Composite Spacer Design for Parasitic Capacitance Reduction
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Solution Overview
Problem
Current semiconductor devices face challenges in improving carrier mobility, operating speed, and power consumption due to limitations in the design of active regions and spacers, particularly in reducing parasitic capacitance and enhancing channel width.
Innovation Solution
The semiconductor device incorporates epitaxially grown active regions with silicon germanium (SiGe) and a spacer structure featuring a high dielectric constant upper spacer and a low dielectric constant lower spacer, along with a gate pattern that surrounds channel regions, reducing parasitic capacitance and increasing channel width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single dielectric material is used for the spacer, then the manufacturing process is simple, but the parasitic capacitance cannot be effectively reduced
Solution Approach 1:
The spacer is divided into two distinct segments: a first spacer portion and a second spacer portion, each with different dielectric materials. The first spacer portion has a higher dielectric constant than the second spacer portion. This segmentation allows the spacer to simultaneously provide mechanical support while reducing parasitic capacitance between the gate electrode and source/drain regions, as the lower dielectric constant material in the second portion reduces the capacitive coupling.
Solution Approach 2:
Different regions of the spacer are assigned different dielectric properties to optimize local functions. The first spacer portion (closer to the gate electrode) uses a higher dielectric constant material for better electrical isolation, while the second spacer portion (closer to source/drain) uses a lower dielectric constant material to minimize parasitic capacitance. This local differentiation of material properties resolves the contradiction between isolation effectiveness and parasitic capacitance reduction.
2Speed
If the channel width is increased to improve carrier mobility, then the operating speed improves, but the parasitic capacitance increases
Solution Approach 1:
The dielectric constant parameter of the spacer material is changed along its length, transitioning from a higher dielectric constant in the first portion to a lower dielectric constant in the second portion. This parameter gradient allows the spacer to maintain effective gate control over a wider channel while minimizing the parasitic capacitance that would otherwise increase with channel width, thus enabling improved operating speed without proportional increases in parasitic capacitance.
3Reliability
If the spacer height is increased to improve gate control, then the gate control improves, but the parasitic capacitance increases
Solution Approach 1:
The spacer is segmented into vertical portions with different dielectric materials. The first spacer portion (typically the lower portion closer to the gate electrode) has a higher dielectric constant to provide strong gate control, while the second spacer portion (the upper portion closer to source/drain) has a lower dielectric constant to reduce parasitic capacitance. This vertical segmentation allows the spacer to simultaneously achieve good gate control and low parasitic capacitance.
Solution Approach 2:
Different vertical regions of the spacer are assigned different dielectric qualities optimized for their specific functions. The region closer to the gate electrode uses high dielectric constant material for maximum gate control, while regions farther away use lower dielectric constant material to minimize capacitive coupling with source/drain regions, resolving the contradiction between gate control and parasitic capacitance.
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 configuration enhances carrier mobility, reduces power consumption, and improves the operating speed of the semiconductor device by minimizing parasitic capacitance and increasing the channel width, resulting in improved transistor performance.
Implementation Method 1
a first electrically insulating spacer is provided on a sidewall of the electrically conductive pattern... The first upper spacer has a greater dielectric constant relative to a dielectric constant of the first lower spacer
Implementation Method 2
The active regions of the semiconductor device may be formed by selective epitaxially grown process
Data Source
AI summary
An integrated circuit device includes an electrically conductive pattern on a substrate. This electrically conductive pattern may be a gate pattern of a field effect transistor. A first electrically insulating spacer is provided on a sidewall of the electrically conductive pattern. The first electrically insulating spacer includes a first lower spacer and a first upper spacer, which extends on the first lower spacer and has a side surface vertically aligned with a corresponding side surface of the first lower spacer. The first upper spacer has a greater dielectric constant relative to a dielectric constant of the first lower spacer. A pair of parallel channel regions may also be provided, which protrude from a surface of the substrate. The electrically conductive pattern may surround top and side surfaces of the pair of parallel channel regions.