450 mm Silicon Wafer Growth with Dynamic Pulling Rate
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Solution Overview
Problem
Producing semiconductor wafers with a diameter of at least 450 mm that maintain uniform defect properties, particularly addressing v-defects, i-defects, BMD, and OSF, is challenging due to the increased complexity from the jump in diameter from 300 mm, with existing methods struggling to achieve defect-free or uniformly defect-profiled wafers.
Innovation Solution
A method involving pulling a single crystal with a conical section transitioning to a cylindrical section of at least 450 mm diameter and 800 mm length, with a pulling rate increase of at least 1.8 times during the transition, and utilizing a cooling power of at least 20 kW, along with side wall heat feeding and a 70 mm gap between the heat shield and melt, to produce wafers with controlled defect regions extending from center to edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter of semiconductor wafers is increased from 300 mm to 450 mm, then the productivity and capacity are improved, but the manufacturing precision and uniformity of defect properties deteriorate
Solution Approach 1:
The single crystal is divided into two distinct growth sections: a conical section for initial growth and a cylindrical section for final wafer production. This segmentation allows different growth conditions to be applied to different parts of the crystal, enabling the large-diameter cylindrical section to be grown with uniform defect properties while maintaining high productivity.
Solution Approach 2:
The pulling rate is dynamically adjusted during the growth process, being at least 1.8 times higher during the transition from conical to cylindrical section compared to the average pulling rate during cylindrical section growth. This dynamic control optimizes the defect profile uniformity in the final wafer section while maintaining efficient production.
2Productivity
If the pulling rate is increased to improve productivity, then the production efficiency is improved, but the quality and uniformity of defect properties worsen
Solution Approach 1:
The conical section is grown first as a preliminary stage with specific growth conditions, preparing the crystal structure for the subsequent cylindrical section. This preliminary action ensures that when the cylindrical section is grown at optimized pulling rates, the defect properties remain uniform throughout the final wafer section.
Solution Approach 2:
The pulling rate is dynamically controlled with at least 1.8 times higher rate during the transition phase compared to the cylindrical section growth phase. This dynamic adjustment allows high productivity while maintaining uniform defect properties in the final product.
3Manufacturing precision
If cooling power is increased to improve crystal quality, then the defect properties are improved, but the energy consumption increases
Solution Approach 1:
Cooling is applied locally and selectively during specific stages of crystal growth, particularly during the transition from conical to cylindrical section. The cooling power of at least 20 kW is applied where and when needed to control defect formation, rather than continuously throughout the entire growth process, optimizing both crystal quality and energy efficiency.
4Manufacturing precision
If the gap between heat shield and melt is increased to improve temperature distribution, then the uniformity of defect properties is improved, but the heat loss increases
Solution Approach 1:
The gap distance between the heat shield and melt surface is optimized to at least 70 mm, creating an appropriate thermal environment that ensures uniform temperature distribution during crystal growth. This parameter optimization reduces thermal gradients that cause defects while managing heat loss through the optimized gap configuration.
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 method achieves high-yield production of semiconductor wafers with reduced OSF defects, minimal radial resistivity variation, and controlled oxygen concentration, enabling their use as substrates for electronic components with improved defect profiles.
Implementation Method 1
cooling the growing single crystal with a cooling power of at least 20 kW
Implementation Method 2
feeding heat from the side wall of the crucible to the growing single crystal, wherein a gap having a height of at least 70 mm is present between a heat shield surrounding the growing single crystal and the surface of the melt
Data Source
AI summary
Silicon semiconductor wafers are produced by:pulling a single crystal with a conical section and an adjoining cylindrical section having a diameter ≧450 mm and a length of ≧800 mm from a melt in a crucible, wherein in pulling the transition from the conical section to the cylindrical section, the pulling rate is at least 1.8 times higher than the average pulling rate during the pulling of the cylindrical section;cooling the growing single crystal with a cooling power of at least 20 kW;feeding heat from the side wall of the crucible to the single crystal, wherein a gap having a height of ≧70 mm is present between a heat shield surrounding the single crystal and the melt surface.