Polycrystalline Silicon Carbide
Polycrystalline Silicon Carbide
Polycrystalline Silicon Carbide (Polycrystalline SiC), as a representative high-performance structural ceramic and key material for semiconductor equipment, plays a critical role in optical windows, semiconductor equipment components, vacuum chambers, and high-energy laser systems due to its exceptional hardness, high thermal conductivity, excellent chemical stability, and wear resistance. Its polycrystalline structure effectively avoids the anisotropy of single crystals, providing high thermal shock stability while maintaining high strength and rigidity. However, the high hardness and brittleness of polycrystalline SiC pose significant challenges for precision machining, especially in optical and semiconductor applications requiring nanoscale surface finish and sub-micron form accuracy. The surface machining quality directly determines component performance and lifespan.
Hemei Company possesses profound experience and technical accumulation in the field of ultra-hard materials and ceramic precision machining. Targeting the material characteristics of polycrystalline SiC, Hemei has developed a polishing and planarization solution that balances high-efficiency material removal with ultra-precision surface formation. This process system covers the entire workflow from blank forming to the final optical-grade surface, ensuring it meets the stringent requirements for high flatness, low roughness, and damage-free sub-surface surfaces demanded by optical systems, semiconductor equipment, and advanced detectors.
Application Requirements
The objectives for polishing and surface treatment of polycrystalline SiC materials include:
Reducing surface roughness (Ra) to < 1 nm to decrease optical scattering loss and enhance optical performance.
Achieving thickness uniformity (TTV) of ≤ 2 μm to ensure optical imaging quality and system integration accuracy.
Obtaining a surface free of chipping, cracks, and sub-surface damage layers, ensuring reliability under high load and long-term use.
The process is suitable for polycrystalline SiC with different grain sizes and sintering densities, supporting planar components with thicknesses from millimeter to centimeter scale and sizes from 50mm to 200mm.
To achieve these goals, Hemei's process employs customized bonding systems and multi-step polishing procedures to ensure geometric accuracy and surface integrity during processing.
System Specifications
Hemei's modular polishing system supports processing polycrystalline SiC of various sizes and shapes. Core systems include:
HSM-L/LP Series lapping Equipment: For initial material removal and thickness control.
HSM-CMP Series Chemical Mechanical Polishing (CMP) System: For achieving ultra-smooth, damage-free surfaces.
Key subsystems include:
Wafer/Crystal-specific Bonding Unit (WB)
SJ/ASJ Series Precision Polishing Fixtures
C-ASJ Drive Head High-Speed Polishing System
Processing Flow
Bonding and Mounting: The polycrystalline SiC is temporarily bonded to a support plate using the WB unit, then mounted onto the polishing fixture.
Rough and Intermediate Polishing: Controlled grinding is performed on the HSM-L equipment to remove the processing damage layer.
Fine Polishing: The HSM-CMP system performs the final polish. Parameters like pressure, rotation speed, and slurry flow are adjusted in real-time to achieve nanometer-level surface smoothness.
Typical Results
Surface roughness Ra < 0.8 nm (measured by white light interferometer).
Total Thickness Variation (TTV) ≤ 1.5 μm.
Material removal rate can reach 5-15 μm/min in the rough grinding stage and is controlled at 0.2-1 μm/min in the fine polishing stage.
Capable of processing polycrystalline SiC plates and window components with a maximum diameter of 200 mm and thickness not exceeding 30 mm.
Summary
Hemei Company provides an efficient and controllable ultra-precision polishing and planarization solution for polycrystalline silicon carbide.
This solution stably delivers nanoscale surface quality and excellent form accuracy, robustly supporting the reliable application and performance enhancement of polycrystalline SiC in high-end optical systems, semiconductor process equipment, space payloads, high-power laser devices, and other fields.
