Copper Pixel Electrode Adhesion via Molybdenum Oxide Barrier
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Solution Overview
Problem
Copper electrodes in TFT-LCD pixel structures face issues such as oxidation, corrosion, and poor adhesion due to reactive gases during manufacturing processes, leading to peeling off or bubble formation, which affects the reliability and performance of the display panels.
Innovation Solution
A pixel structure design where a semiconductor layer acts as a buffer for the copper or copper alloy metal layer and barrier layer, preventing damage from reactive gases during subsequent processes, such as CVD, by positioning the metal and barrier layers within the semiconductor's projection area and using a passivation layer to maintain adhesion and prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used as electrode material to reduce resistivity and improve conductivity, then electrical performance is improved, but adhesion to substrate deteriorates and oxidation/corrosion resistance worsens
Solution Approach 1:
The patent uses a composite structure consisting of a copper layer combined with a molybdenum oxide barrier layer. The copper provides low resistivity and high conductivity, while the molybdenum oxide layer provides adhesion promotion and oxidation resistance. This composite material approach allows simultaneous achievement of electrical performance and mechanical strength requirements.
Solution Approach 2:
The molybdenum oxide layer serves as an intermediary between the copper electrode and the substrate/dielectric layer. It mediates the interaction by providing adhesion promotion and preventing direct contact between copper and reactive gases, thereby solving both adhesion and oxidation problems while maintaining copper's electrical benefits.
2Reliability
If copper lines are used to minimize RC delay and reduce electrostatic capacity, then signal transmission performance is improved, but susceptibility to oxidation and corrosion from reactive gases worsens
Solution Approach 1:
The molybdenum oxide barrier layer creates an inert protective environment for the copper electrode, preventing direct exposure to reactive gases during manufacturing processes. This barrier effectively isolates the copper from harmful oxidation and corrosion, maintaining signal transmission performance without compromising against environmental degradation.
Solution Approach 2:
The composite structure of copper combined with molybdenum oxide provides both the electrical performance needed for signal transmission and the chemical resistance required to withstand reactive gases in manufacturing processes.
3Strength
If copper oxide barrier layer is disposed between copper layer and dielectric layer to prevent copper diffusion, then adhesion is improved, but peeling off and bubble formation occur due to reduction by reactive gases in subsequent processes
Solution Approach 1:
The patent changes the chemical parameter of the barrier layer from copper oxide to molybdenum oxide. Molybdenum oxide has higher chemical stability and resistance to reduction by reactive gases compared to copper oxide. This parameter change maintains adhesion promotion while preventing the reduction reactions that cause peeling and bubble formation.
Solution Approach 2:
The molybdenum oxide barrier layer serves as a sacrificial protective layer that can withstand the harsh manufacturing environment without being reduced or damaged. It maintains its protective function throughout the manufacturing process, preventing copper diffusion and promoting adhesion without suffering from the reduction issues that plague copper oxide barriers.
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 semiconductor layer effectively protects the copper or copper alloy metal layer and barrier layer from damage, ensuring stable adhesion and preventing peeling or bubble formation, thereby enhancing the performance and reliability of the pixel structure and TFT devices.
Implementation Method 1
The semiconductor layer effectively protects the copper or copper alloy metal layer and barrier layer from damage
Implementation Method 2
using a passivation layer to maintain adhesion and prevent peeling
Data Source
AI summary
A pixel structure disposed on a substrate including a thin film transistor (TFT), a bottom capacitor electrode, a dielectric layer, an upper capacitor electrode, a passivation layer, and a pixel electrode is provided. The TFT having a source/drain and the bottom capacitor electrode are disposed on the substrate. The dielectric layer is disposed on the bottom capacitor electrode. The upper capacitor electrode has a semiconductor layer, a barrier layer, and a metal layer. The semiconductor layer is disposed on the dielectric layer above the bottom capacitor electrode. The barrier layer is disposed on the semiconductor layer. The metal layer whose material includes copper, a copper alloy, or a combination thereof is disposed on the barrier layer. The passivation layer covers the TFT and the upper capacitor electrode and has a first opening exposing the source/drain. The pixel electrode is electrically connected to the TFT through the first opening.