Mask Cut Process for IC Conductive Features
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Solution Overview
Problem
As semiconductor integrated circuit (IC) geometry sizes decrease, existing metallization processes face challenges in achieving the necessary resolution and fidelity for forming conductive features, particularly due to issues like the photoresist island effect and line end corner rounding, which affect the formation of sharp and uniform conductive features.
Innovation Solution
The method involves categorizing conductive features into different masks, using a single mask for joined features and a cut mask to separate them, allowing for the use of larger mask features that improve resolution and uniformity, and employing multiple photoresist and hard mask layers to enhance etching and conductive material deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If geometry size is decreased to increase production efficiency, then productivity is improved, but manufacturing precision deteriorates due to difficulties in controlling conductive feature formation
Solution Approach 1:
The patent divides the mask pattern formation into multiple stages: first forming a preliminary pattern with initial photoresist, then using a second photoresist layer to define final conductive feature boundaries. This segmentation allows each layer to be optimized for its specific function, maintaining precision even as feature sizes decrease
Solution Approach 2:
The patent transitions from two-dimensional planar masking to three-dimensional multi-layer photoresist structuring. By adding vertical layering with different photoresist materials having distinct etch selectivities, the process achieves higher precision in controlling conductive feature formation at smaller dimensions
2Ease of manufacture
If conventional photolithography is used to transfer mask patterns, then ease of manufacture is maintained, but manufacturing precision deteriorates due to photoresist island effect and line end corner rounding
Solution Approach 1:
The patent introduces a second photoresist layer as an intermediary that mediates between the preliminary pattern and the final conductive feature formation. This intermediate layer allows for correction and refinement of pattern defects without requiring changes to the original mask design
Solution Approach 2:
The patent changes the material parameters by using two different photoresist materials with different etch selectivities. This parameter change enables selective removal of the second photoresist layer to expose hard mask material, thereby achieving sharper and more uniform conductive features
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 improves the formation of conductive features by enhancing resolution, uniformity, and separation, addressing the challenges of smaller critical dimensions and higher densities in IC manufacturing, despite increasing complexity and cost.
Implementation Method 1
During exposure, radiation such as ultraviolet light passes through or reflects off the mask before striking a photoresist coating on the wafer
Implementation Method 2
The wafer then undergoes processing steps that take advantage of the shape of the remaining photoresist to create cavities in the insulating layer
Data Source
AI summary
A method for optimizing masks used for forming conductive features and a method for creating the mask features on an IC device are disclosed. An exemplary embodiment includes receiving a design database including a plurality of conductive features. First and second features suitable for joining are identified from the plurality of conductive features. A joined feature corresponding to the first and the second features is characterized. A cut shape configured to separate the first and second features from the joined feature is also characterized. The joined feature is categorized into a first conductive mask, the cut shape is categorized into a cut mask, and a third feature is categorized into a second conductive mask. The categorized shapes and features of the first conductive mask, the second conductive mask, and the cut mask are provided for manufacturing a mask set corresponding to the categorized shapes and features.