Quartz Wafer Boat

Quartz Wafer Boats

Wafer boats hold silicon wafers vertically during thermal processing in horizontal furnaces, or horizontally in vertical furnace designs. The boat’s dimensional accuracy controls wafer-to-wafer spacing, gas flow uniformity, and contamination levels throughout the batch process.

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Standard Specifications

Horizontal Boat (Standard Slot Configuration)

Wafer Size	Slots (Standard)	Slot Pitch	Overall Length	Height	Material
4” (100 mm)	25	4.76 mm	130 mm	130 mm	Grade 1
6” (150 mm)	25	6.35 mm	175 mm	180 mm	Grade 1
8” (200 mm)	25	7.62 mm	215 mm	230 mm	Grade 1/2
12” (300 mm)	25	9.52 mm	265 mm	335 mm	Grade 2

Custom slot counts (13, 26, 50, 100) and pitches available on request.

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Vertical Boat (for Vertical Furnaces)

Vertical boats use a tube-and-rod construction with precision-slotted rings at defined pitch.

Wafer Size	Standard Slots	Slot Pitch	Overall Height
8” (200 mm)	100	4.76 mm	520 mm
12” (300 mm)	100	7.62 mm	820 mm

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Slot Geometry

The slot geometry must accommodate wafer thickness variation and prevent sticking while maintaining a near-vertical seating angle for uniform gas exposure.

Feature	Standard	Tight-Tolerance
Slot width	Wafer thickness + 0.3 mm	Wafer thickness + 0.15 mm
Slot depth	5–8 mm	5–8 mm
Seating angle	88° ± 1°	88° ± 0.5°
Slot pitch	±0.2 mm	±0.1 mm
Slot parallelism	< 0.2 mm	< 0.1 mm

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Material Selection

• Grade 1 (Natural fused quartz): Suitable for all processes up to 1150°C where < 20 ppm metal contamination is acceptable
• Grade 2 (Synthetic fused silica): Required for processes where trace metal contamination at ppb level is critical — LPCVD gate oxide, ultra-high-purity diffusion

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Accessories

Quartz wafer boats are typically used with:

• Quartz push rods — for loading/unloading boats from furnace tubes
• Quartz baffles — gas flow conditioning at boat ends
• Quartz cantilever paddles — for large-diameter wafer handling