Circular Pattern Fracturing for Semiconductor Lithography
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Solution Overview
Problem
The manufacturing of semiconductor devices with features smaller than 80 nm half pitch faces difficulties in creating accurate square patterns for contacts and vias due to corner rounding, making it impractical and expensive to produce large numbers of square patterns, especially with optical lithography.
Innovation Solution
The method involves using circular patterns on photomasks manufactured with charged particle beam writers, allowing for the formation of circular patterns on semiconductor wafers through varying charged particle beam dosage and fracturing techniques using character projection (CP) and variable shaped beam (VSB) shots, which reduce the number of shots required and improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If square patterns are used for contacts and vias in optical lithography, then the area connecting conductive material is maximized, but corner rounding occurs making it impractical and expensive to produce large numbers of patterns at 80 nm half pitch and below
Solution Approach 1:
Instead of using square patterns on the photomask that suffer from corner rounding, the invention inverts the approach by using circular patterns on the photomask. This inversion allows the formation of near-circular contacts and vias on the wafer, which can be manufactured with high precision at 80 nm half pitch and below without the corner rounding problems that plague square patterns in optical lithography
Solution Approach 2:
The invention changes the geometric parameter of the pattern shape from square to circular. This parameter change fundamentally alters how the patterns behave during optical lithography, eliminating corner rounding issues and enabling high-volume manufacturing of contacts and vias at advanced technology nodes with improved precision and productivity
2Manufacturing precision
If charged particle beam writers are used to manufacture photomasks with circular patterns, then the accuracy of contact and via formation is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The invention replaces conventional optical lithography methods with charged particle beam writers for photomask manufacturing. This substitution enables precise formation of circular patterns on the photomask, which subsequently transfer accurate near-circular contacts and vias to the wafer, improving contact and via formation accuracy despite the increased complexity of using charged particle beam technology
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 Mask Error Enhancement Factor (MEEF) and enables the efficient creation of circular patterns, improving the manufacturing process by lowering the number of shots needed and enhancing the accuracy of contact and via formation, making it more practical for smaller feature sizes.
Implementation Method 1
charged particle beam lithography is used to transfer patterns to a substrate such as a semiconductor or silicon wafer
Implementation Method 2
optical lithography is a printing process in which a lithographic mask or photomask manufactured from a reticle is used to transfer patterns to a substrate such as a semiconductor or silicon wafer
Data Source
AI summary
A method for manufacturing a semiconductor device using a photomask and optical lithography is disclosed, wherein circular patterns on the semiconductor wafer are formed by using circular patterns on the photomask, which is manufactured using a charged particle beam writer. In one embodiment, circular patterns of varying sizes have been formed on the photomask using a single character projection (CP) character, by varying the charged particle beam dosage. A method for fracturing circular patterns is also disclosed, either using circular CP characters or using VSB shots wherein the union of the plurality of VSB shots is different than the set of desired patterns.