Graduated Etch Stop Layer for Semiconductor Device
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Solution Overview
Problem
Conventional etch stop layers in semiconductor manufacturing face challenges in achieving selective etching depth and compatibility with different materials, often resulting in undesirable material interfaces that affect device performance and reliability.
Innovation Solution
A graduated etch stop layer composed of silicon dioxide, silicon oxynitride, and silicon nitride materials is used, with a thickness profile that changes from silicon dioxide at the bottom to silicon nitride at the top, providing improved etch stopping capability and reducing undesirable material interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional etch stop layer is used to control etching depth, then etching depth control is achieved, but undesirable material interfaces are created that trap electrons and reduce device reliability
Solution Approach 1:
The etch stop layer is segmented into multiple sub-layers with different materials (silicon dioxide, silicon oxynitride, silicon nitride) and different thicknesses. This segmentation allows the etch front to pass through progressively, with each sub-layer providing partial etch stopping, thereby eliminating the sharp interface that traps electrons while maintaining etch depth control.
Solution Approach 2:
Different regions of the etch stop layer have different material compositions and thicknesses tailored to local requirements. The first sub-layer (silicon dioxide) provides initial etch stopping, the second sub-layer (silicon oxynitride) provides intermediate stopping, and the third sub-layer (silicon nitride) provides final stopping. This local quality variation eliminates electron trapping interfaces while maintaining precise etch depth control.
2Manufacturing precision
If an etch stop layer is used to stop the etching process, then etching depth is controlled, but contact quality between gate metal and silicon is degraded due to material interfaces
Solution Approach 1:
The etch stop layer is divided into multiple sub-layers that progressively stop the etch process. The third sub-layer (silicon nitride) is positioned closest to the silicon substrate, ensuring that the etch front passes through it last, thereby maintaining direct contact between gate metal and silicon without intervening material interfaces that would degrade contact quality.
Solution Approach 2:
Instead of placing the most etch-resistant material at the bottom (conventional approach), the invention places it at the top (silicon nitride in the third sub-layer). This inversion ensures that the etch front encounters progressively less resistant materials as it approaches the silicon substrate, eliminating interfaces between etch stop materials and silicon, thereby improving gate metal to silicon contact quality.
3Device complexity
If a simple etch stop layer is used, then the process is simple, but selectivity between different dielectric materials is poor
Solution Approach 1:
The etch stop layer is formed as a composite structure with three different materials (silicon dioxide, silicon oxynitride, silicon nitride), each providing different etch selectivity characteristics. This composite structure enables highly selective etching of different dielectric materials while maintaining a relatively simple single-layer deposition process, thus improving manufacturing precision without significantly increasing process complexity.
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
The solution enables precise control of etching depth, enhances contact quality between gate metal and silicon, and improves hot carrier injection characteristics by eliminating interfaces that trap electrons, resulting in better device reliability and performance.
Implementation Method 1
An etch stop layer is usually consisted of materials that feature drastically different etch characteristics from the material to be etched. The etch stop layer is generally placed underneath the etched material to stop etching process.
Implementation Method 2
Chemical drying etching usually involves generating reactive species in plasma, providing these species to the surface of material being etched, species being absorbed, reacting of these species on the surface to form volatile by-product, absorbing or the by-product by the surface, and diffusing of the desorbed species diffusing into gas.
Data Source
AI summary
A system and method for improved dry etching system. According to an embodiment, the present invention provides a partially completed integrated circuit device. The partially completed integrated circuit device includes a semiconductor substrate having a surface region. The partially completed integrated circuit device also includes an etch stop layer overlying the surface region. The etch stop layer is characterized by a thickness having at least a first thickness portion and a second thickness portion. The second thickness portion includes an etch stop surface region. The partially completed integrated circuit device additionally includes a silicon dioxide material provided within the first thickness portion of the etch stop layer. The partially completed integrated circuit device includes a silicon nitride material provided within the second thickness portion of the etch stop layer. In addition, the partially completed integrated circuit device includes a profile characterized by the silicon dioxide material in the first thickness portion changing to the silicon nitride material in the second thickness portion.