Silicon Wafer Edge Defect Control for Strength
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Solution Overview
Problem
Conventional methods for maintaining semiconductor wafer strength during thermal processing are inadequate, leading to undesirable wafer distortion, substrate lattice dislocation, and breakage due to the formation of bulk micro defects, which reduces yields and causes failures.
Innovation Solution
A method is introduced to analyze the distribution of bulk micro defects at the edge of semiconductor wafers, measuring properties such as oxygen concentration and defect density, and determining a statistical profile to qualify wafers for subsequent processing, ensuring the profile falls within a predetermined range to prevent warpage and breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal processing is performed to form Bulk Micro Defects for metal contamination gathering, then metal gathering effect is improved, but wafer strength is reduced leading to wafer distortion and breakage
Solution Approach 1:
The patent segments the wafer into different regions (edge region within 10mm of outermost edge and bulk region) and applies different BMD concentration criteria to each. The edge region requires BMD concentration between 1×10^8 to 1×10^10 cm^-3 while the bulk region allows 1×10^9 to 1×10^11 cm^-3, enabling localized optimization that maintains wafer strength at edges while preserving metal gathering in bulk
Solution Approach 2:
The patent implements local quality control by specifying different BMD concentration ranges for different spatial locations within the wafer. The edge region (within 10mm of outermost edge) is assigned a lower BMD concentration range (1×10^8 to 1×10^10 cm^-3) compared to the bulk region (1×10^9 to 1×10^11 cm^-3), creating spatially varying properties that simultaneously achieve metal gathering and maintain structural integrity
2Ease of manufacture
If conventional methods control overall oxygen concentration and crystalline defect densities across entire ingot, then manufacturing simplicity is maintained, but manufacturing precision of wafer strength is insufficient
Solution Approach 1:
The patent divides the wafer into distinct measurement and control zones: an edge region within 10mm of the outermost edge and a bulk region extending to the center. This segmentation enables location-specific BMD concentration control, improving manufacturing precision for wafer strength while maintaining relatively simple process implementation through region-based criteria
Solution Approach 2:
The patent replaces conventional mechanical/chemical control methods (overall oxygen concentration control) with a physical characterization approach using BMD concentration measurement and statistical profiling. This substitution enables more precise prediction and control of wafer strength through non-destructive evaluation and data-driven qualification
Data Source
AI summary
Some embodiments relate to a silicon wafer having a disc-like silicon body. The wafer includes a central portion circumscribed by a circumferential edge region. A plurality of sampling locations, which are arranged in the circumferential edge region, have a plurality of wafer property values, respectively, which correspond to a wafer property. The plurality of wafer property values differ from one another according to a pre-determined statistical edge region profile.