Dark-Periphery Mask Fabrication via Dual Photoresist Segmentation
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Solution Overview
Problem
Conventional processes for manufacturing phase shift masks are inefficient and prone to quality issues, especially when producing features smaller than 0.18 microns, as they require longer processing times and are cumbersome, leading to challenges in achieving high circuit density and complexity in integrated circuits.
Innovation Solution
A method involving a sandwich structure of a substrate with an opaque film, a negative photoresist layer, a stop layer, and a positive photoresist layer, where the positive resist is patterned to form window openings, exposing the negative photoresist while protecting it with the stop layer, and then developing and removing layers to create a patterned mask, which can be used for manufacturing integrated circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional negative photoresist processes are used for manufacturing masks with feature sizes less than 0.18 microns, then manufacturing precision is improved, but processing time increases significantly and productivity decreases
Solution Approach 1:
The photoresist system is segmented into two distinct layers: a positive photoresist layer for initial patterning and a negative photoresist layer for final mask formation. This segmentation allows each layer to perform its optimal function - the positive resist enables rapid patterning while the negative resist provides precise feature definition, thereby resolving the contradiction between precision and productivity
Solution Approach 2:
The positive photoresist layer performs preliminary patterning actions by forming a first pattern that defines the mask regions. This preliminary action creates a structured foundation that guides subsequent processing, allowing the negative photoresist to be applied more efficiently and reducing overall processing time while maintaining precision
2Manufacturing precision
If conventional negative photoresist processes are used for manufacturing masks with feature sizes less than 0.18 microns, then manufacturing precision is improved, but process complexity increases and ease of manufacture deteriorates
Solution Approach 1:
By dividing the photoresist system into positive and negative layers with distinct functions, each layer can be optimized independently for its specific role. The positive resist handles preliminary patterning with simpler processes, while the negative resist focuses on precise feature formation, making the overall manufacturing process more manageable and easier to execute with high precision
Solution Approach 2:
The positive photoresist layer acts as an intermediary that facilitates the patterning process by creating an initial structure. This intermediary layer simplifies the overall process by breaking down the complex task of direct high-precision patterning into more manageable steps, making the manufacturing process easier to control while achieving the required precision
3Ease of manufacture
If conventional single-layer photoresist processes are used, then process simplicity is maintained, but manufacturing precision for sub-0.18 micron features deteriorates
Solution Approach 1:
The dual-layer photoresist structure segments the patterning function into two specialized layers. The positive photoresist layer handles the preliminary patterning with simpler processes, while the negative photoresist layer provides the precise sub-0.18 micron feature definition. This segmentation allows the system to maintain relative process simplicity while achieving high manufacturing precision that would be difficult with a single layer
4Manufacturing precision
If exposure time for positive photoresist is increased to ensure proper patterning, then manufacturing precision is improved, but processing time increases and productivity decreases
Solution Approach 1:
The positive photoresist layer performs a partial patterning function rather than the complete patterning task. By exposing and developing only the positive resist first to create preliminary patterns, the process achieves sufficient pattern accuracy for the mask regions without requiring excessive exposure time, as the final precision is refined by the negative photoresist layer in subsequent steps
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 method provides a more efficient and accurate process for producing phase shift masks with higher device yields and compatibility with conventional technology, enabling the production of advanced integrated circuits with increased complexity and density without substantial equipment modifications.
Implementation Method 1
patterning the positive photoresist layer
Implementation Method 2
patterning the exposed portion of the negative photoresist layer
Data Source
AI summary
A photo mask blank structure for transferring a mask to an integrated circuit includes a transparent substrate, which has a surface region. The photo mask structure further includes an opaque film overlying the surface region, a negative photoresist material overlying the opaque film, a stop layer overlying the negative photoresist material, and a positive photoresist material overlying the stop layer. The positive photoresist material includes a first opening pattern, and the stop layer includes a second opening pattern that is associated with the first opening pattern of the positive photoresist material. The negative photoresist material includes a third opening pattern that is associated with the first and second opening patterns. The stop layer provides a separation between the negative photoresist material and the positive photoresist material.