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Buying GuideMay 12, 20265 min readBy Caladan Semi

This guide is for: a process engineer at a midsize foundry who needs to source a replacement focus ring for a damaged etch chamber and is trying to avoid another expensive capital purchase.

I remember the time I walked into a fab in Austin and saw an entire maintenance team huddled around a stripped-down Lam 9400 etch tool. They were staring at a cracked focus ring like it was the reason they lost their weekend. I’ve seen that look before. You see it when a part that costs $15,000 to $20,000 is just gone—poof. Not broken, not worn, just gone. That’s focus ring failure. And it costs you time, money, and sometimes a shipment of wafers.

Let’s cut to it: focus rings are one of those parts in etch chambers you can’t afford to ignore. They do critical work, they fail in predictable ways, and you can save a lot of money by sourcing used. I’ll show you how.

What Focus Rings Actually Do in Etch Chambers

Focus rings sit on the backside of the wafer holder in most reactive ion etch (RIE) or plasma etch systems. Their job is to shape the plasma sheath and control the ion energy that hits the wafer. Think of it as a lens in a camera—except it’s for plasma. Without a properly functioning focus ring, you’ll see etch rate variations, corner erosion, and worse: non-uniform etch profiles.

Common models include:

AMAT 0020-09564 Focus Ring — used in Centura systems
AMAT 0021-36716 Edge Ring — often used as a companion to the focus ring
AMAT 0021-40940 Confinement Ring — part of the full stack

These parts are usually made of quartz or ceramic, and they’re not just “consumables”—they’re precision components. last_updated: "May 2026"

Why Focus Rings Fail (And How Often)

Here’s the bad news: focus rings don’t last forever. Some don’t even last a full year. Here’s what I’ve seen over the years:

Thermal shock cracks: This is the most common failure. When the system cools too fast or heats up too fast, the ring cracks. I’ve seen it happen during a simple power cycle.
Plasma erosion: The edges wear out, especially if the process is aggressive or if the ring is not cleaned regularly.
Installation damage: Yes, it happens. If you’ve ever seen someone drop a focus ring on the floor, you know it’s a lost cause.

On average, I see focus rings fail every 8–12 months in high-volume etch tools. Some last longer, especially if the process is mild and the chamber is well-maintained.

Should You Buy New or Used?

Let’s get real. If you can afford a new focus ring, go for it. But for most of you, the cost is just not justified. A new Lam 9400 focus ring can set you back $18,000–$22,000. A used one in good condition? $6,000–$9,000. That’s a difference of $9,000–$13,000. You could buy a whole new edge ring and still have money left over.

Used focus rings are not “cheap parts.” They’re precision components that just happen to come with a lower price tag. The key is sourcing them from a reputable seller who can provide verification of material integrity, cleanliness, and originality.

How to Buy a Quality Used Focus Ring

Here’s what I always tell people:

Verify the model number: Make sure it’s the exact part for your system. No “close enough.” You’re not working in a lab—this is a production tool.
Check for cracks and erosion: Ask for photos of the backside and the edges. Cracks are a showstopper. Erosion is a red flag.
Request a material spec sheet: The ring should be made of quartz or a compatible ceramic. No cheap substitutes.
Confirm it’s clean: A used ring should be plasma-cleaned and ready for immediate installation.
Ask for process history: If the ring was used in an aggressive etch process, it may have a shorter life left.

I’ve sold hundreds of used focus rings. The ones that get returned are the ones people got from eBay or some random guy in China. Don’t be that guy.

5 Actionable Steps to Source a Used Focus Ring

Know your model number. Write it down. If you don’t know it, ask the tool engineer.
Set a budget. Used parts can range from $5,000 to $10,000, depending on condition and origin.
Ask for inspection reports. A good seller will provide photos and process history.
Request a test etch. If you can, have the ring tested in a dummy wafer run before installation.
Get a return policy. If the ring is cracked or doesn’t work, you want to be able to send it back.

Frequently Asked Questions

How much does a used focus ring cost?
Used focus rings typically range from $6,000 to $9,000, depending on model, condition, and whether it’s been cleaned and verified.

How often do focus rings need to be replaced?
In high-volume production, expect to replace focus rings every 8–12 months. Some last longer with proper maintenance.

Can I clean and reuse a focus ring?
You can, but it’s not recommended unless you have a dedicated cleaning chamber and process validation. Plasma cleaning is preferred.

Where can I find a used focus ring for my Lam 9400?
You can find used focus rings for Lam 9400 etch tools from reputable used equipment brokers who verify part numbers and condition.

Do focus rings come with a warranty?
It depends on the seller. Some used focus rings come with a 30–90 day performance warranty. Always check the terms before purchase.