Low-k Gate Spacer Structures for Stray Capacitance Reduction
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Solution Overview
Problem
As semiconductor technology advances to smaller geometries, stray capacitance between gate structures and source/drain contacts in field effect transistors increases, posing challenges for switching speed, power consumption, and coupling noise, despite existing low-k materials not fully addressing these issues.
Innovation Solution
The implementation of low-k gate spacer structures made of materials like silicon oxide, which surround gate stacks and reduce the dielectric constant between the gate and source/drain contacts, thereby lowering stray capacitance and interface stress, improving channel carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-k materials are used as insulator materials surrounding gate structures, then stray capacitance is reduced, but switching speed and channel carrier mobility are not sufficiently improved
Solution Approach 1:
The patent changes the dielectric constant parameter of the gate spacer material from conventional high-k materials (such as silicon nitride with k≈7.5) to low-k materials (such as silicon oxide with k≈3.9). This parameter change directly reduces the stray capacitance between the gate structure and source/drain contacts, thereby improving switching speed and reducing power consumption.
Solution Approach 2:
The patent employs composite material structures where low-k materials (silicon oxide) are combined with conventional materials (silicon nitride) in specific configurations. The gate spacer consists of a first portion made of low-k material and a second portion made of conventional material, creating a composite structure that optimizes both capacitance reduction and carrier mobility enhancement.
2Productivity
If semiconductor technology scales to smaller geometries, then production efficiency increases, but stray capacitance between gate and source/drain contacts increases
Solution Approach 1:
As transistor dimensions scale down, the patent applies parameter changes by using low-k materials with lower dielectric constants to compensate for the reduced physical distances. The lower dielectric constant reduces the capacitance effect that becomes more pronounced at smaller geometries, maintaining switching performance despite continued scaling.
3Ease of manufacture
If conventional gate spacer materials are used, then manufacturing is simpler, but interface stress increases and channel carrier mobility decreases
Solution Approach 1:
The patent changes the material parameter from silicon nitride to silicon oxide for the gate spacer, which has different mechanical properties. Silicon oxide provides a better match to the semiconductor channel material, reducing interface stress and improving carrier mobility while remaining compatible with existing manufacturing processes.
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
The use of low-k gate spacer structures effectively decreases stray capacitance and interface stress, enhancing switching speed, reducing power consumption, and improving channel carrier mobility in semiconductor devices.
Implementation Method 1
low-k gate spacer structures made of materials like silicon oxide, which surround gate stacks and reduce the dielectric constant between the gate and source/drain contacts, thereby lowering stray capacitance
Data Source
AI summary
A semiconductor device includes a substrate having a channel region; a gate stack over the channel region; a seal spacer covering a sidewall of the gate stack, the seal spacer including silicon nitride; a gate spacer covering a sidewall of the seal spacer, the gate spacer including silicon oxide, the gate spacer having a first vertical portion and a first horizontal portion; and a first dielectric layer covering a sidewall of the gate spacer, the first dielectric layer including silicon nitride.