Atomic Layer Deposition for Microelectronic Applications

Effect of Growth Temperature during the Atomic Layer Deposition of the SrTiO3 Seed Layer on the Properties of RuO2/SrTiO3/Ru Capacitors for Dynamic Random Access Memory Applications

“…SrTiO 3 (STO) thin films have been studied for about two decades as one of the promising candidates for the next-generation dielectric of the dynamic random access memory (DRAM) capacitors. − With the aid of the atomic layer deposition (ALD) technique, dielectric films with a permittivity of over 100 can be obtained in a three-dimensional structure, which can mitigate the charge loss problem of aggressively shrunken DRAM capacitors. − Leskelä’s group first accomplished the ALD growth of STO films with a permittivity of 100. , Thereafter; several other groups joined this research field with various strategies, such as intermixing Sr- and Ti-rich STO or film growth with the aid of plasma energy. ,− The authors’ group has also focused on the thermal ALD and performance improvement of the STO films since 2005. ,,,,− Thermal ALD is a preferred method for growing such dielectric films over the plasma-based processes because of its almost unlimited capability to grow a conformal film in a severely three-dimensional structure. The DRAM capacitor node, whose minimum lateral dimension is as small as 20 nm and whose height is ∼1000 nm, is an example structure, making the aspect ratio as high as ∼50.…”

Nanofabrication via Maskless Localized Atomic Layer Deposition of Patterned Nanoscale Metal Oxide Films

“…Regarding the latter concerns, atomic layer deposition (ALD) appears well suited as it is a technique to fabricate (ultra) thin films at low temperatures with a thickness controlled at the angstrom level. Based on sequential exposure of the substrate to different precursors reacting with the surface in a self-limited manner, it has already proven to be a technique of choice for microelectronics applications and for fabricating complex nano-/heterostructures. , Due to its high conformability and accuracy, it has been implemented to nanopatterning, in particular for spacer deposition in multiple patterning, using conventional lithography and lift-off techniques . Because ALD is based on sequential self-saturated surface reactions, area-selective deposition (ASD) has also been developed using either activation or deactivation of the surface to favor or inhibit the growth on specific areas.…”

Asymmetry in electrical properties of Al‐doped TiO2 film with respect to bias voltage

“…1 Introduction Al-doped TiO 2 (ATO) film is emerging as a promising candidate material for the high-k dielectric layer in the capacitor of the next-generation dynamic random access memory (DRAM) [1][2][3]. This is fundamentally due to the highest k value of rutile-phased TiO 2 film, which has been reported to be as high as 100, among the reported binary oxide films.…”

“…The weakness of rutile TiO 2 , however, compared with the current ZrO 2 -based DRAM capacitor dielectric layer is its smaller band gap (~3.2 eV) which can invoke the leakage current concern. Doping the rutile TiO 2 with Al greatly mitigated such a problem by increasing the conduction band offset, since Al ions generally work as acceptor centers in rutile TiO 2 , and thereby balance the n-and p-type carriers [4]. This decreased the leakage current by 10 5 -10 6 times at a capacitor voltage of ~0.8 V [4].…”

“…Ti(OC 3 H 7 ) 4 and Al(CH 3 ) 3 were used as the Ti and Al precursors, respectively, and O 3 with a concentration of 250 g/m 3 was used as the oxygen source. The BE RuO 2 layer was deposited via chemical vapor deposition using Ru(EtCp) 2 and O 2 gases at a wafertemperature of 300 °C. To incorporate Al ions into the films, Al-O deposition cycles were introduced discretely into the film.…”