Topological Insulator Transistor Thickness Control

Solution Overview

Problem

Current semiconductor devices, particularly transistors, face limitations in design improvements, with a need for enhanced performance and efficiency in electronic applications due to the challenges in controlling the properties of topological insulator materials based on their thickness.

Innovation Solution

A tunable gap ultra-thin body transistor is developed using a topological insulator material like Bi2Se3, where the channel layer is formed below the critical thickness to exhibit semiconductor properties, and the source/drain regions are grown above this thickness to have conductive surface states, allowing for efficient electricity flow and reduced contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the channel layer thickness is reduced to improve electrostatic control and suppress short-channel effects, then transistor performance is improved, but the material transitions from semiconductor properties to topological insulator properties with conductive surface states that increase contact resistance

Engineering Contradiction:

Improveelectrostatic controlVSAvoidcontact resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies different thicknesses of the same topological insulator material in different regions: the channel layer is formed with thickness below the critical thickness to maintain semiconductor properties and low contact resistance, while the source/drain regions are formed with thickness above the critical thickness to provide conductive surface states for efficient electricity flow. This local differentiation resolves the contradiction between electrostatic control and contact resistance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the thickness parameter of the topological insulator material to control its electrical properties. By adjusting the thickness below the critical thickness in the channel region, the material exhibits semiconductor properties with a band gap suitable for transistor operation. This parameter change enables the material to transition between different electrical states to resolve the contradiction.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If the channel layer thickness is increased to reduce manufacturing complexity, then fabrication is simplified, but electrostatic control deteriorates and short-channel effects increase

Engineering Contradiction:

Improvefabrication simplicityVSAvoidelectrostatic control

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent utilizes the critical thickness parameter of topological insulator materials to enable simple manufacturing processes. By controlling the deposition thickness below the critical value, the material naturally exhibits semiconductor properties, eliminating the need for complex doping processes. This parameter-based control simplifies fabrication while maintaining excellent electrostatic control and suppressing short-channel effects.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If topological insulator material thickness is controlled below critical thickness to achieve semiconductor properties, then contact resistance is reduced, but the material loses the conductive surface states that enable efficient electricity flow

Engineering Contradiction:

Improvecontact resistanceVSAvoidelectricity flow efficiency

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent applies different thicknesses of the same topological insulator material in different regions: the channel layer is formed with thickness below the critical thickness to maintain semiconductor properties and low contact resistance, while the source/drain regions are formed with thickness above the critical thickness to provide conductive surface states for efficient electricity flow. This local differentiation resolves the contradiction between electrostatic control and contact resistance.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11664218B2Semiconductor device and method

Publication Date: 2023.05.30 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A transistor based on topological insulators is provided. In an embodiment a topological insulator is used to form both the channel as well as the source/drain regions, wherein the channel has a first thickness such that the topological insulator material has properties of a semiconductor material and the source/drain regions have a second thickness such that the topological insulator has properties of a conductive material.