edfas.org 9 ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 25 NO. 2 FUNDAMENTALS OF CIRCUIT EDIT David Akerson Thermo Fisher Scientific, Hillsboro, Oregon david.akerson@thermofisher.com EDFAAO (2023) 2:9-13 1537-0755/$19.00 ©ASM International® INTRODUCTION For semiconductor manufacturers, accelerating product development and time-to-market are critical, as missing a technology window, or falling behind, can result in significant loss of revenue. Increased densities, smaller features, complex device designs, and advanced packaging make it more likely that first silicon will not function as intended. As semiconductors become more complex, the circuit edit function continues to grow in strategic importance for reducing development costs, improving performance and functionality, and accelerating time to market. FIB CIRCUIT EDITING AND BENEFITS Focused ion beam (FIB) chip circuit editing is a wellestablished technique that enables the direct repair of integrated circuit defects. A precisely tuned and accurately placed ion beam with nanoscale resolution, in conjunction with process gases, selectively uncovers internal circuitry, allowing a skilled FIB operator to make functional changes to the device or the copper wiring pattern (Fig. 1). The FIB operator then reseals the chip surface to produce a device with revised circuit logic functions. For the integrated circuit (IC) developer and the IC company, circuit edit enables several benefits. For IC developers, FIB circuit editing enables debugging and validating fixes, exploring design optimization changes, duplicating and scaling pre-production parts, and prototyping new devices. These prototypes support the product and platform development efforts of internal teams, such as software and firmware, validation, and manufacturing to keep projects on schedule. Externally, functional prototypes can support ecosystem enablement and end customer design-in activities. For the IC company, circuit edit provides the ability to eliminate unnecessary wafer costs and accelerate time-to-market. The remainder of this article is a starting point for engineers and scientists who would like to learn more about circuit edit or are just starting their career in circuit edit. But be forewarned, becoming an “expert” practitioner takes time and practice. The good and bad news is, nobody, not even “expert” practitioners, have a 100% success rate. BUILDING THE UNDERLYING SKILLS Successful circuit editing is built upon two skills: proficiency with ion beam technology and an understanding of the chemistries that can be applied using a gas injection system (GIS). An understanding of circuit layout and the structure of ICs is also needed as explained below. Readers coming into this with experience in one area, both areas, or neither will find adding GIS knowledge to FIB, or vice versa, is relatively straightforward. Fig. 1 The circuit edit system enables direct access to each layer. From left to right: N-well, FinFET/Poly, metal, and contact/via.
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