Gate Cut Trench Profiling for Uniform Metal Gate Isolation
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Solution Overview
Problem
Existing semiconductor manufacturing technologies result in nonuniform critical dimensions of gate isolation structures, leading to variations in metal gate layers, which affect the performance and integration density of non-planar transistor devices.
Innovation Solution
The method involves tuning the conditions of multiple stages of the etching process to form gate cut trenches with uniform critical dimensions, using a combination of anisotropic and isotropic etching to ensure consistent dimensions regardless of the dummy fin dimensions, allowing for uniform gate isolation structures and improved metal gate layer coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to form gate cut trenches, then the manufacturing process is simple, but the critical dimensions of gate isolation structures are nonuniform
Solution Approach 1:
The etching process is divided into multiple stages with different etching conditions. The first stage uses a first etching condition to form an initial gate cut trench, and the second stage uses a second etching condition to complete the trench formation. This segmentation allows each stage to be optimized for specific dimensional control requirements, resulting in uniform critical dimensions of gate isolation structures.
Solution Approach 2:
The patent changes etching parameters between stages, including gas flow rates, radio frequency power, and pressure. Specifically, the first etching condition differs from the second etching condition in these parameters, enabling precise control over the trench formation process and achieving uniform critical dimensions that would not be possible with a single etching condition.
2Manufacturing precision
If dummy fins with varying dimensions are used, then the device layout is flexible, but the metal gate layer coupling becomes nonuniform
Solution Approach 1:
The gate cut trench is formed completely through the dummy fin structure before metal gate layer deposition. This preliminary action ensures that regardless of the dummy fin dimensions, the metal gate layer will be deposited over a uniform trench structure, achieving uniform coupling without requiring all dummy fins to have identical dimensions.
Solution Approach 2:
The gate cut trench acts as an intermediary structure that mediates between the varying dummy fin dimensions and the metal gate layer. By forming a uniform trench through all dummy fins regardless of their original dimensions, the trench serves as a standardized interface that ensures uniform metal gate layer coupling across 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
This approach enables the formation of gate cut trenches with uniform critical dimensions, enhancing the uniformity and performance of metal gate layers, thereby improving the integration density and reliability of non-planar transistor devices.
Implementation Method 1
performing an etching process that includes a plurality of stages, each of the plurality of stages including a combination of anisotropic etching and isotropic etching
Implementation Method 2
performing an etching process that includes a plurality of stages, each of the plurality of stages including a combination of anisotropic etching and isotropic etching
Data Source
AI summary
A method includes forming a first semiconductor fin and a second semiconductor fin over a substrate that both extend along a first direction. The method includes forming a dielectric fin extending along the first direction and is disposed between the first and second semiconductor fins. The method includes forming a dummy gate structure extending along a second direction and straddling the first and second semiconductor fins and the dielectric fin. The method includes removing a portion of the dummy gate structure over the dielectric fin to form a trench by performing an etching process that includes a plurality of stages. Each of the plurality of stages includes a combination of anisotropic etching and isotropic etching such that a variation of a distance between respective inner sidewalls of the trench along the second direction is within a threshold.