Univ of Illinois Micro + Nanotechnology Lab 2016 Highlights Report | Page 10

MacEtch method makes tall , narrow finFETs
Exploring next-generation 2D materials and transistor designs
Illinois researchers led by Professor Xilung Li ( right ) have developed a method to etch tall , thin transistors for high performance with less error . Other team members include graduate student Yi Song ( center ) and ECE Emeritus Professor Ilesanmi Adesida ( left ).

MacEtch method makes tall , narrow finFETs

Smaller and faster has been the trend for electronic devices since the inception of the computer chip , but flat transistors have gotten about as small as physically possible . For researchers pushing for even faster speeds and higher performance , building up is one way to go . ECE Professor Xiuling Li has developed a way to etch very tall , narrow finFETs , a type of transistor that forms a tall semiconductor “ fin ” for the current to travel over . Her group ’ s unique etching technique , known as metal-assisted chemical etching ( MacEtch ), addresses many problems in trying to create 3-D devices , typically done now by stacking layers or carving out structures from a thicker semiconductor wafer . Li ’ s smooth finFETS , which are made of indium phosphide , have aspect ratios that are impossible for other existing fabrication methods to reach . In addition to transistors , the MacEtch technique could also apply to many other types of devices or applications that use 3-D semiconductor structures , such as computing memory , batteries , solar cells and LEDs , as well as scaffolds for biomaterials .
Source : IEEE Electron Device Letters , “ Ultra-high aspect ratio InP junctionless finFETs by a novel wet etching method ,” volume 37 , issue 8 , August 2016 .

Exploring next-generation 2D materials and transistor designs

Although it has driven innovation in the semiconductor industry for 50 years , silicon CMOS technology is reaching its limits as transistor feature sizes ( 14 nanometers and shrinking ) may soon become too small to manufacture efficiently and cost effectively . ECE Assistant Professor Wenjuan Zhu and her students are exploring next-generation two-dimensional ( 2D ) materials and transistor designs as an alternative to silicon CMOS . In 2016 , her group demonstrated heterojunction transistors made from germanium selenium ( GeSe ) and molybdenum disulfide ( MoS 2
). These 2D transistors are essential components of tunnel field-effect transistors ( TFETs ) and are ideally suited for low power applications such as mobile phones and implanted medical devices . Her group also systematically investigated the spatial / temporal photocurrent and electronic transport of monolayer MoS 2 grown by chemical vapor deposition ( CVD ), which provides a viable path for nextgeneration flexible electronic and optoelectronic circuits . Source : Applied Physics Letters , “ Spatial / temporal photocurrent and electronic transport in monolayer molybdenum disulfide grown by chemical vapor deposition ,” volume 108 , issue 8 , February 2016 .
ECE Assistant Professor Wenjuan Zhu and her students demonstrated novel 2D transistors that could someday be used in mobile phones and implanted medical devices .
MNTL | 8 | University of Illinois at Urbana-Champaign