FinFET Gate Structure With Mixed Gate Pitch for Alignment Control
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Solution Overview
Problem
As technology nodes shrink, there are challenges in implementing metal gate structures in CMOS fabrication, particularly due to misalignment issues that can cause source/drain regions to short with metal gate structures.
Innovation Solution
The use of FinFET devices with a gate last process, where a metal gate electrode is formed over a fin-like structure, allows for reduced high-temperature processing and the use of high-dielectric-constant gate dielectric layers to mitigate gate leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal gate structures are used in CMOS fabrication, then device performance is improved, but misalignment issues cause source/drain regions to short with metal gate structures
Solution Approach 1:
The source/drain regions are formed before the metal gate structure is deposited. This preliminary formation allows the source/drain regions to be precisely positioned and configured before the gate is added, preventing misalignment issues that would occur if the gate were formed first. The gate is then deposited conformally over the pre-formed source/drain regions and fin structure.
Solution Approach 2:
The patent transitions from planar transistor architecture to three-dimensional FinFET structure. By creating vertical fins that extend from the substrate, the gate can wrap around the fin in multiple dimensions, providing better control over the channel while maintaining precise alignment through conformal deposition processes that follow the three-dimensional topology.
2Productivity
If gate length is decreased to maintain performance with smaller transistors, then device scaling is achieved, but gate leakage increases
Solution Approach 1:
The patent changes the dielectric constant parameter of the gate insulation layer by using high-k materials (such as hafnium oxide, tantalum oxide, or their alloys) instead of traditional silicon dioxide. This parameter change allows the gate insulation to maintain effective electrical isolation even when the physical gate length is reduced for scaling, thereby preventing gate leakage while enabling continued device scaling.
Solution Approach 2:
The gate structure employs composite materials including high-k dielectric layers combined with metal gate electrodes (such as tungsten, titanium nitride, or tantalum nitride). This composite approach provides both the electrical isolation needed to prevent leakage and the conductive properties needed for gate control, while the multi-layer structure allows optimization of each material's specific properties.
Data Source
AI summary
An IC structure includes a plurality of first channel regions and a plurality of second channel regions over a substrate, a plurality of first gate structures traversing the plurality of first channel regions, and a plurality of second gate structures traversing the plurality of second channel regions. The first gate structures have a first gate pitch. The second gate structures have a second gate pitch different than the first gate pitch. The IC structure further includes first gate contact over a first one of the second gate structures. The first gate contact overlaps a location where the first one of the second gate structures traverses across a first one of the second channel regions. The first gate contact further overlaps a location where the first one of the second gate structures traverses across a second one of the second channel regions.