LTPS TFT Step-Like Gate Structure for Process Simplification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The conventional manufacturing process for Low Temperature Poly Silicon Thin Film Transistors (LTPS TFTs) with heavily doped source/drain electrode structures is complex due to strong electrical fields causing thermoelectronic effects, which affect stability, and the transition to lightly doped structures increases process complexity with multiple patterning steps.
Innovation Solution
A method involving a single patterning process to form a step-like gate structure, followed by two ion implantation procedures to create heavily and lightly doped areas, simplifying the process and reducing the number of patterning steps required for manufacturing LTPS TFTs with lightly doped source/drain electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing process with multiple patterning steps is used to create lightly doped source/drain electrodes, then doping precision is improved, but device complexity increases
Solution Approach 1:
The gate structure is segmented into two distinct levels: a first gate electrode at a first level and a second gate electrode at a second level. This segmentation allows different doping regions to be formed simultaneously during a single ion implantation process, eliminating the need for multiple patterning steps while maintaining precise doping control.
Solution Approach 2:
The invention introduces a vertical dimension by creating a step-like gate structure with two different levels. The first and second gate electrodes are positioned at different heights, allowing ion implantation to selectively dope regions corresponding to each level in a single process step, thereby simplifying the overall manufacturing process.
2Reliability
If heavily doped source/drain electrode structure is used, then electrical field strength is improved, but thermoelectronic effects increase affecting stability
Solution Approach 1:
Different regions of the source/drain electrodes are assigned different doping concentrations: lightly doped regions adjacent to the channel and heavily doped regions at the source/drain contacts. This local quality variation reduces thermoelectronic effects near the channel while maintaining strong electrical fields at the contacts, thereby improving electrical stability.
Solution Approach 2:
The doping concentration parameter is varied across different regions of the source/drain electrodes. By changing from uniform heavy doping to a gradient structure with light and heavy doped regions, the invention reduces thermoelectronic effects while maintaining necessary electrical field strength for device operation.
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, shortens production time, and improves the stability of the electronic device by alleviating thermoelectronic effects while maintaining the benefits of lightly doped source/drain electrodes.
Implementation Method 1
performing a first ion implantation procedure to form a first heavily doped area and a second heavily doped area; performing a second ion implantation procedure to form a first lightly doped area and a second lightly doped area
Data Source
AI summary
A thin film transistor, its manufacturing method, and a display device are provided. The method comprises: forming a gate metal layer (35), forming a step-like gate structure (352) by one patterning process; performing a first ion implantation procedure to forming a first heavily doped area (39a) and a second heavily doped area (39b), the first heavily doped area (39a) being separated apart from the second heavily doped area (39b) by a first length; forming a gate electrode (353) from the step-like gate structure (352); performing a second ion implantation procedure to form a first lightly doped area (38a) and a second lightly doped area (38b), the first lightly doped area (38a) being separated apart from the second lightly doped area (38b) by a second length less than the first length. By the above method, the process for manufacturing the LTPS TFT having the lightly doped source/drain structure can be simplified.