Mission Critical Tools at MITs Microsystems Technology Labs

Mission Critical Tools at MIT’s Microsystems Technology Labs Dr. Vicky Diadiuk MTL Associate Director, Operations Massachusetts Institute of Technology

MTL Mission · Support EDUCATION (graduate & undergraduate) through research in semiconductor devices and processes · Support RESEARCH in micro- & nanosystems, technologies and structures · Provide FACILITIES and infrastructure for research in micro- & nanosystems and associated technologies

MTL – Infrastructure (Fab and CAD) Fabrication (Supported by 16 Technical Staff) • Integrated Circuits Laboratory (ICL) • Class 10 – 2, 800 sq. ft. (6”, some 4” & pieces) • Mostly CMOS compatible processes • Silicon, Germanium, Quartz, III-V, Ga. N • Technology Research Laboratory (TRL) • Class 100 – 2, 200 sq. ft. (up to 6”) • Flexible Processing • Silicon, III-V, Glass, Organics, Polymers • Exploratory Materials Laboratory (EML) • Class 10, 000 – 2, 000 sq. ft. • Thin Film Processing Facility • Electron Beam Lithography Laboratory (EBL) • Class 100 – 400 sq. ft • Elionix EFS-125; operated jointly with RLE CAD and IT (Supported by 4 Staff) • CAD platforms; foundry access

2015 User Distribution by Primary Research Area & Material (from Self-Reported Data) Fab Users = 412

MTL Research Activities: Length Scale Mo. S 2 FET (Palacios) In. Ga. As Fin. FETs (del Alamo) Magnetic Domain Wall Logic Devices Graphene Nanoporous (Baldo) Membrane (Karnik) Si Field-Emitter Array (Akinwande) 320 GHz RX chip for Coherent THz Imager (R. Han) Microhydraulic Actuator (Kim) Flexible Tactile Sensor (Lang) AC-DC Power Factor Correction Circuit Architecture (Perreault) Roll-to-Roll Graphene Transfer Tool (Kong, Palacios) Slide courtesy of Jesus del Alamo

The Process Technology Committee (PTC) Key to avoiding cross-contamination among processes • Meets weekly to review and approve new processes, materials and protocols; reviewed within 1 week of submission. • Interviews users who request 24 -hr status • Is composed of 3 -4 faculty, 4 students/post-docs (who serve for 1 year), rotating MTL Specialists and the Assoc. Director of Operations, who chairs it • Provides process advice, since members cover different research areas • Maintains and updates the PTC Matrix PTC members are available for assistance with processes or questions on new materials, protocols, etc.

PTC Matrix http: //mtlweb. mit. edu/services/fabrication/ptc_matrix. html

How to use the PTC Matrix Y- axis: Machines (by lab); X-axis: wafer attributes Some Wafer attributes are permanent (*), some are added by a machine (o+), some can be removed by a machine (o-) An o indicates that a wafer is allowed in that tool, an x that it isn’t

Major Fab Areas • Diffusion: atmospheric & LPCVD furnaces; RTP • Photolithography: mask-aligners, stepper • E-beam Lithography: Elionix EFS-125 • Dry Etch: various chemistries, depth, wall angle • Deposition: PECVD, e-beam, sputtering • Wet Processes: clean, etch, release • Metrology: thickness, index, morphology • Packaging: CMP, die-saw, wire-bond http: //mtlweb. mit. edu/services/fabrication/equipment. html

Need Tools for New & Traditional Research Directions Periodically, fabs need to replace tools & acquire new capabilities New research directions, as well as some traditional projects, often need special tools, that are useful to general users, so they belong appropriately in shared cleanrooms. Examples are: • RIE & DRIE for various materials (Si, III-Vs, etc) • Deposition systems for CNT, graphene & other 2 D materials & the corresponding transfer hoods So how does the MTL shared facility acquire process tools?

Tool Acquisition Modes at MTL • Industrial donations - very selective on what is accepted • MTL acquisitions - with MIT capital equipment replacement funds • Individual research grants - tools may be fully shared or mission-critical; no private tools are allowed in cleanrooms (due to space limitations & management issues) What is a mission-critical tool? - Group that acquires mission-critical tool still pays fabfees - May get some reserved-use time - Can veto materials that would compromise “the mission” - Restrictions get captured in PTC Matrix - Advantages to the group: professional maintenance, shared consumable costs MTL staff maintains and supports all tools; develops basic processes

Examples of Mission Critical Tools Angstrom Engineering Evo. Vac deposition system • Sputtering, e-beam and thermal evaporation Funded by a research grant Mission restriction: CMOS metals only Applied Materials Centura 5200 dielectric deposition system • PECVD of very tightly controlled Si nitrides an oxides Donated to a research group by the OEM Mission restriction: no metals on wafers STS Multiplex ICP DRIE system • Deep RIE of Si Funded by a research grant Mission restriction: no polyimide

Summary MTL provides shared fabrication facilities that: • Provide hands-on training in micro- and nano-fabrication • Enable researchers to cross disciplinary boundaries • Encourage free flow of information across projects and technologies • Careful control of process flows avoids cross-contamination • Provide access to a large variety of tools, obtained by: donation, internal & research-grant funding • No private tools are allowed, but tool-level restrictions are acceptable for mission critical machines; this has enormous benefits for the entire nano/micro- fabrication community

Thank you for your attention

Sample Process Using the PTC Matrix User Jorg Scholvin programmed the PTC Matrix in Excel Basic for auto-checking THANKS!