Local Focus Point Selection for Hotspot-Aware E-Beam Inspection
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Solution Overview
Problem
Existing methods for determining local focus points (LFPs) in charged particle beam systems are time-consuming, unreliable, and often result in inaccurate or damaging focus adjustments due to manual selection and fixed LFPs, which are not robust and do not account for varying sample processing stages and hotspots.
Innovation Solution
A system and method for determining LFPs through process simulations of resist pattern designs, identifying hotspots, and calculating focus-related characteristics to locate high-quality LFPs prior to or during inspection, using a multi-beam electron beam inspection system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual selection of local focus points is used, then the system can determine LFPs with some degree of accuracy, but the inspection process becomes time-consuming and operator-dependent
Solution Approach 1:
The system automatically determines local focus points by analyzing hotspot locations and focus-related characteristics without requiring manual operator selection. The controller autonomously identifies candidate LFPs based on process simulations and hotspot data, eliminating operator dependency and reducing inspection time while maintaining accuracy
Solution Approach 2:
The system performs process simulations and identifies hotspots and focus-related characteristics before the actual inspection begins. This preliminary analysis prepares the optimal LFP locations in advance, so that during inspection, the system can directly use pre-determined high-quality focus points without time-consuming manual selection
2Ease of operation
If fixed local focus points are used, then the system simplifies the focusing process, but the LFPs are not robust and do not account for varying sample processing stages and hotspots
Solution Approach 1:
Instead of using uniform fixed LFPs across all samples, the system determines location-specific LFPs based on local hotspot characteristics and focus-related properties of each resist pattern design. Each LFP is optimized for its specific location and processing stage, making the focusing process both simple to execute and highly reliable for varying sample conditions
Solution Approach 2:
The system transitions from static fixed LFPs to dynamic LFPs that adapt to different resist pattern designs, hotspots, and processing stages. The controller adjusts LFP locations based on process simulations and identified characteristics, enabling the system to maintain robustness across varying sample conditions while keeping the operation simple through automated adaptation
3Stability of the object's composition
If traditional focus adjustment methods are used, then the system can maintain focus, but inaccurate or damaging focus adjustments may occur due to lack of hotspot consideration
Solution Approach 1:
The system performs process simulations to identify hotspots and determines optimal LFP locations before inspection begins. By pre-identifying areas prone to focus-related defects and selecting LFPs away from these hotspots, the system prevents potential sample damage and focus instability issues before they occur during actual inspection
Solution Approach 2:
The system uses focus-related characteristics derived from process simulations and hotspot analysis to guide focus adjustments. The controller continuously monitors and adjusts focus based on these pre-determined characteristics, ensuring stable focus while avoiding locations that could cause sample damage, thereby creating a feedback-driven protective mechanism
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 efficient and accurate determination of robust LFPs, reducing inspection time and minimizing damage to samples by focusing on high-quality focus points that are sensitive to focus adjustments, thereby improving inspection accuracy and yield.
Implementation Method 1
The primary electrons interact with the wafer and may be backscattered or may cause the wafer to emit secondary electrons
Implementation Method 2
The primary electrons interact with the wafer and may be backscattered or may cause the wafer to emit secondary electrons
Implementation Method 3
electrons of a single primary electron beam, or electrons of a plurality of primary electron beams, can be focused at locations of interest of a wafer under inspection
Data Source
AI summary
Apparatuses, systems, and methods for determining local focus points (LFPs) on a sample are provided. In some embodiments, a controller including circuitry may be configured to cause a system to perform selecting a first plurality of resist pattern designs; performing a plurality of process simulations using the first plurality of resist pattern designs; identifying a hotspot that corresponds to a resist pattern design based on results of the performed process simulations; determining focus-related characteristics that correspond to a plurality of candidate resist patterns, wherein the plurality of candidate resist pattern designs is a subset of the first plurality of resist pattern designs and the subset is selected based on the identified hotspot; and determining locations of a plurality of LFPs based on the generated focus-related characteristics.