E-Beam Pattern Drawing System Fogging Effect Correction
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Solution Overview
Problem
Existing methods for correcting dimensional changes in semiconductor photomask manufacturing, such as the proximity effect and fogging effect, require extensive calculation times due to the wide range of the fogging effect, leading to increased correction errors when both effects are addressed simultaneously.
Innovation Solution
A pattern drawing system that calculates a backward scattering coefficient based on an approximating function for the global pattern coating rate, allowing for precise adjustment of beam irradiation quantities to minimize dimensional changes, using an electrically charged beam irradiating mechanism and control section to draw patterns on a photomask substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the irradiation quantity correcting method is used to restrict dimensional changes caused by the fogging effect, then the dimensional precision is improved, but the calculation time increases tremendously due to the large region required for calculating pattern coating rate
Solution Approach 1:
The patent divides the fogging effect correction into two stages: (1) coarse correction using partition-based irradiation quantity adjustment over a wide region, and (2) fine correction using proximity effect correction over a narrow region. This segmentation allows the system to address the large-range fogging effect without requiring calculation over the entire drawing region, thus reducing calculation time while maintaining dimensional precision.
Solution Approach 2:
The patent applies partial correction by focusing calculation resources on specific partitions rather than the entire drawing region. By calculating pattern coating rates only within selected partitions and applying correction selectively, the system achieves sufficient dimensional precision without the tremendous calculation time required for full-region correction.
2Manufacturing precision
If both proximity effect correction and fogging effect correction are applied simultaneously, then the dimensional precision is improved, but the correction error increases due to synergetic effects
Solution Approach 1:
The patent segments the correction process into distinct stages: first applying partition-based fogging effect correction, then applying proximity effect correction. By separating these corrections rather than applying them simultaneously, the system avoids the synergetic effects that amplify correction errors, while still achieving comprehensive dimensional control.
Solution Approach 2:
The patent performs fogging effect correction as a preliminary step before proximity effect correction. This preliminary action prepares the irradiation quantity distribution to account for wide-range effects, allowing subsequent proximity effect correction to focus on narrow-range dimensional adjustments without the interference of simultaneous synergetic effects.
3Loss of time
If the partition-based correction method is used to restrict fogging effect, then the calculation time is reduced, but the correction precision for narrow-range proximity effect deteriorates
Solution Approach 1:
The patent segments correction into two complementary approaches: partition-based correction for wide-range fogging effects (reducing calculation time) and position-based proximity effect correction for narrow-range precision (maintaining correction accuracy). Each segment addresses specific spatial scales, allowing the system to benefit from both speed and precision.
Solution Approach 2:
The patent merges two different correction methodologies: partition-based irradiation quantity adjustment for fogging effect and position-based irradiation quantity adjustment for proximity effect. By combining these approaches in sequence, the system achieves both reduced calculation time and maintained correction precision.
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 significantly reduces calculation time and correction errors by considering the global coating rate, effectively restricting both proximity and fogging effects, thereby improving dimensional precision in semiconductor device manufacturing.
Implementation Method 1
a resist film applied on a mask substrate is irradiated with electron beams or electrically charged beams, and a mask pattern is graphically drawn on the resist film
Implementation Method 2
The electron beams incident to the resist film at the time of this drawing transmit through this resist film, and are reflected from the mask substrate. Thus, the incident electrons are scattered.
Implementation Method 3
By these scattered electrons, the resist film is exposed again. The exposure by the scattered electrons covers a resist film beyond the contour of a preset drawing range using the incident electron beams and has an effect such as dimensional change on a pattern formed at the periphery of a drawn pattern. This phenomenon is known as a 'proximity effect'.
Implementation Method 4
there is a 'fogging effect' that the electron beams reflected from a mask substrate are reflected again on a structure of a drawing device such as an objective lens, and the resist film is exposed again. The fogging effect caused by the reflected electron beams cover a wider range than that in the proximity effect.
Data Source
AI summary
A pattern drawing system includes a beam irradiating mechanism which irradiates electrically charged beams on a film to be drawn, a coefficient calculating section which calculates a backward scattering coefficient relevant to a drawing pattern in the film to be drawn, based on an approximating function for approximating a relationship between a global coating rate of the drawing pattern and a backward scattering coefficient of the electrically charged beams in the film to be drawn, and based on the global coating rate of the drawing pattern, and an irradiation quantity calculating section which calculates an electrically charged beam irradiation quantity used for drawing the pattern using an electrically charged beams irradiating mechanism, based on the backward scattering coefficient of the pattern.