Silicon Wafer

Core Features

1. Excellent Infrared Optical Performance

   It exhibits high transmittance in the 1.2~8 μm infrared band, with a peak transmittance ≥90% (1 mm thickness, uncoated). The refractive index is stable, reaching 3.42 at 10.6 μm (CO₂ laser wavelength), with a refractive index uniformity deviation ≤±1×10⁻⁴. Optical loss is low, with an infrared absorption coefficient ≤0.01 cm⁻¹ and negligible scattering loss, meeting the requirements of high-resolution infrared imaging and laser transmission.
2. Ultra-High Surface Quality and Dimensional Accuracy

   The surface is treated by chemical mechanical polishing (CMP) with a roughness Ra≤0.3 nm, free of scratches, pits and polishing defects. The flatness is ≤1 λ (λ=632.8 nm), parallelism ≤3 arcsec, and thickness tolerance ≤±1 μm. Circular wafers have a diameter of φ10~φ300 mm, while special-shaped wafers can be customized into rectangular, square and trapezoidal structures with a dimensional tolerance ≤±0.05 mm, suitable for high-precision optical assembly.
3. Good Mechanical and Thermal Properties

   With a flexural strength ≥200 MPa and fracture toughness ≥0.8 MPa·m¹/², it can undergo secondary processing such as precision cutting, drilling and coating. The thermal expansion coefficient is 2.6×10⁻⁶/℃ (20~300℃), and the thermal conductivity is ≥148 W/(m·K). It can maintain optical and structural stability even under drastic temperature changes, suitable for extreme working conditions such as aerospace.
4. Customizable Surface Treatment and Function Expansion

   Optical-grade surface modification is supported: single/double-sided anti-reflection (AR) coating, high-reflection (HR) coating, beam-splitting coating and other coating treatments, which can increase the transmittance of specific bands to more than 99%. Ion implantation and surface doping processes are also available to realize optoelectronic function integration. Ultra-thin wafers (thickness ≤50 μm) and flexible wafers can be customized to meet the needs of miniaturized and flexible optical devices.

Technical Parameters (Typical Values)

Application Fields

1. Infrared Thermal Imaging Systems

   As the core substrate for lenses and windows of infrared thermal imagers, it realizes high-resolution imaging of target temperatures by virtue of its infrared transmittance in the 1.2~8 μm band. Widely used in security monitoring, industrial temperature measurement, medical diagnosis and automotive night vision, it is compatible with cooled and uncooled infrared detectors.
2. Laser Radar (LiDAR)

   Used for emission windows, receiving lenses and beam splitters of vehicle-mounted LiDAR and industrial LiDAR, it has excellent optical performance in the 1.55 μm (eye-safe band) and 10.6 μm band. It can withstand high-power laser irradiation, ensuring ranging accuracy and stability, and is a key component for autonomous driving and industrial automation.
3. Infrared Remote Sensing and Aerospace

   As the optical window and lens substrate for satellite infrared remote sensors and missile seekers, it combines infrared transmittance with radiation resistance. It can work stably in extreme temperature and vacuum environments, realizing long-range detection and identification of ground targets.
4. Optical Communication and Laser Devices

   Used for coupling lenses in infrared fiber optic communication, and mirrors and windows in laser resonators. Its low optical loss characteristic ensures efficient transmission of laser signals, and its high refractive index is suitable for the design of miniaturized optical systems, applicable to high-end devices such as fiber lasers and optical communication modules.

Preparation Process

1. Ultra-Pure Ingot Growth: Using 6N-grade high-purity polycrystalline silicon as raw material, monocrystalline silicon ingots are grown by float zone (FZ) or Czochralski (CZ) method to control crystal orientation and defects. 7N-grade products require multiple float zone purification.
2. Directional Cutting and Forming: The crystal orientation is determined by an X-ray orienter, and the ingot is cut into thin slices by diamond wire cutting. Special-shaped wafers require precision contour cutting.
3. Precision Grinding and Thinning: The cut wafers are double-side ground to remove the cutting damage layer, control thickness tolerance and parallelism. Ultra-thin wafers require plasma thinning.
4. Chemical Mechanical Polishing (CMP): High-purity polishing slurry and soft polishing pads are used for chemical mechanical polishing of the wafer surface to achieve an atomically flat surface with a roughness Ra≤0.3 nm.
5. Optical Inspection and Surface Treatment: Optical performance and surface quality are detected by spectrophotometer, interferometer and atomic force microscope (AFM). Functional treatments such as coating and doping are performed according to requirements, and the final products are vacuum-sealed and packaged.

Usage and Storage Recommendations

1. Usage Notes
   • Avoid touching the wafer surface with bare hands; use clean gloves or special vacuum tweezers for operation to prevent fingerprint and oil contamination from affecting optical performance.
   • Elastic fixtures should be used for installation to avoid wafer warpage or cracking caused by mechanical stress; plasma cleaning of the surface is required before coating to remove surface-adsorbed impurities.
   • Avoid contact with strong alkalis and hydrofluoric acid to prevent wafer corrosion; a cooling system must be equipped for high-power laser applications to avoid thermal deformation.
2. Storage Conditions

   Vacuum-sealed and stored in an anti-static, dust-free special packaging box, with storage temperature 10~30℃ and relative humidity ≤30%. Avoid moisture, dust contamination, severe collision and ultraviolet radiation. The shelf life is 12 months in an unopened state.
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