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As-grown sapphire boule

As-grown sapphire boule Featured Image
  • As-grown sapphire boule
  • As-grown sapphire boule
  • As-grown sapphire boule
  • As-grown sapphire boule

Short Description:

An as-grown sapphire boule is a single-crystal sapphire ingot produced directly from the growth furnace and supplied before secondary processing such as orientation, slicing, or polishing. It offers exceptional hardness, chemical inertness, high thermal stability, and broad optical transparency from UV to IR. These properties make it an ideal starting material for downstream fabrication into windows, wafers/substrates, lenses, and protective covers. Typical end-uses include LED and laser components, infrared/visible windows, wear-resistant watch and instrument faces, and substrates for RF, sensor, and other electronic devices. Boules are commonly graded by crystal orientation, diameter/length, dislocation or defect density, color uniformity, and inclusions, with optional services available for orientation and cutting to customer specifications.


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    • Features

    Ingot quality

    ingot size

    Ingot Photo

    Detailed Diagram

    sapphire ingot11
    sapphire ingot08
    as grown sapphire ingot01

    Overview

    A sapphire boule is a large, as-grown single crystal of aluminum oxide (Al₂O₃) that serves as the upstream feedstock for sapphire wafers, optical windows, wear-resistant parts, and gem cutting. With Mohs 9 hardness, excellent thermal stability (melting point ~2050 °C), and broadband transparency from UV to mid-IR, sapphire is the benchmark material where durability, cleanliness, and optical quality must coexist.

    We supply colorless and doped sapphire boules produced by industry-proven growth methods, optimized for GaN/AlGaN epitaxy, precision optics, and high-reliability industrial components.

    Why Sapphire Boule from Us

    • Crystal quality first: low internal stress, low bubble/striae content, tight orientation control for downstream slicing and epitaxy.

    • Process flexibility: KY/HEM/CZ/Verneuil growth options to balance size, stress, and cost for your application.

    • Scalable geometry: cylindrical, carrot-shape, or block boules with custom flats, seed/end treatments, and reference planes.

    • Traceable & repeatable: batch records, metrology reports, and acceptance criteria aligned to your spec.

    Growth Technologies

    • KY (Kyropoulos): Large-diameter, low-stress boules; favored for epi-grade wafers and optics where birefringence uniformity matters.

    • HEM (Heat-Exchanger Method): Excellent thermal gradients and stress control; attractive for thick optics and premium epi feedstock.

    • CZ (Czochralski): Strong control of orientation and reproducibility; good choice for consistent, high-yield slicing.

    • Verneuil (Flame-Fusion): Cost-efficient, high throughput; suitable for general optics, mechanical parts, and gem preforms.

    Crystal Orientation, Geometry & Size

    • Standard orientations: c-plane (0001), a-plane (11-20), r-plane (1-102), m-plane (10-10); custom planes available.

    • Orientation accuracy: ≤ ±0.1° by Laue/XRD (tighter upon request).

    • Shapes: cylindrical or carrot-type boules, square/rectangular blocks, and rods.

    • Typical size envelope: Ø30–220 mm, length 50–400 mm (larger/smaller made to order).

    • End/Reference features: seed/end face machining, reference flats/notches, and fiducials for downstream alignment.

    Material & Optical Properties

    • Composition: Single-crystal Al₂O₃, raw material purity ≥ 99.99%.

    • Density: ~3.98 g/cm³

    • Hardness: Mohs 9

    • Refractive index (589 nm): nₒ ≈ 1.768, nₑ ≈ 1.760 (negative uniaxial; Δn ≈ 0.008)

    • Transmission window: UV to ~5 µm (thickness- and impurity-dependent)

    • Thermal conductivity (300 K): ~25 W·m⁻¹·K⁻¹

    • CTE (20–300 °C): ~5–8 × 10⁻⁶ /K (orientation-dependent)

    • Young’s modulus: ~345 GPa

    • Electrical: Highly insulating (volume resistivity typically ≥ 10¹⁴ Ω·cm)

    Grades & Options

    • Epitaxy Grade: Ultra-low bubbles/striae and minimized stress birefringence for high-yield GaN/AlGaN MOCVD wafers (2–8 inch and above downstream).

    • Optical Grade: High internal transmission and homogeneity for windows, lenses, and IR viewports.

    • General/Mechanical Grade: Durable, cost-optimized feedstock for watch crystals, buttons, wear parts, and housings.

    • Doping/Color:

      • Colorless (standard)
        Cr:Al₂O₃ (ruby), Ti:Al₂O₃ (Ti:sapphire) preforms
        Other chromophores (Fe/Ti) on request

    Applications

    Semiconductor: Substrates for GaN LEDs, micro-LEDs, power HEMTs, RF devices (sapphire wafer feedstock).

    Optics & Photonics: High-temperature/pressure windows, IR viewports, laser cavity windows, detector covers.

    Consumer & Wearables: Watch crystals, camera lens covers, fingerprint sensor covers, premium exterior parts.

    Industrial & Aerospace: Nozzles, valve seats, seal rings, protective windows, and observation ports.

    Laser/Crystal Growth: Ti:sapphire and ruby hosts from doped boules.

    At-a-Glance Data (Typical, for reference)

    Parameter Value (Typical)
    Composition Single-crystal Al₂O₃ (≥ 99.99% purity)
    Orientation c / a / r / m (custom on request)
    Index @ 589 nm nₒ ≈ 1.768, nₑ ≈ 1.760
    Transmission Range ~0.2–5 µm (thickness-dependent)
    Thermal Conductivity ~25 W·m⁻¹·K⁻¹ (300 K)
    CTE (20–300 °C) ~5–8 × 10⁻⁶/K
    Young’s Modulus ~345 GPa
    Density ~3.98 g/cm³
    Hardness Mohs 9
    Electrical Insulating; volume resistivity ≥ 10¹⁴ Ω·cm

     

    Sapphire Wafer Manufacturing Process

    1. Crystal Growth
      High-purity alumina (Al₂O₃) is melted and grown into a single sapphire crystal ingot using the Kyropoulos (KY) or Czochralski (CZ) method.

    2. Ingot Processing
      The ingot is machined to a standard shape — trimming, diameter shaping, and end-face processing.

    3. Slicing
      The sapphire ingot is sliced into thin wafers using a diamond wire saw.

    4. Double-sided Lapping
      Both sides of the wafer are lapped to remove saw marks and achieve uniform thickness.

    5. Annealing
      The wafers are heat-treated to release internal stress and improve crystal quality and transparency.

    6. Edge Grinding
      The wafer edges are beveled to prevent chipping and cracking during further processing.

    7. Mounting
      Wafers are mounted onto carriers or holders for precision polishing and inspection.

    8. DMP (Double-sided Mechanical Polishing)
      The wafer surfaces are mechanically polished to improve surface smoothness.

    9. CMP (Chemical Mechanical Polishing)
      A fine polishing step combining chemical and mechanical actions to create a mirror-like surface.

    10. Visual Inspection
      Operators or automated systems check for visible surface defects.

    11. Flatness Inspection
      Flatness and thickness uniformity are measured to ensure dimensional precision.

    12. RCA Cleaning
      Standard chemical cleaning removes organic, metallic, and particulate contaminants.

    13. Scrubber Cleaning
      Mechanical scrubbing removes remaining microscopic particles.

    14. Surface Defect Inspection
      Automated optical inspection detects micro-defects such as scratches, pits, or contamination.

     

    Sapphire Boule (Single-Crystal Al₂O₃) — FAQ

    Q1: What is a sapphire boule?
    A: An as-grown single crystal of aluminum oxide (Al₂O₃). It is the upstream “ingot” used to make sapphire wafers, optical windows, and high-wear components.

    Q2: How does a boule relate to wafers or windows?
    A: The boule is oriented → sliced → lapped → polished to produce epi-grade wafers or optical/mechanical parts. Uniformity of the source boule strongly affects downstream yield.

    Q3: Which growth methods are available and how do they differ?
    A: KY (Kyropoulos) and HEM yield large, low-stress boules—preferred for epitaxy and high-end optics. CZ (Czochralski) offers excellent orientation control and lot-to-lot consistency. Verneuil (flame-fusion) is cost-efficient for general optics and gem preforms.

    Q4: What orientations do you supply? What accuracy is typical?
    A: c-plane (0001), a-plane (11-20), r-plane (1-102), m-plane (10-10), and customs. Orientation accuracy typically ≤ ±0.1° verified by Laue/XRD (tighter on request).

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    • Optical-Grade Crystals with Responsible In-House Scrap Management

    All our sapphire boules are manufactured to optical grade, ensuring high transmission, tight homogeneity, and low inclusion/bubble and dislocation densities for demanding optics and electronics. We control crystal orientation and birefringence from seed to boule, with full lot traceability and consistency across runs. Dimensions, orientations (c-, a-, r-plane), and tolerances can be customized to your downstream slicing/polishing needs.
    Importantly, any material that falls short of specification is processed entirely in-house through a closed-loop workflow—sorted, recycled, and disposed of responsibly—so you get reliable quality without handling or compliance burdens. This approach reduces risk, shortens lead times, and supports your sustainability goals.

    Ingot Weight Band (kg) 2″ 4″ 6″ 8″ 12″ Notes
    10–30 Suitable Suitable Limited/possible Not typical Not used Small-format slicing; 6″ depends on usable diameter/length.
    30–80 Suitable Suitable Suitable Limited/possible Not typical Broad utility; occasional 8″ pilot lots.
    80–150 Suitable Suitable Suitable Suitable Not typical Good balance for 6–8″ production.
    150–250 Suitable Suitable Suitable Suitable Limited/R&D Supports initial 12″ trials with tight specs.
    250–300 Suitable Suitable Suitable Suitable Limited/tightly specified High-volume 8″; selective 12″ runs.
    >300 Suitable Suitable Suitable Suitable Suitable Frontier-scale; 12″ feasible with strict uniformity/yield control.

     

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