Thin Film Transistor Contact Hole Segmentation for Ion Implantation
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Solution Overview
Problem
The manufacturing process of thin film transistors (TFTs) with a lightly doped drain (LDD) structure faces challenges in achieving efficient ion implantation and contact hole formation, which affects the transistor's performance and manufacturing cost.
Innovation Solution
The process involves forming a semiconductive layer with LDD and HDD regions using poly-silicon materials, followed by ion implantation through specifically designed contact holes with varying cross-sectional shapes to optimize doping concentrations and reduce manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ion implantation methods are used for LDD structure, then doping can be achieved, but the manufacturing process is complex and costly
Solution Approach 1:
The patent combines the formation of LDD and HDD regions into a single ion implantation process by designing contact holes with varying cross-sectional shapes. The contact hole has a first section with a first cross-sectional shape for LDD doping and a second section with a second cross-sectional shape for HDD doping, allowing both doping regions to be created simultaneously through one implantation step, thereby reducing process complexity while maintaining doping efficiency
Solution Approach 2:
The contact hole is segmented into multiple sections with different cross-sectional shapes along its depth. The first section has a shape that allows ion implantation for LDD region formation, while the second section has a different shape for HDD region formation. This segmentation enables selective doping at different depths and locations within the semiconductor layer through a single contact hole structure
2Manufacturing precision
If multiple ion implantation processes are used to form LDD and HDD regions, then doping precision can be achieved, but manufacturing time and cost increase
Solution Approach 1:
The patent merges multiple ion implantation processes into one by using a contact hole with varying cross-sectional shapes. The first section of the contact hole enables precise LDD doping while the second section enables precise HDD doping, both achieved simultaneously through single ion implantation process, thereby maintaining doping precision while improving manufacturing efficiency
Solution Approach 2:
The contact hole structure transitions from a simple cylindrical shape to a complex multi-section shape with varying cross-sectional areas along the depth dimension. This dimensional complexity allows the same contact hole to serve multiple doping functions at different depths and radial positions, enabling precise control of doping concentrations for both LDD and HDD regions in a single process step
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 efficient ion implantation and reduces manufacturing costs by allowing the formation of LDD and HDD regions in a single ion implanting process, improving TFT performance and efficiency.
Implementation Method 1
an ion implanting process is performed to implant ions into a portion of the semiconductive layer
Data Source
AI summary
A thin film transistor (TFT) includes a semiconductive layer, a first inter-layer drain (ILD) layer, a second ILD layer, and at least one contact hole passing through the first ILD layer and the second ILD layer. The semiconductive layer includes a channel region, a first lightly doped drain (LDD) region, a second LDD region, a first heavily doped drain (HDD) region, and a second HDD region. The at least one contact hole includes a first portion passing through the second ILD layer and a second portion passing through the first ILD layer. The second portion gradually narrows along a direction from a top to a bottom of the first ILD layer.