TDI Sensor Defect Ablation Protection
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Solution Overview
Problem
Current defect inspection systems in semiconductor manufacturing face challenges with defect ablation when using high-power laser beams, leading to unintended creation of additional defects due to attenuation issues with the weak leading beam, which can result in blind spots and inability to detect large defects.
Innovation Solution
A system employing a time-delay and integration (TDI) sensor to detect both the leading and main beams, allowing for separate fields of view and real-time attenuation of the main beam based on leading beam data to prevent defect ablation, using an optical arrangement with lenses and beam splitters to direct and adjust the beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a weak leading beam is used to detect defects before the main beam reaches them, then defect detection capability is improved, but the beam attenuation causes a blind time period where defects cannot be detected
Solution Approach 1:
The patent combines the detection functions of both the leading beam and main beam into a single TDI sensor. The sensor integrates signals from both beams over time, allowing defect detection from the leading beam while maintaining continuous monitoring capability during the main beam passage, thereby eliminating the blind period caused by separate sensor attenuation issues
Solution Approach 2:
The TDI sensor serves multiple functions: it detects the weak leading beam signal for early defect warning, simultaneously integrates the stronger main beam signal for confirmation, and provides continuous monitoring across the entire beam sequence. This multi-functionality resolves the contradiction by making a single sensor capable of handling both detection requirements without the limitations of dedicated separate sensors
2Quantity of substance
If a more powerful main beam is used to detect larger defects, then detection coverage is improved, but greater attenuation is necessary which further attenuates the leading beam and increases the minimum detectable defect size
Solution Approach 1:
The system uses the TDI sensor's integrated signal from the leading beam as feedback to trigger real-time attenuation of the main beam. This feedback mechanism allows the use of a high-power main beam for detecting larger defects while dynamically reducing its intensity when a defect is detected by the leading beam, preventing ablation and maintaining the ability to detect smaller defects
Solution Approach 2:
The patent dynamically changes the main beam's power parameter based on leading beam detection results. The TDI sensor's integrated output triggers attenuation control that adjusts the main beam intensity in real-time, allowing the system to switch between high-power mode for large defect detection and low-power mode for small defect protection, thus resolving the contradiction between detection coverage and minimum detectable size
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 effective detection of defects and attenuation of the main beam to prevent ablation, allowing for simultaneous mapping of leading and main beam data, thereby improving defect detection accuracy and reducing the creation of additional defects.
Implementation Method 1
The TDI sensor may be configured to receive electromagnetic radiation from the leading beam incidence and thereby generate a first accumulated charge portion. The TDI sensor may also be configured to receive electromagnetic radiation form the main beam incidence and thereby generate a second accumulated charge portion.
Implementation Method 2
The optical arrangement may be configured to selectively attenuate the main beam
Data Source
AI summary
Systems, methods, and apparatuses are disclosed herein for directing, using an optical arrangement including one or more lenses, a main beam and a leading beam toward a specimen such that the main beam is incident on the specimen at a main beam incidence and the leading beam is incident on the specimen at a leading beam incidence. The main beam intensity is greater than a leading beam intensity of the leading beam. A TDI sensor receives electromagnetic radiation from the leading beam incidence, thereby generating a first accumulated charge portion, and receives electromagnetic radiation from the main beam incidence, thereby generating a second accumulated charge portion. A processor maps the first accumulated charge portion to a first FOV, thereby yielding leading beam data, and maps the second accumulated charge portion to a second FOV, thereby yielding main beam data.