Silicon Wafer Defect Region Determination via Optical Scattering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining defect regions in silicon wafers sliced from silicon single crystals manufactured by the CZ method are time-consuming and destructive, degrading product yield.
Innovation Solution
A method involving mirror-surface processing of silicon wafers to achieve a haze level of 0.06 ppm or less, using a particle counter with a 266 nm laser to measure defects sized 15 nm or less, and determining defect regions based on the measured defect density distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If heat treatment or oxidation treatment is performed to determine defect regions, then defect regions can be identified, but the inspection time becomes excessively long (approximately 20 hours for heat treatment alone)
Solution Approach 1:
The patent replaces the thermal field-based heat treatment method with an optical field-based particle counter measurement method. The particle counter uses laser light to detect and count defects on the wafer surface, eliminating the need for time-consuming heat treatment processes while maintaining the ability to identify defect regions through non-contact optical measurement.
Solution Approach 2:
The patent creates an optical copy or image of the defect regions on the wafer surface through the particle counter's optical detection system. Instead of physically altering the wafer through heat treatment, the system creates a detectable optical signature that allows virtual replication and analysis of defect characteristics without physical modification.
2Measurement precision
If destructive inspection methods are used to determine defect regions, then defect regions can be identified, but product yield is degraded
Solution Approach 1:
The patent replaces destructive mechanical or thermal inspection methods with non-contact optical measurement. The particle counter uses laser light to detect defects without touching or heating the wafer, thereby avoiding any physical alteration or damage to the product while maintaining accurate defect region identification capability.
Solution Approach 2:
The patent introduces optical fields as an intermediary between the inspection system and the wafer. The laser light acts as a mediator that can penetrate or reflect off the wafer surface to reveal defect characteristics without direct physical contact, allowing inspection without the destructive effects of traditional methods.
3Measurement precision
If conventional defect detection methods are used, then defects can be detected, but the detection sensitivity is insufficient for small defects (15 nm or less)
Solution Approach 1:
The patent changes the detection parameters of the particle counter to operate at a wavelength of 266 nm, which enhances the scattering signal from small defects. By adjusting this optical parameter, the system achieves increased sensitivity for detecting defects as small as 15 nm or less, overcoming the limitations of conventional detection methods.
Solution Approach 2:
The patent applies local quality enhancement by using wavelength-specific optical interaction (266 nm laser) that creates enhanced scattering signals specifically for small defects. This localized optical approach allows the system to selectively enhance detection capability for small defects without requiring changes to the entire measurement system.
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
Enables accurate and rapid nondestructive inspection of defect regions, specifically the V, OSF, and N regions, reducing determination time and preventing yield loss.
Implementation Method 1
a haze level of a surface thereof in haze measurement performed by a particle counter which uses a laser having a wavelength of 266 nm
Implementation Method 2
measuring the number of defects and/or a defect density distribution on the mirror-surface-processed surface of the silicon wafer by using a particle counter capable of measuring defects having a size of 15 nm or less
Data Source
AI summary
A method for determining a defect region of a silicon wafer which is sliced off from a silicon single crystal manufactured by a CZ method, the method including: (1) mirror-surface processing the silicon wafer in such a manner that a haze level of a surface thereof in haze measurement performed by a particle counter which uses a laser having a wavelength of 266 nm becomes 0.06 ppm or less; (2) measuring the number of defects and/or a defect density distribution on the mirror-surface-processed surface of the silicon wafer by using a particle counter capable of measuring defects having a size of 15 nm or less; and (3) determining the defect region of the silicon wafer from the measured number of the defects and/or defect density distribution.