Electron Beam Lithography Energy Correction for CD Uniformity
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Solution Overview
Problem
In electron beam and ion beam lithography, scattering of charged particles leads to indirect exposure of neighboring areas, causing non-uniformity in the layout pattern on semiconductor wafers, which affects the critical dimension (CD) uniformity and resolution.
Innovation Solution
A control system adjusts the amount of energy delivered to the resist material by analyzing the layout pattern and resist material information, calculating indirect exposure, and controlling the electron beam energy and timing to maintain the total energy at a threshold level, thereby minimizing indirect exposure and ensuring CD uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electron beam energy is increased to ensure full exposure of selected locations, then exposure completeness improves, but neighboring areas become significantly exposed due to scattering
Solution Approach 1:
The patent applies local quality by varying the electron beam energy delivery across different spatial locations based on the layout pattern. Areas with different densities of features receive different amounts of energy to compensate for scattering effects, ensuring uniform total energy (direct + indirect) across the entire pattern while preventing over-exposure in neighboring regions
2Object-generated harmful factors
If electron beam energy is reduced to prevent over-exposure of neighboring areas, then indirect exposure decreases, but selected locations may not be fully exposed
Solution Approach 1:
The patent applies preliminary action by calculating the indirect exposure contribution from each feature before actual exposure. This pre-calculation allows the system to determine the optimal direct energy delivery for each location, ensuring that the sum of direct and indirect energy equals the threshold exactly, thus preventing both under-exposure and over-exposure
3Device complexity
If uniform energy delivery is applied to all features, then process simplicity is maintained, but CD uniformity deteriorates between features in dense and dispersed areas
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the electron beam energy delivery parameters based on the local layout pattern. The system calculates and applies different energy levels to different features depending on their density and position, thereby maintaining critical dimension uniformity across the entire wafer surface
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 maintains CD uniformity between features in dense and dispersed areas, reducing the broadening of exposed regions and enhancing the resolution and accuracy of the layout pattern, suitable for applications like FinFET manufacturing.
Implementation Method 1
charged particle beams, e.g., electron beams and ion beams, have been used for high resolution lithographic resist exposure
Implementation Method 2
Some of the electrons or ions entering the resist material that is being exposed may be scattered around and into neighboring areas
Data Source
AI summary
A method of generating a layout pattern includes determining a first energy density indirectly exposed to a first feature of one or more features of a layout pattern on an energy-sensitive material when the one or more features of the layout pattern on the energy-sensitive material are directly exposed by a charged particle beam. The method also includes adjusting a second energy density exposed the first feature when the first feature is directly exposed by the charged particle beam. A total energy density of the first feature that comprises a sum of the first energy density from the indirect exposure and the second energy density from the direct exposure is maintained at about a threshold energy level to fully expose the first feature in the energy-sensitive material.