Self-Aligned TFT Manufacturing via Photopolymerization
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Solution Overview
Problem
The conventional manufacturing process of thin film transistors (TFTs) using photolithography requires multiple steps, increasing costs and complexity, especially when dealing with large substrates, and lacks a self-aligned method for forming electrode layers, leading to potential misalignment issues.
Innovation Solution
A method involving an organic layer with photopolymerizable reactive groups that becomes insoluble to specific solvents upon light irradiation is used, combined with a gate insulating layer containing inorganic material, to control wettability differences, allowing for self-aligned formation of source and drain electrode layers through selective polymerization and droplet discharging, reducing the number of photolithography steps and enhancing productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography technique is used to form patterns, then pattern transfer can be achieved, but the number of manufacturing steps increases and manufacturing cost increases
Solution Approach 1:
The patent combines multiple photolithography steps into a single step by using a resin composition that contains both positive and negative photoresist properties. This dual-function resin allows simultaneous formation of different pattern regions from one coating and exposure process, eliminating the need for separate positive and negative resist applications and reducing the total number of manufacturing steps while maintaining pattern transfer accuracy
Solution Approach 2:
The resin composition is designed to serve multiple functions: it acts as both positive and negative photoresist, provides self-alignment through differential solubility, and enables multi-layer patterning. This universal material replaces multiple specialized resist materials and processing steps, reducing device complexity while preserving manufacturing precision
2Manufacturing precision
If multiple photolithography steps are used, then complex patterns can be formed, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple photolithography operations into a single processing step by using a dual-function resin composition. This allows complex patterns requiring both positive and negative resist processing to be formed in one go, significantly reducing manufacturing cost while maintaining the ability to create complex pattern geometries through the resin's differential solubility characteristics
Solution Approach 2:
The patent changes the chemical parameters of the resin composition to achieve both positive and negative photoresist behavior. By adjusting the molecular structure and solubility properties of the resin, the material responds differently to various developers and processing conditions, enabling complex pattern formation without requiring multiple separate photolithography steps, thus reducing manufacturing cost
3Ease of manufacture
If photolithography steps are reduced, then manufacturing cost decreases, but alignment precision between layers may worsen
Solution Approach 1:
The patent employs self-alignment mechanisms where the resin composition automatically positions patterns correctly through differential solubility and selective etching. The resin's inherent properties cause it to self-organize and align with underlying structures during processing, eliminating the need for separate alignment steps. This self-service approach maintains high alignment precision while reducing the number of photolithography steps and manufacturing cost
Solution Approach 2:
The resin composition exhibits different local properties in different regions, with areas having different solubility characteristics that respond differently to developers and etchants. This local quality variation enables precise local alignment and pattern definition without requiring global alignment steps, maintaining manufacturing precision while reducing overall process complexity and cost
4Manufacturing precision
If conventional resist masks are used, then patterns can be formed, but material waste increases due to single-use masks
Solution Approach 1:
The patent enables recovery and reuse of the resin mask material through its differential solubility properties. After serving its patterning function, the resin can be selectively removed or retained in different regions, allowing the same material to be reused for subsequent patterning steps. This reduces resist material waste while maintaining pattern formation accuracy through the resin's consistent photoreactive properties
Solution Approach 2:
The resin composition serves multiple functions throughout the manufacturing process: it acts as the patterning agent, the protective mask, and the alignment reference. This multi-functionality eliminates the need for separate single-use masks for each patterning step, reducing material waste while maintaining precise pattern formation through the resin's consistent and reliable photoreactive behavior across multiple processing stages
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 simplifies the manufacturing process, reduces costs, and ensures high-yield production of reliable semiconductor and display devices by eliminating misalignment defects and minimizing material waste, while enabling efficient formation of electrode layers on large substrates.
Implementation Method 1
an organic layer containing a photopolymerizable reactive group which becomes insoluble to a specific solvent (such as an organic solvent) by light irradiation is used and the organic layer containing a photopolymerizable reactive group is selectively polymerized to be processed into a desired shape by rear light-exposure
Implementation Method 2
Difference in adsorption property for a liquid repellent between a gate insulating layer containing an inorganic material and the organic polymer layer are utilized to make wettability of the gate insulating layer and that of the organic polymer layer be different from each other
Data Source
AI summary
A method of manufacturing a semiconductor device includes steps of forming a gate electrode over a light-transmitting substrate, forming a gate insulating layer containing an inorganic material over the gate electrode and the substrate, forming an organic layer containing a photopolymerizable reactive group over the gate insulating layer, polymerizing selectively the organic layer by irradiating the organic layer with light from back side of the substrate, using the gate electrode as a mask, forming an organic polymer layer by removing a residue of the organic layer, being other than polymerized, forming an organosilane film including a hydrolytic group over the gate insulating layer in a region other than a region in which the organic polymer layer is formed, forming source and drain electrodes by applying a composition containing a conductive material over the organic polymer layer, and forming a semiconductor layer over the gate electrode, the source and drain electrodes.