Transistor Active Region Segmentation for Single-Step Doping
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Solution Overview
Problem
Fabricating high-voltage transistors with different drive currents poses challenges due to the need for multiple doping steps, which increases fabrication costs and complexity, as each transistor requires a specific optimum doping concentration.
Innovation Solution
Introducing dielectric features within the active region of high-voltage transistors to break up the doping area, allowing a single dopant concentration to be used across transistors of varying widths, thereby shifting the dopant-response characteristics to achieve desired breakdown voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple doping steps are used to achieve different doping concentrations for transistors with different drive currents, then the breakdown voltage characteristics can be optimized for each transistor, but the fabrication process complexity and cost increase
Solution Approach 1:
The active region is segmented into multiple zones with different doping concentrations by introducing dielectric features that create spatially separated doped regions. This allows different portions of the same transistor active region to have different doping levels, enabling optimization for both high and low drive current transistors using a single fabrication process.
Solution Approach 2:
Different regions of the active area are given different doping concentrations tailored to their specific functional requirements. The dielectric features enable local doping variations, so that regions requiring higher breakdown voltage have different doping characteristics than regions requiring higher drive current, all within a single transistor structure.
2Ease of manufacture
If a single doping step is used for all high-voltage transistors, then fabrication cost and complexity are reduced, but it becomes difficult to achieve optimal doping concentrations for transistors with different drive currents
Solution Approach 1:
The active region is segmented into multiple zones with different doping concentrations by introducing dielectric features that create spatially separated doped regions. This allows different portions of the same transistor active region to have different doping levels, enabling optimization for both high and low drive current transistors using a single fabrication process.
Solution Approach 2:
The doping concentration parameter is varied spatially within the active region through the introduction of dielectric features. By changing the local doping concentration in different zones, the structure can accommodate transistors with different drive current requirements while using a single global doping process step.
3Device complexity
If the active region is left uniform without dielectric features, then the fabrication process remains simple, but transistors with different widths cannot achieve their respective optimum doping concentrations
Solution Approach 1:
The active region is segmented into multiple zones with different doping concentrations by introducing dielectric features that create spatially separated doped regions. This allows different portions of the same transistor active region to have different doping levels, enabling optimization for both high and low drive current transistors using a single fabrication process.
Solution Approach 2:
The dielectric feature structure serves multiple functions: it segments the active region for different doping zones, acts as a mask during doping, and enables the same fabrication process to produce transistors with different drive current characteristics. This multi-functionality maintains structural simplicity while achieving doping adaptability.
Data Source
AI summary
Some embodiments include integrated circuits having first and second transistors. The first transistor is wider than the second transistor. The first and second transistors have first and second active regions, respectively. Dielectric features are associated with the first active region and break up the first active region. The second active region is not broken up to the same extent as the first active region. Some embodiments include methods of forming transistors. Active areas of first and second transistors are formed. The active area of the first transistor is wider than the active area of the second transistor. Dielectric features are formed in the active area of the first transistor. The active area of the first transistor is broken up to a different extent than the active area of the second transistor. The active areas of the first and second transistors are simultaneously doped.