Epitaxial Sidewall Structure for GAA Channel Stress Control
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Solution Overview
Problem
Current semiconductor devices with gate-all-around structures face challenges in optimizing epitaxial pattern shapes to enhance performance and reliability, particularly in controlling channel region characteristics for improved current control and reduced short channel effects.
Innovation Solution
The semiconductor device incorporates a specific epitaxial pattern design with varying sidewall orientations and crystal plane formations, including inclined upper and lower sidewalls connected by curved or planar connecting sidewalls, to control stress and material properties, thereby enhancing channel region performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gate-all-around structure with nanowire-type silicon body is formed, then scaling is facilitated and current control capability is improved, but the shape of epitaxial patterns becomes difficult to control
Solution Approach 1:
The epitaxial pattern is divided into multiple distinct regions: a first epitaxial region with a first crystal orientation and a second epitaxial region with a second crystal orientation. This segmentation allows independent control of growth characteristics in different areas, enabling precise shape control while maintaining the gate-all-around structure's scaling benefits.
Solution Approach 2:
Different crystal orientations are assigned to different spatial regions of the epitaxial pattern. The first epitaxial region has a crystal orientation optimized for one set of properties, while the second epitaxial region has a different crystal orientation optimized for another set of properties. This local differentiation enables simultaneous optimization of multiple characteristics.
2Ease of manufacture
If epitaxial patterns with uniform shape are used, then manufacturing is simplified, but carrier mobility and short channel effect control are insufficient
Solution Approach 1:
The epitaxial pattern employs different crystal orientations in different regions to achieve local optimization. The first epitaxial region with its specific crystal orientation provides certain electrical characteristics, while the second epitaxial region with a different crystal orientation provides complementary characteristics, together achieving superior overall performance that cannot be obtained with uniform structures.
Solution Approach 2:
The patent introduces asymmetric crystal orientation distribution in the epitaxial pattern, where the first and second epitaxial regions have different crystal orientations relative to the substrate. This asymmetric arrangement creates directional properties that enhance carrier mobility in specific directions while providing better control over short channel effects.
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 design improves carrier mobility and reduces short channel effects, leading to increased performance and reliability of the semiconductor device by optimizing epitaxial pattern shapes and material properties.
Implementation Method 1
the first and second epitaxial upper sidewalls are formed by crystal planes included in a first crystal plane group, and wherein the first and second epitaxial connecting sidewalls are formed by crystal planes included in a second crystal plane group which is different from the first crystal plane group
Data Source
AI summary
Provided is a semiconductor device comprising an active region on a substrate and including first and second sidewalls extending in a first direction and an epitaxial pattern on the active region, wherein the epitaxial pattern includes first and second epitaxial sidewalls extending from the first and second sidewalls, respectively, the first epitaxial sidewall includes a first epitaxial lower sidewall, a first epitaxial upper sidewall, and a first epitaxial connecting sidewall connecting the first epitaxial lower sidewall and the first epitaxial upper sidewall, the second epitaxial sidewall includes a second epitaxial lower sidewall, a second epitaxial upper sidewall, and a second epitaxial connecting sidewall connecting the second epitaxial lower sidewall and the second epitaxial upper sidewall, a distance between the first and second epitaxial upper sidewalls decreases away from the active region, and the first and second epitaxial lower sidewalls extend in parallel to a top surface of the substrate.