mm 1*4 NIST NISTIR 6884 Silicon Microelectronics Programs AT THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY Programs, Activities and Accomplishments JULY 2002 Edited by Stephen Knight Joaquin V. Martinez de Pinillos and Michele Buckley National Institute of Standards and Technology Technology Administration, U.S. Department of Commerce Cover Picture Caption Silicon Microelectronics Programs at the National Institute of Standards and Technology is a NIST- wide effort to meet the highest priority measurement needs of the semiconductor industry and its supporting infrastructure. Research efforts include development of standard test structures for inter- connect reliability evaluation; fundamental measurements of ionization cross sections of gas species used in plasma processing of integrated circuits; development of advanced at-speed test techniques for gigahertz integrated circuits; and development of precise measurement techniques for characterizing aspheric lenses for Extreme Ultraviolet Lithography. m Silicon Microelectronics Programs at National Institute of Standards and Technology Programs, Activities, and Accomplishments B| NISTIR 6884 July 2002 m U.S. DEPARTMENT OF COMMERCE Donald L. Evans, Secretary Technology Administration Phillip J. Bond, Under Secretary of Commerce for Technology National Institute of Standards and Technology Arden L. Bement, Jr., Director Disclaimer Disclaimer: Certain commercial equipment and/or software are identified in this report to adequately describe the experimental procedure. Such identification does not imply recommendation or endorse- ment by the National Institute of Standards and Technology, nor does it imply that the equipment and/or software identified is necessarily the best available for the purpose. References: References made to the International Technology Roadmap for Semiconductors (ITRS) apply to the most recent edition, dated 1999. This document is available from the Semiconductor Industry Association (SLA), 181 Metro Drive, Suite 450, San Jose, CA 95110, phone: (408) 436-6600; fax: (408) 436-6646. Appendices: The reader will notice that there are acronyms and abbreviations throughout this docu- ment that are not spelled out due to space limitations. To enable the reader to learn more about these acronyms and abbreviations, we have included an acronyms/abbreviations list is in an appendix at the end of this report. We have also included a list of the National Semiconductor Metrology Program (NSMP) projects, which demonstrates the synergism resulting from this matrix-managed program. — - Contents Welcome and Introduction v Office of Microelectronics Programs Organization vii Lithography 1 Metrology Supporting Deep Ultraviolet Lithography 2 Metrology Supporting EUV Lithography 7 Polymer Photoresist Fundamentals for Next-Generation Lithography 10 Critical Dimension and Overlay Metrology Program 13 Atom-Based Dimensional Metrology 14 Scanning Electron Microscope-Based Dimensional Metrology 18 Opticai-Based Dimensional Metrology 22 Scanning Probe Microscope-Based Dimensional Metrology 27 Electrical-Based Dimensional Metrology 31 X-Ray and Neutron Small Angie Scattering-Based Dimensional Metrology 36 Model-Based Linewidth Metrology 40 Thin Film and Shallow Junction Metrology Program 44 Two- and Three-Dimensional Dopant Profiling 45 Boron and Nitrogen Thin Film and Implant Standards Using Neutron Depth Profiling 51 Gate Dielectric Metrology. 53 Chemical Metrology of Materials & Particle Contamination 65 Thin Film X-ray Metrology for Microelectronics 69 Second Harmonic Generation from the Silicon-Silicon Dioxide Interface 72 Interconnect and Packaging Metrology Program 74 Superconformai Deposition of Copper and Advanced Interconnect Materials 75 Porous Thin Films Metrology for Low K Dielectric 78 Interconnect Dielectric Characterization Using Transmission-Line Measurement 82 Wire Bonding to Cu/Low-k Semiconductor Devices 84 Solders and Solderability Measurements for Microelectronics 85 Interconnect Materials and Reliability Metrology. 88 Thermal Measurements and Packaging Reliability. 93 Dielectric Metrology Supporting Integrated Passive Device Technology. 100 Wafer Characterization and Process Metrology Program 102 Wafer and Chuck Flatness Metrology 103 Modeling, Measurements, and Standards for Wafer Surface Inspection 107 High Resolution Microcalorimeter X-ray Spectrometer for Chemical Analysis Ill Thermophysicai Property Data for Modeling CVD Processes and for the Calibration ofMass Flow Controllers 116 Advanced IC Interconnects - Process Metrology and Models 121 Temperature Measurements and Standards for Rapid Thermal Processing 125 Low Concentration Humidity Standards 129 Plasma Process Metrology 133 Measurements for Vacuum Process Control 137 Test Metrology Program 140 Metrology for System-on-a-Chip (SoC) 141 Nonlinear Device Characterization 143 At-Speed Test ofDigital Integrated Circuits 146 Jitter and Propagation Delay Measurement 148 Manufacturing Support 150 NIST/SEMA TECH Engineering Statistics Internet Handbook 151 Supply Chain Communication and Automation Needs Assessment in the Semiconductor Industry 152 Abbreviations and Acronyms 154 Technical Contacts 158 Welcome and Introduction Welcome The microelectronics industry supplies vital components to the electronics industry and to the U.S. economy, enabling rapid improvements in productivity and in new high technology growth industries such as electronic commerce and biotechnology. To achieve its goal of strenghting the U.S. economy, the National Institute of Standards and Technology, NIST, works with industry to develop and apply technology, measurements and standards. NIST has substantial efforts on behalf of the semiconductor industry and its infrastructure; this report describes the many projects being conducted at NIST that constitute that effort. Historical Perspective NIST’s predecessor, the National Bureau of Standards (NBS), began work in the mid-1950’s to meet the measurement needs of the infant semiconductor industry. While this effort was initially focused on transistor applications m other government agencies, in the early 1960’s the Bureau sought industry guidance from the American Society for Testing and Materials (ASTM) and the (U.S.) Electronic Industries Association (EIA). To address ASTM’s top priority of accurate was the accurate measure- ment of silicon resistivity, NBS scientists developed a practical non-destructive method ten times more precise than previous destructive methods. This method is now the basis for five industrial standards and for resistivity standard reference materials widely used to calibrate the industry’s measurement instruments. The second project, recommended by a panel of EIA experts, addressed the “second breakdown” failure mechanism of transistors. The results of this project have been widely applied, including solving a problem in main engine control responsible for delaying the launch of a space shuttle. From these beginnings, by 1980 the semiconductor metrology program had grown to employ a staff of sixty with a $6 million budget, mostly from a variety of other government agencies. Congressional funding in that year gave NBS the internal means to maintain its semiconductor metrology work. Meeting industrial needs remained the most important guide for managing the program Industrial Metrology Needs By the late 1980’s, NBS (now NIST) recognized that the semiconductor industry was applying a much wider range of science and engineering technology than the existing NIST program was designed to cover. The necessary expertise existed at NIST, but in other parts of the organization. In 1991, NIST established the Office of Microelectronics Programs (OMP) to coordinate and fund metrological re- search and development across the agency, and to provide the industry with easy single point access to NIST’s widespread projects. Roadmaps developed by the (U.S.) Semiconductor Industry Association (SLA) have independently identified the broad technological coverage and growing industrial needs for NIST’s semiconductor metrology developments. As the available funding and the scope of the activi- ties grew, the collective name became the National Semiconductor Metrology Program (NSMP), operated by the OMP. The NSMP has stimulated a greater interest in semiconductor metrology, motivating most of NIST’s laboratories to launch additional projects of their own and to cost-share OMP-funded projects. The projects described in this book represent this broader portfolio of microelectronics projects. Most, but not all, of the projects described are partially funded by the NSMP, which provided a $12 million budget in fiscal year 2002. Fostering NIST’s Relationships with the Industry NIST’s relationships with the SIA, International SEMATECH, and the Semiconductor Research Cor- poration (SRC) are also coordinated through the OMP. Staff from OMP represent NIST on the SIA committees that develop the International Technology Roadmap for Semiconductors (ITRS) as well as on numerous SRC Technical Advisory Boards. OMP staff are also active in the semiconductor stan- dards development work of the ASTM, the Deutsches Institut fiir Normung (DIN), the EIA, the Inter- national Organization for Standardization (ISO), and Semiconductor Equipment and Materials Interna- tional (SEMI). Learn More about Semiconductor Metrology at NIST This publication provides summaries of NIST’s metrology projects for the silicon semiconductor industry and their suppliers of materials and manufacturing equipment. Each project