Pixel Electrode Relay Structure for High-Aspect Contact Holes
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Solution Overview
Problem
The existing electro-optical devices face challenges in forming high aspect ratio contact holes through thick layers, which requires long etching times and the use of hard masks, leading to the disappearance of conductive layers during mask removal.
Innovation Solution
A layered structure comprising a metal material layer, an insulating material layer, and another metal material layer is used, where the metal material layer acts as an etching stopper and the insulating material layer has a lower etching rate than the hard mask, allowing for the formation of high aspect ratio contact holes without losing the conductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a hard mask is used to form high aspect ratio contact holes through thick layers, then the etching process can be maintained for long durations, but the conductive layer exposed at the bottom of the contact hole disappears together with the hard mask when the mask is removed
Solution Approach 1:
The conductive layer is segmented into two separate layers: a first conductive layer that serves as the functional electrode and a second conductive layer that serves as the etching stopper. This segmentation allows the second layer to be removed with the hard mask while the first layer remains intact and functional, resolving the contradiction between maintaining etching precision and preserving conductive layer stability.
Solution Approach 2:
The second conductive layer acts as an intermediary between the hard mask and the first conductive layer. It provides the necessary etching stopper function during the etching process and can be selectively removed with the hard mask, thereby protecting the first conductive layer from disappearing while still enabling precise contact hole formation.
2Productivity
If a hard mask is used for long duration etching, then high aspect ratio contact holes can be formed, but the etching process causes the conductive layer to disappear when the mask is removed
Solution Approach 1:
By segmenting the conductive layer into two functional layers, the patent enables the use of hard masks for efficient long-duration etching while ensuring that only the sacrificial second layer is removed, not the functional first layer. This maintains both productivity and electrical connection stability.
Solution Approach 2:
The second conductive layer serves as a disposable sacrificial layer that is intentionally designed to be removed along with the hard mask. This disposable layer enables efficient etching processes while the permanent first conductive layer maintains stable electrical connections, resolving the contradiction between productivity and reliability.
3Length of stationary object
If the layer thickness is large, then the lens can be properly formed, but a high aspect ratio contact hole must be formed requiring long etching time
Solution Approach 1:
The patent changes the material parameters of the conductive layers, specifically making the second conductive layer have different etching characteristics compared to the first conductive layer. This parameter change enables selective removal of the second layer with the hard mask, significantly reducing the effective etching time required while maintaining the necessary layer thickness for proper lens formation.
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 enables efficient formation of high aspect ratio contact holes with improved reliability and reduced etching time, ensuring stable electrical connections between the transistor and pixel electrode while preventing the disappearance of the conductive layer during mask removal.
Implementation Method 1
a first conductive layer provided at a layer between the transistor and the pixel electrode, and including a first layer containing a metal material, a second layer containing an insulating material, and a third layer containing a metal material
Implementation Method 2
a second layer containing an insulating material having a lower etching rate with respect to an etchant for removing the mask than that of the mask
Data Source
AI summary
Provided are a transistor, a pixel electrode provided corresponding to the transistor, a relay layer provided at a layer between the transistor and the pixel electrode and including, in this order from the pixel electrode side, a metal material layer containing a metal material, an insulating material layer containing an insulating material, and a metal material layer containing a metal material, and a lens layer provided at a layer between the relay layer and the pixel electrode and including a contact hole for electrically connecting the relay layer and the pixel electrode, and in the relay layer, portions of the metal material layer and the insulating material layer overlapping the contact hole are removed.