Anisotropic SiGe:B Epitaxy for hGAA Source/Drain Void Reduction
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Solution Overview
Problem
Current methods for forming source/drain regions in horizontal gate all-around (hGAA) semiconductor device structures suffer from poor wetting, faceting, and uneven growth, leading to voids and reduced effectiveness due to challenges in growing these regions on non-crystalline and dielectric materials.
Innovation Solution
A method involving the selective deposition of source/drain layers using a multi-material layer with alternating crystalline and non-crystalline layers, exposed to a gas mixture containing silicon, germanium, and p-type dopant precursors, including chlorine, which promotes growth predominantly on the top surface of the substrate, reducing faceting and void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If source/drain regions are grown on both <100> and <110> surfaces simultaneously, then growth coverage is improved, but voids or openings are formed within the source/drain regions adjacent to non-crystalline or dielectric material layers
Solution Approach 1:
The patent applies local quality by directing growth to occur predominantly on <100> surfaces while suppressing growth on <110> surfaces. This is achieved through selective epitaxial growth conditions that exploit the different crystallographic orientations, allowing the source/drain regions to grow uniformly on the top surface and sidewalls facing <100> oriented channels, while avoiding void formation that would occur with simultaneous growth on both orientations.
2Ease of manufacture
If source/drain regions are grown with uniform conditions on all surfaces, then growth simplicity is maintained, but faceting occurs and wetting is poor on non-crystalline sidewalls
Solution Approach 1:
The patent employs parameter changes by utilizing the difference in growth rates between <100> and <110> crystallographic orientations. By controlling epitaxial growth parameters (temperature, pressure, gas composition, precursor ratios), the process selectively promotes growth on <100> surfaces while suppressing growth on <110> surfaces. This parameter control enables good wetting on non-crystalline sidewalls and prevents faceting, achieving reliable source/drain region formation without compromising manufacturing simplicity.
3Area of stationary object
If growth occurs on multiple crystallographic orientations, then coverage is improved, but uneven film growth and intersecting growth boundaries are created
Solution Approach 1:
The patent applies local quality by making growth orientation-specific, allowing different growth behaviors on different crystallographic surfaces. Growth is permitted and encouraged on <100> surfaces where uniform film deposition is needed, while growth on <110> surfaces is suppressed to avoid creating intersecting boundaries. This localized control of growth properties ensures uniform film thickness and composition throughout the source/drain regions without the defects that would arise from simultaneous multi-orientation growth.
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 results in improved wetting, reduced faceting, and controlled growth directions, significantly decreasing voids and enhancing the effectiveness of the source/drain regions by increasing the growth rate on the top surface while minimizing growth on sidewalls, thus improving the overall performance of the hGAA structure.
Implementation Method 1
exposing the substrate and the multi-material layer to a gas mixture, and forming a source/drain layer on the substrate with predominantly <100> growth
Implementation Method 2
forming a multi-material layer on a substrate, exposing the substrate and the multi-material layer to a gas mixture, and forming a source/drain layer on the substrate with predominantly <100> growth. The multi-material layer includes a plurality of crystalline first layers and a plurality of non-crystalline second layers arranged in an alternating pattern
Data Source
AI summary
Embodiments described herein relate to a method of epitaxial deposition of p-channel metal oxide semiconductor (MMOS) source/drain regions within horizontal gate all around (hGAA) device structures. Combinations of precursors are described herein, which grow of the source/drain regions on predominantly <100> surfaces with reduced or negligible growth on <110> surfaces. Therefore, growth of the source/drain regions is predominantly located on the top surface of a substrate instead of the alternating layers of the hGAA structure. The precursor combinations include a silicon containing precursor, a germanium containing precursor, and a boron containing precursor. At least one of the precursors further includes chlorine.