LTPS TFT Single Mask Doping Process
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Solution Overview
Problem
The existing LTPS TFT manufacturing process requires two separate mask processes for heavy and light doped areas in the source and drain, leading to high costs and prolonged manufacturing times.
Innovation Solution
A method involving the formation of semiconductor and LTPS layers on a base layer, with oxide layers and cobalt layers, and sequential doping using ion implantation, followed by an ashing process to reduce photoresist thickness, allowing for single masking and reduced manufacturing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two separate mask processes are used for heavy and light doped areas in source and drain, then doping precision is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent merges the heavy doping and light doping mask processes into a single mask step. By forming a unified mask pattern that defines both the lightly doped drain region and the heavily doped source/drain region simultaneously, the process eliminates the need for sequential masking operations, thereby reducing manufacturing time while maintaining doping precision through carefully designed mask geometry and doping sequence
Solution Approach 2:
The patent performs preliminary actions by first forming the mask pattern before any doping operations, and by conducting light doping before heavy doping. This sequence allows the single mask to serve both purposes: it protects the lightly doped drain region during light doping, and subsequently protects the source/drain regions during heavy doping after the mask is removed and re-formed or after selective doping through the same mask structure
2Manufacturing precision
If two separate mask processes are used for heavy and light doped areas in source and drain, then doping precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the heavy doping and light doping mask processes into a single mask step. By forming a unified mask pattern that defines both the lightly doped drain region and the heavily doped source/drain region simultaneously, the process eliminates the need for sequential masking operations, thereby reducing manufacturing time while maintaining doping precision through carefully designed mask geometry and doping sequence
Solution Approach 2:
The single mask structure performs multiple functions: it serves as the patterning element for both light doping and heavy doping operations, acts as a protective layer during respective doping steps, and defines the boundaries for both lightly doped and heavily doped regions. This multi-functional mask design simplifies the overall process by eliminating redundant masking steps
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 decreases the number of masking processes and shortens the manufacturing time while maintaining high-resolution and low power consumption capabilities of LTPS TFTs.
Implementation Method 1
doping high-concentration doping ions into a first specific area of the semiconductor layer; doping low-concentration doping ions into a second specific area of the semiconductor layer
Implementation Method 2
applying an ashing process to a portion of the first photoresist layers to obtain second photoresist layers of a second predetermined thickness
Data Source
AI summary
The present disclosure discloses a LTPS TFT and the manufacturing method thereof. The method includes: forming a semiconductor layer and a LTPS layer on the same surface on a base layer; forming an oxide layer is formed on one side of the semiconductor layer facing away the base layer, and forming the oxide layer on one side of the LTPS layer facing away the base layer; forming a first photoresist layer of a first predetermined thickness on the oxide layer; arranging a corresponding first cobalt layer on each of the photoresist layers, a vertical projection of the first cobalt layer overlaps with the vertical projection of the corresponding first photoresist layer; doping high-concentration doping ions into a first specific area of the semiconductor layer. With such configuration, the number of the masking process is decreased and the manufacturing time is reduced.