Thin Film Transistor with Lightly Doped Region for Leakage Current Reduction

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Solution Overview

Problem

Thin film transistors in liquid crystal displays experience significant leakage current, leading to display gray scale deviations and increased energy consumption, which existing manufacturing methods fail to adequately address.

Innovation Solution

A manufacturing method for thin film transistors that includes forming an active layer with a source ohmic contact region, a drain ohmic contact region, a channel region, and a lightly doped region between the drain and channel, reducing leakage current by concentrating hot carriers near the drain and increasing carrier mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional thin film transistor structure is used, then manufacturing process is simple, but leakage current is too large causing display gray scale deviation and increased energy consumption

Engineering Contradiction:
Improveleakage currentVSAvoidactive layer structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The active layer is segmented into multiple functional regions: source ohmic contact region, drain ohmic contact region, channel region, and lightly doped region. This segmentation allows each region to perform its specific function optimally, with the lightly doped region specifically designed to reduce leakage current while maintaining overall manufacturing feasibility

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the active layer are assigned different doping concentrations and properties: the source and drain regions have high doping for ohmic contact, the channel region has appropriate doping for carrier transport, and the lightly doped region has low doping to reduce leakage. This local differentiation of properties enables the transistor to achieve low leakage current without completely redesigning the entire device structure

Inventive Principle:
Principle #3Local quality

2Reliability

If lightly doped region is added to active layer, then leakage current decreases and on-state current increases, but manufacturing process complexity increases

Engineering Contradiction:
Improvetransistor performanceVSAvoidmanufacturing process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The lightly doped region is formed during the active layer fabrication process itself, before subsequent transistor structure formation. This preliminary action integrates the leakage reduction feature into the base manufacturing flow rather than requiring separate additional processing steps, thereby improving reliability without proportionally increasing manufacturing complexity

Inventive Principle:
Principle #10Preliminary action

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 method effectively decreases leakage current, enhances the on-state current, and improves the overall performance of the thin film transistor, resulting in better comprehensive performance and reduced energy consumption.

Implementation Method 1

increasing carrier mobility

Methodology Applied
Scientific EffectCarrier mobility enhancement:

Implementation Method 2

concentrating hot carriers near the drain

Methodology Applied
Scientific EffectHot carrier concentration:

Data Source

PatentEP3242319B1Thin film transistor and manufacturing method therefor, and array substrate and manufacturing method therefor
Publication Date: 2023.07.19 BOE TECHNOLOGY GROUP CO LTD
  • EP3242319B1 patent drawingFigure 1~2
  • EP3242319B1 patent drawingFigure 3
  • EP3242319B1 patent drawingFigure 4

AI summary

Embodiments of the present invention provide a thin film transistor and a manufacturing method thereof, an array substrate including the thin film transistor, and a manufacturing method of the array substrate, relate to the field of the display technology and can reduce the leakage current of the thin film transistor. The thin film transistor comprises an active layer, a gate insulation layer, a gate, an interlayer insulation layer, a source and a drain formed on a base substrate, the interlayer insulation layer and the gate insulation layer are provided therein with through holes corresponding to the source and the drain; the active layer comprises a source ohmic contact region connected with the source, a drain ohmic contact region connected with the drain, a channel region serving as a channel located below the gate, and a lightly doped region between the drain ohmic contact region and the channel region, or the active layer comprises a source ohmic contact region connected with the source, a drain ohmic contact region connected with the drain, a channel region serving as a channel located below the gate, and two lightly doped regions located between the drain ohmic contact region and the channel region and between the source ohmic contact region and the channel region respectively.