Pulsed Charged-Particle Beam Timing for High-Throughput Inspection
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Solution Overview
Problem
Current multiple charged-particle beam apparatuses face limitations in efficient beam current usage and maintaining individual beam quality, particularly in defect detection for shrinking IC components, leading to compromised productivity and inspection throughput.
Innovation Solution
A multi-beam apparatus that includes a deflector to form multiple charged-particle beams from a primary beam, a detector to detect signals from probe spots, and a controller to synchronize timing information for efficient beam formation and detection, utilizing a pulsed radio-frequency source and electron optical systems for high-resolution imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple charged-particle beams are used to increase inspection throughput, then productivity is improved, but beam current usage efficiency deteriorates
Solution Approach 1:
The patent employs pulsed charged-particle beams instead of continuous beams, where beams are generated in periodic pulses and directed to different probe spots in a time-multiplexed manner. This periodic operation allows the system to achieve multiple beam functionality while maintaining high beam current efficiency by concentrating the beam current into discrete pulses rather than distributing it continuously across multiple beams.
2Productivity
If multiple charged-particle beams are used to increase inspection throughput, then productivity is improved, but individual beam quality deteriorates
Solution Approach 1:
The patent segments the inspection process into discrete time intervals, with each pulse of the charged-particle beam dedicated to a specific probe spot. By using a single high-quality beam source and sequentially directing it to different locations through fast deflectors, the system maintains the high beam quality characteristics of a single beam while achieving multi-point inspection capability through time-division multiplexing.
3Measurement precision
If beam current is increased to improve imaging quality, then measurement precision is improved, but Coulomb effect and cross-talk increase
Solution Approach 1:
By operating in pulsed mode with short-duration beam pulses, the system can use high peak beam currents to achieve excellent imaging quality and signal-to-noise ratio during each pulse, while the inter-pulse intervals allow the charged particle cloud to dissipate, thereby minimizing Coulomb repulsion effects and cross-talk between adjacent probe spots.
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
The solution enhances beam usage efficiency, increases productivity, and improves inspection throughput by reducing the Coulomb effect and cross-talk issues, allowing for high-quality imaging and defect detection in IC manufacturing.
Implementation Method 1
The charged-particle source may comprise a pulsed radio-frequency source having a source frequency in a range of 100 MHz to 10 GHz
Implementation Method 2
a deflector configured to form a plurality of deflected charged-particle beams from a primary charged-particle beam
Data Source
AI summary
Apparatuses and methods for charged-particle detection may include a deflector system configured to direct charged-particle pulses, a detector having a detection element configured to detect the charged-particle pulses, and a controller having a circuitry configured to control the deflector system to direct a first and second charged-particle pulses to the detection element; obtain first and second timestamps associated with when the first charged-particle pulse is directed by the deflector system and detected by the detection element, respectively, and third and fourth timestamps associated with when the second charged-particle pulse is directed by the deflector system and detected by the detection element, respectively; and identify a first and second exiting beams based on the first and second timestamps, and the third and fourth timestamps, respectively.