Why Epitaxy on Wafer Substrate?

What is the benefit of making another layer of silicon atom epitaxy on the silicon wafer substrate? In CMOS silicon technology, epitaxial growth (EPI) on wafer substrate is a very important process step.

1. Improve crystal quality

nitial substrate defects and impurities: The wafer substrate may have certain defects and impurities during the manufacturing process. The growth of the epitaxial layer can generate a high quality, low defect and impurity concentration monocrystalline silicon layer on the substrate, which is very important for subsequent device manufacturing.

Uniform crystal structure: Epitaxial growth ensures a more uniform crystal structure and reduces the influence of grain boundaries and defects in the substrate material, thereby improving the crystal quality of the entire wafer.

Improve electrical performance

Optimized device characteristics: By growing an epitaxial layer on the substrate, the doping concentration and type of silicon can be precisely controlled to optimize the electrical performance of the device. For example, the doping of the epitaxial layer can precisely adjust the threshold voltage and other electrical parameters of the MOSFET.

Reduced leakage current: High-quality epitaxial layers have a lower defect density, which helps reduce leakage current in the device, thereby improving the performance and reliability of the device.

Support for advanced process nodes

Feature size reduction: At smaller process nodes (e.g., 7nm, 5nm), device feature sizes continue to shrink, requiring more fine and high-quality materials. Epitaxial growth technology can meet these requirements and support high performance and high density IC manufacturing.

Increased penetration resistance: The epitaxial layer can be designed to have a high penetration resistance voltage, which is critical for manufacturing high power and high voltage devices. For example, in power devices, epitaxial layers can increase the breakdown voltage of the device and increase the safe operating range.

4. Process compatibility and multi-layer construction

Multilayer structure: The epitaxial growth technique allows multilayer structures to be grown on the substrate, and different layers can have different doping concentrations and types. This is very helpful for manufacturing complex CMOS devices and realizing 3D integration.

Compatibility: The epitaxial growth process is highly compatible with existing CMOS manufacturing processes and can be easily integrated into existing manufacturing processes without requiring significant modification of process lines.

Summary: The application of epitaxial growth in CMOS silicon process is mainly to improve the crystal quality of wafers, optimize the electrical performance of devices, support advanced process nodes, and meet the manufacturing needs of high-performance and high-density integrated circuits. Through epitaxial growth technology, the doping and structure of the material can be precisely controlled, and the performance and reliability of the overall device can be improved.