On-Chip Thermoelectric Cooling of Semiconductor Hot Spot

The Moore's Law progression in semiconductor technology, including shrinking feature size, increasing transistor density, and faster circuit speeds, is leading to increasing total power dissipations and heat fluxes on silicon chip. Moreover, in recent years, increasing performance has resulted in greater non-uniformity of on-chip power dissipation, creating microscale hot spots that can significantly degrade the processor performance and reliability. Application of conventional thermal packaging technology, developed to provide uniform chip cooling, to such chip designs results in lower allowable chip power dissipation or overcooling of large areas of the chip. Consequently, novel thermoelectric cooler (TEC) has been proposed recently for on-chip hot spot cooling because of its unique ability to selectively cool down the localized microscale hot spot. In this dissertation the potential application of thermoelectric coolers to suppress on-chip hotspots is explored using analytical modeling, numerical simulation, and experimental techniques. Single-crystal silicon is proposed as a potential thermoelectric material due to its high Seebeck coefficient and its thermoelectric cooling performance is investigated using device-level analytical modeling. Integrated on silicon chip as an integral, on-chip thermoelectric cooler, silicon microcooler can effectively reduce the hotspot temperature and its effectiveness is investigated using analytical modeling and numerical simulation, and found to be dependent of doping concentration in silicon, electric contact resistance, hotspot size, hotspot heat flux, die thickness and microcooler size. The other novel on-chip hotspot cooling solution developed in this dissertation is to use a mini-contact enhanced TEC, where the mini-contact pad connects the silicon chip and the TEC to concentrate the thermoelectric cooling power onto a spot of top surface of the silicon chip and therefore significantly improve the hotspot cooling performance. Numerical simulation shows hotspot cooling is determined by thermal contact resistance, thermoelectric element thickness, chip thickness, etc. Package-level experiment demonstrates that spot cooling performance of such mini-contact enhanced TEC can be improved by about 100%

Investigation of a Novel Thermoelectric Cooler for Building/Infrastructure Application

With the enormous building/infrastructure construction in advanced and emerging economies, the energy demand and carbon emissions from building/infrasturcture continues to rise. Buildings/infrastructure construction sectors contributed to 30% of global energy consumption and 27% of total energy emissions. To align with the carbon net zero scenario, carbon footprint from building need to more than halve by 2030, which requiring significant efforts on adopting clean and efficient technologies applicable to all end-uses. For energy consumption of modern building, heating, ventilation, and air-conditioning (HVAC) system play a critical role, which accounts for 40% of total building consumption and 70% of landlord consumption.Thermoelectric coolers (TECs) are highly dependable, scalable, and noiseless devices. Beyond their conventional use, TECs have been investigated for a wide range of applications, including waste heat energy harvesting, electronics cooling, wearable device technology, power generation, and more. Numerous researches have unveiled their substantial potential in both domestic and industrial sectors, particularly in distributed building air conditioning. However, the cooling/energy performance of the TECs faces challenges in terms of building structures embedding, which limits its application. In particular, the integrated structure of TEC makes it difficult to dissipate heat to outside of building.To overcome these challenges, the proposed research aims to investigate a novel TEC air cooler which has a number of distinguished innovations: (1) First-of-its-kind trial in separating hot and cold ends enabling placement of one side of TEC to outside of the building and another side of TEC to inside of building, thus creating an increased temperature gradient between the ends and increased cooling capacity. Furthermore, separated TEC makes it possible to be integrated with the building façade. (2) Initiative optimization of the TEC geometries enables the enhanced energy performance and cooling capacity that makes the TEC more building applicable; (3) Pioneering full-day case studies of TEC performance illustrates the applicability and adaptation of the coolers across different climatic conditions of the world.This thesis employs a fundamental approach that integrates both theoretical and experimental analyses. The methodology comprises an exhaustive literature review, a conceptual design phase, mathematical analysis, model development, validation, and an in-depth examination of performance and thermal characteristics for thermoelectric geometry optimization. Furthermore, the thesis includes a conceptual design phase, mathematical analysis, model development, experimental testing, model validation, performance analysis, and real-climatic condition case studies.Trials on the separated configuration TEC indicate that the specialist TEC, when applying 10 K temperature difference and 5A of current, led to reduction in cooling capacity by 5.6% compared to the integrated TEC, varying from 7.13 W to 6.76 W. However, the TEC device height will be doubled. While sacrificing a small portion of cooling capacity, the TEC’s application scenarios have been significantly broadened. It is noteworthy that separated-TEC configuration exhibits excellent cooling power density. The cooling capacity per unit area could exceed 15 kW/m2 under high current (I=5A), even at low current (I=0.5A), it is up to 500 W/m2.Geometry optimization of the TEC reveals that the proposed design excels in both cooling performance and thermal-mechanical characteristics. The study demonstrates that under specified conditions, the truncated cone-shaped module (g) exhibits a noteworthy improvement in cooling capacity. In comparison to a traditional TEC, the cooling capacity from 0.1429 W increases to 0.1557 W, when operating at a temperature difference of 50 K, marking an 8.9% enhancement. This translates to a rise in the overall TEC device's cooling capacity from 18.15 W to 19.78 W. Additionally, the 'g' module, characterized by its absence of corners or edges, effectively reduces the peak von Mises stress.A number of case studies were undertaken. The results show that, by introducing the separated-configuration structure, the unit cooling capacity of TEC system increases from 16.66 W/m2 to 18.82 W/m2 by 13%, while the cooling surface temperature is reduced by 0.2 °C.This research shows that the TEC geometry optimization and separated TEC configuration create an opportunity to allow the TEC to be well integrated into a building. The cooling performance of the TEC could be improved by establishing the optimal geometry and its proper connection and configuration

On-Chip Thermoelectric Hotspot Cooling

Increased power density and non-uniform heat dissipation present a thermal management challenge in modern electronic devices. The non-homogeneous heating in chips results in areas of elevated temperature, which even if small and localized, limit overall device performance and reliability. In power electronics, hotspot heat fluxes can be in excess of 1kW/cm2. Although novel package-level and chip-level cooling systems capable of removing the large amounts of dissipated heat are under development, such “global” cooling systems typically reduce the chip temperature uniformly, leaving the temperature non-uniformity unaddressed. Thus, advanced hotspot cooling techniques, which provide localized cooling to areas of elevated heat flux, are required to supplement the new “global” cooling systems and unlock the full potential of cutting-edge power devices. Thermoelectric coolers have previously been demonstrated as an effective method of producing on-demand, localized cooling for semiconductor photonic and logic devices. The growing need for the removal of localized hotspots has turned renewed attention to on-chip thermoelectric cooling, seeking to raise the maximum allowable heat flux of thermoelectrically-cooled semiconductor device hotspots. This dissertation focused on the numerical and empirical determination of the operational characteristics and performance limits of two specific thermoelectric methods for high heat flux hotspot cooling: monolithic thermoelectric hotspot cooling and micro-contact enhanced thermoelectric hotspot cooling. The monolithic cooling configuration uses the underlying electronic substrate as the thermoelectric material, eliminating the need for a discrete cooler and its associated thermal interface resistance. Micro-contact enhanced cooling uses a contact structure to concentrate the cooling produced by the thermoelectric module, enabling the direct removal of kW/cm2 level heat fluxes from on-chip hotspots. To facilitate empirical validation of on-chip thermoelectric coolers and characterization of advanced thin film thermoelectric coolers, it was found necessary to develop a novel laser heating system, using a high power laser and short-focal length optics. The design and use of this illumination system, capable of creating kW/cm2-level, mm-sized hotspots, will also be described

Opportunities for mesoscopics in thermometry and refrigeration: Physics and applications

This review presents an overview of the thermal properties of mesoscopic structures. The discussion is based on the concept of electron energy distribution, and, in particular, on controlling and probing it. The temperature of an electron gas is determined by this distribution: refrigeration is equivalent to narrowing it, and thermometry is probing its convolution with a function characterizing the measuring device. Temperature exists, strictly speaking, only in quasiequilibrium in which the distribution follows the Fermi-Dirac form. Interesting nonequilibrium deviations can occur due to slow relaxation rates of the electrons, e.g., among themselves or with lattice phonons. Observation and applications of nonequilibrium phenomena are also discussed. The focus in this paper is at low temperatures, primarily below 4 K, where physical phenomena on mesoscopic scales and hybrid combinations of various types of materials, e.g., superconductors, normal metals, insulators, and doped semiconductors, open up a rich variety of device concepts. This review starts with an introduction to theoretical concepts and experimental results on thermal properties of mesoscopic structures. Then thermometry and refrigeration are examined with an emphasis on experiments. An immediate application of solid-state refrigeration and thermometry is in ultrasensitive radiation detection, which is discussed in depth. This review concludes with a summary of pertinent fabrication methods of presented devices.Comment: Close to the version published in RMP; 59 pages, 35 figure

Cooling Storage for Vehicles Using Thermoelectric Cooler

This project addresses the above situation and as a further development of the solid state system, it is intended to build a cooler box for use in vehicles. The thermoelectric cooler device used is pettier which follow Peltier Effect Theory that produces heat difference from electrical voltage. The product promises a big market by looking at the growth of automotive market over the years

Spaceborne sensors (1983-2000 AD): A forecast of technology

A technical review and forecast of space technology as it applies to spaceborne sensors for future NASA missions is presented. A format for categorization of sensor systems covering the entire electromagnetic spectrum, including particles and fields is developed. Major generic sensor systems are related to their subsystems, components, and to basic research and development. General supporting technologies such as cryogenics, optical design, and data processing electronics are addressed where appropriate. The dependence of many classes of instruments on common components, basic R&D and support technologies is also illustrated. A forecast of important system designs and instrument and component performance parameters is provided for the 1983-2000 AD time frame. Some insight into the scientific and applications capabilities and goals of the sensor systems is also given

PORTABLE COOLING COMPARTMENT FOR STORAGE OF MEDICATION

This is a project on development oftemperature balancing circuit. The objective of this project is to monitor the temperature of a confined space and keep it at a preset value 10°C. The scope ofstudy covers the microcontroller circuit used to monitor the input by the temperature sensor and give output signal to current amplifier circuit to the peltier device. It also covers the current amplifier circuit and container design to maintain the temperature. Other important components of the system also include heat transfer concept, DC Fan, heatsink and insulation material. Experiments on the peltier device have been performed and its characteristics have been studied. High power with good insulation and heat removal system are most important on the matter of increasing the performance of the peltier. Prototype of the project has been constructed and tested and worked according to specification of cooling the container uptolO°C. I

Pulsed laser deposition of Bismuth Telluride compounds for human body energy scavengers

The world wide research interest in Bismuth Telluride thin films is due to the fact that they are the most commonly efficient thermoelectric materials at temperatures as low as room temperature, which is typically suitable for implementing such thin films through the fabrication of miniaturized thermoelectric generators and human body energy scavengers. This work aims to characterize various Bismuth Telluride -based thin films deposited by Pulsed Laser Deposition technique in order to optimize their thermoelectric performance represented in their thermoelectric figures of merit. This has been achieved by investigating the electrical and thermoelectric properties of the deposited thin films as well as studying the structural properties of such thin films that is necessary for future micromachining and fabrication of energy scavengers; the results of this effort are really promising. The first chapter is an introductory overview concerning thermoelectric effects and thermoelectric generators. The second chapter deals with the different deposition techniques and the reasoning behind the employment of PLD to deposit Bismuth Telluride thin films. The third chapter includes some of Bismuth Telluride chemical and physical properties in addition to a literature survey of what other groups have already achieved concerning this material. The fourth chapter covers all the experiments and includes the results of this work. Finally, the fifth chapter includes the summary, conclusion and recommendation for future progress in this topic

National MEMS Technology Roadmap - Markets, Applications and Devices

MEMS teknologiaa on jo pitkään käytetty lukuisien eri laitteiden valmistamiseen. Osa näistä laitteista on ollut markkinoilla jo useita vuosia, kun taas osa on vasta kehitysvaiheessa. Jotta tutkimus ja kehitystyötä osattaisiin jatkossa kohdistaa oikeille painopistealueille, on tärkeää tietää mihin suuntaan kehitys on menossa. Tämä työ on osa kansallista MEMS teknologioiden tiekartta -projektia ja sen tavoitteena oli selvittää MEMS laitteiden kehityksen suuntaa. Työ toteutettiin laajana kirjallisuustutkimuksena. Lisäksi tulosten tueksi haastateltiin asiantuntijoita Suomen MEMS teollisuudesta. Työssä tarkasteltiin lukuisia jo markkinoilta löytyviä ja vasta kehitteillä olevia MEMS laitteita ja analysoitiin niitä sekä teknisestä että kaupallisesta näkökulmasta. Tutkimuksen perusteella kävi ilmi, että MEMS markkinat ovat pitkään muodostuneet vakiintuneista laitteista kuten mustesuihkupäistä, kiihtyvyysantureista, paineantureista sekä RF suotimista. Lisäksi mikrofonit, gyroskoopit ja optiset laitteet ovat olleet kaupallisesti saatavilla jo pitkään. Markkinat ovat hiljattain alkaneet tehdä tilaa myös uusille MEMS laitteille, joita tulee ulos nopeaa vauhtia. Viimeisimpänä markkinoille tulleita laitteita ovat erilaiset mikrofluidistiikka laitteet, mikrobolometrit sekä yhdistelmäanturit. Pian kaupallisesti saatavia laitteita ovat magnetometrit, automaattitarkennuslaitteet sekä MEMS oskillaattorit. Näiden laitteiden lisäksi kehitteillä on monia uusia MEMS laitteita, jotka saattavat tarjota merkittäviä mahdollisuuksia tulevaisuudessa. Kehitteillä olevia laitteita ovat erilaiset lääketieteelliset laitteet, atomikellot, mikrojäähdyttimet, mikrokaiuttimet, energiantuottolaitteet sekä RFID-laitteet. Kaikki kehitteillä olevista laitteista eivät välttämättä tule menestymään kaupallisesti, mutta jatkuva tutkimustyö osoittaa, että monilla MEMS laitteilla on potentiaalia useissa eri sovelluksissa. Markkinanäkökulmasta tarkasteltuna suurin potentiaali piilee kuluttajaelektroniikka markkinoilla. Muita tulevaisuuden kannalta potentiaalisia markkinoita ovat lääketieteelliset ja teollisuusmarkkinat. Tutkimus osoitti että MEMS laitteiden tutkimukseen ja kehitykseen liittyy monia potentiaalisia painopistealueita tulevaisuudessa. Käyttömahdollisuuksien parantamiseksi monet jo vakiintuneet laitteet kaipaavat vielä parannuksia. Toisaalta, jo olemassa olevia laitteita voidaan hyödyntää uusissa sovelluksissa. Lisäksi monet uusista ja kehitteillä olevista MEMS laitteista vaativat vielä kehitystyötä.MEMS technology has long been applied to the fabrication of various devices from which some have already been in use for several years, whereas others are still under development. In order to find future focus areas in research and development activities in the industry, it is important to know where the development is going. This thesis was conducted as a part of National MEMS technology roadmap, and it aimed for determining the evolution of MEMS devices. The work was conducted as an extensive literature review. In addition, experts from the Finnish MEMS industry were interviewed in order obtain a broader insight to the results. In this thesis various existing and emerging MEMS devices were reviewed and analyzed from technological and commercial perspectives. The study showed that the MEMS market has long been composed of established devices, such as inkjet print-heads, pressure sensors, accelerometers and RF filters. Also gyroscopes, microphones and optical MEMS devices have already been on the market for a long time. Lately, many new devices have started to find their place in the markets. The most recently introduced commercial devices include microfluidic devices, micro bolometers, and combo sensors. There are also a few devices including magnetometers, MEMS oscillators, and auto-focus devices that are currently crossing the gap from R&D to commercialization. In addition to the already available devices, many new MEMS devices are under development, and might offer significant opportunities in the future. These emerging devices include various bioMEMS devices, atomic clocks, micro-coolers, micro speakers, power MEMS devices, and RFID devices. All of the emerging devices might not find commercial success, but the constant stream shows, that there are numerous applications, where MEMS devices could be applied in. From a market point of view, the greatest potential in the future lies in consumer electronics market. Other highly potential markets include medical and industrial markets. The results of the thesis indicate that there are many potential focus areas in the future related to MEMS devices, including improvements of the existing devices in order to gain better utilization, application of the existing devices in new areas, and development work among the emerging devices