Rare-earth oxide isolated semiconductor fin structure
Solution Overview
Problem
FinFETs on bulk substrates suffer from poor electrical isolation among adjacent devices, leading to performance degradation due to leakage paths, while semiconductor-on-insulator substrates are costly to manufacture.
Innovation Solution
A semiconductor structure is formed with a stack of a rare-earth oxide fin portion and a semiconductor fin portion, where a dielectric template layer is deposited on a substrate, and line trenches are etched to create a dielectric material layer providing lateral electrical isolation, with the rare-earth oxide and semiconductor materials being epitaxially deposited within these trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If finFETs are formed on a bulk substrate, then manufacturing cost is reduced, but electrical isolation among adjacent devices deteriorates
Solution Approach 1:
The substrate is segmented into isolated fin structures by introducing dielectric material layers between adjacent fins. This segmentation divides the continuous bulk substrate into electrically isolated regions, preventing leakage paths while maintaining bulk substrate cost advantages.
Solution Approach 2:
A dielectric material layer is introduced as an intermediary between adjacent fin structures. This intermediate layer acts as an electrical barrier that blocks leakage currents while allowing the fins to be formed on a bulk substrate, thus resolving the isolation problem without requiring expensive SOI substrates.
2Reliability
If finFETs are formed on a semiconductor-on-insulator substrate, then electrical isolation among devices is improved, but manufacturing cost increases
Solution Approach 1:
Instead of using expensive semiconductor-on-insulator substrates, the invention uses a bulk substrate with selectively deposited dielectric material layers. This approach replaces the costly SOI substrate with a more economical bulk substrate combined with localized dielectric isolation structures.
Solution Approach 2:
Dielectric material is deposited locally between adjacent fin structures rather than throughout the entire substrate. This localized approach provides electrical isolation only where needed between devices, reducing material costs while maintaining effective isolation.
3Reliability
If a dielectric material layer is deposited between adjacent fins, then electrical isolation is enhanced, but device complexity increases
Solution Approach 1:
The dielectric material layer serves multiple functions: it provides electrical isolation between adjacent fins, acts as a barrier to leakage currents, and maintains structural integrity of the fin array. This multi-functionality reduces the need for additional specialized components.
Solution Approach 2:
The dielectric material deposition is combined with the existing fin formation process sequence. The dielectric layer is deposited as part of the overall device fabrication flow, merging the isolation function with the structural formation steps rather than requiring separate complex isolation processing.
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 enhances electrical isolation among fin structures, improving device performance without the high manufacturing costs associated with semiconductor-on-insulator substrates.
Implementation Method 1
A lower portion of each line trench is filled with an epitaxial rare-earth oxide material by a selective rare-earth oxide epitaxy process
Implementation Method 2
A lower portion of each line trench is filled with an epitaxial rare-earth oxide material by a selective rare-earth oxide epitaxy process
Implementation Method 3
An upper portion of each line trench is filled with an epitaxial semiconductor material by a selective semiconductor epitaxy process
Implementation Method 4
Line trenches are formed within the dielectric template layer by an anisotropic etch that employs a patterned mask layer
Data Source
AI summary
A dielectric template layer is deposited on a substrate. Line trenches are formed within the dielectric template layer by an anisotropic etch that employs a patterned mask layer. The patterned mask layer can be a patterned photoresist layer, or a patterned hard mask layer that is formed by other image transfer methods. A lower portion of each line trench is filled with an epitaxial rare-earth oxide material by a selective rare-earth oxide epitaxy process. An upper portion of each line trench is filled with an epitaxial semiconductor material by a selective semiconductor epitaxy process. The dielectric template layer is recessed to form a dielectric material layer that provides lateral electrical isolation among fin structures, each of which includes a stack of a rare-earth oxide fin portion and a semiconductor fin portion.