EUV Mask Patterning via Pre-Mask Segmentation
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Solution Overview
Problem
Current extreme ultraviolet lithography (EUVL) tools face challenges in achieving the required precision for the 7-nm technology node due to high mask error enhancement factor (MEEF) values, especially for horizontal lines, which makes it difficult to produce devices with minimum pitches of 22 nm, exceeding the capability of state-of-the-art exposure tools.
Innovation Solution
The use of EUV scanners with a 4× reduction projection printing and the creation of EUV masks with a reflective multilayer coating and an absorber layer, where pre-masks are generated using electron beam writers and then patterned using EUV scanners to achieve the necessary precision, reducing the overall MEEF and enabling the production of features with dimensions as small as 11 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lithography is used, then existing infrastructure can be maintained, but manufacturing precision deteriorates at 28-nm node and below
Solution Approach 1:
The patent introduces an intermediary EUV mask making process that uses electron beam writers to create pre-masks, which are then transferred to final masks using EUV scanners. This intermediary step enables precise pattern transfer at 7-nm node while managing the complexity of transitioning from conventional optical lithography to EUV lithography.
2Manufacturing precision
If EUV lithography with 4× reduction projection printing is used, then manufacturing precision improves for 7-nm node, but mask error enhancement factor increases for horizontal lines
Solution Approach 1:
The patent applies preliminary action by using electron beam writers to create highly precise pre-masks before the EUV scanning process. This pre-patterning step ensures that the subsequent EUV exposure with 4× reduction projection printing starts from an already high-precision master pattern, compensating for the MEEF challenge and maintaining pattern fidelity.
3Ease of manufacture
If direct electron beam maskless lithography is used, then mask cost is reduced, but manufacturing precision deteriorates for very fine features at advanced technology nodes
Solution Approach 1:
The patent segments the mask-making process into two distinct stages: (1) electron beam writing to create pre-masks with relaxed pitch requirements, and (2) EUV scanning with 4× reduction to produce final masks with fine features. This segmentation allows each stage to operate in its optimal performance range, achieving both cost efficiency and high 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 allows for the production of semiconductor devices with critical dimensions within the ±1 nm tolerance requirement for the 7-nm technology node, ensuring that the EUVL process can meet the specifications for advanced technology nodes like N07, N14, and N10, while reducing production costs and infrastructure changes.
Implementation Method 1
extreme ultraviolet lithography (EUVL) are leading candidates. Although it is claimed that MEBDW does not require a mask, MEBDW requires delineating 1× feature sizes directly on the substrates, which could be quite challenging for advanced technology nodes with very fine features. EUVL uses a much shorter wavelength, such as about 13.5 nm, which is about 1/10 the effective wavelength of ArF immersion lithography, to enhance resolution.
Implementation Method 2
During a patterning process, the circuit design is written onto the mask, for example, by exposing portions of the resist to an electron beam or ultraviolet light
Implementation Method 3
The EUV mask has a number of copies of the pattern on the EUV pre-mask
Data Source
AI summary
The embodiments described provide mechanisms for patterning features for advanced technology nodes with extreme ultraviolet lithography (EUVL) tools. One or more EUV pre-masks are generated by using a mask writer to form an EUV mask with an EUV scanner. The wafers are then patterned by using the EUV mask. The demagnification factor of the EUV scanner(s) used in preparing the EUV mask by exposing the EUV pre-mask(s) enable the wafers prepared by such mechanisms to meet the requirements for the advanced technology nodes.