Stainless steels have become indispensable in the semiconductor industry. The special material properties of these alloys can be perfectly tailored to the requirements of semiconductor production.

Corrosive gases, extreme temperatures or structurally demanding geometries pose particular challenges for High Purity (HP) and Ultra High Purity (UHP) systems. The focus here is on the surfaces of the production environment that come into contact with media, including peripheral systems for vacuum generation.

A crucial aspect in semiconductor manufacturing is an ultra-clean and particle-free production environment. Even a few particles can destroy the physical properties of a wafer which leads to critical impacts to the overall production process. The highest purity requirements therefore apply to piping and evacuation systems.

An important point here is the functionality of the surfaces with media contact. Topography, morphology, especially in the area of ​​the weld seams, and also the energy level play an essential role in the release of particles. In the manufacture of semiconductors, attention must therefore be paid to this when selecting the correct surface finish. The cleaner the inner surface of an Ultra High Purity (UHP) system that comes into contact with the media, the better the evacuation and flushing properties. This can significantly reduce the process times for this, with associated cost savings.

But is this effort to generate ultra clean electropolished stainless steel surfaces actually justified given the available purifiers and filter stations?

Whereas highly-developed filters can reliably filter out incoming particles, more particles means more filter exchange cycles which in turn means increased costs, system disturbances and downtime.

As already mentioned in addition electropolished UHP stainless steel surfaces allow the creation of highly pure and corrosion-free surfaces and weld seams which leads to low-particle and particle-generation-free stainless steel surfaces with minimum topographical expansion, highest-quality morphology and a low energy level structure.

This ends in positive absorption behaviour of electropolished stainless steel surfaces in regard to gas media change and corresponding flushing times, as well as moisture deposits and the release of such molecules into the flowing medium.

Dry Down Time

For these reasons electropolished stainless steel tubing and fittings in high-purity gas installations complement in an optimum way the purifier systems and gas filter systems either from a technical and economical perspective.

We offer two surface finishes that are particularly interesting for the semiconductor industry.

Anodic cleaning


Non-contacting material removal process as reversal of the galvanic process
(principle setup see electropolishing)
Non-contacting material removal process as reversal of the galvanic process
(principle setup see electropolishing)
Deposits and material removal of approx. 3 to 5 µmUsual deposit and material removal from approx. 10 – 25 µm
Semi-matt surface finishShiny surface finish
The method is mainly used to remove deposits and surface contaminationsProcess serves for the universal overall improvement of the surface structure (tension, topography, morphology)
Slight reduction in surface tensionSignificant reduction in surface tension
Minor leveling of the micro-topographyStrong leveling of the micro-topography (micro smoothing)
Reduction of the initial roughness (Ra) by approx. 30 – 50%
With optimal pretreatment are Ra values below 0.1 µm possible
Improvement of the morphology by removing the interfering layers (Beilby layer)
Low adsorption of liquids (e.g. water) and gases (e.g. air, oxygen)

Surface analysis after electropolishing and final cleaning proves the quality criteria for SEMI application criteria for High Purity (HP) and Ultra High Purity (UHP).

Test methods according to the relevant SEMI standardsAcceptance criteria HP (UHP) according to the relevant SEMI standards
SEMDefects/photo ≤ 30 (10) (avg.) and ≤ 50 (20) (max.)
XPS/ESCA (or AES by agreement)Cr/Fe ≥ 1.0 (1.5) and Cr-oxide /Fe-oxide ≥ 1.0 (2.0)
Oxide thickness d > 1.5 nm (d > 15 Å)

HP = High Purity, UHP = Ultra High Purity

On request also following quality criteria can be achieved.

Test methods according to the relevant SEMI standardsAcceptance criteria according to AM
XPS/ESCA (or AES by agreement)Cr/Fe ≥ 2.0 and and Cr-oxide /Fe-oxide ≥ 3.0
Oxide thickness d > 2.0 nm (d > 20 Å)
Surface contamination S < 1 At.-% and P < 2 At.-%
CPTCorrosion resistance as agreed upon between user and supplier; but basically shift to higher temperatures

Relevant SEMI standards are among others SEMI F73 (SEM), SEMI F60 (XPS/ESCA), SEMI F72 (AES), ASTM G150 (CPT) etc. for test methods and SEMI F17, SEMI F19 etc. for specification of acceptance criteria.
To ensure particle-free delivery, we offer additional clean room cleaning in clean rooms of ISO classes 4, 5 and 7. Here, the final cleaning of components with defined media as well as closing of the tube ends with caps take place under fully controlled clean room conditions.

Final rinse is done with DI water (el. resistance at 25°C > 18MΩ cm, TOC < 30 ppb, silica < 5ppb, live bacteria < 2 colonies per 100 ml, 0,1µm point of use filter at a temperature if 60 – 80°C) and for drying N2 5.0 (99,999%) is been used.

Quality assurance for high demands

For a consistently high quality of the components in semiconductor applications, we use various test methods in the clean room.
• Surface roughness measurement
• Visual inspection, also under UV light
• Residual moisture measurement
• Particle measurement in the gas flow

Packaging and labelling of tubes and fittings take place in clean area. Optionally single or multiple packing as well as labelling according to customer specification.

Your advantages with HENKEL surfaces for the semiconductor industry:

Over forty years of expertise in the electrochemical processing of stainless steels and in the production of functional surfaces.

Processes that are optimally tailored to your product (customer processing specifications are standard for us). Tube fix lengths 19 – 26 ft. (6-8 m) long are standard (larger and smaller lengths on requests). Coil tubing up to 100 ft. (30.48 m) long is possible. Tube diameters for internal EP starting from ID 2 mm (0,078“) (smaller diameters on request); Tube length for outer EP up to 60 ft. (18 m) (including U-Tubes)

Final cleaning of your components in clean rooms of ISO classes 4, 5 and 7 (US-Fed. Standard 209 D)

Particles per m³

Component / surface testing through extensive quality assurance

Surface treatment documentation for electropolishing and surface analysis of electropolished (coil and straight) tubing according to SEM F73.

Additional services from a single source such as degreasing, pickling, marking, etc. – talk to us

ISO-certified specialist company according to ISO 14001 and 9001

Well-known customers from the semiconductor industry and their suppliers

We are the right partner for the semiconductor industry. HENKEL surfaces – for the highest demands on stainless steel surfaces and components.