Quartz Viewport Window

Quartz & Sapphire Viewport Windows

Viewport windows allow optical access to semiconductor process chambers for endpoint detection, optical emission spectroscopy (OES), pyrometry, laser heating, and visual inspection — without compromising chamber vacuum or gas purity.

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Window Material Selection

Property	Fused Quartz	Synthetic Fused Silica	Sapphire
Transmission range	Application-specific optical range should be reviewed	Application-specific optical range should be reviewed	Application-specific optical range should be reviewed
Temperature requirement	Reviewed by application and mounting method	Reviewed by application and mounting method	Reviewed by application and mounting method
Chemical / plasma exposure	Requires process review	Requires process review	Requires process review
Purity / material certificate	Depends on material source and order scope	Depends on material source and order scope	Single-crystal material certificate may be available by source
Surface finish	Reviewed by optical specification	Reviewed by optical specification	Reviewed by optical specification
Best use case	General monitoring	High-purity CVD	Plasma + high-temp

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Unmounted Windows (Blanks)

Polished window blanks without flanges — for customer-integration into existing viewport assemblies.

Specification	Standard	Precision
Diameter tolerance	Reviewed by drawing	Reviewed by drawing
Thickness tolerance	Reviewed by drawing	Reviewed by drawing
Surface roughness (both faces)	Reviewed by optical specification	Reviewed by optical specification
Flatness (surface form)	Reviewed by optical specification	Reviewed by optical specification
Parallelism	Reviewed by drawing	Reviewed by drawing
Edge chamfer	0.3–0.5 mm × 45°	0.1–0.3 mm × 45°
Clear aperture	≥ 85% of diameter	≥ 90% of diameter

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Flanged Viewport Assemblies

Complete viewport assemblies with metal flanges for direct bolt-on installation to chamber walls.

Flange Type	Description	Leak Rate
CF (ConFlat) flange	Metal knife-edge style interface	Leak testing can be arranged when specified
ISO-KF flange	Quick-release O-ring style interface	Leak testing can be arranged when specified
Custom bolt-pattern flange	Per customer drawing	Per spec

Window-to-flange attachment methods: optical contact bonding, metallic indium seal, or brazed (sapphire only).

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Anti-Reflection Coatings

Coating or optical specifications should be reviewed case by case for specific wavelength applications:

Coating	Wavelength	Reflectance	Application
Single-layer MgF₂	Broadband VIS	Reflectance target reviewed by coating partner/specification	General monitoring
V-coat	193 nm (ArF)	Reviewed by wavelength and substrate	DUV process monitoring
V-coat	248 nm (KrF)	Reviewed by wavelength and substrate	KrF process monitoring
V-coat	532 / 1064 nm	Reviewed by wavelength and substrate	Laser pyrometry
Dual-band	355 + 1064 nm	Reviewed by wavelength and substrate	Multi-wavelength systems

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Typical Applications

• OES endpoint detection — plasma etch process control
• Pyrometry windows — temperature measurement via IR transmission
• Laser heating observation ports — RTP, annealing
• In-situ reflectometry — CVD film thickness monitoring
• UV process monitoring — DUV lamp-based cleaning/curing systems