Hybrid Silicon Wafer Segmentation for Dummy Wafer Cost Reduction
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Solution Overview
Problem
The high cost and limited availability of single-crystal silicon wafers with diameters of 400 mm or more, along with their mechanical limitations, make them unsuitable for use as dummy wafers in semiconductor manufacturing, and existing polycrystalline silicon wafers lack the necessary mechanical properties to effectively mimic single-crystal silicon for process testing.
Innovation Solution
A hybrid silicon wafer is created by integrating polycrystalline silicon and single-crystal silicon, where the polycrystalline silicon is melted around a high-purity single-crystal silicon ingot using induction heating, resulting in a wafer with improved mechanical strength and reduced production costs, capable of mimicking the properties of both materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-crystal silicon wafer with diameter of 400 mm or more is used, then the mechanical properties and testing accuracy are improved, but the production cost increases significantly
Solution Approach 1:
The wafer is divided into two functional regions: a central single-crystal silicon region (300 mm diameter) providing mechanical strength and testing accuracy, and a peripheral polycrystalline silicon region providing structural support and cost reduction. This segmentation allows each region to be optimized for its specific function while reducing overall production cost compared to a full single-crystal wafer.
Solution Approach 2:
The invention creates a composite silicon wafer combining single-crystal silicon and polycrystalline silicon in a single structure. The single-crystal region provides the necessary mechanical properties for testing, while the polycrystalline region reduces production costs. This composite approach resolves the contradiction between high mechanical properties and low production cost.
2Ease of manufacture
If a polycrystalline silicon wafer is used as a dummy wafer, then the production cost is reduced, but the mechanical strength and similarity to single-crystal silicon deteriorate
Solution Approach 1:
The wafer structure segments the functional requirements: the central single-crystal region (300 mm diameter) provides the necessary mechanical strength and similarity to single-crystal silicon for accurate testing, while the peripheral polycrystalline region provides cost reduction. This segmentation ensures that the critical testing area maintains high mechanical properties.
Solution Approach 2:
Different regions of the wafer have different material qualities optimized for their specific functions. The central region has single-crystal quality for mechanical strength and testing accuracy, while the peripheral region has polycrystalline quality for cost efficiency. This local quality differentiation resolves the contradiction between cost and mechanical strength.
3Strength
If the thickness of the silicon sintered compact is increased, then the mechanical strength is improved, but the density decreases and manufacturing complexity increases
Solution Approach 1:
The invention changes the material parameter from polycrystalline silicon to single-crystal silicon for the central region, fundamentally improving mechanical strength without relying on increased thickness. The single-crystal structure provides inherent strength that eliminates the need for thickening to achieve mechanical properties, thereby maintaining high density while improving strength.
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 hybrid silicon wafer enhances production yield and reduces costs by providing a cost-effective alternative with improved mechanical strength, allowing it to be used as a dummy wafer for semiconductor manufacturing and process testing, while maintaining the characteristics of both single-crystal and polycrystalline silicon wafers.
Implementation Method 1
integrating polycrystalline silicon and single-crystal silicon, where the polycrystalline silicon is melted around a high-purity single-crystal silicon ingot using induction heating
Data Source
AI summary
Provided is a hybrid silicon wafer made of a wafer comprised primarily of two or more types of concentric single-crystal silicon or polycrystalline silicon prepared by mutually integrating one in a molten state and another in a solid state, and having specific resistances that differ by two orders of magnitude or more. Additionally provided is a method of manufacturing a hybrid silicon wafer, wherein high specific resistance silicon or an ingot comprised primarily of silicon is disposed at a central portion or a decentered position in a crucible, a nugget or powdered silicon having a specific resistance that is lower by two orders of magnitude or more than the ingot is filled in a void part around the ingot in the crucible, the nugget or powdered silicon is selectively melted and integrated with the ingot to form a complex, and a wafer shape is cut out therefrom. The provided hybrid silicon wafer comprises the functions of both a polycrystalline silicon wafer and a single-crystal wafer, or two or more polycrystalline silicon wafers having different functions.