Stepped Sidewall Contact Holes in Display Substrates
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Solution Overview
Problem
Existing display substrates face challenges in forming reliable contact holes with stepped sidewalls, which are crucial for maintaining electrical connectivity between conductive layers, often resulting in disconnection issues and increased manufacturing complexity.
Innovation Solution
A method involving sequential stacking of conductive and insulation layers, followed by etching processes to create a contact hole with a stepped sidewall, ensuring the third conductive layer contacts both the side and upper surfaces of the second conductive layer, thereby preventing disconnection and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching processes are used to form contact holes through multiple insulation layers, then the contact holes can be formed, but the sidewalls become irregular and disconnection between conductive layers occurs
Solution Approach 1:
The contact hole formation process is segmented into multiple etching stages with different etch selectivities. The first etching process forms the contact hole through the second insulation layer with a first etch selectivity, and the second etching process adjusts the sidewall shape with a second etch selectivity. This segmentation allows independent control of each etching step to achieve the desired stepped sidewall profile while ensuring reliable electrical connectivity.
Solution Approach 2:
The patent changes etching parameters including etch selectivity ratios between different insulation layers. By controlling the etch selectivity of the first etching process to be different from the second etching process, the sidewall profile is transformed from irregular to stepped. This parameter change enables precise control of contact hole geometry while maintaining manufacturing feasibility.
2Manufacturing precision
If multiple photolithography processes are used to create stepped sidewalls, then contact hole precision is improved, but manufacturing complexity and time increase
Solution Approach 1:
The patent merges the sidewall shaping function into the etching process itself rather than requiring separate photolithography steps. By using etch selectivity differences between insulation layers, the stepped sidewall profile is formed during the etching process. This merging eliminates the need for additional photolithography processes, reducing manufacturing complexity while maintaining precision.
Solution Approach 2:
The etching process is given multiple functions: it simultaneously creates the contact hole opening and shapes the sidewalls with the desired stepped profile. The first etching process both opens the contact hole and begins sidewall formation, while the second etching process completes the shaping. This multi-functionality reduces the total number of process steps required.
3Reliability
If the third conductive layer is formed to contact both side and upper surfaces of the second conductive layer, then electrical connectivity is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The stepped sidewall profile is formed in advance during the contact hole etching process, before the third conductive layer is deposited. By pre-shaping the contact hole sidewalls with the correct geometry, the third conductive layer naturally forms the desired contact configuration when deposited. This preliminary action eliminates the need for additional shaping steps after conductive layer formation, simplifying the overall manufacturing process.
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 enhances electrical connectivity between layers, reduces manufacturing inefficiencies, and minimizes the number of photolithography processes required, leading to a more reliable and cost-effective display substrate.
Implementation Method 1
etching a first part of the second insulation layer; etching the second conductive layer; etching a second part of the second insulation layer; and etching the first insulation layer
Data Source
AI summary
A display substrate includes a first conductive layer on a base substrate, a first insulation layer on the first conductive layer, a second conductive layer on the first insulation layer, a second insulation layer on the second conductive layer, and a third conductive layer on the second insulation layer. The third conductive layer is connected to the first conductive layer and the second conductive layer through a contact hole passing through the first insulation layer, the second conductive layer, and the second insulation layer. A sidewall of the contact hole has a stepped shape.