, some other sizes may be accommodated |
| Chemicals Used |
Hydrogen peroxide Ammonium hydroxide Hydrochloric acid Hydrofluoric acid |
| Equipment Manual | |
| Overview | System overview |
| Operating Procedure | SOP |
| Supported Processes | Prefurnace RCA Clean |
| Maintenance | Maintenance |
Prefurnace Clean (or PFC) is used for an RCA Clean of wafers before furnace processes. The RCA clean is a widely-used, 3-stage method of cleaning Si wafers and is effective at removing organic and ionic surface contaminants.
RCA cleaning is the only process supported and allowed at the PFC 01 bench.
The PFC 01/RCA cleaning procedure is required for all wafers prior to being placed in any CMOS-clean furnace (all S1-S5 tubes except for the S1/T1 sintering tube). Schedule your furnace process the same day as your pre-furnace clean. If you are unable to schedule these the same day, place your wafers in S2T1, the storage tube.
It is a three-stage cleaning process composed of:
1) a 5:1:1 mixture of water, ammonium hydroxide, and hydrogen peroxide at 85°C (known as Standard Clean 1, SC-1, or the ‘Organic’ clean)
2) a brief etch in dilute, room temperature hydrofluoric acid (10:1 for Si wafers or 100:1 for SiO2 wafers)
3) a 6:1:1 mixture of water, hydrochloric acid, and hydrogen peroxide at 85°C (known as Standard Clean 2, SC-2, or the ‘Ionic’ clean).
Contents
Announcements
The Spin Rinse Driers for this tool have had a resistivity requirement implemented. Wafers that have undergone Pre-Furnace Cleaning but which do not reach a resistivity of 16.5 MΩ/cm will require further Pre-Furnace Cleaning until they meet that resistivity requirement. (Implemented Spring 2024)
System overview
Chemicals used
- Hydrogen peroxide (H2O2) (30%, CMOS grade)
- Ammonium hydroxide (NH4OH) (29%, CMOS grade)
- Hydrochloric acid (HCl)(22-40%, CMOS grade)
- Hydrofluoric acid (HF) (49%, CMOS grade)
Hardware details
This bench contains a heated tank for RCA SC-1, a heated tank for RCA SC-2, and unheated tanks for 100:1 and 10:1 mixtures of DI H2O:HF. Two of the HF tanks are sized for 4" cassettes; two of the HF tanks are sized for 6" cassettes.
Waste from this bench goes into the LNF’s acid waste neutralization system and then to city sewers. No solvents can be used or disposed of here.
Substrate requirements
- Standard 4" and 6" diameter silicon wafers
- Some other sample sizes may be accommodated. Check with tool engineers via the Helpdesk ticket system.
- High purity fused silica is allowed with staff approval. Prelimary RCA cleaning in RCA Bench 81 is needed.
Safety
 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. To minimize the chance of accident, make sure you always:
- Wear personal protective equipment.
- LNF Glove Policy
- 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.
- Do not use this bench without proper training.
- There are three routes of disposal from this bench: .
- Water aspirator: Only water, acids and bases can be disposed of using this aspirator. Do not aspirate solvents with this aspirator.
- Tank drain: The solution baths must be below 75C before the tanks can be drained.
- Sink drain: Only water, acids and bases can be disposed of using the sink drain. Do not pour solvents into this drain.
Material restrictions
This is a CMOS-clean bench. Silicon substrates, high purity fused silica, and CMOS-clean furnace-grown silicon, silicon dioxide, and silicon nitride thin films are allowed in this bench. No metals, photoresist or glass wafers (except high purity fused silica) are allowed. Wafers are not allowed in this bench or in the furnaces if they have ever had metal on them.
Silicon wafers that have been processed in non-CMOS-clean chemicals and tools are not allowed. Wafers that have been processed through any wet benches other than Acid 02 or RCA 81 cannot be cleaned in PFC 01.
A special case are wafers which have been polished using CMP, developed in metal-ion bearing developer (e.g. AZ 400K) or etched in KOH; they must be given an additional piranha clean and SC2 in Acid Bench 92, and an RCA clean in RCA Bench 81 prior to being cleaned in PFC Bench 01.
High purity fused silica is allowed with staff approval. Prelimary RCA cleaning in RCA Bench 81 is needed. An extended 10:1 DI:HF dip (1 min) is required in this case.
The PFC Bench 01 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
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Standard operating procedure
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Checkout procedure
- Take the General Wet Bench Training, if you haven't already.
- Take Rise Online Course for PFC
- Read through this page and the Standard Operating Procedure above.
- Practice with your mentor or another authorized user until you are comfortable with tool operation.
- If your mentor is not an authorized user or you do not know of an authorized user that can train you, proceed to the next step.
- Score 100% on this quiz: PFC Checkout Quiz
- Open a helpdesk ticket and request a checkout.
- A tool engineer will schedule a time for checkout.
Maintenance
HF tanks for this bench are changed by lab users. The HF tank should be changed if it is older than 7 days. Check the logsheet for date of last tank change. Rinse the tank 3 times before refilling with chemical.
