Novel self-assembled ultra-low-k porous silica films with high mechanical strength for 45 nm BEOL technology

Oku, Y.; Yamada, Kazuhiro; Goto, Tetsuya; Seino, Yutaka; Ishikawa, Akira; Ogatal, T.; Kohmura, Kazuo; Fujii, Nobutoshi; Hata, Nobuhiro; Ichikawa, R.; Yoshino, T.; Negoro, Chie; Nakano, Akinori; Sonoda, Y.; Takada, S.; Miyoshi, Hidenori; Oike, Shunsuke; Tanaka, Hirofumi; Matsuo, Hiroki; Kinoshita, Keizo; Kikkawa, Takamaro

doi:10.1109/iedm.2003.1269184

Cited by 16 publications

(16 citation statements)

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“…The TMCTS treatment was known as a method of adding hydrophobicity to porous silica. 7,8 This effect is also seen in Fig. 5, where the absorption intensity of the OH bond recovered to the initial value by the TMCTS treatment after the CMP process.…”

Section: Resultssupporting

confidence: 69%

“…Then the wafer rotation was stopped, and the IPA was maintained on the wafer for 60 s by surface tension. The TMCTS treatment of porous silica was performed using a vertical furnace at 400°C for 4 h. [7][8][9] * Electrochemical Society Active Member. z E-mail: Ishikawa.Akira@mirai.aist.go.jp To investigate degradation by CMP chemicals and affection of the recovery process, dipping examination was performed, i.e., the porous silica film was dipped into the CMP chemicals for 1 min, rinsed in deionized ͑DI͒ water or ethanol for 8 min, and dried by N 2 blow.…”

Section: Methodsmentioning

confidence: 99%

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Influence of CMP Chemicals on the Properties of Porous Silica Low-k Films

Ishikawa

Shishida

Yamanishi

et al. 2006

J. Electrochem. Soc.

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This paper describes the influence of the chemical mechanical polishing ͑CMP͒ process on the degradation in the leakage currents and dielectric constants of porous silica low-k films. It is found that the leakage current and dielectric constant increased by post-CMP cleaning solution due to the increase of CH x and OH bonds according to Fourier transform infrared ͑FTIR͒ absorption. This is because the surfactant in the post-CMP cleaning solution permeated into the porous silica. The permeated surfactant in the porous silica can be removed by rinsing with 2-propanol or ethanol after the CMP process. Degradations of the leakage current density and dielectric constant can be recovered by ethanol rinse and subsequent 1,3,5,7-tetramethyl-cyclo-tetrasiloxane vapor treatment, which makes the pore wall surfaces hydrophobic.The chemical mechanical polishing ͑CMP͒ process is necessary to form copper damascene interconnects in ultralarge-scale integrated circuits ͑ULSI͒. Recently, low-dielectric-constant ͑low-k͒ materials have been used for interlayer dielectrics to meet the demands for high-speed operation and low-power consumption in ULSI. For the 65 nm half-pitch technology node, low-k materials whose dielectric constants are 2.4 or less are required. 1 It was reported that degradation in low-k materials was caused during the Cu/low-k damascene process. Yoon et al. 2 and Kodera et al. 3 reported that the film peeling and the crack occurred during the CMP process because the adhesion between the low-k material and other films was weak. Baklanov et al. 4 reported that the low-k material with porous structure was degraded by etching gas and wet chemicals. In order to solve the problems, the low-pressure CMP process was developed to suppress the film peeling and the crack in the CMP process. In addition, the cap film was layered in damascene structure to protect the low-k film from the CMP chemicals ͑CMP slurries and post-CMP cleaning solutions͒.It is necessary to lower the effective dielectric constant ͑k eff ͒ to achieve higher-speed operation and lower power consumption. Figure 1 shows a typical structure of Cu/low-k damascene for 32 nm half-pitch technology node. Table I shows properties of cap layer and stopper layer for two cases considered in the present work: A and B. Figure 2 shows the calculated effective dielectric constant as a function of thickness of cap layers for the two cases. As seen, it is necessary to lower the dielectric constant and the thickness of the cap layer. As an extreme case, the damascene structure without the cap layer is worth considering. To achieve this cap-layer-less structure, it is necessary to clarify the degradation of low-k materials due to the CMP chemicals to establish the recovery process of degradation and the CMP chemicals free from degradation. Kondo et al. 5 investigated the deterioration of low-k material due to the post-CMP cleaning solution and reported on a post-CMP cleaning solution by which the deterioration of dielectric constant was not caused. However, neither the c...

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Section: Resultssupporting

confidence: 69%

Section: Methodsmentioning

confidence: 99%

Influence of CMP Chemicals on the Properties of Porous Silica Low-k Films

Ishikawa

Shishida

Yamanishi

et al. 2006

J. Electrochem. Soc.

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“…The 3-D cubic or disordered pore structures with well-controlled pore sizes are also known to be readily achievable by a self-assembling technology. [10][11][12][13] In this study, we calculate k and E for low-k materials with the 3-D cubic and disordered pore structures and compare the E vs k relationship with that of 2-D hexagonal structures. The k and E relationship for films with randomly distributed spherical pores is also calculated as a reference.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Investigation of Dielectric Constant and Elastic Modulus of Three-Dimensional Isotropic Porous Silica Films with Cubic and Disordered Pore Arrangements

Miyoshi

Yamada

Kohmura

et al. 2005

Jpn. J. Appl. Phys.

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The dielectric constant (k) and elastic modulus (E) of self-assembled three-dimensional porous silica films were investigated by analytical and numerical calculations to reveal the relationship between k and E. It was found that cubic pore arrangements have E values higher than those of random pore arrangements and two-dimensional periodic hexagonal pore arrangements for the same k. It was also found that disordered isotropic porous silica films having cylindrical pores with well-controlled pore size distributions exhibit an E vs k relationship similar to that of two-dimensional hexagonal periodic porous silica films. The elastic modulus of the skeletal silica was determined to be 40 GPa from the combination of the calculated results and experimental data on ultralow-k disordered porous silica film with a k value of 2.0 and a modulus of 8 GPa.

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“…The porous SiOC film was deposited by PECVD using ethoxymethylsiloxane and an organic monomer. The SiO 2 film was deposited by PECVD using SiH 4 and O 2 gases. The low-k/Cu damascene interconnects were formed as shown in Fig.…”

Section: Sample Structurementioning

confidence: 99%

Ultralow-k/Cu Damascene Multilevel Interconnects Using High Porosity and High Modulus Self-Assembled Porous Silica

Chikaki¹,

Kinoshita²,

Kohmura

et al. 2010

J. Electrochem. Soc.

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We introduced a high porosity ultralow-k film into a Cu damascene interconnect without increasing the dielectric constant ͑k͒ of a low-k film after interconnect formation. A high elastic modulus ͑9 GPa͒ with ultralow-k value ͑Ͻ2.1͒ was achieved by using a self-assembled porous silica film formed with UV irradiation and a silylation anneal. Performing the silylation anneal after trench etching results in recovery of the k value and dielectric properties. A sidewall protection process carried out before metalization protects the low-k film against process-induced damage. The time-dependent-dielectric breakdown lifetime is 10 years at a high electric field of 2.3 MV/cm.To reduce signal propagation delay and power consumption, the time constants of Cu interconnects in large-scale integrations ͑LSIs͒ must be improved, which can be achieved by using ultralow dielectric constant ͑k͒ interlayer dielectrics ͑ILDs͒ between the interconnects. Reducing the density of a dielectric material lowers the k value of the dielectric film. However, it also causes an unacceptable reduction of mechanical strength. Self-assembled porous silica ͑Po-SiO͒ is a promising material for forming low-k/Cu damascene interconnects with high porosity and high mechanical strength, which can be extended over several generations of technology nodes. [1][2][3][4] In this study, we introduced self-assembled Po-SiO into low-k/Cu damascene multilevel interconnects and investigate the feasibility of a low-k/Cu damascene process for 200 nm pitch multilevel interconnects with 65 nm node technology. Comparison of Effective Dielectric ConstantsEffective k ͑k eff ͒ values of stacked ILD films for 100 nm pitch multilayered Cu damascene interconnects are shown in Fig. 1a. k eff is calculated by using a two-dimensional capacitance simulator ͑Maxwell͒. The calculation process was as follows: The parasitic capacitance of an electrode ͑line͒ of a sample interconnect structure was calculated by using the simulator and by fitting the capacitance of a monolithic dielectric ͑k = k eff ͒/Cu interconnect with changing k eff . Figure 1 shows the cross section of the compared Cu interconnect structures with the Po-SiO film as a line and via low-k layers and with an air gap as a line low-k layer. The air gap structure must be thick enough for the cap film to avoid unlanded via issues due to lithography misalignment. 5 For the air gap structure, only a high modulus dielectric can be used for the cap layer and via low-k layer, as shown in Fig. 1b and Table I. The k eff value using a conventional cap film ͑k = 3.0͒ and an etch-stop film ͑k = 4.0͒ can be reduced from 3.3 to 2.45 by applying an advanced Po-SiO film ͑k = 1.9͒, as shown in Fig. 1a. With a conventional k value and thick ͑45 nm͒ cap film, the k eff of the proposed air gap structures is 2.66. Therefore, the k eff value of the Po-SiO interconnect can be lower than that of the air gap interconnect if the same cap and etch-stop films are used. ExperimentalA self-assembled scalable Po-SiO film was formed, followed by a Xe ...

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Novel self-assembled ultra-low-k porous silica films with high mechanical strength for 45 nm BEOL technology

Cited by 16 publications

References 1 publication

Influence of CMP Chemicals on the Properties of Porous Silica Low-k Films

Influence of CMP Chemicals on the Properties of Porous Silica Low-k Films

Theoretical Investigation of Dielectric Constant and Elastic Modulus of Three-Dimensional Isotropic Porous Silica Films with Cubic and Disordered Pore Arrangements

Ultralow-k/Cu Damascene Multilevel Interconnects Using High Porosity and High Modulus Self-Assembled Porous Silica

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