LTPS TFT Single-Step Ion Implantation for Doping Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for manufacturing LTPS TFTs are complex and costly due to the need for two mask processes and double ion injection steps for forming heavily and lightly doped layers.
Innovation Solution
A method that simplifies the process by using a single mask step and a single ion injection step to form both heavily and lightly doped layers, with a specific structure of the poly-Si layer and gate insulation layer that allows for efficient contact between the source and drain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two mask processes and double ion injection steps are used to form heavily and lightly doped layers, then the doping precision and reliability are improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent combines two separate mask processes and double ion injection steps into a single integrated process. A multi-layer gate insulation structure is formed with different thicknesses, and a single ion injection step simultaneously creates both heavily doped regions (where the ion beam passes through thinner portions) and lightly doped regions (where the ion beam passes through thicker portions). This merging of processes reduces manufacturing complexity while maintaining doping precision through the structural design of the gate insulation layer.
2Manufacturing precision
If two mask processes are used to form heavily and lightly doped regions, then the doping distribution control is improved, but the production time and cost increase
Solution Approach 1:
The patent performs preliminary action by pre-forming a gate insulation layer with spatially varying thickness before the ion injection step. The gate insulation layer is designed with thicker and thinner regions in advance, so that when ion injection is performed, the doping distribution is automatically controlled by the thickness pattern. This preliminary structural preparation enables precise doping distribution control in a single step, eliminating the need for sequential mask processes and improving production efficiency.
3Reliability
If double ion injection is performed to form heavily and lightly doped layers, then the electrical performance is improved, but the manufacturing cost and process time increase
Solution Approach 1:
The patent applies local quality by creating spatial variations in the gate insulation layer thickness, where different regions have different thicknesses tailored to produce specific doping characteristics. Thinner regions allow higher ion transmission for heavily doped areas, while thicker regions provide lower ion transmission for lightly doped areas. This local structural differentiation enables the formation of both heavily and lightly doped regions in a single ion injection step, maintaining electrical performance while reducing process complexity.
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 method and reduces costs by integrating the formation of doped layers into a single step, enhancing the efficiency and cost-effectiveness of the LTPS TFT production.
Implementation Method 1
injecting ions twice for forming heavily doped layer and lightly doped layer
Data Source
AI summary
A LTPS TFT (Lower Temperature Polycrystal Silicon thin film transistor) is provided. The LTPS TFT includes substrate, poly-Si layer, gate insulation layer, grid, layer insulation layer, first through hole, second through hole, source and drain. The poly-Si layer includes an undoped layer, a heavily doped layers and a lightly doped layer. The gate insulation layer includes a first layer, a second layer and third layer respectively corresponding to undoped layer, lightly doped layer and third layer. The thickness of second layer is greater than sum of a thickness of first layer and third layer. A manufacture method of LTPS TFT and OLED display device are also provided in invention. The LTPS TFT of this invention has simplify manufacture method and low cost.