Bottom Anti-reflective Coating Layer Research Articles

Wafer-scale nanofabrication of sub-100 nm arrays by deep-UV displacement Talbot lithography

In this manuscript, we demonstrate the potential of replacing the standard bottom anti-reflective coating (BARC) with a polymethylglutarimide (PMGI) layer for wafer-scale nanofabrication by means of deep-UV displacement talbot lithography (DTL). PMGI is functioning as a developable non-UV sensitive bottom anti-reflective coating (DBARC). After introducing the fabrication process using a standard BARC-based coating and the novel PMGI-based one, the DTL nanopatterning capabilities for both coatings are compared by means of the fabrication of etched nanoholes in a dielectric layer and metal nanodots made by lift-off. Improvement of DTL capabilities are attributed to a reduction of process complexity by avoiding the use of O2 plasma etching of the BARC layer. We show the capacity of this approach to produce nanoholes or nanodots with diameters ranging from 95 to 200 nm at a wafer-scale using only one mask and a proper exposing dose. The minimum diameter of the nanoholes is reduced from 118 to 95 nm when using the PMGI-based coating instead of the BARC-based one. The possibilities opened by the PMGI-based coating are illustrated by the successful fabrication of an array of nanoholes with sub-100 nm diameter for GaAs nanowire growth on a 2″ GaAs wafer, a 2″ nanoimprint lithography (NIL) master stamp, and an array of Au nanodots made by lift-off on a 4″ silica wafer. Therefore, DTL possess the potential for wafer-scale manufacturing of nano-engineered materials.

Dispersion and origin of surface optical-like waves in a two-dimensional antidot-patterned structure with a soft intervening layer

The phonon dispersion of a square-lattice antidot-patterned Ni80Fe20 film on a bottom-anti-reflective coating (BARC)/Si substrate has been investigated by Brillouin spectroscopy and finite element simulations. Band structures, measured along Γ-M and Γ-X, exhibit Bragg gap openings, surface optical-like and acoustic-like waves, and an acoustically isolating feature arising from the soft BARC layer. A qualitative explanation of the origin of the optical-like waves is presented, by mapping their displacement fields onto reciprocal space. Interestingly, these waves can be frequency shifted, almost independently of the acoustic-like mode frequencies, by varying one of the dimensions of the patterned array on the Ni80Fe20 film.

Precise Cross-Sectional Measurement of Photoresist Shrinkage Caused by Electron Beam Irradiation

A mechanism of the photoresist shrinkage induced by electron-beam (EB) irradiation was studied in detail. A precise cross-sectional profile of a photoresist pattern is obtained by a scanning transmission electron microscope (STEM) after HfO2 atomic layer deposition on a sample. Photoresist lines and spaces formed on either of bottom anti-reflective coating (BARC) layer or spin-on-glass (SOG) layer were exposed to EB at a much higher dose than a practical dose (to accelerate shrinkage intentionally). The obtained STEM images of the patterns before and after EB irradiation showed that EB irradiation causes necking of the pattern profile as well as linewidth slimming. In addition, it was suggested that the BARC layer shrinkage results in the elastic deformation of the pattern profile, whereas the SOG layer does not shrink. Furthermore, EB irradiation only to the lines or spaces was performed. The EB irradiation to spaces caused sidewall shrinkage and necking of the pattern profile, although no electron was irradiated directly into the pattern. This result is considered to be due to the electrons scattered from the spaces to the pattern sidewall. Finally, a Monte Carlo simulation showed that the distribution of the deposited energy on the pattern surface corresponds to the change of the pattern shape. Consequently, our study clarifies the importance of the effect of elastic shape change and the impact of the electrons scattered from the underlying layer to the sidewall on photoresist shrinkage.

Influence of Photoresist and BARC Selection on the Efficiency of a Post-Etch Wet Strip in BEOL Applications

All-wet processes are gaining a renewed interest for the removal of post-etch photoresist (PR) and Bottom AntiReflective Coating (BARC) in the back-end-of-line (BEOL) semiconductor manufacturing, as plasma ash, traditionally used to remove the PR and BARC layer after etch, cause damage to the low-k dielectric. This study investigates the modification of 193 nm post-etch PR and BARC layer by UV irradiation, that can be used as an intermediate step to enhance PR and BARC wet strip by O3/H2O.

Towards Fully Aqueous Ozone Wet Strip of 193 nm Photoresist Stack Using UV Pre-Treatments in Low-k Patterning Applications

All-wet processes are gaining a renewed interest for the removal of post-etch photoresist (PR) and Bottom Anti Reflective Coating (BARC) in the Back-End-Of-Line (BEOL) semiconductor manufacturing, as an alternative to plasma strip, which may cause damage to advanced porous low-k materials. However, degradation of DUV PR by etch plasmas results in a modified top layer that is cross-linked (so-called crust) and therefore not soluble anymore using pure organic solvents. This study investigates the combination of UV with ozonated processes to remove PR and BARC in BEOL applications. Treatment of PR and BARC by UV irradiation was proved to be an interesting process to increase the concentration of reactive C=C bonds in the post-etch PR and BARC layer. Another effect of UV irradiation is that it can cause scissioning of C–C bonds in the PR main chain, thereby improving the dissolution of the PR in solvents. This UV pre-treatment was used as a preliminary step to enhance PR and BARC removal by ozonated wet strips. Different pathways were studied in detail, leading to the development of a fully aqueous ozonated wet strip process.

Removal of Photoresist and BARC in Cu BEOL using an All-wet Process

Wet removal of post-etch photoresist (PR) and bottom anti-reflective coating (BARC) was studied using "multi functional" cleaning solutions based on BASFs tool box. For blanket wafer, Fourier-transform infrared (FTIR) data showed that both PR and BARC layers were completely removed at a megasonic power of 10 W for 2 min. For patterned structure, the plasma used for opening of the BARC layer and metal hard mask resulted in the formation of fluorine- and titanium-containing species in the PR crust. Cross-sectional secondary electron microscopy (SEM) and X-ray photoemission spectroscopy (XPS) data indicated that complete removal of post-etch PR can be achieved under experimental conditions typical for single wafer processing. Subsequent patterning of porous low-k layer showed good low-k profile. Wet processes using solvent-based chemistry followed by a bake at 350 {degree sign}C for 1 min at low pressure was found to have no detrimental impact on k-value degradation.

Diluted Low Dielectric Constant Materials as Bottom Antireflective Coating Layers for both KrF and ArF Lithography Processes

In this paper, we report on a bottom antireflective coating (BARC) layer for both KrF and ArF lithography processes. The antireflective layers are composed of diluted low-dielectric constant materials, such as bisbenzo(cyclobutene) (BCB), fluorinated poly(arylene)ether (FLARE) and SiLK. By adding an optimized thickness of diluted low-dielectric constant materials, the reflectance of less than 1% at the resist/silicon substrate interface can be achieved. Diluted low-dielectric constant materials also have great potential to be used as BARC layers on various highly-reflectance substrates for metal-interconnect applications. Using this structure, it is easy to reduce reflectance without adding an extra BARC layer for patterning low-dielectric materials. After the lithography procedure, the diluted low-dielectric constant layer need not be removed.

Low Dielectric Constant Polymer Materials as Bottom Antireflective Coating Layers for both KrF and ArF Lithography

In this paper, we demonstrate a new bottom antireflective coating (BARC) layer for both KrF and ArF lithography. The antireflective layers are composed of a novel low-dielectric constant polymer material (SiLK) and its etching hard-mask layer. By adding an optimized hard-mask layer, the reflectance of less than 1% at the resist/silicon substrate interface can be achieved. SiLK also has great potential to be used as BARC layers on various highly-reflectance substrates for metal-interconnect applications with large thickness-controlled tolerance. By using this novel structure, it is easy to reduce reflectance without adding an extra BARC layer for patterning low-dielectric materials. In this paper, suitable etching characteristics and thermal stability of SiLK-based BARC layers are also described.

Low-dielectric constant FLARE 2.0 films for bottom antireflective coating layers in KrF lithography

In this paper, we demonstrate a new bottom-antireflective coating (BARC) layer for KrF lithography. The antireflective layer is composed of a commercial low-dielectric constant FLARE 2.0-based film. By adding an optimized etching hard-mask layer, reflectance of less than 3% at the resist/silicon substrate interface can be achieved. FLARE 2.0 films also have great potential to be used as BARC layers on highly reflective substrates for metal interconnect applications. It is easy to reduce reflectance without adding an extra BARC layer for patterning low-dielectric materials. It is convenient to use this novel BARC structure in KrF lithography. In this paper, suitable etching characteristics of FLARE 2.0-based BARC layers are also described.

Low-dielectric constant bisbenzo(cyclobutene) and fluorinated poly(arylene)ether films as bottom anti-reflective coating layers for ArF lithography

In this article, we demonstrate a bottom anti-reflective coating (BARC) layer for ArF lithography. The anti-reflective layers are composed of a commercial low-dielectric constant bisbenzo(cyclobutene) (BCB)- and fluorinated poly(arylene)ether (FLARE)-based films. By adding an optimized etching hard-mask layer, reflectance of less than 1% at the resist/silicon substrate interface can be achieved. BCB and FLARE also have great potential to be used as BARC layers on highly reflective substrates for metal interconnect applications. It is easy to reduce reflectance without adding an extra BARC layer for patterning low-dielectric materials. It is convenient to use this BARC structure in ArF lithography. In this article, suitable etching characteristics and thermal stability of BCB- and FLARE-based BARC layers are also described.

Hexamethyldisiloxane film as the bottom antireflective coating layer for ArF excimer laser lithography

We demonstrate a new bottom antireflective coating (BARC) layer for ArF excimer laser lithography. The antireflective layer is composed of hexamethyldisiloxane (HMDSO) film, which is deposited by the conventional electron cyclotron resonance-plasma-enhanced chemical-vapor deposition process. We obtain the appropriate HMDSO films for BARC layers by varying the gas-flow rate ratio of oxygen to HMDSO. Such a process has several advantages: high deposition rate, low process temperature, easy film removal, and reduced cost. Measured reflectances of less than 0.5% on both Al-Si and silicon crystal substrates have been achieved and agree well with the simulated reflectances. The swing effect is shown to be significantly reduced by addition of the HMDSO-based BARC layer.