Device Substrate Bevel Region for Imprint Overlay Accuracy
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Solution Overview
Problem
The nano-imprint technique faces challenges in achieving accurate overlay between semiconductor wafers and imprint patterns due to uneven bevel surfaces and deformation at imperfect shot areas, leading to shear forces and poor flatness, which affect the die-by-die alignment and pattern formation.
Innovation Solution
A device substrate with a multilayer film structure that includes a patterning region and a bevel region with a controlled inclination angle of 10° to 90°, where the mask film is removed from the bevel region to prevent interference and ensure uniform resist thickness, reducing shear forces and improving overlay accuracy during the imprint process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the template is placed at imperfect shot areas where the bevel surface is poor in flatness, then the template can be used for imprinting, but shear force is generated on the template and semiconductor wafer during die-by-die alignment due to RLT differences
Solution Approach 1:
The patent removes the mask film specifically from the bevel region while maintaining it in the patterning region. This extraction of the mask film from the problematic bevel area eliminates the source of RLT differences and subsequent shear forces during alignment, allowing the template to be used at imperfect shot areas without generating harmful shear forces.
Solution Approach 2:
The patent applies different structures to different regions: the mask film is present in the patterning region but removed in the bevel region. This local differentiation allows the bevel region to have uniform height without mask film interference, while the patterning region maintains its mask film for proper patterning function, thus resolving the shear force issue locally without affecting overall template utilization.
2Ease of operation
If the bevel surface has poor flatness at imperfect shot areas, then the template can contact the semiconductor wafer, but the resist thickness becomes non-uniform (RLT difference) affecting overlay accuracy
Solution Approach 1:
The mask film is extracted from the bevel region to eliminate the source of height variation. By removing the mask film from the bevel area, the underlying semiconductor wafer surface is exposed, allowing the resist to form with uniform thickness across the bevel region, thereby improving overlay accuracy while maintaining template contact capability.
Solution Approach 2:
The patent creates local quality differentiation by removing the mask film only in the bevel region. This allows the bevel region to have uniform resist thickness without mask film interference, while the patterning region maintains its mask film for proper patterning, thus locally resolving the RLT difference issue without compromising overall pattern formation.
3Productivity
If the template deforms at imperfect shot areas, then the template can be used for imprinting, but the deformation amount is hard to estimate causing deterioration of overlay accuracy
Solution Approach 1:
The mask film is removed from the bevel region where template deformation occurs during imprinting. This extraction eliminates the constraint that causes unpredictable deformation, allowing the template to flex more naturally in the bevel area without generating unestimated deformation amounts, thereby improving overlay accuracy while maintaining imprint process continuity.
Solution Approach 2:
The patent applies local quality control by removing the mask film specifically from the bevel region where deformation occurs. This allows the template to have different mechanical properties in different regions: constrained by mask film in the patterning region for precise pattern transfer, and free from mask film in the bevel region to reduce unestimated deformation, thus locally resolving the overlay accuracy issue.
4Productivity
If the resist thickness varies due to bevel surface flatness issues, then the imprint process can proceed, but shear force increases as resist behaves as an elastic body
Solution Approach 1:
The mask film is extracted from the bevel region to eliminate the source of resist thickness variation. By removing the mask film from the bevel area, the resist can form with uniform thickness, preventing the resist from behaving as an elastic body with varying properties, thus eliminating the generation of shear force during alignment while allowing the imprint process to proceed.
Solution Approach 2:
The patent creates local quality differentiation by removing the mask film only in the bevel region. This allows the resist to have uniform thickness and consistent elastic properties in the bevel region without mask film interference, while the patterning region maintains its mask film for proper patterning. This local resolution prevents shear force generation in the bevel area while maintaining overall imprint process execution.
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
The controlled bevel region structure enhances the flatness and uniformity of the resist film, reducing shear forces and improving the overlay accuracy between the template and the semiconductor wafer, thereby enhancing the precision of pattern formation and reducing resist leakage during the imprint process.
Implementation Method 1
a resist is dropped on the semiconductor wafer, such that rugged patterns formed on the main face of the template on the semiconductor wafer side are filled with the resist, and then the resist is cured
Data Source
AI summary
According to one embodiment, a device substrate includes a multilayer film that includes a film constituting a device element and is disposed on a substrate. A main face on which the device element is disposed includes a patterning region on which a resist is to be applied during an imprint process, and a bevel region provided as a region from a peripheral edge portion of the patterning region to an end portion of the device substrate. The bevel region includes a region where an upper surface of the bevel region becomes lower toward the end portion of the device substrate relative to an upper surface of the patterning region. The upper surface of the bevel region has an inclination angle of 10° or more and 90° or less with respect to the upper surface of the patterning region, at a boundary between the patterning region and the bevel region.