Semiconductor Shot Grouping for LER Reduction
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Solution Overview
Problem
In semiconductor device manufacturing, existing methods face challenges in reducing the overall number of shots required for pattern formation and line edge roughness (LER) in semiconductor devices, which can lead to inaccuracies and increased production time due to excessive radiation and heat damage.
Innovation Solution
A method is introduced where shots are classified into first and second pass shot sets based on size and beam dosage, with a time interval between exposures to avoid overlapping and heat damage, and organized into pass-based or scanning-based patterns to optimize shot placement and reduce LER.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of shots is increased to improve pattern coverage, then manufacturing completeness is improved, but production time and heat damage increase
Solution Approach 1:
The patent divides the pattern formation process into multiple passes, where each pass writes a subset of shots. The shot set is segmented into first pass shots and second pass shots, allowing systematic coverage of the entire pattern while maintaining control over the number of shots executed in each pass, thereby balancing completeness with production time efficiency.
Solution Approach 2:
The patent implements periodic action by alternating between first pass exposure and second pass exposure with a time interval in between. This periodic writing approach allows the reticle to cool down between passes, reducing cumulative heat damage while ensuring complete pattern coverage through multiple cycles of shot execution.
2Manufacturing precision
If beam dosage is increased to improve pattern definition, then manufacturing precision is improved, but heat damage to reticle increases
Solution Approach 1:
The patent applies periodic action by introducing a time interval between first pass exposure and second pass exposure. This pause allows the reticle to dissipate heat accumulated during the first pass, preventing excessive heat damage while maintaining sufficient beam dosage for accurate pattern definition. The periodic writing cycle balances precision requirements with thermal management.
Solution Approach 2:
The patent segments the total beam dosage into two separate passes, distributing the cumulative dose across first pass shots and second pass shots. This segmentation prevents concentration of excessive energy in a single pass, reducing peak heat exposure to the reticle while achieving the required pattern definition through cumulative dosing.
3Productivity
If shots are written continuously to improve productivity, then production speed is improved, but line edge roughness increases
Solution Approach 1:
The patent segments the shot writing process into distinct first pass and second pass sequences, with each pass handling specific subsets of shots. This segmentation allows systematic alternation between passes, preventing continuous writing-induced line edge roughness while maintaining high productivity through efficient pass organization and overlapping shot strategies.
Solution Approach 2:
The patent implements periodic action by alternating between first pass exposure and second pass exposure with intervals in between. This periodic writing pattern prevents the continuous beam exposure that causes line edge roughness, while the structured alternation maintains productivity by optimizing shot placement and reducing redundant exposures.
4Object-affected harmful factors
If multiple passes are used to reduce heat damage, then reticle protection is improved, but process complexity increases
Solution Approach 1:
The patent segments the exposure process into first pass exposure and second pass exposure, each handling specific shot sets. This segmentation simplifies the management of heat damage by clearly defining separate operational phases with a simple time interval between them, making the multi-pass process easier to control and implement compared to more complex alternating patterns.
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 reduces the number of shots needed, minimizes line edge roughness, and decreases the time required for pattern formation by spacing exposures and optimizing beam dosage, thereby improving accuracy and reducing heat damage to the reticle.
Implementation Method 1
A first pass exposure of radiating an electron beam can be performed to a reticle for the first pass shot set and a second pass exposure of radiating the electron beam to the reticle can be performed for the second pass shot set
Data Source
AI summary
A method of forming a semiconductor device can include determining a shot set including a plurality of shots, based on a final pattern used to form a mask. Shots included in the plurality shots can be classified as being in a first pass shot set or in a second pass shot set, where each can include a plurality of non-directly neighboring shots. A first pass exposure can be performed to radiate a reticle to provide the first pass shot set and a second pass exposure can be performed to radiate the reticle to provide the second pass shot set.