Decontamination of used semiconductor equipment

Why decontamination comes first

A used etcher, implanter or CVD tool holds the chemistry it ran. Chlorine and bromine compounds on the walls of a metal etcher, arsenic and phosphorus deposits in an implanter source housing, fluorides in an exhaust line and hydrolysable residues in a pump all stay in place after the last wafer. They can release toxic or corrosive gases when the system is vented, opened or exposed to humid air.

That is why semiconductor equipment decontamination comes before any other work. Nobody should open the chamber, de-install the tool, crate it or ship it until it has been decontaminated and the work is written down. Many carriers and receiving sites will not accept a tool without a decontamination statement.

Scope

The scope follows the process history. A typical decontamination covers:

• Gas panel and process gas lines: purged with inert gas, then capped and labelled
• Process chamber and load lock: residue removal by wiping, washing or a method suited to the residue
• Implanter source housing, beamline parts and vacuum pumps that saw dopant gases
• Exhaust lines and connections up to the house exhaust or abatement
• Pumps: oil drained and disposed of as hazardous waste where the oil may hold process residue
• Wet benches and spray tools: tanks, plumbing and drains flushed and neutralised

Parts that cannot be cleaned reliably, such as heavily loaded pump oil, filters and some soft parts, are removed and disposed of instead.

Decontaminating while the tool is still installed

Where the tool is still installed, we purge the gas lines and clean the chamber and pumps while it is connected to your exhaust and abatement. That is the safest order and it keeps the hazardous waste inside a site that is set up for it. Once cleaned, open lines and ports are capped and the tool is labelled with its status. If the tool is being moved, the decontamination statement goes with it as part of de-installation and crating.

Typical downtime

Decontamination is usually short compared with a full refurbishment, but it has to be planned around your safety procedures, permits and the availability of the exhaust and abatement system. Implanters and tools with toxic precursor history take longest. We put the planned time in the quote.

What we need from you

• The full process history: gases, chemicals, dopants and precursors, as far as it is known
• Your site safety rules, permit-to-work process and any required training
• Access to exhaust, abatement and N2 purge while the work is done
• A contact on your EHS team for waste handling and sign-off

Results and documentation

You receive the plan, a record of what was cleaned, removed and disposed of, and a written decontamination statement. The statement describes the work done and the residues addressed; it is not a certification by an outside body. On tools we sell, decontamination is done before the chamber refurbishment and is recorded in the inspection report. This matters most on ion implanters and on etch and CVD tools that ran chlorine, bromine or toxic precursors.