Silicon Carbide Epitaxial Substrate Uniformity via Feedback Control
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Solution Overview
Problem
The existing methods for forming silicon carbide epitaxial layers on substrates face challenges in achieving uniform carrier concentration and thickness due to variations in rotational speed and gas flow, leading to non-uniformity in the circumferential and in-plane directions.
Innovation Solution
Implementing a gas foil system with feedback control on gas flow rate based on monitored rotational speed of the susceptor plate to stabilize the rotational speed and improve uniformity of the silicon carbide layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional epitaxial growth method is used, then silicon carbide layer can be formed, but uniformity of carrier concentration and thickness is poor due to rotational speed and gas flow variations
Solution Approach 1:
The patent implements a feedback control system where the rotational speed of the susceptor plate is monitored in real-time, and gas flow rate is automatically adjusted based on the monitored speed to maintain stable deposition conditions. This closed-loop control ensures that variations in rotational speed do not translate into variations in layer uniformity.
Solution Approach 2:
The patent dynamically adjusts gas flow rate parameters in response to rotational speed variations. By changing the gas flow parameter based on actual operational conditions, the system compensates for speed fluctuations and maintains consistent epitaxial growth quality.
2Productivity
If gas flow rate is increased to improve deposition speed, then productivity increases, but uniformity of carrier concentration deteriorates
Solution Approach 1:
The feedback control system monitors rotational speed and adjusts gas flow rate accordingly, allowing the system to operate at higher deposition speeds while maintaining uniformity. The automatic adjustment ensures that gas flow remains optimized for uniformity regardless of speed variations.
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
This approach enhances the circumferential and in-plane uniformity of carrier concentration and thickness of the silicon carbide layer, resulting in improved uniformity and performance of the silicon carbide epitaxial substrate.
Implementation Method 1
a method of forming a silicon carbide layer on a silicon carbide single-crystal substrate by epitaxial growth
Data Source
AI summary
The silicon carbide layer has a second main surface. The second main surface has a peripheral region within 5 mm from an outer edge thereof, and a central region surrounded by the peripheral region. The silicon carbide layer has a central surface layer. An average value of a carrier concentration in the central surface layer is not less than 1×1014 cm−3 and not more than 5×1016 cm−3. Circumferential uniformity of the carrier concentration is not more than 2%, and in-plane uniformity of the carrier concentration is not more than 10%. An average value of a thickness of a portion of the silicon carbide layer sandwiched between the central region and the silicon carbide single-crystal substrate is not less than 5 μm. Circumferential uniformity of the thickness is not more than 1%, and in-plane uniformity of the thickness is not more than 4%.