Contains reports on one research project.Defense Advanced Research Projects Agency MDA 972 88-K-000

Doughty, Francis M.

Heytens, Michael L.

Iwai, Kyle K.

Kashani, Abbas

Ko, Weng-Yew

Lohman, Thomas J.

Martinez, Wilberto

McIlrath, Michael B.

Troxel, Donald E.

DSpace@MIT

Chapter 2. Computer-Aided Fabrication System StructureChapter 2. Computer-Aided Fabrication SystemStructureAcademic and Research StaffProfessor Donald E. Troxel, Michael B. Mcllrath, Wilberto Martinez, Thomas J. LohmanGraduate StudentsMichael L. Heytens, Kyle K. Iwai, Abbas Kashani, Weng-Yew KoTechnical and Support StaffFrancis M. Doughty2.1 CAFE-The MITComputer-Aided FabricationEnvironmentSponsorDefense Advanced Research Projects AgencyMDA 972 88-K-00082.1.1 Research Goals and ObjectivesCAFE (Computer-Aided Fabrication Environment)is a software system being developed at MIT foruse in the fabrication of integrated circuits andmicrostructures. The distinguishing feature ofCAFE is that it can be used in all phases ofprocess design, development, planning, and manu-facturing of integrated circuit wafers. This manu-facturing software system is unique because aprocess flow representation is developed and inte-grated into actual fabrication operations.Presently CAFE provides day-to-day support toresearch and production facilities at MIT with bothflexible and standard product capabilities. Thissoftware system provides a platform for work inseveral active research areas including"technology" (process and device) computer-aided design (TCAD), process modeling, manufac-turing quality control, and scheduling.2.1.2 ArchitectureThe CAFE architecture is a computer integratedmanufacturing (CIM) framework for the deploy-ment and integration of integrated circuits andprocess design and manufacturing software. CAFEuses an object-oriented database model which isimplemented in a layered manner on top of a rela-tional database. Our database schema is based onGESTALT, an object-oriented extensible datamodel. GESTALT is a layer of abstraction whichmaps user defined objects onto existing databasesystems (e.g., a relational DBMS) and shieldsapplication programs from the details of the under-lying database. The integration architectureincludes the conceptual schema and models usedto represent the integrated circuit manufacturingdomain in CAFE, and the user and programmaticinterfaces with its various applications. Twoimportant CAFE applications relate process simu-lation and actual wafer fabrication to the sameprocess flow representation.2.1.3 Process Flow RepresentationDuring the past year, progress in process flowrepresentation (PFR) was made in three majorareas: fundamental modeling, application to fabri-cation at MIT, and cooperative efforts withindustry to define and test a process representationstandard.A high level conceptual model for describing andunderstanding semiconductor manufacturingprocess knowledge is a crucial component both ofthe research program and CAFE implementation.Driven by the needs of process control and opti-mization research, including sophisticated mod-eling, design, and experimental model verification,our fundamental conceptual process model hasevolved from a two-stage generic process modelinto one which is part of a more general processmodeling framework. The two-stage model istreated as a special case.To take advantage of an opportunity to apply ourresearch, extensive effort was directed towardindustrial efforts in Technology (process anddevice) CAD Framework (TCAD) to define abroadly applicable semiconductor process repre-sentation (SPR) standard. Based largely on theconceptual process model described above, a high261Chapter 2. Computer-Aided Fabrication System Structurelevel information model of semiconductor pro-cesses is being developed in conjunction withMotorola, IBM, and Texas Instruments, as well asother representatives from industry and universi-ties. A prototype SPR implementation and pro-gramming interface was developed and employedin the TCAD Framework demonstration in August1991.2.1.4 CAFE ApplicationsThe fabrication of wafers with a process repres-ented as a PFR involves several steps. A suitablePFR for the specific process must be created andinstalled. Wafer lots must be created and associ-ated with this specific PFR. These lots must thenbe "started" to create a task data structure which isisomorphic to the hierarchical structure of the PFR.At this point, actual machine operations can bescheduled and reservations made for bothmachines and operators. Finally, the machineoperations can be performed, instructions given tothe operator and machines, and data collectedfrom the operator or machine and entered into thedatabase.An experimental fabrication run of the MITbaseline CMOS process was made in which alloperations were driven by the CAFE system usinga PFR representation of the process. We havebeen evaluating the results of this experiment, per-formed in conjunction with the Integrated CircuitsLaboratory staff, and preparing a plan forexpanding use of PFR in the lab to other processesincluding research processing.Current work involves the implementation ofhierarchical scheduling, real time process controlusing PFR, and integration of a microelectro-mechanical TCAD system using PFR.2.1.5 PublicationsBoning, D.S., M.B. Mcilrath, P. Penfield, and E.Sachs, "A General Semiconductor ProcessModeling Framework." IEEE Trans. Semicond.Manufact. Forthcoming.Ko, W.-Y. Graphical Framework for Computer-Aided Fabrication Environment's Process FlowRepresentation. S.M. thesis, Dept. of Electr.Eng. and Comput. Sci., MIT, 1991.Mcllrath, M. "A General Semiconductor ProcessModeling Framework." Presentation at theSemiconductor Research Corporation (SRC)Computer Integrated Manufacturing of Inte-grated Circuits (CIM-IC) Workshop, Raleigh,North Carolina, August 21-23, 1991.Mcllrath, M. Current Concepts in SemiconductorProcess Representation. CFI Document No.91-T-2. Austin, Texas: CAD Framework Initi-ative, 1991.Mcllrath, M. "Semiconductor Process Represen-tation (SPR) Server Prototyping." Presentationat the Technology Computer-Aided Design(TCAD) Working Group, San Francisco,California, June 21, 1991 (see CFI DocumentNo. 91-M-8).Mcllrath, M. "Report on SPR Prototyping." Pres-entation at the TCAD SPR Working Group,Palo Alto, California, August 10, 1991 (see CFIDocument No. 91-M-10).Mcllrath, M. "TCAD Framework ArchitecturalIssues." Presentation at the TCAD FrameworkPlenary Session, Palo Alto, California, August10, 1991 (see CFI Document No. 91-M-10).Mcllrath, M. "Mini-SPR Prototype ProgrammingInterface." Unpublished technical report deliv-ered to the TCAD SPR Working Group, June21, 1991.Mcllrath, M. "TCAD Framework ArchitecturalIssues." Unpublished technical report deliveredto the TCAD Framework Group, Palo Alto,California, August 10, 1991.262 RLE Progress Report Number 134

Computer-Aided Fabrication System Structure

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Computer-Aided Fabrication System Structure

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