EUV Photo Mask Blank Substrate with CD Compensation Layer
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Solution Overview
Problem
Current photolithography techniques, such as those using ArF lasers, struggle to transfer patterns with line widths of 40 nm or less effectively, necessitating the development of next-generation lithography methods like extreme ultraviolet (EUV) lithography to improve resolution in semiconductor fabrication.
Innovation Solution
A blank substrate for EUV photo masks is fabricated with a reflection layer of alternately stacked molybdenum and silicon layers, a buffer layer, an absorption layer, and a critical dimension (CD) compensation layer of molybdenum silicon nitride, which allows for precise pattern transfer by compensating CD variations through etching and dry etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography techniques using ArF lasers are used, then the existing photolithography process can be maintained, but the resolution for patterns with line widths of 40 nm or less cannot be achieved
Solution Approach 1:
The patent changes the fundamental parameters of the photolithography system by transitioning from conventional ArF laser light to extreme ultraviolet (EUV) light with wavelength of 13.5 nm, and from transmissive optical systems to reflective optical systems. This parameter change enables the achievement of 40 nm or less line width patterns that cannot be produced with conventional techniques.
Solution Approach 2:
The patent employs composite material structures including a reflection layer composed of alternating molybdenum and silicon layers, and an absorption layer composed of tungsten or tungsten nitride. These composite structures are specifically designed to interact with EUV light and enable precise pattern transfer at the required resolution.
2Manufacturing precision
If a reflection layer is added to the blank substrate, then EUV light reflection and pattern transfer capability are improved, but the structure and fabrication process become more complex
Solution Approach 1:
The reflection layer is segmented into multiple thin alternating layers of molybdenum and silicon, with each layer having a thickness of 1-10 nm. This segmentation creates a multilayer reflective structure that achieves high EUV reflectivity while maintaining manageable fabrication complexity through sequential deposition processes.
Solution Approach 2:
The blank substrate is pre-fabricated with the reflection layer, buffer layer, and absorption layer in a specific sequence before the actual pattern transfer process. This preliminary structuring prepares the substrate to receive and transfer patterns with high accuracy, reducing the need for complex in-process adjustments.
3Reliability
If multiple layers are stacked on the substrate, then the functional performance for EUV lithography is improved, but the fabrication process becomes more complex
Solution Approach 1:
The patent specifies precise thickness parameters for each layer (reflection layer: 1-10 nm per sub-layer, absorption layer: 1-100 nm) to optimize EUV interaction. These parameter specifications enable reliable photo mask performance while providing clear fabrication guidelines that simplify the manufacturing process.
Solution Approach 2:
The patent uses composite material combinations with specific properties: molybdenum and silicon for the reflection layer to achieve high EUV reflectivity, and tungsten or tungsten nitride for the absorption layer to provide adequate light absorption. These composite choices balance performance requirements with manufacturability using standard deposition techniques.
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 enables the formation of EUV photo masks that can accurately transfer fine patterns by compensating for critical dimension variations, enhancing the resolution and precision in semiconductor wafer patterning.
Implementation Method 1
a reflection layer on the substrate
Implementation Method 2
an absorption layer on the reflection layer opposite to the substrate
Data Source
AI summary
Blank substrates for an extreme ultraviolet (EUV) photo mask are provided. The blank substrate includes a substrate, a reflection layer on the substrate, an absorption layer on the reflection layer opposite to the substrate, and a critical dimension (CD) compensation layer on the absorption layer opposite to the reflection layer. Methods of forming an extreme ultraviolet (EUV) photo mask using the blank substrate are also provided.