Inclined Epitaxial Layer Structure for Cap Layer Isolation
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Solution Overview
Problem
In semiconductor devices, the shrinking line width poses challenges such as short circuits between devices due to a thick cap layer and voids on the epitaxial layer surface due to a thin cap layer, leading to unexpected silicide flow during self-aligned silicide processes.
Innovation Solution
A semiconductor device structure comprising a gate structure, a first epitaxial layer, a second epitaxial layer with a surface inclined at 15 to 35 degrees, and a cap layer, fabricated using selective epitaxial growth processes to reduce the probability of short circuits and unexpected silicide flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap layer has a thicker thickness, then short circuits between devices are reduced, but voids are formed on the epitaxial layer surface
Solution Approach 1:
The patent introduces a new dimensional parameter - the inclined angle of the epitaxial layer surface (15-35 degrees relative to horizontal). By changing the surface geometry from flat to inclined, the cap layer can be thinner while still preventing void formation, as the inclined surface allows better material flow and reduces trapped voids during deposition.
Solution Approach 2:
The patent changes the geometric parameter of the epitaxial layer surface from a flat configuration to an inclined configuration with specific angle ranges (15-35 degrees). This parameter change allows optimization of both cap layer thickness and void prevention, resolving the contradiction between reliability and manufacturing precision.
2Manufacturing precision
If the cap layer has a thinner thickness, then manufacturing precision is improved, but short circuits between devices occur
Solution Approach 1:
By inclining the epitaxial layer surface at 15-35 degrees, the effective coverage and isolation capability is enhanced in the horizontal direction, allowing thinner cap layers to still provide sufficient device isolation and prevent short circuits.
3Ease of manufacture
If the epitaxial layer surface is flat, then manufacturing process is simple, but silicide flows along voids to unexpected positions
Solution Approach 1:
The inclined surface geometry (15-35 degrees) modifies the path of silicide flow during self-aligned silicide processes. The inclination redirects the silicide material flow, preventing it from flowing along voids to unexpected positions while still maintaining relatively simple fabrication processes.
4Manufacturing precision
If the inclined angle of epitaxial layer surface is increased, then void formation is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent specifies an optimal range for the inclined angle (15-35 degrees) that balances void formation reduction with manufacturing feasibility. This parameter optimization ensures sufficient void prevention while avoiding excessive structural complexity that would complicate manufacturing.
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 described structure and fabrication method effectively reduce the probability of short circuits and unexpected silicide flow by minimizing void formation on the epitaxial layer surface and optimizing the cap layer thickness.
Implementation Method 1
A second epitaxial layer is formed on the first epitaxial layer, in which an included angle between a surface of the second epitaxial layer and a horizontal direction is 15 degrees to 35 degrees
Data Source
AI summary
A semiconductor device includes a gate structure, a first epitaxial layer, a second epitaxial layer and a cap layer. The gate structure is disposed on a substrate. The first epitaxial layer is disposed in the substrate and at two sides of the gate structure. The second epitaxial layer is disposed on the first epitaxial layer, in which an included angle between a surface of the second epitaxial layer and a horizontal direction is 15 degrees to 35 degrees. The cap layer is disposed on the second epitaxial layer.