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.

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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.

Particularly significant accomplishments during this reporting period include (1) initiation of development of measurement technology for characterizing boron nitride diffusion sources and hydrogen chloride purging gas, (2) application of de electrical methods with a sensitivity of about 0.1 um to the measurement of critical dimensions such as the width of diffusion windows, (3) completion of an initial comparison of linewidth measurements made with an imageshearing eyepiece and a filar eyepiece, and (4) development of procedures for measuring electrically the thermal resistance of the output transistor of integrated Darlington pairs. Highlights of progress in these and other technical task areas are listed below.

monly available automatic equipment. The results agreed well with measurements scaled from a photomicrograph.

Other test structures on test pattern NBS-3 are being used in the reevaluation of Irvin's curves. These include the square-array collector resistor, which yielded resistivity values in good agreement with standard fourprobe measurements; a circular MOS capacitor over the collector; and a circular basecollector junction.

Initial measurements in the evaluation of the CCD test structure connected as an MOS capacitor or as an MOS field effect transistor were completed.

Photolithography Detailed analyses of various state-of-the-art technologies for automatic inspection of photomasks were begun. The criteria selected were ability to detect a defect of dimension 2 um and misregistration of ±0.25 um. The first system analyzed was one composed of a TV camera tube which views the mask through a microscope. It was concluded that inspection of a 3 in. by 3 in. mask in 11 or 12 min would be possible using state-of-the-art components although this is significantly faster than existing prototype of this system.

A polarizing interferometer with 1 nm displacement resolution was constructed for use in making in situ measurements of the position of a scanning electron microscope stage. Preliminary measurements using standard stages revealed the need for a more rigid stage assembly with fewer than the usual degrees of freedom for micrometrology experi

ments.

A preliminary experiment established that it is possible to transfer a line-spacing measurement to a line-width measurement using a multilayer metal artifact in a scanning electron microscope (SEM). The artifact was designed for use in calibrating the magnification of a SEM; it does not simulate the conditions encountered in making dimensional measurements on photomasks. A different artifact was designed with 1 to 10 um wide lines to simulate the properties of a photomask. This artifact is intended to be fabricated in a film of chromium or iron oxide on an optically flat glass plate.

Comparative measurements of the width of a chromium line on a glass substrate were made using both bright field and dark field illumination and filar and image shearing eyepieces. The measured value was significantly