Etch Stop Layer for SiGe FinFET Source/Drain Depth Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor devices is achieving uniform depth for source/drain regions in silicon germanium (SiGe) fin field effect transistors (FinFETs) or multi-gate transistors, as etching SiGe fins is difficult due to varying germanium concentrations, leading to performance deterioration.
Innovation Solution
Incorporating an etch stop layer inside the channel layer to adjust the depth of the source/drain regions, enhancing the uniformity and distribution of these regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching is performed to form source/drain regions in SiGe fins, then the desired depth adjustment is achieved, but variations in etched recess depths occur due to different germanium concentrations
Solution Approach 1:
An etch stop layer is introduced as an intermediary component between the SiGe channel layer and the source/drain region. This layer has a specific germanium concentration (higher than the channel layer) that causes it to selectively stop the etching process. By positioning this etch stop layer at a predetermined depth within the channel layer, the etching process automatically terminates at the desired depth, ensuring uniform source/drain region depths across different regions with varying germanium concentrations.
Solution Approach 2:
The invention changes the germanium concentration parameter to create the etch stop layer. By forming a layer with higher germanium content than the surrounding channel layer, the etch stop layer exhibits different etch characteristics. This parameter change (increasing germanium concentration) creates a selective etch resistance that enables precise depth control of source/drain regions, transforming the harmful etch rate variation into a useful depth-stopping mechanism.
2Productivity
If multi-gate transistors are used to increase device density, then scaling is achieved, but controlling etch depth uniformity becomes more difficult
Solution Approach 1:
In multi-gate transistor structures, the etch stop layer serves as a mediator that ensures uniform etch depth across multiple channels. Each multi-gate transistor contains an etch stop layer within its channel region, which independently stops the etching process at the correct depth. This intermediary layer compensates for variations in germanium concentration across different channels, ensuring that all source/drain regions achieve uniform depth despite the complexity of the multi-gate structure.
Data Source
AI summary
A semiconductor device includes first and second fin-shaped patterns disposed on a substrate and extending in a first direction, first and second channel layers disposed on the first and second fin-shaped patterns, first and second etch stop layers disposed inside the first and second channel layers, first and second gate structures extending in a second direction different from the first direction on the first channel layer with a first recess formed therebetween, third and fourth gate structures extending in the second direction on the second channel layer with a second recess formed therebetween, the first recess having a first width in the first direction and having a first depth in a third direction perpendicular to the first and second directions, the second recess having a second width different from the first width in the first direction, and having a second depth equal to the first depth in the third direction.