FinFET Height Variation for Current Scaling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing finFETs in integrated circuits face challenges in achieving varying on-state currents while maintaining constant width and pitch configurations, which can lead to increased footprint and difficulty in enhancing current by a fractional amount, such as 50 percent, due to the need for additional fins.
Innovation Solution
The approach involves forming finFETs with fins of different exposed heights, where the gates extend down the sidewalls, allowing for greater effective channel widths and increased on-state currents in some finFETs compared to others, while maintaining uniform fin and gate widths and pitches, thereby optimizing circuit density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If additional fins are added to increase on-state current, then on-state current increases, but footprint increases
Solution Approach 1:
The patent applies dimensionality change by varying the vertical height of fins while maintaining constant planar footprint. Specifically, different fin heights (e.g., 50nm, 75nm, 100nm) are formed within the same lateral space, allowing on-state current to be adjusted by 50% or more without increasing the device footprint. This vertical dimension exploitation resolves the contradiction between increasing current and maintaining compact area.
Solution Approach 2:
The patent changes the physical parameter of fin height to control on-state current. By forming fins with different heights using selective etching or deposition processes, the effective channel width is modified, thereby adjusting the current-carrying capacity. This parameter change approach allows fractional current increases (e.g., 50%) without adding integral numbers of fins, solving both the current enhancement and footprint constraints.
2Power
If fins are added in integral numbers to increase on-state current, then on-state current increases, but it is difficult to achieve fractional increases such as 50 percent
Solution Approach 1:
The patent enables continuous current adjustment by changing the fin height parameter rather than adding discrete fins. Fin heights can be varied in continuous steps (e.g., 50nm, 75nm, 100nm), allowing precise control of on-state current at fractional increments like 50%. This parameter-based control provides fine-grained adaptability for different circuit requirements without being constrained to integral fin additions.
Solution Approach 2:
The patent introduces dynamic adjustability in fin dimensions through multi-step fabrication processes that can selectively modify fin heights. By using techniques such as selective chemical mechanical polishing (CMP) or targeted deposition, the fin structure can be dynamically adjusted to achieve desired current levels, providing versatility for various circuit applications requiring different current specifications.
Data Source
AI summary
An integrated circuit containing finFETs may be formed with fins extending above isolation oxide. A first finFET and a second finFET have exposed fin heights which are different by at least 25 percent. The exposed fin height is a vertical height of a sidewall of the fin above the isolation oxide. Gates are formed over the fins. In one version, a fin height of the first finFET is less than a fin height of the second finFET; a thickness of the isolation oxide adjacent to fins of the first finFET and the second finFET is substantially uniform. The fin height is the height of a top of the fin above the substrate. In another version, the isolation oxide is thinner at the first finFET than at the second finFET; the fin heights of the first finFET and the second finFET are substantially equal.