Dummy Gate Stacks for Uniform Stress in Semiconductor Devices
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Solution Overview
Problem
Current semiconductor device structures with strained epitaxy SiGe features suffer from mismatch issues and performance degradation due to non-symmetric source and drain regions, poor shallow trench isolation (STI) edge leakage, and decreased channel stress, which are not effectively addressed by existing circuit design optimizations.
Innovation Solution
The semiconductor structure incorporates an active region with extended length, where dummy gate stacks are positioned within the active region instead of isolation regions, aligned with operational devices, to enhance uniform stress and reduce STI-related stress, and includes dummy active regions to tune substrate stress and improve carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxy SiGe features are used to enhance carrier mobility, then device performance is improved, but mismatch issues and performance degradation occur at active region edges
Solution Approach 1:
The patent applies local quality by introducing dummy gate stacks specifically at the active region edges where mismatch occurs, rather than uniformly across the entire device. These dummy gates provide localized stress compensation and structural symmetry only where needed, maintaining the beneficial SiGe strain in the channel while correcting the edge effects that cause mismatch and performance degradation.
Solution Approach 2:
The patent addresses asymmetry by adding dummy gate stacks to create structural symmetry at the active region edges. The conventional device structure is asymmetric at the edges due to the facet shape, causing channel stress reduction. The dummy gates balance this asymmetry by providing matching structures on both sides of the active region, thereby maintaining uniform stress distribution and improving device performance.
2Ease of manufacture
If active region has facet shape at edge, then device structure is formed, but channel stress is decreased and device performance is degraded
Solution Approach 1:
The patent applies preliminary anti-action by introducing dummy gate stacks before final device operation to counteract the stress reduction caused by the facet shape. These dummy gates pre-establish the necessary stress conditions by providing structural support and stress distribution that compensates for the inherent stress loss at the faceted edges, thereby maintaining adequate channel stress for optimal device performance.
3Stability of the object's composition
If dummy gate stacks are added to active region, then stress uniformity is improved, but device structure complexity increases
Solution Approach 1:
The patent applies copying by creating dummy gate stacks that are identical copies of the operational gate stack structure. These dummy gates replicate the same materials, dimensions, and configuration as the functional gates, ensuring that the stress and electrical characteristics are matched. This copying approach provides effective stress uniformity while maintaining consistency with the existing device fabrication processes.
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 configuration improves device performance by minimizing layout degradation effects, reducing STI-edge leakage, and maintaining uniform stress, while maintaining the existing fabrication process flow without additional costs.
Implementation Method 1
a strained substrate using epitaxy silicon germanium (SiGe) may be used to enhance the carrier mobility
Implementation Method 2
The source and drain regions are formed by an epitaxy process with a semiconductor different from silicon to achieve the strained channel
Data Source
AI summary
The present disclosure provides an integrated circuit. The integrated circuit includes a semiconductor substrate having an active region; at least one operational device on the active region, wherein the operational device include a strained channel; and at least one first dummy gate disposed at a side of the operational device and on the active region.