SiC Epitaxial Wafer PL Uniformity Through Quartz Degassing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
SiC epitaxial wafers exhibit non-uniform photoluminescence (PL) emission intensity, making it difficult to accurately evaluate defects and leading to potential carrier lifetime issues in semiconductor devices.
Innovation Solution
A manufacturing method using a quartz-based apparatus where quartz members are subjected to vacuum heat treatment at 600°C or higher under 1 kPa or lower for 1 hour or more to prevent water molecule desorption, ensuring uniform PL emission intensity across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoluminescence measurement is used to evaluate SiC epitaxial wafers, then defect evaluation can be performed, but non-uniform emission intensity makes accurate evaluation difficult
Solution Approach 1:
The patent changes the physical-chemical parameters of the quartz members by subjecting them to vacuum heat treatment at high temperatures (600°C or higher) under reduced pressure (1 kPa or lower) for 1 hour or more. This treatment modifies the quartz structure to prevent water molecule desorption during epitaxial growth, thereby achieving uniform PL emission intensity across the wafer surface and improving defect evaluation accuracy
Solution Approach 2:
The patent applies preliminary vacuum heat treatment to the quartz members before they are installed in the epitaxial growth apparatus. This preliminary action removes adsorbed water molecules and stabilizes the quartz structure in advance, preventing non-uniform PL emission during subsequent wafer production and ensuring consistent defect evaluation
2Ease of manufacture
If quartz members are used in the epitaxial growth apparatus, then manufacturing capability is maintained, but water molecule desorption causes non-uniform PL emission intensity
Solution Approach 1:
The patent modifies the thermal and pressure parameters during quartz treatment by applying vacuum heat treatment at 600°C or higher under 1 kPa or lower pressure for 1 hour or more. This parameter change eliminates water molecules from the quartz structure without compromising the quartz material's suitability for epitaxial growth, thus maintaining manufacturing capability while achieving uniform PL emission
Solution Approach 2:
The patent converts the potentially harmful effect of water molecule desorption from quartz into a beneficial outcome. By pre-treating quartz under vacuum at high temperature, the water molecules are removed in a controlled manner, preventing non-uniform PL emission during production. The harmful water desorption is transformed into a one-time treatment process that ensures uniform emission throughout the wafer's lifecycle
3Illumination intensity
If vacuum heat treatment is applied to quartz members, then uniform PL emission intensity is achieved, but treatment time and temperature requirements increase process complexity
Solution Approach 1:
The patent establishes specific parameter ranges for vacuum heat treatment (temperature: 600°C or higher, pressure: 1 kPa or lower, time: 1 hour or more) that optimize the removal of water molecules from quartz. These defined parameters create a standardized process that, while requiring precise control, ensures consistent uniformity of PL emission and can be integrated into existing manufacturing workflows
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves uniform PL emission intensity, enhancing evaluation accuracy and preventing carrier lifetime degradation in semiconductor devices by eliminating high-emission regions without defects.
Implementation Method 1
at least some of the members made of quartz are subjected to vacuum heat treatment before being installed in the epitaxial apparatus. In the vacuum heat treatment, the members are held at a temperature of 600° C. or higher under a pressure of 1 kPa or lower for 1 hour or more
Implementation Method 2
a SiC epitaxial layer stacked on a surface of a SiC single crystal substrate
Implementation Method 3
a SiC epitaxial wafer in which results of irradiating the SiC epitaxial wafer with excitation light having a wavelength of 313 nm and measuring emission intensity of photoluminescence light having a wavelength of 660 nm or more
Data Source
AI summary
This SiC epitaxial wafer includes a SiC epitaxial layer on a surface thereof, wherein results of irradiating the SiC epitaxial wafer with excitation light having a wavelength of 313 nm and measuring an emission intensity of photoluminescence light having a wavelength of 660 nm or more for each square measurement region of 2 mm on a side, which is obtained by dividing the surface, satisfy the following formula (1).{(IMAX−Imin)/Iaverage}×100≤40(%) (1)(IMAX: a maximum value of the emission intensity in the entire measurement region, Imin: a minimum value of the emission intensity in the entire measurement region, and Iaverage: an average value of the emission intensity of the entire measurement region)