Rare Earth Oxide Isolation Layer for GAA Source/Drain Separation
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Solution Overview
Problem
As semiconductor devices scale down, the increased circuit complexity and reduced reliability due to merged source/drain regions over isolation layers in GAA and finFETs pose challenges in maintaining performance and design simplicity.
Innovation Solution
Incorporating a rare earth metal oxide layer on the top portion of the isolation layer to protect it from etching during source/drain region formation, either through rare earth metal implantation or deposition, which prevents the merging of source/drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If source/drain regions are formed during scaling down, then device density increases, but source/drain regions merge over isolation layers causing circuit complexity and reliability issues
Solution Approach 1:
A rare earth metal oxide layer is introduced as an intermediary protective layer between the isolation layer and the etching process. This layer prevents direct contact between the etchant and the isolation layer, thereby preventing source/drain region merging while allowing the formation process to continue
Solution Approach 2:
The rare earth metal oxide layer is formed on the isolation layer before the source/drain region formation process. This preliminary protective coating is applied in advance to prevent the harmful merging effect that would otherwise occur during subsequent etching operations
2Productivity
If source/drain regions are formed during scaling down, then device density increases, but reliability decreases due to merged regions
Solution Approach 1:
The rare earth metal oxide layer serves as a protective intermediary that maintains the integrity of the isolation layer during source/drain formation. This prevents merging of source/drain regions and maintains device reliability while allowing continued scaling for higher density
Solution Approach 2:
The rare earth metal oxide layer is applied beforehand to cushion and protect the isolation layer from the harmful effects of the etching process. This pre-protective measure ensures that the isolation layer remains intact and prevents reliability degradation from merged regions
3Reliability
If rare earth metal oxide layer is added to prevent merging, then reliability improves, but device complexity increases
Solution Approach 1:
The rare earth metal oxide layer is applied locally only where needed - specifically on the isolation layer in regions where source/drain formation occurs. This localized application provides protection without adding complexity to the entire device structure
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 rare earth metal oxide layer reduces circuit complexity and enhances device performance and reliability by preventing the merging of source/drain regions, thereby maintaining design simplicity and performance.
Implementation Method 1
implanting a rare earth metal into a top portion of the isolation layer to form a rare earth metal oxide layer
Data Source
AI summary
The present disclosure describes a semiconductor device with a rare earth metal oxide layer and a method for forming the same. The method includes forming fin structures on a substrate and forming superlattice structures on the fin structures, where each of the superlattice structures includes a first-type nanostructured layer and a second-type nanostructured layer. The method further includes forming an isolation layer between the superlattice structures, implanting a rare earth metal into a top portion of the isolation layer to form a rare earth metal oxide layer, and forming a polysilicon structure over the superlattice structures. The method further includes etching portions of the superlattice structures adjacent to the polysilicon structure to form a source/drain (S/D) opening and forming an S/D region in the S/D opening.