Low-k Channel Isolation Structure for FET RC Delay Reduction
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Solution Overview
Problem
As semiconductor devices scale down, the increased resistance-capacitance (RC) delay due to reduced width of insulating material between adjacent channel structures in field effect transistors (FETs) leads to performance degradation.
Innovation Solution
Implementing channel isolation structures formed of low-k dielectric material, such as boron nitride, with a dielectric constant ranging from 1.9 to 4.5, to reduce parasitic capacitance and RC delay, while maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the width of insulating material between adjacent channel structures is reduced to enable scaling down of FETs, then device density is improved, but resistance-capacitance (RC) delay increases leading to performance degradation
Solution Approach 1:
The patent changes the dielectric constant parameter of the insulating material from conventional values (k>3.9) to low-k values (k<3.9, specifically 2.5<k<3.9). This parameter change reduces parasitic capacitance between adjacent channel structures, thereby reducing RC delay even when the insulating material width is reduced for scaling, thus resolving the contradiction between improved device density and increased RC delay
Solution Approach 2:
The patent employs composite material structures including low-k dielectric materials combined with specific deposition techniques (CVD, PECVD, ALD) and material compositions (silicon oxide, silicon oxynitride, fluorinated dielectric materials). These composite approaches enable achieving both low dielectric constant for reduced RC delay and sufficient mechanical strength for structural integrity, resolving the contradiction between reduced insulating material width and increased RC delay
2Loss of time
If low-k dielectric material is used to reduce parasitic capacitance and RC delay, then performance is improved, but mechanical strength may be compromised
Solution Approach 1:
The patent uses composite material approaches where low-k dielectric materials are combined with structural reinforcement techniques and specific material compositions. The low-k materials are integrated with underlying and overlying structures that provide mechanical support, enabling the low-k material to fulfill its electrical isolation function without compromising overall structural strength
Solution Approach 2:
The patent applies low-k dielectric materials specifically in regions where electrical isolation is most critical (between adjacent channel structures), while maintaining conventional materials or alternative structures in regions where mechanical strength is paramount. This localized application of low-k materials optimizes the balance between reducing parasitic capacitance and maintaining structural integrity
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
Significantly reduces RC delay and parasitic capacitance, enhancing the performance of FETs by improving the isolation between channel structures without compromising structural integrity.
Implementation Method 1
resistance-capacitance (RC) delay resulted from the insulating material and conductive features at opposite sides of the insulating material is accordingly increased
Data Source
AI summary
A semiconductor device having a low-k isolation structure and a method for forming the same are provided. The semiconductor device includes channel structures, laterally extending on a substrate; gate structures, intersecting and covering the channel structures; and a channel isolation structure, laterally penetrating through at least one of the channel structures, and extending between separate sections of one of the gate structures along an extending direction of the one of the gate structures. A low-k dielectric material in the channel isolation structure comprises boron nitride.