SiCN Bonding for Micro-LED Thermal Stress Resistance
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Solution Overview
Problem
Conventional bonding methods for compound semiconductor stacks to silicon-based carrier substrates in LED device fabrication are prone to reliability issues due to material mismatch and thermal stress during high-temperature processing, leading to weakened or destroyed bonds.
Innovation Solution
The use of a silicon carbon nitride (SiCN) bonding material with a high post-bond annealing temperature of at least 400°C, equal to or higher than the processing temperature, to enhance bond strength between the compound semiconductor stacks and the silicon-based carrier substrate, allowing for reliable high-temperature processing without bond deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bonding methods are used to bond compound semiconductor stacks to silicon-based carrier substrates, then the bonding process is simple and straightforward, but the bond strength deteriorates during high-temperature processing due to material mismatch and thermal stress
Solution Approach 1:
A silicon carbon nitride (SiCN) bonding layer is introduced as an intermediary between the compound semiconductor stack and the silicon-based carrier substrate. This intermediate layer acts as a buffer that accommodates thermal expansion differences and reduces thermal stress during high-temperature processing, preventing bond deterioration while maintaining strong adhesion between the bonded components
Solution Approach 2:
The bonding process utilizes high-temperature annealing (at least 400°C) to change the physical and chemical parameters of the SiCN bonding layer, enhancing its bonding strength and reliability. The elevated temperature facilitates atomic diffusion and bond formation in the SiCN layer, creating a more robust interface that can withstand subsequent high-temperature LED fabrication processes
2Manufacturing precision
If high-temperature processing is applied to complete LED devices from bonded stacks, then the LED device quality is improved, but the thermal stress weakens or destroys the bonds between stacks and carrier substrate
Solution Approach 1:
The SiCN bonding layer is applied beforehand to both the compound semiconductor stack and the silicon-based carrier substrate before bonding. This pre-applied bonding layer serves as a cushioning interface that will absorb and distribute thermal stress during subsequent high-temperature LED fabrication processes, preventing bond failure while allowing the necessary thermal processing to occur
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 method achieves significantly higher bonding strength and reliability, enabling the fabrication of LED devices, including micro-LED arrays, with improved yields and resistance to thermal stress, suitable for high-temperature processing steps.
Implementation Method 1
annealing, after bonding, the bonded stack and substrate at a temperature equal to or higher than a processing temperature for completing the LED device from the stack, wherein said temperatures are at least 400°C
Implementation Method 2
Due to the material mismatch of the bonded parts, and thus different thermal expansion coefficients, the bonds created between the compound semiconductor stacks and the silicon-based carrier substrate may deteriorate during the high-temperature processing step
Data Source
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AI summary
The present invention presents relates to the technical field of Light Emitting Diode (LED) devices, in particular of micro-LED (µLED) devices. In this field the invention specifically proposes a method for obtaining one or more LED devices reconstituted over a carrier substrate. The method comprises: providing a silicon-based semiconductor substrate as the carrier substrate; providing, per each of the one or more LED devices, a compound semiconductor stack including an LED layer; applying a SiCN layer to the stack and the substrate, respectively; bonding the stack to the substrate, wherein the SiCN layer applied to the stack and the SiCN layer applied to the substrate are contacted; and annealing, after bonding, the bonded stack and substrate at a temperature equal to or higher than a processing temperature for completing the LED device from the stack, wherein said temperatures are at least 400°C.