Photomask Dummy Pattern Layout for Uniform Lithography Wavefronts
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving high-resolution lithography processes due to inhomogeneous energy distributions on the pupil plane of lithography systems, which can lead to aberrations and affect critical dimension (CD) uniformity and process window in semiconductor device manufacturing.
Innovation Solution
The introduction of dummy patterns in the photomask layout to create a modified layout with a homogeneous energy distribution on the pupil plane, which balances pattern density and improves the reliability of manufacturing processes such as etching and CMP, by inserting dummy pattern sets in regions not occupied by main pattern sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If higher resolution lithography processes are performed to achieve smaller geometry sizes, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and determining the optimal exposure dose distribution across the wafer surface before the actual lithography process. This involves simulating the energy distribution and identifying regions that require adjusted exposure doses to achieve uniform critical dimensions, thereby preparing a corrected exposure map in advance that guides the lithography process to achieve high precision without increasing process complexity
Solution Approach 2:
The patent utilizes parameter changes by adjusting the exposure dose parameter across different regions of the wafer based on the calculated energy distribution. By varying the exposure dose locally to compensate for inhomogeneous energy distribution, the method achieves uniform critical dimensions and maintains manufacturing precision while avoiding the need for more complex processing steps
2Ease of manufacture
If inhomogeneous energy distribution is present on the pupil plane, then lithography process is simpler, but manufacturing precision deteriorates due to aberrations
Solution Approach 1:
The patent applies parameter changes by modifying the exposure dose parameter as a function of position on the wafer surface. By calculating the inhomogeneous energy distribution and applying compensating dose adjustments, the method transforms the simple but imprecise uniform exposure process into a controlled variable dose process that achieves uniform critical dimensions without adding significant process complexity
Solution Approach 2:
The patent uses copying by creating a virtual model or simulation of the lithography process to calculate the energy distribution and determine the optimal exposure dose map. This computational copy of the physical process allows for optimization of exposure parameters before actual manufacturing, achieving high precision while maintaining ease of manufacture
Data Source
AI summary
A method comprises generating an original layout having main pattern sets; simulating a first energy distribution of the original layout on a pupil plane of a lithography system, wherein the first energy distribution has a first wavefront; generating a first modified layout by inserting dummy pattern sets in regions of the original layout that are not occupied by the main pattern sets; simulating a second energy distribution of the first modified layout on a pupil plane of a lithography system; determining whether a second wavefront of the simulated second energy distribution is more homogeneous than the first wavefront of the first energy distribution; and performing a first lithography process using a first photomask having the first modified layout in response to second wavefront of the simulated second energy distribution being determined as more homogeneous than the first wavefront of the first energy distribution.