LIST OF FIGURES PAGE 29. Calculated measurement error due to finite contact width for orthogonal pinwheels with four-fold rotational symmetry 45 30. Calculated measurement error due to finite contact width for orthogonal quadrate crosses 37. 38. Helium outgassing rate, R, of sealed borosilicate glass capsules as a function of dwell time between pressurization and measurement as a max Dwell time necessary for helium outgassing rate of sealed borosilicate glass capsules to fall to specified maximum allowable rates, R function of pressurization time.. 39. 40. ASLEEP image of aluminum grid 41. ASLEEP image of MOS capacitor array ASLEEP scan of 30-mil (0.76-mm) diameter MOS capacitors on 35-mil (0.89-mm) centers. Energy dissipation as a function of penetration depth for several electron Examination of silicon p-n junction in the electron beam induced current mode Current gain, IE/I for several beam energies as a function of absorber thickness, t B 47. Nomograph to convert aluminum, silicon dioxide, or aluminum plus silicon dioxide thickness in micrometers to absorber thickness in micrograms per square centimeter . . Comparison of measured electron beam induced currents with the results of the elementary calculation 49. 50. Ratio of backscattered to incident electrons, n, as a function of beam energy 58 60 Photograph of the scanner display screen showing enhancement of 1.15 um photoresponse due to hot-spot operation . . . 61 54. Collector-base characteristic of UHF transistor connected in a commonemitter circuit . . . 62 55. Photographs of the scanner display screen showing electrical nonlinearity in the UHF transistor at certain of the operating points indicated by arrows on the collector-base characteristic LIST OF FIGURES PAGE 56. Photographs of the scanner display screen showing a portion of a p-MOS shift register 57. Photograph of the scanner display screen showing a portion of a p-MOS shift register in the same static condition as in figure 56b except that a logical one was changed to a logical zero 58. Modified circuit for measuring thermal resistance set up as a grounded base, emitter-and-collector switching circuit using the collector-base junction voltage of the input transistor as the temperature sensitive parameter .. 59. 60. 61. Desired current path when measuring the thermal resistance of the input Darlington transistor using the grounded-base, emitter-and-collector switching method with the collector-base junction voltage as the temperature sensitive parameter .. Desired current path when measuring the thermal resistance of the output Darlington transistor using the grounded-emitter, emitter-and-collector switching method with the collector-base junction voltage as the temperature sensitive parameter Safe operating area plots 64 65 67 67 67 68 LIST OF TABLES PAGE 1. 2. Summary and Analysis of Four-Probe Resistivity Measurements on Resident Wafers . 8 Four-Probe Resistivity Measurements on Circulating Wafers 3. 4. Number and Sizes of Microvolumes in Repeat Patterns of Implantation Photomask 5. Object Line Widths and Corresponding RMS Differences Determined from the Curves of Figure 19 . . . 36 6. Line Width Measurement Errors for a Transparent Line (20 μm or Wider) on an 40 7. 8. Measured Values for Dimensions A, B, and C of Interim Measurement Artifact 10. Smallest and Largest Detectable Leak Sizes for Borosilicate Glass Capillary 53 Test Leaks . PREFACE The Semiconductor Technology Program serves to focus NBS efforts to enhance the performance, interchangeability, and reliability of discrete semiconductor devices and integrated circuits through improvements in measurement technology for use in specifying materials and devices in national and international commerce and for use by industry in controlling device fabrication processes. Its major thrusts are the development of carefully evaluated and well documented test procedures and associated technology and the dissemination of such information to the electronics community. Application of the output by industry will contribute to higher yields, lower cost, and higher reliability of semiconductor devices. The output provides a common basis for the purchase specifications of government agencies which will lead to greater economy in government procurement. In addition, improved measurement technology will provide a basis for controlled improvements in fabrication processes and in essential device characteristics. The Program receives direct financial support principally from three major sponsors: the Defense Advanced Research Projects Agency (ARPA), the Defense Nuclear Agency + (DNA), and the National Bureau of Standards (NBS). In addition, the Program receives support from the U. S. Navy Strategic Systems Project Office. The ARPA-supported portion of the Program, Advancement of Reliability, Processing, and Automation for Integrated Circuits with the National Bureau of Standards (ARPA/IC/NBS), addresses critical Defense Department problems in the yield, reliability, and availability of integrated circuits. The DNA-supported portion of the Program emphasizes aspects of the work which relate to radiation response of electron devices for use in military systems. There is considerable overlap between the interests of DNA and ARPA. Measurement oriented activity appropriate to the mission of NBS is a critical element in the achievement of the objectives of both other agencies. Essential assistance to the Program is also received from the semiconductor industry through cooperative experiments and technical exchanges. NBS interacts with industrial users and suppliers of semiconductor devices through participation in standardizing organizations; through direct consultations with device and material suppliers, government agencies, and other users; and through periodically scheduled symposia and workshops. In addition, progress reports, such as this one, are regularly prepared for issuance in the NBS Special Publication 400 sub-series. More detailed reports such as state-of-the-art reviews, literature compilations, and summaries of technical efforts conducted within the Program are issued as these activities are completed. Reports of this type which are published by NBS also appear in the Special Publication 400 subseries. Announcements of availability of all publications in this sub-series are sent by the Government Printing Office to those who have requested this service. A request form for this purpose may be found at the end of this report. Through ARPA Crder 2397, Program Code 5D10 (NBS Cost Center 4259555). All contract work was funded from this source. Through Inter-Agency Cost Reimbursement Order 75-816 (NBS Cost Center 4259522). *Through Scientific and Technical Research Services Cost Centers 4251126, 4252128, and 4254115. Code SP-23, through project order NOO16475PC70030 administered by Naval Ammunition Depot, Crane, Indiana (NBS Cost Center 4251533) and Code SP-27, through IPR SP6-75-4 (NBS Cost Center 4251547). SEMICONDUCTOR MEASUREMENT TECHNOLOGY PROGRESS REPORT January 1 to June 30, 1975 Abstract: This progress report describes NBS activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices. Both in-house and contract efforts are included. The emphasis is on silicon device technologies. Principal accomplishments during this reporting period included (1) completion and analysis of an interlaboratory evaluation of standard reference wafers for resistivity measurement by the four-probe method, (2) analysis of the effect of finite contact size on sheet resistance as measured with a van der Pauw structure, (3) calculation of errors introduced in measuring line width with typical microscope systems, (4) development of procedures for predicting the magnitude of electron beam induced current in silicon device structures, (5) application of the optical flying-spot scanner to observation of hot spots and nonlinearities in UHF power transistors and of logic patterns in an MOS shift register, and (6) determination of a more accurate electrical method, based on peak junction temperature measurement, to establish safe operating area curves for medium power transistors. Also reported are the results of work on spreading resistance measurements, ionization of dopant impurities in silicon, Rutherford backscattering measurements, X-ray photoelectron spectroscopy, ion microprobe mass analysis, tests for determining the surface quality of sapphire substrates, reevaluation of Irvin's curves, mathematical models of dopant profiles, deep depletion measurements of dopant profiles and epitaxial layer thickness, bias-temperature stress tests on MOS capacitors, a high voltage capacitance-voltage method for measuring characteristics of thick insulator films, ion implantation parameters, methods for determining integrity of passivation overcoats, optical imaging and calibration standards for photomask metrology, line-width measurements, charge-coupled device test structures, a test pattern for silicon-onsapphire MOS device technologies, a nondestructive acoustic emission test for beam-lead bonds, pull and shear tests for wire bonds, leak detection by helium mass spectrometry, correlation of moisture infusion in semiconductor packages with leak size and device reliability, an automated scanning low-energy electron probe, electron beam induced damage in silicon device structures, and thermal resistance measurements on Darlington transistors. Supplementary data concerning staff, publications, workshops and symposia, standards committee activities, and technical services are also included as appendices. A sixth appendix summarizes the results of an assessment of the impact of automation of integrated circuit processing and assembly on future measurement requirements in the industry. Key Words: Acoustic emission; beam-lead bonds; bias-temperature stress test; boron redistribution; capacitance-voltage methods; chargecoupled devices; Darlington pairs; deep depletion; dopant profiles; electrical properties; electron beam induced current; electron beam induced damage; electronics; epitaxial layer thickness; hermeticity; leak tests; measurement methods; microelectronics; optical flying-spot scanner; passivation overcoats; photomask metrology; pull test; resistivity; Rutherford backscattering; scanning electron microscope; scanning low energy electron probe; semiconductor devices; semiconductor materials; semiconductor process control; shear test; sheet resistors; silicon; silicon-on-sapphire; spreading resistance; test patterns; thermal resistance; thermal response; transistors; wire bonds; X-ray photoelectron spectroscopy. |