Multi-Height Fin FETs for Granular On-Current Control
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Solution Overview
Problem
Conventional semiconductor fin devices have fixed fin heights, limiting incremental adjustments in output, as the on-current is digitally controlled by the number of fins, resulting in quantized output and difficulty in achieving incremental adjustments less than a single fin's output.
Innovation Solution
The method involves forming semiconductor fins with different channel heights by depositing a dielectric material anisotropically on a substrate, patterning it to surround only some fins, and forming gate structures across both types of fins, allowing for fin field effect transistors with varying channel heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the height of semiconductor fins is fixed and the number of fins is used to control output, then the device structure is simple and easy to manufacture, but the output control becomes quantized and incremental adjustments less than a single fin's output are difficult to achieve
Solution Approach 1:
The patent transitions from controlling output by varying the number of fins (zero-dimensional counting) to varying the height of fins (one-dimensional continuous parameter). This dimensional change enables continuous output control while maintaining simple manufacturing processes, as fin height can be adjusted incrementally during the deposition process.
Solution Approach 2:
The patent changes the physical parameter of fin height from a fixed value to a variable parameter. By allowing fin height to vary across different regions of the substrate, the patent achieves continuous output control without complicating the manufacturing process, directly resolving the contradiction between ease of manufacture and output control granularity.
2Adaptability or versatility
If semiconductor fins have different channel heights, then finer granularity in on-current adjustments is achieved, but the device structure and manufacturing process become more complex
Solution Approach 1:
The patent segments the substrate into different regions with different fin heights, allowing independent control of output in each region. This segmentation approach enables fine-grained output control while keeping each local fin structure simple and easy to manufacture, reducing overall device complexity.
Solution Approach 2:
The patent creates a multi-functional fin structure where fins can serve different functions (different channel heights) within the same device architecture. This universality allows a single fin-based structure to provide both simple operation and fine output control, avoiding the need for completely different device designs.
3Adaptability or versatility
If semiconductor fins have different channel heights, then incremental adjustment of output is improved, but the manufacturing process requires additional steps
Solution Approach 1:
The patent performs preliminary patterning of the substrate into different regions before fin formation. This preliminary action allows subsequent fin deposition to create different heights in different regions in a single step, improving manufacturing efficiency by avoiding multiple deposition cycles.
Solution Approach 2:
The patent uses an intermediary masking or patterning layer to define regions of different fin heights. This intermediary structure enables the deposition process to selectively form fins of different heights without requiring complex direct control, thereby maintaining manufacturing efficiency while achieving fine output control.
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 enables finer granularity in on-current adjustments and output control, overcoming the limitations of fixed fin heights by allowing for different channel heights in fin field effect transistors.
Implementation Method 1
A dielectric material is deposited on the top surfaces of the semiconductor fins and the substrate by an anisotropic deposition
Data Source
AI summary
Semiconductor fins are formed on a top surface of a substrate. A dielectric material is deposited on the top surfaces of the semiconductor fins and the substrate by an anisotropic deposition. A dielectric material layer on the top surface of the substrate is patterned so that the remaining portion of the dielectric material layer laterally surrounds each bottom portion of at least one semiconductor fin, while not contacting at least one second semiconductor fin. Dielectric material portions on the top surfaces of the semiconductor fins may be optionally removed. Each first semiconductor fin has a lesser channel height than the at least one second semiconductor fin. The first and second semiconductor fins can be employed to provide fin field effect transistors having different channel heights.