Display Substrate Active Layer Carrier Concentration Design
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Solution Overview
Problem
The existing manufacturing processes for display devices require multiple mask steps, leading to increased costs and the risk of unintended layer overlap, which can result in parasitic capacitance and RC delay, thereby decreasing display quality.
Innovation Solution
A substrate design with an active layer having areas of varying carrier concentrations, where a contact electrode electrically connects the line to the active layer through strategically formed openings in insulating layers, reducing the need for additional mask steps and minimizing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple mask steps are used to transfer patterns, then pattern formation precision is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines multiple mask steps into a single mask process by designing the active layer pattern to be formed together with the transistor pattern. The active layer is patterned using the same mask that defines the transistor structures, eliminating the need for separate mask steps and reducing manufacturing complexity while maintaining pattern precision.
Solution Approach 2:
The single mask used in the invention serves multiple functions: it defines the transistor patterns (source, drain, gate) and simultaneously patterns the active layer. This multi-functional mask approach reduces the total number of mask steps required while ensuring consistent pattern formation across different structures.
2Object-affected harmful factors
If additional mask steps are added to prevent layer overlap, then parasitic capacitance is reduced, but manufacturing cost and complexity increase
Solution Approach 1:
The patent performs preliminary action by strategically positioning the active layer pattern during the initial mask step, before subsequent processing steps. The active layer is pre-patterned to avoid overlap with conductive lines in critical areas, preventing parasitic capacitance formation from the outset without requiring additional corrective mask steps.
Solution Approach 2:
The invention applies local quality by creating regions of different carrier concentration within the active layer. The active layer has high carrier concentration regions (for electrical connection) and low carrier concentration regions (for reducing parasitic capacitance), with each region optimized for its specific function. This local differentiation allows the structure to simultaneously achieve good electrical connectivity and minimize parasitic effects.
3Ease of manufacture
If the active layer is uniformly doped, then manufacturing process is simplified, but electrical performance varies across different regions
Solution Approach 1:
The patent implements local quality by creating non-uniform doping concentration within the active layer. Different regions of the active layer have different carrier concentrations: high concentration regions provide good electrical contact with electrodes, while low concentration regions minimize parasitic capacitance with overlapping conductive lines. This spatial variation in doping quality optimizes both electrical performance and parasitic reduction.
Solution Approach 2:
The invention changes the doping parameter (carrier concentration) across different regions of the active layer. By varying the doping concentration from high to low in different areas, the patent achieves different electrical characteristics in different regions, allowing optimization of both contact resistance and parasitic capacitance without requiring separate manufacturing processes.
Data Source
AI summary
A substrate for a display device is disclosed. In one aspect, the substrate includes an active layer that is formed on substantially the entire portion of the bottom substrate and comprises a first area and a second area with a higher carrier concentration than the first area. The substrate also includes a line overlapping with the first area and a contact electrode that electrically connects the line to the second area of the active layer.