High-k Dielectric Interface Layer for Low-Leakage Semiconductor Stacks
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Solution Overview
Problem
As semiconductor devices become more integrated, the thinning of dielectric layers increases leakage current, and increasing layer thickness to reduce leakage current leads to increased equivalent oxide layer thickness (EOT), limiting capacitance and causing amorphous characteristics and oxygen loss in the dielectric layer.
Innovation Solution
A semiconductor layer stack with an interface control layer containing a leakage blocking material, a dopant material, and a high bandgap material, along with a high work function material, is used to prevent reduction and increase the dielectric constant of the dielectric layer, formed by sequentially stacking materials like ZrO2, Al2O3, and TiO2, and using Atomic Layer Deposition (ALD) to deposit titanium nitride as the top electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the dielectric layer is increased to reduce leakage current, then leakage current is reduced, but the equivalent oxide layer thickness (EOT) increases
Solution Approach 1:
The dielectric layer is formed as a composite structure comprising a first dielectric layer with a first dielectric constant and a second dielectric layer with a second dielectric constant higher than the first. This composite structure enables reduced EOT while maintaining low leakage current by optimizing the combination of different dielectric materials with complementary properties.
Solution Approach 2:
The patent changes the dielectric constant parameter by introducing a second dielectric layer with higher dielectric constant than the first dielectric layer. This parameter change allows achieving lower EOT for the same physical thickness, resolving the contradiction between leakage reduction and EOT minimization.
2Length of moving object
If the thickness of the dielectric layer is decreased to reduce EOT, then EOT is reduced, but leakage current increases
Solution Approach 1:
The composite dielectric structure with layers of different dielectric constants allows achieving low EOT through optimized material combination rather than simply reducing thickness. The first dielectric layer provides leakage blocking while the second high-k dielectric layer maintains capacitance, enabling thin physical thickness with low leakage.
Solution Approach 2:
Different regions of the dielectric layer are assigned different dielectric constants - the first dielectric layer has lower dielectric constant for leakage control, while the second dielectric layer has higher dielectric constant for capacitance maintenance. This local differentiation resolves the contradiction between thickness reduction and leakage prevention.
3Quantity of substance
If the dielectric layer is made thinner to increase capacitance, then capacitance increases, but the dielectric layer becomes amorphous and oxygen loss occurs
Solution Approach 1:
The composite dielectric structure with multiple layers provides structural stability that prevents amorphous transformation even when individual layers are thin. The first dielectric layer acts as a stable base layer that maintains crystallinity, while the second dielectric layer provides high capacitance, enabling thin total thickness without losing structural integrity.
Solution Approach 2:
The first dielectric layer is formed beforehand as a stable crystalline structure that prevents oxygen loss and amorphous transformation in the subsequent thin second dielectric layer. This prior cushioning structure protects the thin dielectric layer from degradation, enabling high capacitance without compromising structural stability.
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 reduces leakage current, decreases equivalent oxide layer thickness, and increases capacitance while preventing reduction of the dielectric layer, enhancing the electrical characteristics of the semiconductor device.
Implementation Method 1
an interface control layer formed between the dielectric layer and the second conductive layer, and including a leakage blocking material
Implementation Method 2
including a dopant material
Implementation Method 3
including a high bandgap material
Implementation Method 4
The interface control layer may further include a high work function material formed between the high bandgap material and the second conductive layer
Implementation Method 5
using Atomic Layer Deposition (ALD) to deposit titanium nitride as the top electrode
Data Source
AI summary
A semiconductor layer stack includes a first conductive layer, a dielectric layer including a high-k material, which is formed on the first conductive layer, a second conductive layer formed on the dielectric layer, and an interface control layer formed between the dielectric layer and the second conductive layer and including a leakage blocking material, a dopant material, a high bandgap material and a high work function material.