Gate Insulating Film Additive Stabilization for Threshold Voltage Control
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Solution Overview
Problem
In semiconductor devices, the use of high-dielectric constant metal oxide gate insulating films like HfO2 and ZrO2 with polycrystalline silicon gate electrodes leads to significant fluctuations in threshold voltage, making it difficult to control, and the introduction of additive elements to suppress these fluctuations complicates the manufacturing process and increases costs while potentially decreasing dielectric constant and mobility.
Innovation Solution
A semiconductor device with a gate insulating film containing metal, oxygen, and an additive element from Group 5, 6, 15, or 16 at a concentration of 0.003 to 3 atomic % is used, which stabilizes oxygen and reduces oxygen vacancies, thereby minimizing threshold voltage fluctuations and maintaining dielectric constant without excessive additive element concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high-dielectric constant metal oxide gate insulating films (HfO2, ZrO2) are used with polycrystalline silicon gate electrodes, then leakage current is reduced, but threshold voltage fluctuates significantly
Solution Approach 1:
An intermediate layer containing metal, oxygen, and additive elements from Group 5, 6, 15, or 16 is introduced between the high-dielectric constant metal oxide gate insulating film and the polycrystalline silicon gate electrode. This intermediate layer acts as a mediator that suppresses threshold voltage fluctuations while maintaining the low leakage current characteristics of the metal oxide film.
Solution Approach 2:
The gate insulating film structure is designed as a composite material system combining high-dielectric constant metal oxide (HfO2 or ZrO2) with an intermediate layer containing metal, oxygen, and specific additive elements. This composite structure leverages the low leakage current property of metal oxides while using the intermediate layer to stabilize threshold voltage.
2Reliability
If additive elements are added to suppress threshold voltage fluctuations, then threshold voltage stability improves, but manufacturing process becomes complicated and costs increase
Solution Approach 1:
The concentration of additive elements in the intermediate layer is precisely controlled within specific ranges: Group 5 elements (V, Nb, Ta) at 0.003-3 atomic%, Group 6 elements (Cr, Mo, W) at 0.003-3 atomic%, Group 15 elements (P, As, Sb, Bi) at 0.003-3 atomic%, or Group 16 elements (S, Se, Te) at 0.003-3 atomic%. This parameter optimization achieves threshold voltage stability while avoiding excessive process complexity.
Solution Approach 2:
The intermediate layer serves multiple functions simultaneously: it suppresses threshold voltage fluctuations, maintains dielectric constant, and can be formed using existing manufacturing processes like CVD or sputtering, avoiding the need for entirely new fabrication methods.
3Reliability
If high concentration of additive element is added to achieve low threshold voltage, then threshold voltage decreases, but dielectric constant decreases and electron mobility decreases
Solution Approach 1:
The concentration of additive elements is precisely controlled within specific ranges: Group 5 elements (V, Nb, Ta) at 0.003-3 atomic%, Group 6 elements (Cr, Mo, W) at 0.003-3 atomic%, Group 15 elements (P, As, Sb, Bi) at 0.003-3 atomic%, or Group 16 elements (S, Se, Te) at 0.003-3 atomic%. This parameter optimization achieves threshold voltage stability while avoiding excessive process complexity.
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 approach effectively suppresses threshold voltage fluctuations, maintains dielectric constant, and simplifies the manufacturing process by using a controlled concentration of additive elements, thereby preventing device characteristic deterioration and cost increases.
Implementation Method 1
stabilizes oxygen and reduces oxygen vacancies
Implementation Method 2
the diffusion coefficient of an impurity such as boron in such N-containing silicate films is small
Implementation Method 3
formation of a gate insulating film using a material having a relative dielectric constant significantly higher than that of SiO2
Implementation Method 4
an increase in leakage current between a gate and a substrate resulting from direct tunneling of carriers through an insulating film
Data Source
AI summary
It is possible to prevent the deterioration of device characteristic as much as possible. A semiconductor device includes: a semiconductor substrate; a gate insulating film provided above the semiconductor substrate and containing a metal, oxygen and an additive element; a gate electrode provided above the gate insulating film; and source/drain regions provided in the semiconductor substrate on both sides of the gate electrode. The additive element is at least one element selected from elements of Group 5, 6, 15, and 16 at a concentration of 0.003 atomic % or more but 3 atomic % or less.