EUV Mask Venting Features Prevent Bubbling
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Solution Overview
Problem
Extreme ultraviolet (EUV) reflective masks used in semiconductor manufacturing experience defects such as bubbling and delamination due to vaporization of compounds in pattern-free areas, leading to reduced mask quality and lifetime.
Innovation Solution
Incorporating venting features in the EUV absorber layer to provide outlets for vaporized compounds, preventing bubbling and delamination by inserting openings in specific areas of the mask design, which can be either non-printing or printing features depending on their location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous span of EUV absorber layer is used in pattern-free areas, then the mask structure is simple and complete, but bubbling and delamination occur due to vaporized compounds trapped in the absorber layer
Solution Approach 1:
The continuous absorber layer in pattern-free areas is segmented by introducing venting features (openings) that divide the absorber layer into separate regions. This segmentation allows vaporized compounds to escape through the openings, preventing bubbling and delamination while maintaining the overall mask structure.
Solution Approach 2:
Venting features are introduced by removing portions of the absorber layer in pattern-free areas, creating openings that extract and allow the escape of vaporized compounds. This extraction prevents the accumulation of harmful vapors that would otherwise cause defects in the mask.
2Duration of action of stationary object
If venting features are added to the EUV absorber layer, then mask reliability and lifetime are improved, but the mask structure becomes more complex
Solution Approach 1:
Venting features are introduced only in pattern-free areas of the mask where they are needed for vapor escape, while the patterned areas maintain their original continuous absorber layer structure. This localized modification extends mask lifetime without unnecessarily complicating the entire mask structure.
3Reliability
If pattern-free areas are eliminated from the mask design, then bubbling and delamination are prevented, but the manufacturing complexity and cost increase
Solution Approach 1:
Venting features are pre-introduced into the absorber layer during mask fabrication in pattern-free areas. This preliminary action ensures that vapor escape paths are established before the mask is put into service, preventing future bubbling and delamination issues without requiring complete redesign of the mask structure.
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 introduction of venting features significantly reduces defects and extends the lifetime of EUV reflective masks by allowing vaporized compounds to escape, thereby maintaining mask quality and performance.
Implementation Method 1
The EUV absorber layer is patterned to selectively expose the underlying reflective layer such that incident EUV radiation is absorbed by the remaining EUV absorber layer
Implementation Method 2
a reflective mask includes reflective and non-reflective regions. During exposure, the light reflected off the mask is used to form the pattern on the substrate
Implementation Method 3
Exposure to EUV radiation may cause bubbling or even delamination in the pattern-free areas
Data Source
AI summary
A photolithographic mask assembly according to the present disclosure accompanies a photolithographic mask. The photolithographic mask includes a capping layer over a substrate and an absorber layer disposed over the capping layer. The absorber layer includes a first main feature area, a second main feature area, and a venting feature area disposed between the first main feature area and the second main feature area. The venting feature area includes a plurality of venting features.