Junction-isolated electrical test structures for critical dimension calibration standards

• Published in: IEEE transactions on semiconductor manufacturing 2004-05, Vol.17 (2), p.79-83
• Main Authors: Allen, R.A., Cresswell, M.W., Linholm, L.W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Calibration; Devices; Electrical junctions; Electron microscopes; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Energy resolution; Exact sciences and technology; High-resolution imaging; Manufacturing; Metrology; Microelectronic fabrication (materials and surfaces technology); NIST; Reference materials; Scanning electron microscopy; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductors; Silicon on insulator technology; Studies; Testing; Testing, measurement, noise and reliability; Transmission electron microscopy
• ISSN: 0894-6507; 1558-2345
• DOI: 10.1109/TSM.2004.826928

The National Institute of Standards and Technology (NIST) is developing single-crystal reference materials for use as critical dimension (CD) reference materials. In earlier work, the reference features on these reference materials have been patterned in the device layer of a silicon-on-insulator (SOI) wafers, with the buried oxide providing electrical isolation. This paper describes a new method of isolating the structures from the substrate by means of a pn junction. The junction isolation technique is expected to provide several advantages over the SOI technique including minimal susceptibility to charging when imaged in a CD scanning electron microscope (CDSEM), better edge quality, and ease of manufacture. Primary calibration of these reference materials is by imaging the cross-section of the feature with high-resolution transmission electron microscopy (HRTEM) at sufficiently high energy to resolve and count the individual lattice planes while electrical test structure metrology techniques provide the transfer calibration. Secondary calibration is performed with electrical test structure metrology, supplemented by visual techniques to verify that the features meet uniformity requirements. In this paper, we describe results for determining the electrical critical dimensions of these junction-isolated structures. This measurement and data analysis technique is a unique combination of the short-bridge variation of the cross-bridge resistor and the multi-bridge structure.