Enlarged Gate Electrode Structure for Low-Resistance Scaling
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Solution Overview
Problem
Existing semiconductor manufacturing processes are inadequate for further miniaturization of device sizes due to limitations in forming gate electrode structures, leading to unsatisfactory performance and integration levels in semiconductor devices.
Innovation Solution
The process involves forming a gate stack structure with a conductive layer and a gate electrode structure, where the space for the gate electrode is enlarged by etching back the conductive layer, allowing for a wider upper portion and a narrower lower portion, reducing resistance and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate electrode structure is enlarged to reduce resistance and improve performance, then the device performance and integration levels are enhanced, but the device size increases which contradicts the miniaturization trend
Solution Approach 1:
The gate electrode structure is nested within the gate stack structure, with the enlarged gate electrode positioned within the available space of the gate stack. This allows the gate electrode to be larger than conventional structures while still fitting within the overall gate stack footprint, effectively nesting the enlarged electrode within the constrained space to achieve both performance improvement and size control.
Solution Approach 2:
The gate electrode structure transitions from a uniform two-dimensional planar structure to a three-dimensional structure with varying width across different levels. The upper portion has a first width while the lower portion has a second width, creating a stepped or tapered configuration that utilizes vertical and lateral dimensions simultaneously to increase effective gate area without proportionally increasing the planar footprint.
2Productivity
If the device size is miniaturized to increase integration levels, then more devices can be fitted on a chip, but the manufacturing precision and tolerance requirements become more stringent
Solution Approach 1:
The gate electrode structure is segmented into distinct portions with different widths - an upper portion and a lower portion. This segmentation allows each portion to be optimized independently for its specific function, with the upper wider portion providing lower resistance pathways and the lower portion integrating with the underlying conductive layer, thereby achieving performance goals without requiring uniform miniaturization across the entire structure.
Solution Approach 2:
Different regions of the gate electrode structure have different dimensional characteristics - the upper portion has a larger width to reduce resistance, while the lower portion has a smaller width to maintain compact integration. This local variation in quality allows the structure to meet different performance requirements in different locations without being constrained by uniform dimensional tolerances across the entire device.
3Reliability
If the gate electrode structure is made larger with a wider upper portion, then the resistance is reduced and performance improves, but the gate stack area increases which conflicts with scaling requirements
Solution Approach 1:
The gate electrode structure employs asymmetric dimensions where the upper portion has a different width than the lower portion. Specifically, the upper portion is wider to reduce resistance and improve electrical performance, while the lower portion is narrower to minimize the overall gate stack area. This asymmetric configuration optimizes the trade-off between resistance reduction and area minimization by concentrating the enlarged dimensions only where most beneficial for electrical performance.
Data Source
AI summary
A semiconductor structure and a method for forming the same are provided. The semiconductor structure includes a gate stack structure formed over a substrate. The gate stack structure includes a gate electrode structure having a first portion and a second portion and a first conductive layer below the gate electrode structure. In addition, the first portion of the gate electrode structure is located over the second portion of the gate electrode structure, and a width of a top surface of the first portion of the gate electrode structure is greater than a width of a bottom surface of the second portion of the gate electrode structure.