Mask Fabrication Using Imprint Lithography and E-Beam Writing
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Solution Overview
Problem
Conventional mask fabrication methods are inefficient and have low yield due to complex auxiliary patterns and large design data, requiring 20 to 50 hours for completion and being sensitive to defects, critical size, and registration accuracy.
Innovation Solution
A method combining imprint lithography and electron beam writing, where a master template is used to imprint repetitive patterns on a mask substrate, followed by electron beam writing for non-repetitive patterns, allowing for faster and more efficient mask production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional E-beam or laser writing is used to fabricate masks, then patterns can be formed on mask substrates, but the fabrication time is excessively long (20 to 50 hours) and yield is low due to complex OPC patterns and large design data
Solution Approach 1:
The mask fabrication process is segmented into two distinct approaches: imprint lithography for repetitive patterns (such as memory cell array regions) and E-beam writing for non-repetitive patterns (such as peripheral logic regions). This segmentation allows each method to be applied where it is most effective, dramatically reducing overall fabrication time while maintaining pattern quality
Solution Approach 2:
A master template containing the repetitive pattern is created once and then used to imprint multiple copies of the pattern onto mask substrates. This copying approach eliminates the need to write the same complex pattern repeatedly, reducing fabrication time from tens of hours to a fraction of that time while ensuring consistent pattern quality across multiple masks
2Productivity
If conventional writing methods are used, then masks can be produced, but yield is low due to sensitivity to defects, writing mistakes, critical size control, and registration accuracy
Solution Approach 1:
The master template serves as a master copy that is repeatedly imprinted onto multiple mask substrates. This ensures consistent pattern quality and reduces writing mistakes, as the same verified pattern is copied rather than rewritten each time. The copying process significantly reduces defect sensitivity and improves production yield
Solution Approach 2:
The master template is prepared in advance with the complete repetitive pattern before mask fabrication begins. This preliminary action ensures that the pattern is fully verified and optimized before being copied to production masks, reducing the risk of defects and improving registration accuracy across multiple masks
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 significantly reduces fabrication time and improves yield by leveraging imprint lithography for repetitive patterns and electron beam writing for unique patterns, resulting in faster and more economical mask production compared to conventional methods.
Implementation Method 1
The first resist layer in the first region is imprinted with the master template to transfer the first pattern to the first resist layer to form a second pattern
Implementation Method 2
An E-beam writing process is performed on the second resist layer in the second region of the mask substrate using an E-beam
Implementation Method 3
The light-shielding material layer is etched through the first resist layer to form a third pattern
Data Source
AI summary
A method for making a mask, in which, an imprinting lithography process is employed to form a pattern in a first region of a mask substrate, and an E-beam writing process is employed to form another pattern in a second region of the mask substrate. Furthermore, these two patterns may be well stitched through an optical alignment process in an E-beam writing chamber.