[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-316599-105":59,"doc-detail-316599-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","vertical-acoustic-confinement-for-high-q-fully-differential-cmos-rbts","Vertical Acoustic Confinement for High-Q Fully-Differential CMOS-RBTS","","Work demonstrates phononic crystals enabling solid-state phononic waveguides within standard CMOS. The waveguides confine vibrational energy in CMOS front-end-of-line (FEOL) layers. Fully-differential driving supports wave guiding and reduces scattering. Unreleased CMOS resonant body transistors (RBTs) using these waveguides are implemented in IBM 32nm SOI technology. Quality factors above 13,000 are reported at 3.185GHz, with fo·Q reaching 4.2×1013, the best fo·Q for both released and unreleased RBT/MEMS resonators.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":40,"@type":76,"position":81},"https://docshare.wps.com/document/research-report/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/vertical-acoustic-confinement-for-high-q-fully-differential-cmos-rbts/316599/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/vertical-acoustic-confinement-for-high-q-fully-differential-cmos-rbts/316599.png","ImageObject",300,407,{"name":92,"@type":93},"Riley","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-31","2026-09-20",true,{"@type":102,"interactionType":103,"userInteractionCount":52},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What is the main approach used to achieve vertical energy confinement in CMOS resonant devices?","Question",{"text":112,"@type":113},"The work uses phononic crystals to build solid-state phononic waveguides that confine vibrational energy vertically into CMOS FEOL layers.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"Why is fully-differential driving important for the CMOS RBTS in this study?",{"text":117,"@type":113},"Fully-differential driving is shown to be essential for ensuring wave guiding while minimizing scattering.",{"name":119,"@type":110,"acceptedAnswer":120},"What performance results are reported for the unreleased CMOS RBTs?",{"text":121,"@type":113},"Unreleased CMOS resonant body transistors achieve quality factors exceeding 13,000 at 3.185GHz, with fo·Q of 4.2×10^13.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},316599,1790653949,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":39,"category_name":40,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":52,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":19,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":52,"preview_page_count":4},1374391975076,"https://ap-avatar.wpscdn.com/avatar/14000253ca4ec9f6853?x-image-process=image/resize,m_fixed,w_180,h_180&k=1783305029341752051","VERTICAL ACOUSTIC CONFINEMENT FOR HIGH-Q FULLY-DIFFERENTIAL CMOS-RBTS  \nBichoy Bahr1 * and Dana Weinstein2  \n1Massachusetts Institute of Technology, Cambridge, Massachusetts, USA 2Purdue University, West Lafayette, Indiana, USA  \nABSTRACT  \nThis work demonstrates the use of phononic crystals (PnCs) to create solid-state phononic waveguides in standard CMOS technology. Such waveguides confine vibrational energy in CMOS frontend-of-line (FEOL) layers. Fully-differential driving ensures wave guiding and lowers scattering. Unreleased CMOS resonant body transistors (RBTs) based on these waveguides were implemented in IBM 32nm SOI technology. Quality factors exceeding 13,000 are achieved at 3.185GHz for an fo⋅Q of 4.2×1013, marking the highest fo⋅Q RBT and highest fo⋅Q unreleased MEMS resonator to date.  \nINTRODUCTION  \nHigh-Q resonators are crucial components for filters and low phase noise oscillators, which are essential for RF, analog and digital circuits. With the ever expanding demands for higher communication data rates and fast data processing, it is desirable for resonators to scale to GHz-frequencies and beyond. Wearable electronicsand medical implants are examples of critical battery-operated systems that necessitate minimization of power consumption, size and cost. Micro-Electro-Mechanical (MEM) resonators are an attractive solution for today’s demands, with 􀀡 > 10% at GHz-frequencies and footprint on the order of 50􀀧􀀨) . Their monolithic integration with CMOS has been the subject of many research studies, with MEMS-first, MEMS-last and CMOS-MEMS being the most notable approaches [1] .  \nThe authors have previously demonstrated a new class of unreleased CMOS MEMS resonators, the Resonant Body Transistor (RBT), fabricated in the same process and side-by-side with standard CMOS transistors, without the need for any post-processing or packaging [2] . These RBTs rely on phononic crystals constructed in the CMOS back-end-of-line (BEOL) layers to achieve elastic energy confinement. Acoustic resonance is detected by active FET sensing, where the stress in the channel modulates the mobility of the sensing transistor [6] . MOS capacitors (MOSCAPs) are used for electrostatic actuation. It is also important to notice that scaling to GHzfrequencies has the advantage of making Landau-Rumer regime the dominant phonon relaxation process. This allows fo⋅Q to scale linearly with fo, enabling higher Q devices.  \nIn contrast, this work demonstrates phononic waveguides in standard CMOS technology, that confine the elastic vibrational energy vertically to the CMOS front-end-of-line (FEOL) layers. Confinement is achieved by reflection from the top by using a BEOL PnC as in [2], and from the bulk wafer by virtue of the faster sound velocity therein. This is a phenomenon similar to index guiding in photonic waveguides [3] . For CMOS RBTs, fully-differential driving is proven to be essential to ensure wave guiding and to minimize scattering. This wave guiding allows for > 50× increase in quality factor of unreleased CMOS MEMS resonators. RBTs based on these phononic waveguides with fully-differential drive and sense are implemented in IBM 32nm SOI technology as shown in Fig. 1.  \nDEVICE DESIGN  \nBEOL Phononic Crystal  \nPnCs are periodic structures composed of materials with contrasting acoustic impedance, which are characterized by the  \nFigure 1: SEM micrograph showing (a) the full RBT structure (b) sensing FETs with isolation gates and (c) the termination waveguide section.  \npresence of bandgaps in their dispersion relation. Such bandgaps prohibit wave propagation in at least one direction, within the corresponding frequency range. Table 1 shows the mechanical properties of common CMOS BEOL materials. Large acoustic impedance contrast can be observed, especially between copper and the low-k SiCOH dielectric. This enables the realization of BEOL PnCs with large bandgaps. The latter are highly desirable to minimize the effect of CMOS process va","cbCaidYOEfVSu4NI","https://ap.wps.com/l/cbCaidYOEfVSu4NI","pdf",6117609,"English","# Abstract\n# Introduction\n# Device Design\n## BEOL Phononic Crystal\n## Phononic Waveguides","[{\"question\":\"What is the main approach used to achieve vertical energy confinement in CMOS resonant devices?\",\"answer\":\"The work uses phononic crystals to build solid-state phononic waveguides that confine vibrational energy vertically into CMOS FEOL layers.\"},{\"question\":\"Why is fully-differential driving important for the CMOS RBTS in this study?\",\"answer\":\"Fully-differential driving is shown to be essential for ensuring wave guiding while minimizing scattering.\"},{\"question\":\"What performance results are reported for the unreleased CMOS RBTs?\",\"answer\":\"Unreleased CMOS resonant body transistors achieve quality factors exceeding 13,000 at 3.185GHz, with fo·Q of 4.2×10^13.\"}]","Vertical Acoustic Confinement for High-Q Fully-Differential CMOS-RBTS | PDF",1789919434]