Reliable integration of robust porous ultra low-k (ULK) for the advanced BEOL interconnect

Han, Kyou‐Sup; Choi, Seungwook; Yim, Tae Jin; Choi, Sang‐Hoon; Baek, Jong‐Min; Ahn, Sang Hee; Lee, Nae-In; Choi, Suk‐Joo; Kang, Hyunbum; Jung, Eui S.

doi:10.1109/iitc.2013.6615552

Cited by 3 publications

(1 citation statement)

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“…For sub 20 nm those process optimization are facing its limits and alternative have to be revised. Beside the use of novel ULK materials 3 and the promising air-gap technology, [4][5] investigated replacement of damaged ULK seems to be feasible and a less cost-intensive approach. Because of forming inner metal dielectrics (IMD) after the Cu wiring formation, it doesn't need to consider the etch damage, Cu diffusion and ULK integration of k < 2.2 is possible.…”

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Trench Filling Properties of Low k Insulated Layer Using Vacuum Ultraviolet Light-CVD

Lee

Fukuda²,

Kim

et al. 2016

ECS J. Solid State Sci. Technol.

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Photo-induced deposition of SiOCH thin films and their trench filling properties are discussed. Octamethyl-cycloterasiloxan (OMCTS) was used as a precursor and Xe 2 excimer lamp was used as a light source. The deposition temperature was 80 • C and the reactor pressure was maintained at 38.5 Pa. The relative permittivity of as-deposited film was 7.9. Due to the UV cure process, those OH-related bonds in the film were significantly decreased. The k-value of the UV cure film was 2.1. Photo-induced SiOCH was employed to achieve bottom-up filling of high-aspect-ratio features (A/S > 7.5).The wiring space less than 50 nm and the multi-layer interconnection structure more than 10 layers to be needed in order to realize GHz level chip speed. So far, general chip speed is depend on the transistor's switching speed but the wiring space decrease by disturbance due to the cross-talk noise between wirings and RC (R is metal line's resistance, C is capacitance of inner metal dielectrics) delay. 1 In order to reduce RC delay, the reduction of the metal resistance and/or the reduction of the inner metal dielectric's permittivity are essential. Therefore, wiring was converted from Al to Cu and at the same time utilizing the low-k dielectric, Cu/low-k integration is core studied in the semiconductor device development. 2 Since some years ultra-low-k (ULK) dielectric has been used. Due to its low mechanical strength, moisture-absorption, Cu-diffusion and its ease to be damaged, especially during etch process, the use of ULK with k < 2.5 were postponed year by year. As 20 nm production has been started, the influence of ULK damage becomes important more and more. Optimizing the process for ULK like CVD, etch, CMP and cleaning have extended the applicability of ULK. For sub 20 nm those process optimization are facing its limits and alternative have to be revised. Beside the use of novel ULK materials 3 and the promising air-gap technology, 4-5 investigated replacement of damaged ULK seems to be feasible and a less cost-intensive approach. Because of forming inner metal dielectrics (IMD) after the Cu wiring formation, it doesn't need to consider the etch damage, Cu diffusion and ULK integration of k < 2.2 is possible. A liquid-layer forming technology called the flow-fill process or flowable process 6-7 is considerable for IMD replacement. Many of these methods use siloxane reaction and mixing of silane with ozone or other substance offering strong oxidizing power. However, an oxide film embedded the problems of peeling off or breaking due to change in stress during annealing. Sources emitting ultraviolet (UV)/vacuum ultraviolet (VUV) photons in the energy range of 5∼15 eV have found a number of interesting applications 8-14 because such photons are capable of breaking most chemical bonds. They can be used for a variety of photo-initiated volume and surface processes. In this work, photo-induced deposition of SiOCH thin films using VUV-CVD and their trench filled properties are discussed. This idea is to replace the damaged layer of I...

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