WorldWide Drilling Resource

Cool New Microchips Can Take the Heat Adapted from Information Provided by the Fraunhofer Institute for Microelectronic Circuits and Systems Temperatures exceeding 392°F (200°C) are often encountered during geothermal production. Conventional microelectronics hit their limits at these high temperatures; however, new com- pact microchips have been fabricated that keep their cool even at 572°F (300°C). Temperatures up to 12,600°F (7000°C) are thought to exist in the earth’s core. At a depth of 2.5 to 3.5 miles, temperatures range from 302°F (150°C) to over 392°F (200°C). These reserves of heat can be used as a re- newable source of energy for geother- mal power. Drill bits and borehole probes used in geothermal production are high-tech machines. Fitted with a range of sen- sors and control mechanisms, they can be precisely controlled, or autonomously analyze environmental parameters and locate suitable regions for production. Complementary metal-oxide semi- conductors (CMOS) sometimes tolerate temperatures of up to 482°F (250°C), but their performance and reliability rap- idly decreases. Companies often have to test a large quantity of these standard chips using the trial-and-error method before obtaining an acceptable selection. Continuously cooling heat-sensitive microelectronics is one option; but the process is labor-intensive. Specialized high-temperature chips are on the mar- ket already, but they are large. “The solutions available are always associ- ated with certain trade-offs: either they have comparatively large components, or they function with limited perform- ance,” said Holger Kappert, head of high-temperature electronics at the Fraunhofer Institute for Microelectronic Circuits and Systems (IMS). 47 WorldWide Drilling Resource ® OCTOBER 2014 "0",-" - 0 &' '" &) (*-. -&2"- )! )/( ", *# ' !"- "1 -"! &.- *'" +")",- , $ &.- &)$- ((",- ((", &.- &0",.",- " .&++&)$ . &'&2",- ' 1 &.- &+" &+"- *'. *) "".% / - * &'" &. *&) ,*! %*.( &' *( 111 &. *&) /- A First for Greenwich Avenue Compiled by Amy White, Associate Editor WorldWide Drilling Resource ® In Greenwich, Connecticut, 12 geo- thermal wells were drilled for a new three-story, 12,000-square-foot, mixed- use building. Positioned 500 feet below the building, these are the first geother- mal wells ever installed on Greenwich Avenue. Ageothermal system typically begins to pay for itself a few years after it is installed, but owners of the newGreenwich Avenue building are already reaping the benefits. Justin Shaw, principal of JCS Construction Group, said he was happy to introduce something new to Greenwich. JCS Construction is also a partner in the ownership entity of the building, and was thrilled to lease its first floor to celebrity chef Graham Elliot. Elliot’s restaurant, Primary Food & Drink serves a menu of contemporary American seasonal cuisine. From its leather banquet seating, to the oak tables made of reclaimed South Carolina wood, the restaurant’s design is focused around comfort. However, the features providing the most comfort to patrons are the geothermal loops in the ground none of them will ever see. Geothermal wells were drilled on Greenwich Avenue for the first time. Photo courtesy of rew-online.com Microchips from IMS are different. They are considerably smaller than the high-temperature chips currently avail- able. These complex microstructures provide more functionality with less size. To fabricate the heat-tolerant mini- chips, researchers in Duisburg, Germany, use a specialized high-temperature SOI CMOS process. “SOI stands for ‘silicon-on-insulator’ - that means we introduce a layer that insulates the transistors from one another,” Kappert explained. Insulation prevents leakage currents from influencing the chip’s performance. Researchers also use tungsten metallization, which is less temperature-sensitive than the aluminum usually used. This increases the oper- ating life of high-temperature chips. Initial field tests of the new chips have been positive. IMS researchers hope to offer the fabrication process as a service later this year.