Impact of Direct Plasma Densification on Resistivity and Conformality of PEALD Tantalum Nitride
| العنوان: | Impact of Direct Plasma Densification on Resistivity and Conformality of PEALD Tantalum Nitride |
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| المؤلفون: | X. Zhang, Christopher J. Penny, J. Ren, O. van der Straten, Sunny Chiang, J. Maniscalco, Paul F. Ma |
| المصدر: | ECS Transactions. 50:159-164 |
| بيانات النشر: | The Electrochemical Society, 2013. |
| سنة النشر: | 2013 |
| مصطلحات موضوعية: | Materials science, Tantalum, Copper interconnect, chemistry.chemical_element, Nanotechnology, Substrate (electronics), chemistry.chemical_compound, Atomic layer deposition, chemistry, Tantalum nitride, Electrical resistivity and conductivity, Physical vapor deposition, Composite material, Electroplating |
| الوصف: | The integration of dual damascene Cu metallization for features at and beyond ~30nm critical dimension (CD) is very challenging, and its success will likely depend on optimization to near perfection in every area, from uniform patterning profiles, highly controlled metal barrier and seed deposition processes, to robust Cu electroplating methods and wet cleans in order to enable void-free, reliable BEOL interconnects [1]. Metal barrier technology for Cu metallization typically consists of Ta or a bilayer TaN/Ta stack deposited by physical vapor deposition (PVD), and tool and process improvements are continually being made to extend the applicability of these technologies to future interconnect dimensions. Several alternative process technologies are being pursued by the semiconductor industry, and one key process option to replace PVD TaN, or augment deficiencies in PVD TaN, is atomic layer deposition (ALD) of TaN. ALD provides a fundamental benefit in terms of deposition rate control and conformality. One concern, however, with ALD of TaN vs PVD is the attainable TaN resistivity. It remains questionable whether any form of ALD, thermally activated or otherwise, can reduce the available Ta-based precursor chemistries to metallic TaN with a resistivity comparable to Ta-rich PVD TaN [2]. Ion bombardment-induced densification may provide a path towards such low resistivity ALD TaN [3]. In this study PEALD TaN films were deposited using direct hydrogen (H2) plasma reduction of pentakis(dimethylamino)tantalum (PDMAT) at a substrate temperature of 250°C. One PEALD TaN cycle consisted of a PDMAT exposure followed by a H2 plasma exposure at 100W. To study the impact of ion bombardment on TaN film properties, a novel PEALD TaN process was developed for comparison, containing a high-power direct plasma step after each PEALD cycle, consisting of an Ar/H2 plasma exposure at 800W. For the deposition of thermal ALD TaN films, ammonia (NH3) was used as reactant. The effects of this intercycle ion bombardment on key TaN film properties including mass density and resistivity were investigated. After a total of 100 PEALD cycles, a TaNx film thickness of ~7.8nm was obtained on dense oxide (Figure 1). When an ion bombardment step is included after each PEALD cycle, the TaNx film thickness amounts to only ~6.0nm. PEALD TaN exhibited a mass density of 11.6 g/cm as measured by x-ray reflectivity (XRR), while for PEALD TaN with intercycle ion bombardment the mass density increased to 13.9 g/cm. The densification of PEALD TaN by intercycle ion bombardment has a significant impact on TaNx resistivity. With densification, PEALD TaN resistivity values on the order of 415 μΩcm could be achieved, comparable to resistivity values for PVD TaN at moderate N2 flow rates (Figure 2). It is suggested that the densification of PEALD TaN probably results in the transformation to a low-resistivity TaN phase [4]. While ion bombardment can achieve densification of PEALD TaN at the trench bottom of patterned structures, sidewall surfaces appear to show a less significant reduction in film thickness (Figure 3). This effect likely originates from the directionality of ions in the applied high power Ar/H2 plasma, leading to less energetic bombardment of sidewalls. |
| تدمد: | 1938-6737 1938-5862 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e8bb6c8671209019e9a881b7b00cd52e https://doi.org/10.1149/05013.0159ecst |
| حقوق: | CLOSED |
| رقم الأكسشن: | edsair.doi.dedup.....e8bb6c8671209019e9a881b7b00cd52e |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 19386737 19385862 |
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