Integrated OLED Display with Single-Crystal Silicon Substrates
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Solution Overview
Problem
Conventional OLED displays using low temperature polysilicon (LTPS) on glass substrates are limited in pixel density and response time, making them unsuitable for high-resolution applications like virtual reality (VR) and augmented reality (AR) due to the constraints of feature size and mobility of LTPS materials.
Innovation Solution
The use of single-crystal silicon or compound semiconductor substrates for both driving logic and pixel circuits, with vertical interconnect accesses (vias) connecting them, allows for higher pixel density and faster response times by integrating OLEDs, driving logic, and control logic into a single device, reducing wire connections and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low temperature polysilicon (LTPS) on glass substrates is used for driving circuits, then manufacturing is easier and cost is lower, but pixel density is limited to about 1000 PPI and response time is slow
Solution Approach 1:
The patent changes the substrate material parameter from glass to single-crystal silicon or compound semiconductor, and changes the transistor material parameter from LTPS to high-mobility materials. This parameter transformation enables pixel density to exceed 2000 PPI while maintaining manufacturing feasibility through established semiconductor fabrication processes.
2Device complexity
If LTPS on glass substrates is used, then device complexity is lower, but response time is slow and refresh rate is limited
Solution Approach 1:
The patent changes the semiconductor material parameter from LTPS to high-mobility materials such as single-crystal silicon or compound semiconductors. This material parameter change increases carrier mobility, thereby reducing response time and enabling higher refresh rates suitable for VR/AR applications.
3Manufacturing precision
If pixel density is increased beyond 1000 PPI using LTPS, then display resolution improves, but feature size limit and material mobility prevent achieving above 2000 PPI
Solution Approach 1:
The patent transforms the substrate material parameter from glass to single-crystal silicon or compound semiconductor, enabling feature sizes below 1 micrometer. This parameter change allows pixel density to exceed 2000 PPI while maintaining ease of manufacture through standard semiconductor fabrication techniques.
4Device complexity
If conventional LCDs or OLEDs with LTPS are used for VR/AR, then device simplicity is maintained, but pixel density is insufficient for close-to-eye applications
Solution Approach 1:
The patent merges the driving logic circuit and the pixel circuit onto a single substrate, creating an integrated display device. This integration reduces the number of external connections and simplifies the overall device structure while enabling pixel density to exceed 2000 PPI, making it suitable for VR/AR applications.
Data Source
AI summary
Provided are integrated organic light emitting diode (OLED) display apparatus and methods for making the same. In one example, the apparatus includes driving logic on a first substrate of a first die, a plurality of pixel circuits on a second substrate of a second die, and a plurality of OLEDs above the plurality of pixel circuits. The first substrate is made of single-crystal silicon or a compound semiconductor. The second substrate is made of single-crystal silicon or a compound semiconductor. Each OLED corresponds to a respective one of the plurality of pixel circuits. The second die having the plurality of pixel circuits and OLEDs is mounted on the first die having the driving logic. Each pixel circuit is electrically connected to the driving logic through at least one of a plurality of vertical interconnect accesses (vias) penetrating the second substrate of the second die.