Multi-Layer Source Conversion Unit for Dense Multi-Beam Inspection
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Solution Overview
Problem
Existing multi-beam inspection systems face challenges in reducing beamlet pitches while maintaining mechanical stability and electric safety, due to mechanical and electric constraints, which limits the improvement of inspection throughput in semiconductor manufacturing.
Innovation Solution
The implementation of a source conversion unit with an image-forming element array and an aberration compensator array, where micro-compensators are placed in multiple layers, with some functioning as micro-lenses and others as micro-stigmators, and the inclusion of pre-bending element arrays with electrostatic shielding to reduce electrode count and improve safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of beamlets is increased by reducing element pitches in the source conversion unit, then the inspection throughput is improved, but the mechanical stability and electric safety deteriorate due to mechanical and electric constraints
Solution Approach 1:
The patent transitions from a single-layer arrangement to a multi-layer configuration of image-forming elements and micro-compensators. By stacking elements across multiple layers (z-dimension), the system increases the number of beamlets without reducing the in-plane pitch, thereby maintaining mechanical stability and electric safety while improving inspection throughput.
Solution Approach 2:
The source conversion unit is segmented into multiple independent layers, each containing a subset of image-forming elements and micro-compensators. This segmentation allows each layer to be mechanically stable and electrically isolated, while the collective arrangement across layers generates multiple beamlets, resolving the contradiction between beamlet count and system stability.
2Quantity of substance
If a single-layer configuration with many micro-elements is used to generate multiple beamlets, then the beamlet count increases, but the mechanical stability and electric safety are compromised
Solution Approach 1:
The patent distributes micro-elements across multiple layers along the z-axis, transforming a dense single-layer configuration into a spaced multi-layer structure. This dimensional transition maintains the total number of beamlets while improving mechanical stability by reducing in-plane element density and enabling better structural support.
3Quantity of substance
If a single-layer configuration with many micro-elements is used to generate multiple beamlets, then the beamlet count increases, but electric safety deteriorates
Solution Approach 1:
By arranging micro-elements in multiple layers separated along the z-axis, the patent increases the physical distance between electrically active components in the x-y plane. This spatial separation reduces electric field interference and improves electric safety, while the multi-layer configuration collectively generates the required number of beamlets.
Solution Approach 2:
The system segments electrically active elements into multiple isolated layers, with each layer containing a subset of micro-elements. This segmentation reduces electrical interference between adjacent elements by increasing inter-element distance and enabling independent electrical control of each layer, thereby improving electric safety.
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
This configuration allows for the generation of more beamlets with enhanced electric safety, mechanical availability, and stabilization, thereby improving the throughput and resolution of semiconductor inspection systems.
Implementation Method 1
In some source conversion units, each micro-element functions as an electrostatic micro-lens that focuses one beamlet and forms one real image
Implementation Method 2
In some source conversion units, each micro-element functions as an electrostatic micro-deflector, which deflects one beamlet and forms one virtual image
Data Source
AI summary
A multi-beam apparatus for multi-beam inspection with an improved source conversion unit providing more beamlets with high electric safety, mechanical availability and mechanical stabilization has been disclosed. The source-conversion unit comprises an image-forming element array having a plurality of image-forming elements, an aberration compensator array having a plurality of micro-compensators, and a pre-bending element array with a plurality of pre-bending micro-deflectors. In each of the arrays, adjacent elements are placed in different layers, and one element may comprise two or more sub-elements placed in different layers. The sub-elements of a micro-compensator may have different functions such as micro-lens and micro-stigmators.