Integrated Microfluidic Cooling Circuit in Semiconductor Substrate
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Solution Overview
Problem
Existing cooling methods for microelectronic and optoelectronic devices face challenges such as chemical reactions between cooling liquids/gases and device materials, modification of optical behavior in optoelectronic devices, and thermal resistivity issues due to compatibility problems with materials like PDMS, which hinder effective heat dissipation and device miniaturization.
Innovation Solution
Integration of a microfluidic cooling circuit within the substrate made of the same semiconductor material as the device, eliminating the need for a wetting layer and avoiding chemical interactions, by growing a second semiconductor to form the cooling circuit and selectively etching it, thereby simplifying the fabrication process and reducing thermal resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a droplet circuit is used for cooling, then cooling function is provided, but chemical reactions occur between the droplet and device material
Solution Approach 1:
A wetting layer is introduced as an intermediary between the cooling droplet and the device material. This wetting layer prevents direct chemical contact while enabling effective thermal transfer, thus resolving the contradiction between providing cooling function and preventing chemical reactions.
Solution Approach 2:
The invention creates a simplified model of the cooling circuit by integrating it directly into the substrate rather than using separate droplet circuits. This integration eliminates the need for wetting layers and direct droplet-device contact, thereby preventing chemical reactions while maintaining cooling effectiveness.
2Temperature
If a wetting layer is added to improve contact, then thermal contact is improved, but optical behavior is modified
Solution Approach 1:
The wetting layer is completely removed from the system by integrating the cooling circuit directly into the substrate. This extraction eliminates the source of optical interference while maintaining effective thermal contact through direct integration of the cooling channels with the heat-generating regions.
3Ease of manufacture
If PDMS material is used for cooling circuit, then ease of manufacture is improved, but thermal resistivity increases
Solution Approach 1:
The cooling circuit is fabricated using the same semiconductor material as the substrate, creating a homogeneous structure. This eliminates the thermal interface resistance that occurs between dissimilar materials like PDMS and semiconductor substrates, while the integrated fabrication process maintains ease of manufacture.
Solution Approach 2:
The invention uses composite semiconductor structures with different layers having optimized thermal properties. By combining materials with high thermal conductivity in the cooling circuit paths, the system achieves low thermal resistivity while maintaining manufacturability through standard semiconductor fabrication processes.
4Reliability
If cooling circuit is added after device process, then device functionality is preserved, but fabrication complexity increases
Solution Approach 1:
The cooling circuit is fabricated in advance during the substrate preparation stage, before the device structures are built. This preliminary action integrates the cooling function into the substrate itself, eliminating the need for subsequent complex integration steps and reducing overall fabrication complexity while preserving device functionality.
Solution Approach 2:
The cooling circuit fabrication is merged with the substrate fabrication process, using the same epitaxial growth and etching steps. This combining of operations eliminates separate fabrication stages and reduces overall process complexity while ensuring the cooling circuit is fully integrated with the device structure from the beginning.
5Ease of manufacture
If groove-only cooling channel is used, then fabrication is simplified, but liquid/gas confinement is insufficient
Solution Approach 1:
The cooling channel structure is optimized locally with raised walls or embedded structures at critical confinement points. This local enhancement provides sufficient liquid/gas confinement where needed while maintaining the overall simplicity of the groove-based fabrication approach for the majority of the cooling channel structure.
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 enhances thermal dissipation without adding thermal resistivity, reduces the risk of chemical interactions, simplifies the fabrication process, and eliminates the need for a cover layer, thereby improving device performance and miniaturization.
Implementation Method 1
Growing a second semiconductor within the substrate, said second semiconductor presenting the shape of the microfluidic circuit
Implementation Method 2
Selectively etching the second semiconductor
Implementation Method 3
the cooling liquid or gas which is confined in the obtained channel
Data Source
Figure 1a~2e
Figure 3a~3e
Figure 4a~4e
AI summary
The present invention relates to a method for making a microelectronic or an optoelectronic device (7') including a substrate (1) grown in a first semiconductor material, wherein the method comprises integration of a microfluidic cooling circuit (2') within the substrate (1).