Semiconductor Ingot Cut Positioning for Oxygen Uniformity
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Solution Overview
Problem
Existing methods for producing semiconductor wafers from silicon ingots, particularly those grown by the Czochralski method, face challenges in achieving uniform oxygen concentration, leading to inconsistencies and potential device process failures due to localized oxygen concentration shifts, which are not adequately addressed by current evaluation methods.
Innovation Solution
Measuring the oxygen concentration distribution along the growth axis of the ingot to determine optimal cut positions that maximize and minimize oxygen concentrations at block ends, ensuring that wafers produced from these blocks have oxygen concentrations within a predetermined standard range, and using a system to automate this process for precise cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional evaluation methods are used to check oxygen concentration only at end faces of blocks, then the evaluation process is simple, but localized oxygen concentration shifts inside blocks are overlooked leading to potential device process failures
Solution Approach 1:
The patent measures oxygen concentration distribution along the growth axis of the ingot before cutting into blocks. This preliminary measurement allows determination of optimal cut positions that ensure blocks have oxygen concentrations within specified ranges, preventing quality issues before they occur in the final product.
Solution Approach 2:
The patent implements a feedback mechanism where oxygen concentration measurement results are used to determine cut positions. The measured distribution data feeds into the cutting decision process, creating a closed-loop system that ensures quality control based on actual measured values rather than assumptions.
2Manufacturing precision
If cut positions are determined by discretionary methods or simple information, then the cutting process is fast and simple, but oxygen concentration uniformity in produced wafers cannot be ensured
Solution Approach 1:
Oxygen concentration distribution is measured and analyzed before the cutting process to identify optimal cut positions. This preliminary analysis ensures that subsequent cutting produces blocks with guaranteed oxygen concentration ranges, achieving precision without sacrificing efficiency during the actual cutting operation.
Solution Approach 2:
The system uses the ingot's own oxygen concentration distribution data to determine its optimal cut positions. The measurement and analysis process is self-contained, using the material's inherent properties to guide its own processing without requiring external intervention or complex manual evaluation.
3Manufacturing precision
If oxygen concentration is controlled by adjusting growth parameters, then oxygen concentration can be influenced, but dispersion inside the same crystal is inevitable
Solution Approach 1:
The patent recognizes that oxygen concentration varies at different locations within the ingot and uses this local variation information to determine cut positions. By measuring and utilizing the specific oxygen concentration distribution along the growth axis, the system identifies regions that will yield blocks with desired oxygen concentrations, accepting and working with local variations rather than attempting to eliminate them entirely.
Solution Approach 2:
The patent changes the approach from trying to control oxygen concentration during growth to selecting and utilizing specific regions of the grown ingot based on measured oxygen distribution. This parameter change shifts the control strategy from process-parameter adjustment to post-growth selection and positioning.
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 ensures that semiconductor wafers are produced with oxygen concentrations within a standard range, reducing the risk of oxygen-related faults in device processes and improving the reliability of wafer production, while also enabling effective feedback for improving ingot production recipes.
Implementation Method 1
an infrared spectrometer which measures an oxygen concentration distribution in the growth axis direction of the ingot by infrared absorption
Data Source
AI summary
A method for producing semiconductor wafers, from a semiconductor ingot, wherein an oxygen concentration distribution in the growth axis direction is measured in the ingot state (F2), a position at which the oxygen concentration is maximum or minimum in a range of a predetermined length is determined as a cut position according to the measurement results (F3), the ingot is cut in a perpendicular direction to the growth axis at the cut position into blocks each having the oxygen concentrations being maximum and minimum at both ends thereof (F4), each of the blocks is sliced, and thereby semiconductor wafers are produced. Thereby, there can be provided a technique by which when semiconductor wafers are produced from a semiconductor ingot, wafers having oxygen concentration being in a predetermined standard range can be certainly produced.