Embedded Epitaxial Transistor Structure for GIDL Mitigation
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Solution Overview
Problem
The reduction in sidewall spacer thickness in semiconductor transistors leads to gate-induced drain leakage current (GIDL) issues in medium-voltage transistors, and existing devices occupy a large chip area, necessitating improvements in transistor structure.
Innovation Solution
Incorporation of undoped or doped epitaxial SiGe or SiP layers in the drain and source regions of the transistor structure, with specific placement and thickness relative to the junction depth, and the use of silicide layers without direct contact, along with trench isolation and sidewall spacers, to enhance performance and reduce chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the sidewall spacer thickness is reduced to enable smaller transistor size, then the chip area is reduced, but gate-induced drain leakage current (GIDL) problems occur
Solution Approach 1:
An embedded epitaxial structure is introduced as an intermediary layer between the drain LDD region and the heavily doped drain region. This intermediate structure mitigates the direct interaction that causes GIDL, allowing reduced sidewall spacer thickness without suffering from leakage current problems.
Solution Approach 2:
The embedded epitaxial structure is selectively placed only in the drain LDD region where GIDL occurs, rather than uniformly throughout the device. This localized modification addresses the specific problem area while maintaining other device characteristics.
2Ease of manufacture
If the embedded medium-voltage transistor device is fabricated with conventional structure, then the device can be manufactured, but it occupies a large chip area
Solution Approach 1:
The embedded epitaxial structure adds a vertical dimension to the device architecture by inserting a distinct layer between existing horizontal structures. This vertical modification enables shorter gate length and reduced chip area without compromising manufacturability, as the structure can be integrated into existing fabrication processes.
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 proposed structure effectively mitigates GIDL and allows for a shorter gate length, reducing the chip area occupied by medium-voltage transistors while maintaining performance.
Implementation Method 1
A first embedded epitaxial structure is formed in the drain LDD region and between the gate structure and the heavily doped drain region. The first embedded epitaxial structure comprises an undoped epitaxial SiGe layer or an undoped epitaxial SiP layer.
Implementation Method 2
the semiconductor transistor structure further includes a drain silicide layer disposed on the heavily doped drain region
Data Source
AI summary
A semiconductor transistor structure includes a substrate; an active region located on the substrate and surrounded by a trench isolation region; a source structure located in the active region, including a source LDD region and a heavily doped source region; a drain structure located in the active region and spaced apart from the source structure, wherein the drain structure includes a drain LDD region and a heavily doped drain region; a gate structure located on the active region and between the source structure and the drain structure; and a first embedded epitaxial structure disposed in the drain LDD region and located between the gate structure and the heavily doped drain region.