On-chip solid-state cooling for integrated circuits using thin-film microrefrigerators
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Citations
Advanced Thermoelectric Design: From Materials and Structures to Devices
Thermoelectric Devices: A Review of Devices, Architectures, and Contact Optimization
Nanoscale Thermal Transport and Microrefrigerators on a Chip
Nanoscale Thermal Transport and Microrefrigerators on a Chip Devices for cooling high power density and dynamic hot spots can be formed by solid-state thin films on the chip, or they could be buried in, bonded to, or mounted on substrates.
Thermal Management of On-Chip Hot Spot
References
Thin-film thermoelectric devices with high room-temperature figures of merit
CRC Handbook of Thermoelectrics
Thermoelectrics: Basic Principles and New Materials Developments
Heterostructure integrated thermionic coolers
Recent Trends in Thermoelectric Materials Research
Related Papers (5)
Thin-film thermoelectric devices with high room-temperature figures of merit
Frequently Asked Questions (20)
Q2. What are the main effects of a TE module?
Non-ideal effects such as metal-semiconductor contact resistance inside the TE module and the finite thermal resistance of the heat sink start to dominate as the TE module is miniaturized.
Q3. What is the effect of short period superlattices on the thermal efficiency of thermoelectric energy?
Short period superlattices can also reduce lattice thermal conductivity and thus improve the efficiency of thermoelectric energy conversion.
Q4. What is the solution for microscale temperature control?
One attractive solution for microscale temperature control is to monolithically integrate thin-film thermoelectric coolers with active optoelectronic devices.
Q5. How much cooling power density is needed for a TE module?
For current commercial TE modules, the maximum cooling around room temperature is about 70 C, however the cooling power density is low, on the order of 5–10 W cm .
Q6. How can one reduce the current for the same cooling capacity?
In order to decrease the current for the same cooling capacity, one can put many thermoelectric elements electrically in series and thermally in parallel.
Q7. How many amps of current would be required to cool a single TE element?
In a practical cooling application, for example, removing 10 W heat from a surface area of 1 cm , a single -type or -type element would require several amps of current and dozens of millivolts of voltage.
Q8. What is the effect of the Joule heating on the top surface of the device?
The generated Joule heating on the top surface of the device establishes a temperature difference across superlattice and substrate which results in a thermoelectric voltage.
Q9. How does the microrefrigerator cool the hotspots?
When the authors integrated the microrefrigerator at the hotspots and supplied with the optimized current 0.4 A, the hotspots cools down to 91.6 C, which is 0.4 C below the die temperature.
Q10. How do the authors calculate the temperature profile of a silicon die?
To demonstrate microrefrigerators’ effectiveness to remove hotspots in an integrated circuit, the authors use the three-dimensional (3-D) electrothermal model to calculate the temperature profile on top of a silicon die with and without microrefrigerator.
Q11. What is the way to control the temperature of a microelectronic device?
Recent advances in thin-film Si/SiGe superlattice micro-refrigerators allow localized temperature control with large cooling power density W cm .
Q12. How have they been able to deposit 20- m thick legs?
They have been able to deposit 20- m thick legs using sputtering and integrated circuit fabrication techniques to produce coolers on large scale (on 4-in silicon wafers).
Q13. What type of semiconductors are required to put multiple elements in series and in parallel?
In order to put multiple elements electrically in series and thermally in parallel, both - and -type semiconductors are required.
Q14. What is the way to measure the cooling of a micro-refrigerator?
For convenient measurements of cooling, power density, and transient response, the authors integrated a thin layer of metal wire on top of the micro-refrigerators.
Q15. What is the advantage of a thin-film integrated refrigerator?
First of all, very small size and standard thin-film fabrication method makes these micro-refrigerators suitable for monolithic integration inside IC chips.
Q16. What is the penalty for using a better heat sink?
Of course, using better convection condition or better heat sink makes the whole chip temperature drops down 0.9 C, however, this has the penalty that requires significant additional power dissipation in the heat sink.
Q17. What is the smallest cooling capacity of a gas?
The cooling capacity scales with the volume of the gas while many loss mechanisms, such as friction and heat loss, scale with the surface area.
Q18. What is the current limitation of the superlattice coolers?
According to the theoretical simulation, the current limitation of the superlattice coolers still lies in the contact resistance between the metal and cap/buffer layer, which is on the order of 10 cm .
Q19. What is the problem with the power supplies?
This causes problems with the required power supplies, but more importantly, at such high currents Joule heating in the wires and electrical contacts could reduce the maximum cooling and efficiency significantly.
Q20. What is the maximum cooling power density of a TE module?
The maximum cooling power density of a TE module is inversely proportional to the length of its elements (distance between hot and cold junctions).