Electro-optical Contact Hole Design for Diffracted Light Blocking
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Solution Overview
Problem
Existing electro-optical devices with contact holes in liquid crystal devices are insufficiently configured to block diffracted light, leading to optical leakage currents and unstable transistor operation, especially when used in projection-type display devices where intense light is incident.
Innovation Solution
The electro-optical device incorporates a contact hole design with a body portion spaced apart from the channel region and a protruded portion that protrudes towards high concentration impurity regions, along with a light-absorption layer inside the contact hole and between the scanning line and insulating layer, to effectively block diffracted light and prevent optical leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional contact hole configuration is used, then the device structure is simple, but diffracted light enters the gap between the contact hole and semiconductor layer, causing optical leakage currents
Solution Approach 1:
The contact hole is divided into two functional portions: a body portion that provides the primary electrical connection, and a protruded portion that extends toward the semiconductor layer to block diffracted light. This segmentation allows each portion to specialize in its function, with the protruded portion acting as a light-shielding barrier while the body portion maintains electrical connectivity.
Solution Approach 2:
The contact hole structure extends in the planar direction (parallel to the substrate surface) through the protruded portion, rather than only in the vertical direction. This dimensional extension creates an overlapping region with the semiconductor layer that blocks diffracted light paths without requiring increased vertical depth.
2Reliability
If the contact hole is positioned closer to the channel region to block more light, then light shielding improves, but electrical coupling between the scanning line and gate electrode deteriorates
Solution Approach 1:
The contact hole structure exhibits different spatial characteristics: the body portion is positioned to ensure proper electrical coupling with the gate electrode, while the protruded portion extends closer to the semiconductor layer to provide light shielding. This local differentiation of function allows optimal positioning for both electrical and optical requirements.
Solution Approach 2:
The protruded portion of the contact hole acts as an intermediary light-shielding element that blocks diffracted light before it reaches the channel region, while the body portion serves as the primary electrical conduit. This intermediary structure prevents direct contact between the light path and the sensitive channel region.
3Object-affected harmful factors
If a light-absorption layer is added inside the contact hole, then diffracted light is effectively blocked, but the manufacturing process becomes more complex
Solution Approach 1:
The light-absorption layer is integrated into the contact hole formation process, combining the electrical connection function and the light-shielding function into a single structured element. The light-absorption material is deposited or formed within the contact hole structure, merging multiple functions into one manufacturable component.
Solution Approach 2:
The contact hole structure incorporates a light-absorption layer made of materials with high optical absorption coefficients (such as metal oxides or nitrides), creating a composite structure that combines electrical conductivity with optical absorption properties. This composite approach enables effective light blocking while maintaining electrical functionality.
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 configuration significantly reduces the incidence of diffracted light on the semiconductor layer, minimizing optical leakage currents and ensuring stable transistor operation even under intense light conditions, thereby enhancing the reliability of the electro-optical device.
Implementation Method 1
a light-absorption layer inside the contact hole and between the scanning line and insulating layer, to effectively block diffracted light
Implementation Method 2
a protruded portion configured to protrude from the body portion toward a region other than the channel region of the semiconductor layer... significantly reduces the incidence of diffracted light on the semiconductor layer
Data Source
AI summary
An electro-optical device includes a contact hole configured to electrically connect a scanning line and a gate electrode of a TFT as a transistor, the contact hole being provided, in plan view, along a semiconductor layer of the TFT and including a body portion spaced apart from a channel region of the semiconductor layer by a first distance, and a protruded portion protruding from the body portion toward a region other than the channel region of the semiconductor layer, and spaced apart from the region other than the channel region by a second distance, which is less than the first distance.