Custom Shadow Mask Design Guide for Thin-Film Deposition | Research & Industry
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Custom Shadow Mask Design Guide for Thin-Film Deposition
Shadow masks are essential components for defining patterns during PVD, CVD, and sputtering in research laboratories, semiconductor prototyping lines, and materials-science facilities.
This guide provides a complete, engineering-ready framework for designing masks with high precision, stability, and manufacturability.
Quick Overview — Key Principles of Mask Design
If you only remember three rules, remember these:
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Feature size should match mask thickness
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For <40 µm features → thickness ≤0.1–0.15 mm
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For 50–200 µm features → thickness ≤0.2–0.3 mm
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Thick masks (>0.3 mm) cannot support ultra-fine openings (aspect ratio limit)
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Maintain a realistic aspect ratio
A practical limit for high-quality deposition is:
max aspect ratio ≈ 4:1 (thickness : feature width) -
Minimize mask–substrate gap
Even a 20–50 µm gap can cause shadow spreading during PVD.
Design flatness + fixture method accordingly.
Recommended Materials for Research Shadow Masks
| Material | Advantages | Limitations | Typical Thickness |
|---|---|---|---|
| 304 Stainless Steel | Rigid, inexpensive, heat-resistant | Not ideal for <25–30 µm features | 0.05–0.5 mm |
| Molybdenum | High melting point, minimal warping | Higher cost | 0.05–0.3 mm |
| Silicon Mask | Extremely precise features (10–20 µm) | Fragile | 200–500 µm |
| Nickel Foil (Electroformed) | Sub-20 µm features possible | Costly, delicate | 20–100 µm |
Thickness vs Feature Size — Recommended Chart
| Feature Size | Recommended Thickness | Notes |
|---|---|---|
| 20–30 µm | 0.05–0.10 mm | laser or electroforming only |
| 30–50 µm | 0.10–0.15 mm | best overall balance |
| 50–100 µm | 0.15–0.20 mm | stable for PVD and sputtering |
| 100–500 µm | 0.20–0.50 mm | thick mask OK, no risk of collapse |
Thermal & Mechanical Considerations
Thermal Expansion in Vacuum Chambers
During deposition, masks may heat to 100–350°C.
304 stainless expands:
~17 × 10⁻⁶ / °C
Therefore:
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Avoid ultra-tight alignment holes on long masks
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Use flexible clamps to accommodate thermal cycling
Bending and Structural Warping
Large areas (>25 mm span) in 0.05 mm foil may bend.
Solutions:
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Add reinforcement rings
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Increase thickness to 0.1 mm
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Reduce unsupported spans through design segmentation