Electrostatic Projection Lens Array for Multi-Beam Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current charged particle multi-beamlet systems face challenges with resolution distortion and increased complexity due to a common cross-over of beamlets, and the impracticality of individually controlling a large number of lenses for high-resolution lithography systems.
Innovation Solution
A charged particle multi-beamlet system using a common control signal for electrostatic projection lens systems to focus and demagnify a large number of beamlets without individual corrections, with apertures and lenses uniformly controlled to achieve precise focusing and demagnification, reducing system complexity and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common cross-over is used to focus and demagnify all beamlets together, then the system complexity is reduced, but resolution distortion occurs due to interactions between charged particles
Solution Approach 1:
The system divides the beam control into two stages: first, beamlets are individually focused by their own electrostatic lenses without crossing; second, a common electrostatic lens performs demagnification of all beamlets together. This segmentation allows individual beam control to avoid interaction distortions while using a common lens to reduce system complexity.
Solution Approach 2:
The patent introduces a temporal dimension to the focusing process by using sequential operation: individual electrostatic lenses focus beamlets first, then the common electrostatic lens demagnifies them. This two-stage temporal sequence resolves the contradiction by separating the individual control function from the common demagnification function.
2Manufacturing precision
If multiple lenses are provided for individually controlling each beamlet, then resolution is maintained, but system complexity and height increase
Solution Approach 1:
The patent merges the individual beam control function with the common demagnification function by having all electrostatic lenses (both individual and common) operate under a single control signal. This combining approach maintains individual beam control for resolution while reducing control system complexity.
Solution Approach 2:
The common electrostatic lens serves multiple functions: it demagnifies all beamlets simultaneously and works in conjunction with individual lenses under a unified control signal. This multi-functionality reduces the need for separate control mechanisms for each lens, thereby reducing system complexity.
3Ease of operation
If the pitch between lenses is increased to permit access for individual control signals, then lens control is simplified, but the optical column height and vacuum volume increase
Solution Approach 1:
The patent combines the control signals for all electrostatic lenses into a single common control signal. This merging of control functions eliminates the need for separate access pathways to each lens, allowing tighter lens spacing that reduces both optical column height and vacuum volume while maintaining control capability.
4Productivity
If a large number of beamlets are used to achieve high throughput, then productivity increases, but the system becomes impractical to construct with individual lens control
Solution Approach 1:
The patent implements a universal control approach where a single control signal governs all electrostatic lenses (both individual and common). This universality allows the system to scale to large numbers of beamlets for high throughput without proportionally increasing control system complexity, making construction practical.
Solution Approach 2:
The system segments the lens array into individual electrostatic lenses and a common electrostatic lens, where individual lenses handle beam-specific focusing and the common lens handles demagnification. This segmentation allows each lens type to be optimized independently while sharing a common control signal, enabling scalable construction for high beamlet counts.
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 approach enables high-resolution patterning with reduced complexity and cost, achieving focal length uniformity better than 0.05% and spatial distribution variation less than 0.2% of the nominal pitch, while maintaining a compact system design and minimizing alignment errors.
Implementation Method 1
a first plate having a first voltage V1, a second plate having a second voltage V2, and a third plate having a third voltage V3, wherein voltage differences between the plates generate electrostatic projection lens systems
Implementation Method 2
voltage differences between the plates generate electrostatic projection lens systems, each having a focal length and a demagnification factor
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5
AI summary
A charged particle multi-beamlet system for exposing a target using a plurality of beamlets. The system comprises a first plate having a plurality of holes formed in it, with a plurality of electrostatic projection lens systems formed at the location of each hole so that each electron beamlet passes through a corresponding projection lens system. The holes have sufficiently uniform placement and dimensions to enable focusing of the beamlets onto the surface of the target using a common control voltage. Preferably the electrostatic projection lens systems are controlled by a common electrical signal to focus the electron beamlets on the surface without correction of the focus or path of individual electron beamlets.