LCOS Display Unit Vertical MIM Capacitor Structure
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Solution Overview
Problem
As higher resolution requirements reduce pixel area, it becomes challenging to maintain high performance of the pixel switch circuit while holding a high capacitor voltage level, leading to potential current leakage and compromised insulation performance.
Innovation Solution
A Metal-Insulator-Metal (MIM) capacitor is formed using a micromirror layer, an insulation layer, and a light shielding layer, with the light shielding layer grounded, allowing vertical distribution of the pixel switch circuit and capacitor, maximizing pixel area and increasing capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel area is reduced to achieve higher resolution, then resolution is improved, but capacitor voltage holding capability deteriorates
Solution Approach 1:
The patent transitions from a planar capacitor structure to a three-dimensional stacked structure by placing the capacitor vertically above the pixel switch circuit. This vertical stacking allows the capacitor to occupy the Z-dimension rather than competing for XY-plane area, enabling high capacitance values even in reduced pixel areas while maintaining voltage holding capability
Solution Approach 2:
The capacitor structure is nested vertically within the pixel structure, with the capacitor positioned directly above the pixel switch circuit. This nesting approach allows the capacitor to be integrated within the vertical space of the pixel rather than requiring separate lateral space, resolving the conflict between pixel area and capacitance
2Measurement precision
If pixel area is reduced to achieve higher resolution, then resolution is improved, but current leakage increases
Solution Approach 1:
By moving the capacitor to a vertical position above the pixel switch circuit, the patent separates the capacitor from the switching elements in the XY-plane. This spatial separation in the vertical dimension reduces parasitic coupling and current leakage paths that would otherwise be present in planar configurations, especially important in high-resolution displays with densely packed pixels
Solution Approach 2:
The patent introduces an insulating layer between the capacitor electrode and the pixel switch circuit, serving as an intermediary that electrically isolates the two components. This insulating barrier prevents direct current leakage while maintaining the vertical integration benefits
3Reliability
If multiple capacitors are added to increase capacitance, then capacitance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the capacitor structure with the micromirror assembly by using the micromirror electrode as one of the capacitor electrodes. This integration eliminates the need for separate capacitor structures and reduces the number of manufacturing steps, achieving high capacitance without proportionally increasing manufacturing complexity
Solution Approach 2:
The micromirror structure serves dual functions: as the reflective element for light modulation and as an electrode for the capacitor. This multi-functionality reduces the total component count and simplifies the manufacturing process while maintaining sufficient capacitance for the display operation
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 enhances capacitance, reduces refresh rate, and simplifies the manufacturing process, thereby decreasing overall chip manufacturing costs and increasing design flexibility for high-performance switch circuits.
Implementation Method 1
the micromirror layer, the insulation layer and the light shielding layer constituting a capacitor
Data Source
AI summary
An embodiment of the present invention discloses a Liquid Crystal on Silicon (LCOS) display unit, in which a Metal-Insulator-Metal (MIM) capacitor consisting of a micromirror layer, a insulation layer and a light shielding layer is formed by grounding the light shielding layer on a pixel switch circuit layer. Therefore the pixel switch circuit and the capacitor are in vertical distribution, that is, the switch circuit and the capacitor both have an allowable design area of the size of one pixel. Another embodiment of the present invention provides a method for forming a Liquid Crystal on Silicon (LCOS) display unit.