SOI Epitaxial Layer Outer End Shape for TDDB Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor devices formed on SOI substrates, the thinness of semiconductor layers leads to issues such as contact holes penetrating through the layers and buried insulating films, causing erroneous conduction and malfunction, particularly due to insufficient epitaxial growth on the outer circumference ends of active regions, resulting in electric field concentration and reduced TDDB lifetime.
Innovation Solution
A semiconductor device manufacturing method where a first epitaxial layer is selectively formed only on the outer end of an active region surrounded by an isolation portion, and a second epitaxial layer is formed over the entire active region, with the outer circumference end of the epitaxial layer having an angle greater than 30° relative to the boundary plane between the buried insulating film and the semiconductor layer, ensuring adequate thickness and preventing penetration of contact holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a selective epitaxial growth process is used to form raised source and drain structure, then the thickness of semiconductor layers in source and drain regions is increased, but the epitaxial layer becomes thinned and forms an outward thinned and pointed shape on the outer circumference end of wide active regions
Solution Approach 1:
The patent applies preliminary action by forming a first epitaxial layer selectively on the outer end of the active region before forming the second epitaxial layer on the entire active region. This preliminary formation of the first epitaxial layer on the outer end prevents the outward thinning and pointed shape that would otherwise occur during the second epitaxial growth, ensuring uniform thickness and proper shape throughout the process.
2Ease of manufacture
If the epitaxial layer is thinned and formed into an outward thinned and pointed shape on the outer end portion, then manufacturing is simplified, but electric field concentration occurs and TDDB lifetime of buried insulating film is reduced
Solution Approach 1:
The first epitaxial layer is formed selectively on the outer end of the active region before the second epitaxial layer formation, preliminarily establishing proper thickness and shape at the outer end to prevent electric field concentration and ensure reliable TDDB lifetime.
Solution Approach 2:
The patent applies local quality by forming the first epitaxial layer selectively only on the outer end of the active region, giving this specific area different treatment than the central region. This localized approach ensures the outer end has sufficient thickness and proper shape to prevent electric field concentration, while the rest of the active region follows standard epitaxial growth.
3Length of moving object
If semiconductor layers are made thin to reduce device size, then device miniaturization is achieved, but contact holes may penetrate through the layers causing erroneous conduction
Solution Approach 1:
The first epitaxial layer is formed selectively on the outer end of the active region before the second epitaxial layer formation, preliminarily establishing proper thickness and shape at the outer end to prevent electric field concentration and ensure reliable TDDB lifetime.
Solution Approach 2:
The patent applies local quality by forming the first epitaxial layer selectively only on the outer end of the active region, giving this specific area different treatment than the central region. This localized approach ensures the outer end has sufficient thickness and proper shape to prevent electric field concentration, while the rest of the active region follows standard epitaxial 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 improves the lifetime of semiconductor devices by preventing erroneous conduction and enhancing the TDDB lifetime of the buried insulating film by ensuring sufficient epitaxial growth and thickness on the outer circumference ends of active regions, thus maintaining device performance.
Implementation Method 1
a first epitaxial layer is selectively formed only on an end of a semiconductor layer in an active region
Implementation Method 2
thereafter a second epitaxial layer is formed on/over the semiconductor layer in the whole active region of the SOI substrate
Data Source
AI summary
In a manufacturing method for a semiconductor device formed over an SOI substrate, a first epitaxial layer is partially formed over an outer circumference end of a first semiconductor layer in a wide active region. Then, a second epitaxial layer is formed over each of the first semiconductor layers in a narrow active region and the wide active region. Thereby, a second semiconductor layer configured by a laminated body of the first semiconductor layer and the first and second epitaxial layers is formed in the wide active region and a third semiconductor layer configured by a laminated body of the first semiconductor layer and the second epitaxial layer is formed in the narrow active region.