Reflective Active Matrix LCD Four-Layer Metal Wiring
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Solution Overview
Problem
High-resolution reflective active matrix liquid crystal display apparatuses face delays and waveform bluntness in signal transfer due to high pixel density and polysilicon wiring resistance, leading to image quality issues and operational burdens.
Innovation Solution
A four-layer metal wiring structure is implemented, with row-scanning and column-signal electrodes formed in specific metal layers to reduce wiring resistance and parasitic capacitance, enhancing signal transfer characteristics and frequency performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polysilicon wiring is used in high-resolution reflective liquid crystal display, then pixel density can be increased, but signal transfer delay and waveform bluntness increase due to high wiring resistance
Solution Approach 1:
The patent changes the material parameter of the wiring from polysilicon to metal (such as aluminum or copper), which fundamentally alters the electrical resistance characteristic. This material substitution reduces wiring resistance by several orders of magnitude, thereby eliminating signal transfer delay and waveform bluntness while maintaining high pixel density requirements
2Ease of manufacture
If polysilicon wiring is used, then manufacturing process can be simplified, but wiring resistance increases causing signal quality degradation
Solution Approach 1:
The patent employs a composite structure where metal wiring layers are integrated with the existing polysilicon-based liquid crystal display structure. The metal wiring (such as aluminum or copper) is deposited as additional layers that work in conjunction with the underlying polysilicon transistor structures, combining the manufacturing advantages of polysilicon with the electrical performance advantages of metal conductors
Solution Approach 2:
The patent changes the electrical parameter of conductivity by substituting metal material for polysilicon in the wiring function, while maintaining compatibility with the existing manufacturing process flow through standard semiconductor fabrication techniques such as sputtering or electroplating
3Area of stationary object
If high pixel density is achieved with small gaps between reflective pixel electrodes, then aperture ratio is improved, but wiring resistance increases causing operational burden
Solution Approach 1:
The patent changes the resistance parameter of the wiring system by using metal materials with inherently lower resistivity. This allows the wiring to function effectively even when pixel dimensions are reduced to achieve high aperture ratios, eliminating the operational burden that would otherwise result from high resistance in miniaturized structures
Data Source
AI summary
A liquid crystal display apparatus has a transparent substrate having a transparent common electrode formed thereon; an active matrix substrate having pixels with reflective pixel electrodes, the pixels being formed in column and row directions on the matrix substrate in a matrix fashion, each pixel having a switching transistor with a gate, a drain and a source, and a signal-charging capacitor; a liquid crystal layer provided between the common electrode and the pixel electrode; a column-signal electrode driver and a row-scanning electrode driver for activating the matrix substrate; column-signal electrodes connected to the column-signal electrode driver, the gate being connected to each column-signal electrode; and row-scanning electrodes connected to the row-scanning electrode driver, the drain being connected to each row-scanning electrode, each pixel electrode being provided at an intersection of each column-signal electrode and each row-scanning electrode, each pixel electrode and the capacitor being connected to the source. The matrix substrate has a first, a second, a third, and a fourth metal layer formed in order, via interlayer insulating layers between adjacent layers, on a wiring layer having the gate formed therein. The column-signal and row-scanning electrodes are formed in the first and second metal layers, respectively. Or, the column-signal electrodes and the row-scanning electrodes are formed in the second and the first layer, respectively. Wirings for carrying signals to be displayed are connected to the column-signal electrode driver, each wiring having a first wiring portion and a second wiring portion formed in the second and third metal layers, respectively, the first and second portions being electrically connected to each other through a via hole between the second and third metal layers.