Guides / Process

Machined Parts for Semiconductor Equipment: A Buyer's Guide

September 26, 2026

Most drawings that reach a machine shop are read the same way: geometry, tolerances, material, quantity. A part that goes into semiconductor equipment is read differently, or it should be, because the features that decide whether it is accepted are often not the dimensioned ones.

This guide sets out what those features are, what the part families look like, and what to check before you send a drawing to a shop that has not done this work before.

The four part families

Almost everything a machine shop is asked to make for semiconductor equipment falls into one of four groups.

Chamber and lid components. Large aluminum and stainless bodies, lids, liners, shields, showerhead blanks and pedestal bodies. Flatness across a large face and the finish on the sealing surfaces decide whether the chamber holds. Stress relief between roughing and finishing matters more than the cutter.

Wafer handling. End effectors, blades, transfer arms, chucks, rings and aligner parts. Thin, light, often ceramic or coated. Flatness, balance and particle behaviour matter more than a tight positional tolerance.

Gas delivery and vacuum. Manifold blocks, flange bodies, feedthroughs, valve and fitting bodies. Small parts where the interior surface finish, cleanliness and leak integrity are the entire job. Usually 316L, usually electropolished.

Frames, jigs and fixtures. Machine frames, weldments, load port brackets, test and burn-in fixtures, assembly jigs. No vacuum spec, so the whole job is flatness, parallelism and repeatability at a sensible price.

What the pressure tells you

A quick way to read a new drawing is to ask what pressure the part sees in service.

Pressure	Part class	What it implies
Atmosphere	Frames, EFEM, jigs	No vacuum spec, but flatness and parallelism still set the fit
10-3 Torr	Load lock and transfer	Light cleanliness rules, sealing faces appear
10-6 Torr	Process chamber	Material control, finish callouts, real cleaning, controlled packing
10-9 Torr	UHV hardware	Bakeable, full penetration welds, electropolish, no trapped volumes

The step from atmosphere to 10-6 Torr changes the shop you need. The step from 10-6 to 10-9 Torr changes the design rules too, because blind tapped holes and trapped volumes stop being acceptable. The background on why is covered well in the ultra-high vacuum literature.

The five things a shop has to control

These are the points where a competent precision shop and a semiconductor capable shop diverge.

1. Material traceability

Not just “6061”. The grade, the temper, the mill cert, the heat lot, and often a restricted material list that rules out particular alloying elements or particular mills. A shop that buys from whoever has stock this week cannot serve a part with a heat lot requirement, and will not realise that until the first delivery is rejected.

2. Surface finish where it is called out

Ra 0.8 um comes off a finishing cutter without extra effort. Ra 0.4 um means a slower pass, a sharper tool and inspection. Ra 0.2 um and below usually means a secondary process.

The important half of this is where. A sealing face, a wafer contact face and an interior wetted surface each need it for a different reason. Putting one Ra number in the title block is the single most expensive habit in this niche, because the shop has to price the whole part to the tightest thing on it.

3. The finishing chain

Hard anodize, sulfuric anodize, electropolish and passivation are outside processes for almost every shop. Each one adds days, a transport leg and a masking decision. Type III hard anodize grows the part, so the drawing has to say whether the dimension is before or after coating. Getting that wrong produces parts that measure correctly and do not fit.

4. Cleaning and handling

Blast media that is fine for a bracket is a contamination source on a chamber liner. Silicone in any form near the part is a problem that shows up weeks later in the fab, not in the shop. A part that is machined perfectly and then wiped with the wrong cloth is a scrap part with no visible defect.

5. Packing

Precision clean, dry, then bag inside a bag, label the outside, and in some cases purge with nitrogen. This is a line item with a real cost. If the drawing does not ask for it, the quote will not include it, and the shop is not being sharp with you.

What to put on the RFQ

The shops that quote well are the ones that get enough to price without a round of questions. Send:

• A STEP or IGES model and a PDF drawing. The model alone gets you questions, not a price.
• Grade and temper, plus whether a mill cert or a heat lot is required.
• The finish callouts against specific faces, not against the part.
• The cleaning procedure and the packing standard, by name if you have one.
• Quantity now and whether a repeat is expected, because that changes how the shop amortises the fixture.
• Your deadline, honestly. A shop that would have said no to three weeks will say yes and be late.

Before you commit to a new shop

Ask which of the five controls above are in house and which are bought. Ask to see a dimensional report from a similar part with the customer details removed. Ask what they do with blast media between jobs. The answers take five minutes and tell you more than a capability list ever will.

If you would rather not run that screen yourself, that is the job this site does: you send the drawing, and it goes to shops that already run this class of part.

Frequently asked questions

Keep reading

• Load Lock and Transfer Chamber Parts: What Is Machined and What Is Toleranced
• Helium Leak Testing for Machined Vacuum Chamber Parts: What the Drawing Has to Say