Mask Pattern Formation With Sacrificial Film Metal Removal
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Solution Overview
Problem
In EUV lithography, metal components from metal-containing resist films often adhere to the bottom of patterns, forming compounds that inhibit etching and cause defects like bridges, as they are strongly bonded and difficult to remove with acids.
Innovation Solution
A method involving a sacrificial film that is insoluble in the developing solution, where the sacrificial film is formed under the resist film, and its surface layer is removed either by heating or UV irradiation to eliminate remaining metal components, preventing them from adhering to the pattern bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal-containing resist film is used in EUV lithography to achieve higher contrast patterning, then imaging contrast is improved, but metal components remain adhered to the pattern bottom causing etching defects
Solution Approach 1:
A sacrificial film is introduced as an intermediary layer between the substrate and the metal-containing resist film. This sacrificial film serves as a mediator that captures and holds metal components during the patterning process, preventing them from adhering to the final pattern bottom. The sacrificial film is specifically designed to be soluble in the developing solution, allowing it to be removed along with metal components after serving its protective function.
Solution Approach 2:
The sacrificial film is designed as a temporary, disposable component that is intentionally removed after serving its purpose. It is a low-cost, single-use element that protects against metal adhesion during the critical patterning steps, then is completely removed in the developing process along with the metal components it captured, leaving no harmful residues on the final pattern.
2Ease of manufacture
If strong acids are used to remove metal components from the pattern bottom, then metal removal capability is improved, but the pattern itself may be damaged
Solution Approach 1:
The sacrificial film performs the preliminary action of capturing and isolating metal components during the resist development process. By pre-capturing metal components in the sacrificial film matrix, the need for subsequent aggressive acid treatments is eliminated. The metal components are already separated and contained in the sacrificial film, which is then removed in a gentle developing process that does not damage the pattern.
Solution Approach 2:
The patent replaces the mechanical/chemical aggressive acid etching system with a gentler chemical dissolution system. Instead of using strong acids that can damage the pattern to remove metal components, the invention uses the developing solution to dissolve the sacrificial film that has already captured the metal components. This substitution of the removal mechanism eliminates pattern damage while achieving complete metal component removal.
3Ease of manufacture
If the sacrificial film is made soluble in the developing solution to enable removal of metal components, then metal component removal is improved, but the sacrificial film cannot serve as an effective etching mask
Solution Approach 1:
The patent segments the functionality into two distinct phases: The sacrificial film serves as a temporary etching mask during the etching process, then is segmented (separated) from the pattern bottom through dissolution in the developing solution. This segmentation allows the sacrificial film to fulfill its mask function when needed, then be completely removed to enable metal component elimination without compromising either function.
Solution Approach 2:
The sacrificial film performs the preliminary action of serving as an etching mask before being removed. During the etching step, the sacrificial film is in place and functional, protecting the areas that should not be etched. After this preliminary protective action is complete, the sacrificial film is then removed in the developing solution to allow subsequent metal component removal, ensuring both mask functionality and metal removal are achieved sequentially.
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 effectively suppresses metal component adhesion at the pattern bottom, reducing etching defects by ensuring the metal components are removed along with the sacrificial film, thereby enhancing the quality of the circuit patterns formed.
Implementation Method 1
removing at least a surface layer of the sacrificial film facing a bottom of the resist pattern by heating the substrate
Implementation Method 2
cross-linking the resist film by irradiating the surface of the substrate with ultraviolet rays
Data Source
AI summary
A technique for suppressing a metal component from remaining at a bottom of a mask pattern when the mask pattern is formed using a metal-containing resist film. A developable anti reflection film 103 is previously formed below a resist film 104. Further, after exposing and developing the wafer W, TMAH is supplied to the wafer W to remove a surface of the anti-reflection film 103 facing a bottom of the recess pattern 110 of the resist film 104. Therefore, the metal component 105 can be suppressed from remaining at the bottom of the recess pattern 110. Therefore, when the SiO2 film 102 is subsequently etched using the pattern of the resist film 104, the etching is not hindered, so that defects such as bridges can be suppressed.