Selective Substrate Heating for Defect Differentiation in Vacuum
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Solution Overview
Problem
Existing methods, such as using scanning electron microscopes, struggle to distinguish between junction defects and short defects on silicon wafers and are hindered by ion oscillation induced when the wafers are heated, affecting the accuracy and feasibility of defect inspection.
Innovation Solution
A method and system that heat only a portion of a substrate in a vacuum environment using a light beam, allowing for defect identification by a charged particle beam, where the light source projects a focused beam on specific defects to differentiate between junction and short defects based on temperature sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light beam is projected on the substrate to heat it for defect identification, then defect differentiation accuracy is improved, but ion oscillation is induced which interferes with the inspection process
Solution Approach 1:
The patent divides the substrate heating process into two distinct stages: first heating only the defective portion of the substrate to minimize ion oscillation, then heating the entire substrate for comprehensive inspection. This segmentation allows defect identification while reducing interference with the charged particle beam inspection process
Solution Approach 2:
The patent performs preliminary heating of the defective portion before conducting the full substrate inspection. By pre-heating only the area containing defects, the system identifies defect locations and characteristics without inducing widespread ion oscillation that would interfere with the inspection process
2Measurement precision
If the whole substrate is heated for defect identification, then comprehensive defect detection is improved, but ion oscillation increases making inspection difficult
Solution Approach 1:
The patent segments the heating process into selective heating of defective portions followed by comprehensive substrate heating. This approach maintains defect detection capability while managing ion oscillation levels to preserve inspection feasibility
Solution Approach 2:
The patent employs periodic heating cycles where the substrate is heated in controlled intervals - first the defective portion, then the entire substrate. This periodic action allows the system to perform comprehensive inspection while managing thermal effects and ion oscillation to maintain operational feasibility
3Measurement precision
If SEM is used to inspect silicon wafer, then leakage defects can be detected, but junction defects cannot be distinguished from short defects
Solution Approach 1:
The patent changes the physical parameter of temperature by heating the substrate to different extents (first locally, then comprehensively). This temperature variation causes different defect types to exhibit distinct electrical characteristics, enabling the SEM to differentiate between junction defects and short defects that were previously indistinguishable
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 precise identification of defects on silicon wafers by selectively heating a portion of the substrate in a vacuum, reducing ion oscillation interference and improving defect differentiation accuracy.
Implementation Method 1
a light beam emitted from a light source is projected on only a portion of the substrate, such that the portion is significantly heated
Implementation Method 2
a substrate is examined by using a charged particle beam in a vacuum environment, wherein at least one defect is located on the substrate
Data Source
AI summary
A method for heating a substrate in a vacuum environment and a system therefor is provided. The system includes a chamber capable of holding the substrate located in the vacuum environment and a light source capable of projecting a light beam only on a portion of the substrate. The method includes the following steps. First, the substrate is placed in the vacuumed chamber. Thereafter, the light beam emitted from the light source is projected on the portion of the substrate, such that the portion is significantly heated before whole the substrate is heated. When the light beam is a charged particle beam projected by a charged particle beam assembly and projected on defects located on the substrate, the defects are capable of being identified by an examination result provided by an examination assembly after termination of light beam projection.