Printable Semiconductor Structures for Flexible Electronics

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Solution Overview

Problem

Current methods for fabricating flexible electronic devices on plastic substrates face challenges such as incompatibility with traditional silicon-based technologies, limited electronic performance due to material limitations, and mechanical strain issues from flexibility, which restricts the application and durability of these devices.

Innovation Solution

A high-yield fabrication platform using bulk silicon wafers to create printable semiconductor elements with precise control over dimensions, orientations, and doping levels, enabling the production of high-performance flexible electronic devices through anisotropic etching and transfer printing techniques, allowing for integration onto flexible substrates without high-temperature processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional high-temperature processing methods (>1000°C) are used to fabricate single crystalline silicon or germanium semiconductors, then high electronic performance is achieved, but the plastic substrate melts or decomposes

Engineering Contradiction:
Improveelectronic performanceVSAvoidprocessing temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The fabrication process is segmented into two distinct stages: (1) High-temperature processing of semiconductor materials on a sacrificial substrate to achieve single-crystalline quality, and (2) Low-temperature transfer of the finished semiconductor elements to the plastic substrate. This segmentation allows each stage to operate under optimal conditions without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A sacrificial substrate (such as silicon oxide or silicon nitride on a silicon wafer) serves as an intermediary that temporarily holds the semiconductor material during high-temperature fabrication. The semiconductor is grown or processed on this intermediate substrate, then transferred to the final plastic substrate, eliminating direct exposure of the plastic to high temperatures.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If amorphous silicon, organic or hybrid organic-inorganic semiconductors are used to enable solution processing on plastic substrates, then compatibility with plastic substrates is achieved, but electronic performance deteriorates by approximately three orders of magnitude

Engineering Contradiction:
Improvesolution processabilityVSAvoidelectronic performance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The crystal structure parameter of the semiconductor material is changed from amorphous to single-crystalline. This fundamental parameter change transforms the material properties, enabling both solution processability (through controlled crystallization from solution) and high electronic performance (through the ordered atomic structure of single crystals).

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses composite approaches combining organic semiconductor materials with inorganic crystallization templates or catalysts. This composite strategy enables the formation of single-crystalline structures from solution-processable precursors, achieving both ease of manufacture on plastic substrates and high electronic performance.

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If flexible plastic substrates are used to provide mechanical flexibility and ruggedness, then device flexibility and durability are improved, but mechanical strain from bending degrades electronic performance

Engineering Contradiction:
Improvemechanical flexibilityVSAvoidelectronic performance stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention employs thin-film semiconductor structures and flexible interconnect layers that can accommodate substrate bending without generating excessive strain. The thin-film nature of these components allows them to flex with the plastic substrate while maintaining electrical functionality, resolving the contradiction between flexibility and performance stability.

Inventive Principle:
Principle #30Flexible shells and thin films

4Productivity

If continuous high-speed printing techniques are used to fabricate devices over large substrate areas at low cost, then productivity and cost-effectiveness are improved, but manufacturing precision and device performance are compromised

Engineering Contradiction:
Improvefabrication speedVSAvoiddevice fabrication precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

Semiconductor elements are pre-fabricated with high precision on rigid sacrificial substrates using established semiconductor manufacturing techniques. These pre-fabricated elements are then transferred to the flexible plastic substrate using printing or pick-and-place methods. This preliminary action on a stable substrate ensures manufacturing precision is achieved before the elements are moved to the final flexible substrate.

Inventive Principle:
Principle #10Preliminary action

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 the production of flexible electronic devices with performance comparable to conventional single-crystalline semiconductor devices, offering enhanced mechanical flexibility and durability, and the ability to fabricate complex integrated circuits and devices like transistors, diodes, and logic gates on plastic substrates.

Implementation Method 1

fabrication platform using bulk silicon wafers to create printable semiconductor elements with precise control over dimensions, orientations, and doping levels, enabling the production of high-performance flexible electronic devices through anisotropic etching

Methodology Applied
Scientific EffectAnisotropic etching:

Data Source

PatentEP1915774B1Printable semiconductor structures and related methods of making and assembling
Publication Date: 2015.05.20 THE BOARD OF TRUSTEES OF THE UNIV OF ILLINOIS
  • EP1915774B1 patent drawingFigure 1a
  • EP1915774B1 patent drawingFigure 1b
  • EP1915774B1 patent drawingFigure 1c~1f

AI summary

The present invention provides a high yield pathway for the fabrication, transfer and assembly of high quality printable semiconductor elements having selected physical dimensions, shapes, compositions and spatial orientations. The compositions and methods of the present invention provide high precision registered transfer and integration of arrays of microsized and/or nanosized semiconductor structures onto substrates, including large area substrates and/or flexible substrates. In addition, the present invention provides methods of making printable semiconductor elements from low cost bulk materials, such as bulk silicon wafers, and smart-materials processing strategies that enable a versatile and commercially attractive printing-based fabrication platform for making a broad range of functional semiconductor devices.