FinFET Hard Mask Layer Structure for Etching Precision
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Solution Overview
Problem
Existing FinFET devices and fabrication methods face challenges in achieving optimal performance and efficiency due to limitations in reducing the short channel effect and improving current flow, particularly in three-dimensional designs.
Innovation Solution
The method involves forming a FinFET device structure with two hard mask layers, where the first hard mask layer is made of low-k dielectric materials to enhance speed and the second hard mask layer has a higher etching rate, allowing for precise etching and contact formation while protecting the gate structure, and includes the use of low-k dielectric materials and self-aligned processes for patterning and etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single hard mask layer is used over the gate structure, then the fabrication process is simpler, but the etching precision and gate structure protection are insufficient
Solution Approach 1:
The patent divides the hard mask layer into two separate layers: a first hard mask layer in direct contact with the gate structure and a second hard mask layer over the first hard mask layer. This segmentation allows each layer to perform specific functions - the first layer provides gate protection while the second layer enables precise etching control, thereby resolving the contradiction between etching precision and structural complexity.
Solution Approach 2:
The first hard mask layer acts as an intermediary between the gate structure and the second hard mask layer. It provides a protective interface that shields the gate structure during etching processes while allowing the second hard mask layer to define precise etching patterns, thus achieving both gate protection and etching precision without excessive complexity.
2Speed
If low-k dielectric materials are used in the hard mask layer, then the device speed is improved, but the etching rate control becomes more challenging
Solution Approach 1:
The patent segments the hard mask structure into two layers with different material properties. The first hard mask layer uses low-k dielectric material to enhance device speed, while the second hard mask layer is specifically designed with controlled etching characteristics. This segmentation allows simultaneous optimization of speed and etching rate control.
Solution Approach 2:
Different regions of the hard mask structure have different material qualities - the first layer near the gate has low-k dielectric properties for speed enhancement, while the second layer has optimized etching properties for precise pattern formation. This local quality differentiation resolves the contradiction between speed improvement and etching control.
3Ease of manufacture
If the gate structure is exposed during etching, then the etching process is simpler, but the gate structure is damaged
Solution Approach 1:
The first hard mask layer is formed in advance, in direct contact with the gate structure, before the etching process begins. This preliminary protective layer shields the gate structure from etching damage while allowing the etching process to proceed with the second hard mask layer as the patterning element, thus maintaining both gate integrity and process simplicity.
Solution Approach 2:
The first hard mask layer serves as an intermediary protective barrier between the gate structure and the etching environment. It allows the etching process to be performed without directly exposing the gate structure to harsh etching conditions, thereby maintaining gate integrity while keeping the manufacturing process straightforward.
Data Source
AI summary
A method for forming a FinFET device structure is provided. The method for forming a FinFET device structure includes forming a fin structure over a substrate, and forming a source/drain (S/D) structure over the fin structure. The method for forming a FinFET device structure also includes forming an inter-layer dielectric (ILD) structure covering the S/D structure, and forming a gate structure over the fin structure and adjacent to the S/D structure. The method for forming a FinFET device structure further includes forming a first hard mask layer over the gate structure, and forming a second hard mask layer over the first hard mask layer. In addition, the method for forming a FinFET device structure includes etching the ILD structure to form an opening exposing the S/D structure. The opening and a recess in the second hard mask layer are formed simultaneously.