Gallium phosphide polishing solution
Introduction
Gallium Phosphide (GaP), as a second-generation compound semiconductor material, holds a significant position in the fields of optoelectronics and microelectronics due to its unique physical and optical properties. It features high carrier mobility, excellent thermal stability, and a bandgap characteristic that lies between the direct/indirect bandgaps of Gallium Arsenide (GaAs) and Gallium Nitride (GaN). It is widely used in high-efficiency light-emitting diodes (LEDs), laser diodes, high-speed photoelectric devices, and high-brightness displays. However, GaP crystals are hard and brittle with distinct cleavage planes. The precision polishing quality of the GaP substrate and device surface directly determines the epitaxial growth quality and the final device's photoelectric conversion efficiency and reliability.
Hemei Company possesses profound expertise in the processing of compound semiconductor materials. Leveraging a deep understanding of GaP material characteristics, we have developed a polishing and planarization solution that balances high material removal rates with exceptional surface integrity. This process enables high-precision surface treatment from the substrate stage through to post-epitaxial device processing, ensuring it meets the stringent requirements of high-end photoelectric devices for atomically smooth surfaces, ultra-low damage layers, and perfect lattice integrity.
Application Requirements
The objectives for polishing and surface treatment of GaP materials include:
Reducing surface roughness (Ra) to <0.5 nm to ensure high-quality epitaxial growth and low optical scattering loss.
Achieving surface flatness with Total Thickness Variation (TTV) ≤ 1 μm, and Local Thickness Variation (LTV) superior to this value.
Producing surfaces free of scratches, micro-cracks, and sub-surface damage, meeting the performance demands of high-brightness LEDs and laser devices.
Ensuring process compatibility with both semi-insulating and conductive GaP substrates, supporting wafer sizes from 2 inches to 6 inches.
To achieve these goals, the Hemei process utilizes customized bonding systems and a multi-step polishing flow, guaranteeing geometric accuracy and surface integrity throughout the machining process.
System Specifications
Hemei's modular polishing system supports the processing of GaP wafers/crystals of various sizes and shapes. The core system includes:
HSM-L/LP Series Lapping Equipment: Used for initial material removal and thickness control.
HSM-CMP Series Chemical Mechanical Polishing System: Used to achieve ultra-smooth, damage-free surfaces.
Key Subsystems:
Wafer/Crystal-specific Bonding Unit (WB).
SJ/ASJ Series Precision Polishing Fixtures.
C-ASJ Drive Head High-Speed Polishing System.
Process Flow
Bonding and Mounting: The GaP sample is temporarily bonded to a carrier plate using the WB bonding unit and then mounted onto the polishing fixture.
Rough and Intermediate Polishing: Controlled lapping is performed on the HSM-L equipment to remove the machining damage layer.
Fine Polishing: The HSM-CMP system is used for the final polish. Parameters such as pressure, rotational speed, and slurry flow rate are adjusted in real-time to achieve nanoscale surface smoothness.
Typical Results
Surface Roughness Ra < 0.5 nm
Total Thickness Variation (TTV) ≤ 1 μm, Local Thickness Variation (LTV) ≤ 0.3 μm
Stable and controllable material removal rate; typical removal rate during fine polishing is 0.1-0.5 μm/min (adjustable).
Suitable for GaP wafers with diameters ≤ 4 inches.
Summary
Hemei Company provides a complete and reliable polishing and planarization solution for Gallium Phosphide (GaP) materials. This solution consistently delivers atom-level surface quality and excellent photoelectric performance, supporting the advancement of GaP industrialization and the enhancement of device performance in high-end fields such as 5G communication, photoelectric devices, satellite payloads, and high-speed electronics.
