Micro-Transfer Printing via Intermediate Wafer for Large Substrates
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Solution Overview
Problem
Existing methods for transferring micro-scale devices from source wafers to large-format substrates are inefficient, costly, and prone to damage, particularly due to the need for multiple transfer steps and expensive photolithographic processes, which limit the size and material choice of substrates and can result in wasted material and processing costs.
Innovation Solution
The method involves using an intermediate wafer with a patterned array of micro-transfer printable supports to populate source devices from a source wafer, followed by transferring these devices to a destination substrate through a larger intermediate stamp, reducing the number of transfer operations and enabling higher resolution electrical connections at lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple transfer steps are used to move micro-scale devices from source wafers to large-format substrates, then the devices can be distributed over large areas, but the manufacturing time and risk of damage increase
Solution Approach 1:
The transfer process is segmented into two distinct stages: first transferring devices from source wafers to intermediate wafers, then from intermediate wafers to final large-format substrates. This segmentation allows each transfer step to be optimized independently, reducing the total number of transfers needed while managing the complexity of handling large areas.
Solution Approach 2:
Intermediate wafers are introduced as a mediator between source wafers and final substrates. These intermediate wafers serve as temporary holding platforms that enable efficient device accumulation and subsequent bulk transfer to large substrates, reducing the number of direct transfer operations needed.
2Manufacturing precision
If photolithographic processes are used to pattern active components on substrates, then electronically active circuits can be formed, but the substrate material choices are limited and processing costs increase
Solution Approach 1:
Electronically active circuits are formed on source wafers using photolithographic processes before the transfer step. This preliminary action allows the use of precise patterning techniques on small wafers where they are most effective, while the subsequent transfer to large substrates enables the use of diverse substrate materials that would be difficult or expensive to process directly with photolithography.
3Reliability
If mono-crystalline semiconductor wafers are used as substrates, then high-performance integrated circuits can be achieved, but the substrate size is limited and costs are high
Solution Approach 1:
The system is segmented into high-performance mono-crystalline source wafers for circuit fabrication and large-format lower-cost substrates for final application. This allows the performance-critical circuits to be manufactured on small premium wafers while the final product can utilize large areas of affordable substrates.
Solution Approach 2:
Intermediate wafers act as a bridge between small mono-crystalline source wafers and large final substrates. The devices are transferred from the premium source wafers through intermediate holders to the large final substrates, enabling the use of high-performance circuits on large-area low-cost substrates.
4Area of stationary object
If thin-film transistor methods are used to form circuits on large substrates, then large-area devices can be manufactured, but the electronic performance is lower than mono-crystalline circuits
Solution Approach 1:
Intermediate wafers serve as the mediator that enables high-performance thin-film transistors to be transferred onto large substrates. The TFTs are fabricated on small source wafers using thin-film techniques, then transferred via intermediate wafers to large final substrates, achieving both large area coverage and high electronic performance.
Data Source
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AI summary
A method of making a micro-transfer printed system includes providing a source wafer (10) having a plurality of micro-transfer printable source devices (12 arranged at a source spatial density; providing an intermediate wafer (20) having a plurality of micro-transfer printable intermediate supports (24) arranged at an intermediate spatial density less than or equal to the source spatial density; providing a destination substrate (30); micro-transfer printing the source devices from the source wafer to the intermediate supports of the intermediate wafer with a source stamp having a plurality of posts at a source transfer density to make an intermediate device (22) on each intermediate support; and micro-transfer printing the intermediate devices from the intermediate wafer to the destination substrate at a destination spatial density less than the source spatial density with an intermediate stamp having a plurality of posts at an intermediate transfer density less than the source transfer density.