A Single-Side Sapphire Wafer - 4 inches is a high-quality wafer made from synthetic sapphire (Al₂O₃) that has been polished on one side, leaving the other side unpolished or minimally processed. The polished side provides a smooth, flat surface, ideal for various high-precision applications such as semiconductor manufacturing, LED production, optical components, and high-performance electronics.
Key Characteristics of a 4-Inch Single-Side Sapphire Wafer:
Material: Sapphire (Al₂O₃)
Sapphire is a crystalline form of aluminum oxide known for its high hardness (9 on the Mohs scale), optical transparency, chemical stability, and thermal conductivity. These properties make it suitable for demanding applications in fields like semiconductors, optics, LEDs, and MEMS (Microelectromechanical Systems).
The sapphire wafer is typically grown using Czochralski or sublimation methods, ensuring high-quality crystals with low defect densities.
Diameter: 4 inches
A 4-inch sapphire wafer is a standard size used in the semiconductor industry for epitaxial growth and other wafer-based applications. Its size makes it suitable for industrial production, allowing efficient handling and processing.
Sapphire wafers are also available in different diameters, ranging from 2 inches to 8 inches or larger, depending on the application.
Single-Side Polished:
The wafer is polished on one side to a high degree of smoothness and flatness, while the other side is typically left unpolished or treated minimally.
The polished surface provides a defect-free, smooth base for thin-film deposition (e.g., epitaxial growth of semiconductor layers), photolithography, and other processes that require a flat substrate.
The unpolished side is generally used for bonding or backside processing, or it may serve as a reference for other fabrication processes.
Crystal Orientation:
The most common crystallographic orientation for sapphire wafers is the <0001> plane (the c-plane), which is ideal for LED manufacturing and semiconductor processing. The c-plane provides optimal conditions for epitaxial growth of layers such as GaN (gallium nitride) in blue LEDs and high-brightness LEDs.
Other orientations such as <1120> (a-plane) or <1102> (r-plane) may be used for specific applications, depending on the desired properties for the material growth.
Applications:
LEDs and Optoelectronics: Sapphire wafers are widely used as substrates for the production of LEDs and laser diodes, especially in the blue and white LED markets. The smooth, polished surface ensures high-quality epitaxial growth and layer uniformity, essential for efficient LEDs.
Semiconductor Devices: Sapphire's thermal conductivity and electrical insulation properties make it ideal for use in power electronics, microwave devices, and other semiconductor applications.
Optical Components: Due to its optical transparency and chemical resistance, sapphire is used in optical windows, lenses, viewports, and other optical components. It is commonly found in applications requiring high durability, such as aerospace, military, and medical devices.
MEMS (Microelectromechanical Systems): Sapphire wafers are also used in MEMS applications, where their mechanical strength and flatness support the fabrication of microsensors, actuators, and devices that require high precision.
Surface Quality:
The polished surface of the sapphire wafer ensures a smooth, defect-free surface that is essential for high-performance thin-film deposition and precision photolithography. A high-quality surface reduces defects and improves the yield in device fabrication processes.
The smoothness of the surface is also important for ensuring uniform material growth and thin-film adhesion during semiconductor and LED manufacturing.
Thickness and Uniformity:
Thickness: The thickness of the sapphire wafer can vary, but for a 4-inch wafer, typical thicknesses range from 200 µm to several millimeters, depending on the requirements of the application.
Uniformity: The wafer is manufactured to have a uniform thickness and flatness. This is particularly important for epitaxial growth and other precision fabrication processes where consistency across the wafer is essential.
Advantages:
High Mechanical Strength: Sapphire's high hardness and scratch resistance make it suitable for harsh environments and high-wear applications.
Optical Clarity: Sapphire is optically transparent in the visible and UV light ranges, making it ideal for optical applications such as windows, lenses, and viewports.
Thermal Conductivity: Sapphire offers excellent thermal conductivity, making it ideal for high-power devices that require efficient heat dissipation, such as power electronics and LEDs.
Chemical Resistance: Sapphire's chemical inertness makes it resistant to corrosion and chemical damage, even in aggressive environments.