Dielectric Cavity Facet Trapping for Epitaxial Surface Replication
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Solution Overview
Problem
Scaling of bipolar junction transistors (BJTs) in integrated circuits to smaller nodes requires novel approaches in semiconductor processing to manage facet propagation during epitaxial growth, which affects the replication of monocrystalline surfaces.
Innovation Solution
A dielectric layer with strategically formed cavities traps facets of the second semiconductor material during epitaxial growth, using sidewall etch stop liners and controlled etching to create openings and cavities that arrest facet propagation, allowing for precise replication of the monocrystalline surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional epitaxial growth processing is used for scaling BJTs to smaller nodes, then device density increases, but facet propagation occurs which degrades monocrystalline surface replication
Solution Approach 1:
The dielectric layer with cavity is formed prior to epitaxial growth as a preventive structure. This preliminary action creates a physical trap that intercepts propagating facets before they can degrade the monocrystalline surface replication, thereby enabling continued scaling while maintaining surface quality
Solution Approach 2:
The dielectric layer acts as an intermediary structure between the substrate and the growing semiconductor layer. The cavity within the dielectric layer serves as a mediator that captures and arrests facet propagation, preventing the transfer of surface irregularities to the monocrystalline layer being grown
2Speed
If facet propagation is allowed during epitaxial growth, then growth speed increases, but monocrystalline surface continuity is compromised
Solution Approach 1:
The cavity structure converts the potentially harmful facet propagation into a beneficial trapping mechanism. By designing the cavity with specific geometry, the propagating facet is redirected and arrested within the cavity, transforming what would be a surface defect into a controlled feature that preserves overall surface continuity
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
The solution enables accurate replication of the monocrystalline surface in the second semiconductor material, enhancing the scalability and performance of BJTs by preventing facet propagation and maintaining surface continuity, thereby addressing the challenge of scaling.
Implementation Method 1
The cavity in the dielectric layer is configured to trap a facet of the second semiconductor material in the cavity
Implementation Method 2
Scaling of devices in an integrated circuit to smaller nodes typically requires novel approaches to semiconductor processing for fabricating those devices
Data Source
AI summary
The present disclosure generally relates to semiconductor processing including facet trapping for an epitaxial growth process. In an example, a semiconductor device includes a first semiconductor material, a dielectric layer, and a second semiconductor material. The first semiconductor material includes a monocrystalline surface. The dielectric layer is over the first semiconductor material. The dielectric layer has an opening to the monocrystalline surface. The opening is defined at least in part by a sidewall of the dielectric layer and a cavity in the dielectric layer. The cavity is at the monocrystalline surface and under the sidewall. The second semiconductor material is over the first semiconductor material and on the monocrystalline surface. The second semiconductor material is at least partially in the opening through the dielectric layer. The cavity in the dielectric layer is configured to trap a facet of the second semiconductor material in the cavity.