Semiconductor Gate Structure Reducing Cross Diffusion
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Solution Overview
Problem
As semiconductor transistors are scaled down, gate cross diffusion becomes a significant issue, leading to changes in dopant concentrations and threshold voltages, which affects the performance of NMOS and PMOS transistors, and reducing dopant concentrations in the gate regions to mitigate this problem also increases source-to-drain series resistance.
Innovation Solution
The semiconductor structure incorporates multiple source and drain regions with varying dopant concentrations and a gate structure with multiple regions of different dopant concentrations, allowing for controlled dopant implantation and adjustment to minimize the effects of gate cross diffusion while maintaining adequate source and drain dopant levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If dopant concentrations in gate regions are reduced to mitigate gate cross diffusion, then gate cross diffusion effects are reduced, but source-to-drain series resistance increases
Solution Approach 1:
The gate structure is divided into multiple regions with different dopant concentrations: a first gate region with a first dopant concentration and a second gate region with a second dopant concentration. This local differentiation allows the first gate region to have lower dopant concentration (reducing gate cross diffusion) while the second gate region maintains higher dopant concentration (providing adequate source-to-drain conduction), thereby resolving the contradiction between reducing gate cross diffusion and maintaining low series resistance.
2Productivity
If transistors are scaled down to increase device density, then productivity is improved, but gate cross diffusion becomes more significant
Solution Approach 1:
By implementing a gate structure with spatially varying dopant concentrations, the patent enables continued transistor scaling while controlling gate cross diffusion. The differentiated dopant regions allow smaller transistor dimensions to be achieved without the gate cross diffusion becoming excessive, thus maintaining productivity improvements while mitigating the harmful effects of scaling.
Solution Approach 2:
The patent changes the dopant concentration parameter across different gate regions. By adjusting the dopant concentration in specific gate regions rather than uniformly across the entire gate, the patent enables continued scaling while controlling gate cross diffusion effects, thereby maintaining high device density without proportionally increasing gate cross diffusion.
3Object-affected harmful factors
If multiple gate regions with different dopant concentrations are implemented, then gate cross diffusion is reduced, but device complexity increases
Solution Approach 1:
The gate is segmented into multiple regions (first gate region and second gate region) with different dopant concentrations. This segmentation allows control of gate cross diffusion in the first region while maintaining proper source-to-drain conduction in the second region, achieving the goal of reducing gate cross diffusion without requiring completely complex alternative structures.
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 effectively reduces gate cross diffusion, minimizing threshold voltage shifts and maintaining low series resistance, thereby improving the performance and reliability of NMOS and PMOS transistors.
Implementation Method 1
implanting dopant atoms of a second conductivity type through the first opening into the gate structure to form a first gate region
Implementation Method 2
gate cross diffusion becomes a significant issue, leading to changes in dopant concentrations and threshold voltages
Data Source
AI summary
Gate cross diffusion in a semiconductor structure is substantially reduced or eliminated by forming multiple n-type gate regions with different dopant concentrations and multiple p-type gate regions with different dopant concentrations so that the n-type gate region with the lowest dopant concentration touches the p-type gate region with the lowest dopant concentration.