Polysilicon TFT Semiconductor Layer Planarization After Laser Crystallization
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Solution Overview
Problem
Existing display devices with polycrystalline semiconductor layers suffer from protrusions that lead to surface roughness and reduced reliability of transistors.
Innovation Solution
A manufacturing method involving laser-induced crystallization of amorphous silicon to form a polysilicon layer, followed by selective doping with carbon and argon, and controlled etching to reduce protrusions, resulting in a planarized semiconductor layer with improved surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser beams are used to form a polysilicon layer from amorphous silicon, then the semiconductor layer can be formed efficiently, but protrusions are generated on the surface increasing roughness
Solution Approach 1:
A sacrificial layer is formed on the polysilicon layer before doping processes. This sacrificial layer serves as a protective mask during subsequent doping steps, allowing controlled modification of the polysilicon layer without directly affecting the protrusions. The sacrificial layer is later removed to reveal the modified semiconductor layer with reduced surface roughness.
Solution Approach 2:
The patent employs dual doping with different elements (first doping element and second doping element) at different concentrations and depths. By changing the doping parameters (element type, concentration, depth), the physical and chemical properties of the polysilicon layer are modified, causing selective etching that removes protrusions while maintaining the underlying semiconductor structure.
2Manufacturing precision
If protrusions are removed from the polysilicon layer, then surface roughness is reduced, but additional manufacturing steps are required
Solution Approach 1:
The patent combines multiple functions into the doping process: the first doping element modifies the polysilicon layer properties, the second doping element creates selective etching characteristics, and the sacrificial layer protects during processing. These combined actions achieve protrusion removal within the existing manufacturing flow without requiring separate dedicated steps.
Solution Approach 2:
The sacrificial layer acts as an intermediary element that facilitates the protrusion removal process. It is introduced temporarily to enable controlled doping and etching, then removed afterward. This intermediary approach allows complex modifications to be achieved through standard processing steps without directly complicating the main manufacturing flow.
3Manufacturing precision
If doping elements are introduced to modify the polysilicon layer, then protrusions can be reduced through selective etching, but the process requires precise control of doping parameters
Solution Approach 1:
The patent applies different doping elements at different locations and depths within the polysilicon layer. The first doping element is introduced at a first depth with a first concentration, while the second doping element is introduced at a second depth with a second concentration. This local differentiation enables selective etching of protrusions while preserving the functional semiconductor regions.
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
The method effectively reduces protrusions, enhancing the reliability and performance of transistors by providing a substantially planarized semiconductor surface with reduced surface roughness.
Implementation Method 1
forming a polysilicon layer by irradiating laser beams on the amorphous silicon layer
Implementation Method 2
laser-induced crystallization of amorphous silicon to form a polysilicon layer
Implementation Method 3
doping a first doping element to a first doping region including an upper region of the polysilicon layer; doping a second doping element to a second doping region on an upper side of the first doping region
Data Source
AI summary
A display device according to an embodiment includes: a substrate; a semiconductor layer on the substrate; a gate electrode that overlaps a portion of the semiconductor layer; and a source electrode and a drain electrode electrically connected to another portion of the semiconductor layer, wherein the semiconductor layer includes a first region including polysilicon, and a second region including polysilicon and a first doping element, and the first region and the second region are provided in a thickness direction of the substrate.