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Spin Coater
Laurell Technologies Corporation, North Wales, PA, USA
HIGH ● Every lithography step begins with spin-coatingRole in QLT Fabrication
The spin coater applies thin, uniform films of photoresist and functional polymers to the foundry-returned SiN chips. Three distinct spin-coat jobs:
| Job | Material | Target Thickness | Speed | Duration | Purpose |
|---|---|---|---|---|---|
| B1/G4 Resist | SPR-220-3.0 (positive) | 3.0 μm ± 0.1 μm | 3000 RPM | 30 s | Photolithography masking |
| B4 PVDF-TrFE | 70/30 copolymer in MEK | 500 nm ± 50 nm | 4000 RPM | 60 s | Piezoelectric Poovey switch layer |
| Optional ARC | ARC coating | 100–200 nm | 5000 RPM | 30 s | Lithography uniformity |
Process Criticality
Resist thickness uniformity directly determines:
- Exposure dose consistency ● ±10% thickness variation causes ±10% dose variation
- Pattern resolution ● thicker resist limits minimum feature size
- Etch mask integrity ● insufficient resist thickness leads to mask erosion during RIE
- PVDF-TrFE film quality ● Poovey switch performance depends on uniform piezoelectric layer
Edge Bead Consideration
Spin coating on small die (5×5 mm or 10×10 mm) produces significant edge beads ● thick resist ridges at substrate edges. For QLT:
- Edge bead width: ~0.5–1.0 mm from edge (acceptable; our features are > 1 mm from edge)
- Edge bead removal (EBR): Not required for current designs but available via solvent dispensed at edge during spin
- Fragment adapter chuck ensures small die are centered and level during coating
Recommended Configuration
The WS-650 series is the most widely used research spin coater worldwide, with thousands installed in university and startup cleanrooms.
| Parameter | Specification |
|---|---|
| Manufacturer | Laurell Technologies Corporation, North Wales, PA, USA |
| Model | WS-650-23B (standard research-grade, 650 series) |
| Max substrate | 150 mm (6") wafer; 5" × 5" (127 mm) square |
| Speed range | 0–12,000 RPM (programmable; based on 100 mm Si wafer) |
| Acceleration | 0–29,000 RPM/s |
| Control | Digital microprocessor; 20+ stored recipes; PC interface (object-oriented software) |
| Bowl material | Proprietary NPP co-polymer (acid/base/solvent resistant); PTFE Hostaflon® TFM-1600 optional |
| Chuck | Vacuum chuck standard; fragment adapters for pieces as small as 3 mm |
| Lid | Water-clear ECTFE or PVC domed lid; interlocked (rotation disabled when open) |
| Bowl design | Closed clamshell with internal gutter; eliminates splash-back; no splash rings needed |
| Exhaust/Drain | Adjustable down-flow exhaust and drain (standard on EDC™ models); controller monitors exhaust pressure |
| Motor seal | Proprietary labyrinth seal; N₂-purged; particle-free on sub-micron level |
| Safety | Door interlock; latch; rotation lock until lid closed and 0 RPM sensed |
| Power | 300 W; universal input 95–240 VAC, 47/63 Hz |
| N₂/CDA | 60–70 PSIG for labyrinth seal purge (3 ft³/hr standard motor; 20 ft³/hr high-performance) |
| Vacuum | 25–28 inHg; 4.5 SCFM at 0 inHg |
| Footprint | ~35 cm × 35 cm × 25 cm (compact benchtop) |
| Weight | ~15 kg (33 lbs) |
| Parameter | Specification |
|---|---|
| Manufacturer | Laurell Technologies Corporation, North Wales, PA, USA |
| Model | WS-650-23B (standard research-grade, 650 series) |
| Max substrate | 150 mm (6") wafer; 5" × 5" (127 mm) square |
| Speed range | 0–12,000 RPM (programmable; based on 100 mm Si wafer) |
| Acceleration | 0–29,000 RPM/s |
| Control | Digital microprocessor; 20+ stored recipes; PC interface (object-oriented software) |
| Bowl material | Proprietary NPP co-polymer (acid/base/solvent resistant); PTFE Hostaflon® TFM-1600 optional |
| Chuck | Vacuum chuck standard; fragment adapters for pieces as small as 3 mm |
| Lid | Water-clear ECTFE or PVC domed lid; interlocked (rotation disabled when open) |
| Bowl design | Closed clamshell with internal gutter; eliminates splash-back; no splash rings needed |
| Exhaust/Drain | Adjustable down-flow exhaust and drain (standard on EDC™ models); controller monitors exhaust pressure |
| Motor seal | Proprietary labyrinth seal; N₂-purged; particle-free on sub-micron level |
| Safety | Door interlock; latch; rotation lock until lid closed and 0 RPM sensed |
| Power | 300 W; universal input 95–240 VAC, 47/63 Hz |
| N₂/CDA | 60–70 PSIG for labyrinth seal purge (3 ft³/hr standard motor; 20 ft³/hr high-performance) |
| Vacuum | 25–28 inHg; 4.5 SCFM at 0 inHg |
| Footprint | ~35 cm × 35 cm × 25 cm (compact benchtop) |
| Weight | ~15 kg (33 lbs) |
| Option | Description | Cost Impact |
|---|---|---|
| PTFE Housing | Hostaflon® TFM-1600 / Teflon® AF; for high-temp chemistry + sub-micron particle work | +$2,000–$3,000 |
| FEP Teflon® Liners | Removable, reusable chamber liners; included on HL series | +$200–$400 |
| High-Performance Drive | Up to 12,000 RPM (substrate/chuck dependent) | +$500–$1,000 |
| Fragment Adapter | Vacuum adapter for substrates as small as 3 mm | +$200–$400 |
| On-Deck Mounting (OND) | Earthquake-proof base; remote controller; for glovebox or wet-bench mounting | +$500–$1,000 |
| Teflon® Control Valves | Drip-free UD-3 injectors; convert between pump, pressure vessel, or syringe dispensing | +$200–$500 |
| Dispense Pump (BP-1) | Inexpensive, disposable dispense pump | +$100 |
| Bowl-Wash Routine | Automated bowl wash + dry cycle programmable into recipes | Included in firmware |
| Alternative | Pros | Cons | Approx. Price (New) |
|---|---|---|---|
| Laurell WS-400B | Lower cost; 4" max; simpler | Smaller wafer limit; fewer features | $4,000–$6,000 |
| SÜSS MicroTec Delta 80 | Production-grade; integrated hot plate; auto dispense | Expensive; overkill | $30,000–$50,000 |
| Headway Research PWM32 | Classic lab workhorse; proven | Older design; fewer automation features | $3,000–$5,000 used |
| SCS G3P-8 | Excellent for thick resists | Less common | $5,000–$8,000 used |
| Ossila Spin Coater | Ultra-compact; affordable | Small substrate only (25 mm); not cleanroom grade | $3,000 new |
| Chinese generic (MTI, SETCAS) | Very low cost | Poor repeatability; no US support | $500–$2,000 |
Process Integration
Pre-Coat Preparation
- Verify substrate cleanliness (acetone → IPA → DI rinse → N₂ dry on wet bench #06)
- Dehydration bake: 200°C hot plate, 5 min (removes surface moisture for resist adhesion)
- Optional HMDS vapor prime (improves resist adhesion on SiO₂ surface)
- Cool substrate to room temperature (1–2 min on cleanroom bench)
Coating Sequence
- Place substrate on spin coater chuck under yellow safelight
- Verify vacuum hold
- Dispense SPR-220-3.0: 2–3 mL static puddle on center
- Close lid
- Run programmed recipe (Step 1 → 2 → 3 as above)
- Open lid; remove with tweezers
- Transfer to soft-bake hot plate (115°C, 90 s)
Post-Coat Inspection
- Visual inspection: uniform color (thin-film interference); no comets, streaks, or particles
- Optional: measure thickness with reflectometer or profilometer
- Target: 3.0 μm ± 0.1 μm across center 80% of substrate
- Edge bead: acceptable if < 1 mm width from edge
Bowl Maintenance (After Each Session)
- Run bowl-wash program: spin IPA or acetone at 500 RPM to clean internal surfaces
- Wipe bowl interior with cleanroom wipe + IPA
- Replace aluminum foil liner if used
- Verify drain is clear; no dried resist buildup
Vendor Options & Pricing
New System Cost
| Configuration | Estimated New Price |
|---|---|
| WS-650-23B (standard, NPP co-polymer bowl, vacuum chuck set) | $7,000–$10,000 |
| WS-650-23B with PTFE Hostaflon® housing + PC interface | $9,000–$13,000 |
| WS-650-23B + fragment chuck adapter + FEP liner | $8,000–$11,000 |
| WS-400B (4" max, basic) | $4,000–$6,000 |
Laurell does not publish prices. Obtain quote at laurell.com/quote.php.
Used/Refurbished Market
| Condition | WS-650 | WS-400 | Headway PWM32 |
|---|---|---|---|
| "As-is" | $2,000–$4,000 | $1,500–$3,000 | $1,000–$2,500 |
| Tested / functional | $4,000–$6,000 | $2,500–$4,000 | $2,000–$3,500 |
| Refurbished w/ warranty | $6,000–$8,000 | $4,000–$5,500 | $3,000–$5,000 |
Where to Buy
| Dealer | Website | Notes |
|---|---|---|
| Laurell Technologies (OEM) | laurell.com | New units; custom configs; US-made; 2–4 week delivery |
| eBay | ebay.com | Frequent WS-650 listings; $2k–$5k used |
| LabX | labx.com | Lab equipment marketplace |
| DOTmed | dotmed.com | Occasionally lists spin coaters |
| University surplus | Various | Check nearby university surplus stores |
Cost History
SPIN COATER PRICE TREND (Laurell WS-650): New: ~$7-10k consistently for 10+ years (very stable pricing) Used: $2-6k depending on condition (abundant supply) TREND: Extremely stable market. Spin coaters are COMMODITY items. New purchase from Laurell recommended due to low cost, full warranty, and exact configuration control.
Our Budget Recommendation
Buy NEW: $8,000 (Laurell WS-650-23B)
- Justification: New cost is low enough that used savings ($2–4k) don't justify contamination or worn bearing risk
- Include: Standard NPP co-polymer bowl, vacuum chuck set for 100 mm wafers + fragment adapter (3 mm minimum), FEP Teflon® liner, PC interface software
- Lead time: 2–4 weeks from Laurell (stock item)
Facility Requirements
Floor Space
| Dimension | Requirement |
|---|---|
| Footprint | 35 cm × 35 cm (14" × 14") ● benchtop unit |
| With workspace | 0.8 m × 0.6 m section of cleanroom bench |
| Weight | 15 kg (33 lbs) |
| No floor reinforcement needed | ✅ |
Electrical
| Parameter | Requirement |
|---|---|
| Supply | Any standard outlet: 120 V or 240 V, single-phase (universal 95–240 V input) |
| Circuit | Standard 15 A outlet |
| Power | 300 W peak; ~5 W idle |
| No special electrical requirements | ✅ Plug and play |
Utilities
| Utility | Specification |
|---|---|
| Vacuum | 25–28 inHg; dedicated pump or house line (diaphragm pump: $200–$500) |
| N₂ / CDA | 60–70 PSIG; clean, dry; 3–20 ft³/hr consumption |
| Exhaust | Fume hood or downdraft recommended (resist solvents: PGMEA; MEK for PVDF-TrFE) |
| Exhaust flow | 100–200 CFM local exhaust |
Vibration / Sound / Lighting
| Parameter | Specification |
|---|---|
| Vibration sensitivity | NONE ● generates vibration, doesn't receive it |
| Caution | Don't place directly adjacent to mask aligner |
| Noise | 50–60 dB(A) during spin (moderate whine) |
| Special lighting | YES ● YELLOW SAFELIGHT if dispensing photoresist |
| Co-location | Same yellow-lit zone as mask aligner is ideal |
Safety & Handling
| Hazard | Risk Level | Control |
|---|---|---|
| MEK fume exposure (PVDF-TrFE coating) | Medium | Spin under fume hood or downdraft; MEK flash point: -9°C (flammable) |
| Resist solvent vapors (PGMEA) | Low | General ventilation; PGMEA is low toxicity |
| Rotating chuck | Low | Lid interlock prevents access during spin |
| Chemical splash | Low | Closed lid design contains all fluid |
PPE
- Safety glasses
- Nitrile gloves
- Lab coat