Oxide Semiconductor Driver Circuit Hydrogen Concentration Control

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Solution Overview

Problem

Current driver circuits for active matrix display devices require separate manufacturing steps for thin film transistors and resistors, limiting efficiency and increasing complexity due to differences in hydrogen concentration and resistance levels in oxide semiconductor layers.

Innovation Solution

A driver circuit design that incorporates an enhancement-mode thin film transistor and resistor elements formed using an oxide semiconductor layer with controlled hydrogen concentration, where a silicon nitride layer is used to enhance hydrogen introduction in the resistor layer, allowing for a single-step manufacturing process while maintaining lower resistance for the resistor and higher resistance for the transistor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If separate manufacturing steps are used for thin film transistors and resistors, then the required resistance levels can be achieved, but the manufacturing complexity and number of steps increase

Engineering Contradiction:

Improveresistance level controlVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines the manufacturing of thin film transistors and resistors into a single integrated process using oxide semiconductor layers. By forming both transistor channels and resistor elements from the same oxide semiconductor material in one manufacturing step, the process complexity is reduced while maintaining the ability to achieve required resistance levels through selective hydrogen concentration control in different regions

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies local quality by creating different hydrogen concentrations in different regions of the oxide semiconductor layer. The transistor channel region is kept free of hydrogen to maintain high resistance when off, while the resistor region is treated with hydrogen to achieve low resistance, allowing both components to function correctly from a single layered structure

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If hydrogen concentration is increased in oxide semiconductor layer, then resistance decreases for resistor elements, but transistor performance deteriorates due to excessive hydrogen

Engineering Contradiction:

Improveresistance levelVSAvoidtransistor performance

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements local quality by spatially separating hydrogen treatment to different regions: the oxide semiconductor layer forming the transistor channel is protected from hydrogen exposure, while the oxide semiconductor layer forming the resistor is subjected to hydrogen plasma treatment. This allows the resistor to achieve low resistance through hydrogen incorporation while the transistor channel maintains its required electrical characteristics

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses a barrier layer as an intermediary between the hydrogen plasma treatment and the oxide semiconductor layers. This barrier layer is selectively positioned to protect the transistor channel region from hydrogen diffusion while allowing hydrogen to reach the resistor region, thereby mediating the hydrogen distribution to achieve desired resistance levels without compromising transistor performance

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach enables a more efficient and simplified manufacturing process for driver circuits by achieving the necessary resistance levels in oxide semiconductor layers, reducing the number of steps required and improving the dynamic characteristics of the circuit.

Implementation Method 1

a silicon nitride layer formed by plasma CVD using a gas containing a hydrogen compound such as silane (SiH4) and ammonia (NH3) is formed on and in direct contact with the oxide semiconductor layer used for the resistor

Methodology Applied

Scientific EffectHydrogen introduction: Absorption (physical)

Data Source

PatentUS9941310B2Driver circuit with oxide semiconductor layers having varying hydrogen concentrations

Publication Date: 2018.04.10 SEMICON ENERGY LAB CO LTD

AI summary

The silicon nitride layer 910 formed by plasma CVD using a gas containing a hydrogen compound such as silane (SiH4) and ammonia (NH3) is provided on and in direct contact with the oxide semiconductor layer 905 used for the resistor 354, and the silicon nitride layer 910 is provided over the oxide semiconductor layer 906 used for the thin film transistor 355 with the silicon oxide layer 909 serving as a barrier layer interposed therebetween. Therefore, a higher concentration of hydrogen is introduced into the oxide semiconductor layer 905 than into the oxide semiconductor layer 906. As a result, the resistance of the oxide semiconductor layer 905 used for the resistor 354 is made lower than that of the oxide semiconductor layer 906 used for the thin film transistor 355.