In the production of silicon carbide (SiC) wafers, monitoring and testing of process parameters are crucial to ensuring the quality and performance of the wafers. Below are some relevant terms and their explanations:

1. Terms Related to Wafer Manufacturing

Epitaxial Layer: A high-quality single-crystal layer formed on the silicon carbide substrate through the epitaxial growth process, commonly used to enhance device performance.

Epitaxial Thickness: The thickness of the epitaxial layer, usually measured in nanometers or micrometers, which must be precisely controlled to meet device design requirements.

Doping Concentration: The concentration of dopant atoms added to the epitaxial layer or substrate, which affects the electrical conductivity of the semiconductor.

Substrate: The silicon carbide wafer that serves as the base for the growth of the epitaxial layer.

2. Terms Related to Process Parameters

Thermal Gradient: Refers to the temperature difference across different locations on the wafer during growth. Excessive thermal gradients can lead to crystal defects.

Growth Rate: The speed at which the epitaxial layer grows, typically measured in micrometers per hour. Precise control is required to ensure the consistency of the epitaxial layer thickness.

Gas Flow Rate: The rate at which gases are supplied during epitaxial growth, which affects the uniformity of the reaction and the growth rate.

Reaction Pressure: The pressure within the reaction chamber during wafer growth, which impacts the growth rate and quality of the epitaxial layer.

Electrical Conductivity: The ability of the wafer material to conduct electrical current, influenced by temperature, doping concentration, and crystal structure.

3. Terms Related to Defect Detection and Characterization

Dislocation Density: The density of crystal defects in the wafer, which typically affects the reliability and performance of devices.

Stacking Fault: A misalignment of atoms in certain regions of the crystal, commonly found in silicon carbide crystals, affecting their electrical performance.

Leakage Current: The current that flows through a device when it is reverse-biased, often used as an evaluation parameter for wafer quality.

Basal Plane Dislocation (BPD): A defect that propagates along the basal plane (0001) of the silicon carbide crystal, which can affect the device's breakdown voltage and long-term reliability.

4. Terms Related to Testing and Analysis

Photoluminescence (PL): A method that excites the wafer with light and detects its emission characteristics to analyze defects and impurity concentrations.

X-ray Diffraction (XRD): A testing method used to analyze the crystal structure and quality of the wafer, detecting parameters such as crystal orientation and stress.

Atomic Force Microscopy (AFM): Used to measure surface roughness and microscopic morphology of the wafer.

C-V Characterization: A method used to analyze the electrical properties of the wafer, commonly employed to detect doping concentration distribution.

5. Terms Related to Surface and Cleaning

Surface Roughness: The microscopic unevenness of the wafer surface, which affects device contact quality and subsequent processing steps.

Chemical Mechanical Polishing (CMP): A process that uses both mechanical and chemical methods to planarize the wafer surface and remove surface defects.

Cleaning Step: A procedure to remove impurities and contaminants from the wafer surface to ensure high purity, commonly using acidic or basic solutions and ultra-pure water.

These terms play a vital role in the various stages of silicon carbide wafer manufacturing and are key factors in process monitoring and quality testing.