Novel organosiloxane vapor annealing process for improving properties of porous low-k films

Kohmura, Kazuo; Tanaka, Hirofumi; Oike, Shunsuke; Murakami, Masami; Fujii, Nobutoshi; Takada, S.; Ono, Tetsuo; Seino, Yutaka; Kikkawa, Takamaro

doi:10.1016/j.tsf.2006.10.054

Cited by 33 publications

(39 citation statements)

References 12 publications

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“…This band corresponds to -OH ͑H 2 O͒ absorbance ͑3200-3800 cm −1 ͒. 8,9,[17][18][19] Uchida et al 17 studied this region in detail and they decomposed it into three contributions: Si-OH with a H bond due to chemically absorbed H 2 O, isolated Si-OH ͑without an accompanying H bond͒, and H 2 O. However, we could not observe a peak ͑3740 cm −1 ͒ of the isolated Si-OH.…”

Section: Ftir Measurements-mentioning

confidence: 68%

Paramagnetic Defect Generation and Microstructure Change in Porous Low-k SiOCH Films with Vacuum Baking

Tanbara

Kamigaki

2010

J. Electrochem. Soc.

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We studied in detail the paramagnetic defect generated in the porous low-k SiOCH films, which is called the T b center with the oxygen-carbon mixed back bonds. We baked the SiOCH films in vacuum from 600 to 1000°C, which could correspond to temperature elevation at a local area in cases of UV or electron-beam curing and Joule heating in circuits. The amount of the T b center increased abruptly around 775°C by electron spin resonance spectroscopy, at which we observed 30% volume shrinkage by ellipsometry and network change from a cage link to a ring link by Fourier transform IR spectroscopy. These phenomena might be due to the crush of microholes wrapping Si-CH 3 end groups. Therefore, we consider that the generation of the T b center suggests the quality change of the porous low-k SiOCH films for the ultralarge-scale integration reliability.As device densities increase in ultralarge-scale integration ͑ULSI͒ semiconductor chips, the signal propagation delay in multilevel interconnects becomes more critical for device performance. SiOCH films ͑silicon oxide containing hydrocarbon groups, k = 3.0͒ have been used for the low-dielectric-constant ͑low-k͒ dielectrics of the most advanced ULSI interconnects because of their high compatibility with the silicon process. 1 Recently, the nanometer level pores in a SiOCH film have been introduced to reduce k ͑Ͻ2.7͒. 2 The porous low-k SiOCH films have a lower mechanical strength than the conventional dielectric films. So, the porous SiOCH films were cured by UV light exposure or electron-beam ͑EB͒ irradiation to enhance mechanical strength. 3,4 However, the defects, called the T b centers having oxygen-carbon mixed back bonds, can be generated in the porous SiOCH films by excess UV/EB curing. 3,5-7 The generation of paramagnetic defect ͑T b center͒ is thought to be one of the ULSI interconnect reliability issues. In this work, we investigated in detail the behavior of the T b center in the porous low-k SiOCH films using vacuum baking instead of UV/EB curing. UV curing ͑high energy photon; about 5 eV͒ corresponds to local annealing, and vacuum baking ͑low energy phonon; at most 0.1 eV͒ corresponds to uniform annealing. Both processes are thought to give rise to the same microstructure change. We used an electron spin resonance ͑ESR͒ technique to detect the defects, ellipsometry to measure the film thickness and refractive index, and Fourier transform infrared ͑FTIR͒ spectroscopy to analyze the atomic network in the porous low-k SiOCH films. ExperimentalSample preparation.-The 500 nm thick, porous low-k SiOCH films ͑k = 2.6͒ were deposited on 300 mm ͑100͒ silicon wafers ͑10-15 ⍀ cm͒ with plasma-enhanced chemical vapor deposition. The film composition was determined to be Si:O:C:H = 1.0:1.7:0.9:2.9 by Rutherford backscattering analysis. 7 To actualize the defects in the low-k films, the samples were baked up to 1000°C in the vacuum chamber ͑15-25 Pa͒, where the samples were maintained at a certain setup temperature for 30 min and taken out below 300°C.Characterization.-The ESR m...

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Section: Ftir Measurements-mentioning

confidence: 68%

Paramagnetic Defect Generation and Microstructure Change in Porous Low-k SiOCH Films with Vacuum Baking

Tanbara

Kamigaki

2010

J. Electrochem. Soc.

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“…3b. 15 The effect of silylation was confirmed by electrical, mechanical, and spectroscopic measurements. To measure the dielectric constant of the film, aluminum electrodes with a diameter of 2.0 mm and thickness of 1 m were deposited on the silica film using a vacuum evaporation system through a stencil mask.…”

Section: Methodsmentioning

confidence: 83%

Effect of Silylation Hardening on the Electrical Characteristics of Mesoporous Pure Silica Zeolite Film

Seo

Yoshino

Ohnuki

et al. 2009

J. Electrochem. Soc.

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A pure silica zeolite film was formed by use of hydrothermally crystallized zeolite nanoparticles in a porous silica precursor. The effects of silylation hardening by tetramethylcyclotetrasiloxane ͑TMCTS͒ vapor treatment on the electrical characteristics of pure silica zeolite films were investigated. The results from Fourier-transform-IR spectroscopy indicated that the O-H bond decreased by zeolite formation, resulting in the decrease of the leakage current by 1/10. Silylation hardening by TMCTS vapor treatment could reduce the leakage current by 4 orders of magnitude due to the reduction of Si-OH and O-H bonds. The elastic modulus of 5.18 GPa and the dielectric constant of 1.96 were achieved simultaneously by silylation hardening. Consequently, the electrical and mechanical characteristics of the pure silica zeolite film as well as the time dependent dielectric breakdown lifetime were improved.With the shrinking of interconnect feature sizes of silicon ultralarge-scale integrated circuits, 1 the signal delay time increases due to the increase of interconnect resistance and parasitic capacitance. To overcome this problem, low-dielectric-constant interlayer dielectric films are needed. Mesoporous silica with pore sizes ranging from 2 to 50 nm have been studied as a potential candidate for ultralow-k materials. 2 However, the mechanical strength of the low-k film is degraded when mesopores are introduced into the skeletal materials to reduce the film density. Chemical mechanical polishing may cause damage to the porous low-k material. Moreover, it is known that the low-k film to which mechanical strength is weak receives damage in the packaging, so both low-k and high mechanical strength are required. Pure silica zeolite is a promising candidate as an advanced low-k material. 3,4 The Young's modulus of the zeolite is 110 GPa, 3 which is larger than that of SiO 2 ͑73 GPa͒. This is because the silica network in the zeolite has a three-dimensional crystal structure. The zeolite also has low-k because the film density is lower than that of quartz due to the micropores in the crystalline silica. It has a higher elastic modulus, thermal conductivity, and hydrophobicity than SiO 2 . 4-10 The mobile 11 ͑MEL͒-type zeolite was adopted in this work. 11,12 The zeolite was made by a hydrothermal crystallization method. MEL-type zeolite has a 10-membered ring with pore diameters of 0.53 and 0.54 nm as shown in Fig. 1. In this paper, the effects of silylation on the film properties of pure silica zeolite dielectric films are investigated. ExperimentalThe formation process of MEL-type zeolite is shown in Fig. 2. A few nanometers thick native oxide was formed on the surface of Si wafer. First, the precursor solution of tetrabutyl ammonium hydroxide ͑TBAOH͒, tetraethyl orthosilicate ͑TEOS͒, and ethyl alcohol ͑EtOH͒ were mixed and stirred for 24 h at room temperature. Hydrolysis of TEOS was caused by EtOH. TBAOH was purified by filtering with the ion exchange resin. Both TEOS and EtOH were of semiconductor grade. The hydrothermal cr...

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“…8(a). This band corresponds to -OH (H 2 O) absorbance (3200~3800 cm -1 ) (14,15). The increment of -OH (H 2 O) absorption band appeared at just the temperature 775 o C in which range the T b center generated abnormally ( Fig.…”

Section: Esr and Ellipsometry Measurementsmentioning

confidence: 90%

Paramagnetic Defects Generation and Structure Change in the Porous Low-k SiOCH Films with Excess Ultraviolet and Electron-beam Curing

Tanbara

Kamigaki

2009

ECS Trans.

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We have studied in detail the paramagnetic defect generated in the porous low-k SiOCH films, which is called as T b center with the oxygen-carbon mixed back bonds. We baked the SiOCH films in vacuum at the temperature from 600 o C to 1000 o C, which could correspond to local temperature enhancement when UV/EB curing and Joule heating in circuits. We have found that the amount of the T b center increased abnormally around the temperature 775 o C by ESR spectroscopy. Moreover, we have observed 30%-volume shrinkage by ellipsometry and network change from cage link to ring link by FTIR spectroscopy. These phenomena might be concerned to a crush of micro holes wrapping Si-CH 3 end groups.Therefore, we consider that the generation of the T b center indicates the quality change of the porous low-k SiOCH films as for the ULSI reliability.

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Novel organosiloxane vapor annealing process for improving properties of porous low-k films

Cited by 33 publications

References 12 publications

Paramagnetic Defect Generation and Microstructure Change in Porous Low-k SiOCH Films with Vacuum Baking

Paramagnetic Defect Generation and Microstructure Change in Porous Low-k SiOCH Films with Vacuum Baking

Effect of Silylation Hardening on the Electrical Characteristics of Mesoporous Pure Silica Zeolite Film

Paramagnetic Defects Generation and Structure Change in the Porous Low-k SiOCH Films with Excess Ultraviolet and Electron-beam Curing

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