Semiconductor Wafer Profile Analysis for Slice-Cutting Direction Detection
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Solution Overview
Problem
Existing methods fail to effectively identify the slice-cutting direction of a wire saw, which is crucial for detecting peculiar wavy shapes on semiconductor wafers that can lead to residual film abnormalities and device fabrication failures.
Innovation Solution
A method involving profile measurement data acquisition using a wafer-profile measurement system, followed by extraction of diameter-direction profile data, differentiation to obtain differential profiles, and comparison to determine the slice-cutting direction, allowing for precise evaluation and screening of wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If nanotopography measurement is used to evaluate wafer surface, then measurement of minute asperity is achieved, but slice-cutting direction cannot be identified
Solution Approach 1:
The patent segments the wafer surface measurement into two distinct components: nanotopography (minute asperity) and macroscopic profile (diameter-direction shape). By separating these measurement scales and analyzing them independently, the system can identify slice-cutting direction from macroscopic profile while maintaining nanotopography measurement precision for quality evaluation.
Solution Approach 2:
The patent transitions from two-dimensional nanotopography surface mapping to three-dimensional macroscopic profile measurement in the thickness direction. By adding the vertical dimension (thickness direction) to the measurement, the system can detect diameter-direction shape variations that reveal slice-cutting direction information lost in planar nanotopography measurements.
2Manufacturing precision
If conventional wafer shape evaluation is used, then peripheral shape is evaluated, but slice-cutting direction cannot be identified
Solution Approach 1:
The patent extracts the slice-cutting direction information from the overall wafer shape data by specifically analyzing diameter-direction profile variations. Instead of evaluating all shape parameters equally, the system isolates and focuses on the diameter-direction measurements that contain slice-cutting direction signatures, separating this critical information from other shape characteristics.
3Reliability
If slice-cutting direction identification method is established, then peculiar wavy shape detection is improved, but measurement and evaluation complexity increases
Solution Approach 1:
The patent performs preliminary identification of slice-cutting direction before conducting detailed wavy shape detection and evaluation. By first determining the slice-cutting direction from macroscopic profile measurements, the system can then orient subsequent nanotopography measurements and analysis along the correct directional axes, simplifying the overall detection process and improving reliability without requiring complex real-time multi-parameter analysis.
Data Source
AI summary
An evaluation method including steps of: acquiring profile measurement data on an entire surface in a thickness direction of a mirror-polished wafer; identifying a slice-cutting direction by performing first-order or second-order differentiation on diameter-direction profile measurement data on the wafer to acquire differential profiles at predetermined rotation angles and pitches, and comparing the acquired differential profiles; acquiring x-y grid data by performing first-order or second-order differentiation on profile measurement data at a predetermined pitch in a y-direction at a predetermined interval in an x-direction perpendicular to the y-direction, which is the identified slice-cutting direction; acquiring, from the x-y grid data, a maximum derivative value in an intermediate region including the wafer center in the y-direction and a maximum derivative value in upper-end-side and lower-end-side regions located outside the intermediate region; and judging failure incidence possibility in a device fabrication process based on the maximum derivative values.