Bottom Antireflective Coating Materials Research Articles

The effects of the bottom anti-reflective coating with different baked temperatures and thicknesses on nanoscale patterns

The bottom anti-reflective coating (BARC) material can enhance the resolution of the nanopatterns structures in laser interference lithography process. In this study, WIDE-B ARC material was investigated to confirm the reduction of the vertical standing wave which leads to defect of nanopatterns. And the critical dimension (CD) of 100nm L/S patterns with and without the application of BARC material was fabricated by laser interference lithography technology. The compared results showed that BARC can effectively reduce CD swing and obtain more uniform nanopatterns. Meanwhile, we also verified the influence of cured temperature and film thickness of BARC on the uniformity of nanopatterns.

Investigation of the effects of bottom anti-reflective coating on nanoscale patterns by laser interference lithography

Enhanced resolution of the structures can be achieved by employing the bottom anti-reflective coating (BARC) material in laser interference lithography process. The purpose of the BARC is to control the reflection of light at the surface of the wafer to minimize the effects caused by reflection. Lloyd's mirror interferometer is utilized for the experiment with 257 nm wavelength Ar-Ion laser used as the light source to generate one-dimensional nanoscale patterns. By adjusting reflectivity through application of the BARC material, scattering of the patterns are reduced. The effects of BARC material are explored to confirm the reduction of the vertical standing wave, which is the main cause of undesirable nanoscale patterns. It is also highlighted that improvements through utilization of BARC material enables smaller pattern size with a set pitch size by controlling the exposure energy.

Study of High Etch Rate Bottom Antireflective Coating and Gap Fill Materials Using Dextrin Derivatives in ArF Lithography

In the present paper, we describe a novel class of bottom antireflective coating (BARC) and gap fill materials using dextrin with a-glycoside bonds in a polysaccharide. ArF resist underlayer materials containing a dextrin ester polymer for lithography were studied. Dextrin is a high molecular weight compound with several hydroxyl groups and a low solubility in resist and BARC solvents. Therefore, it is difficult to use dextrin polymers in resist underlayer materials such as BARC and gap fill materials. The main polymer needs to be soluble in propylene glycol monomethylether, propylene glycol monomethylether acetate, and ethyl lactate as common solvents to avoid the issue of defects in the coater cup due to incompatability. The dextrin ester polymer in this study was obtained by the esterification of the hydroxyl groups of dextrin resulting in improved solubility of these organic solvents. The etch rate of the new BARC and gap fill materials of the dextrin ester polymers was more than twofold faster than the etch rate of the ArF resists evaluated under a CF4 gas condition using reactive ion etching. The improved etch performance was also verified by comparison with poly(4-hydroxystyrene) and poly(2-hydroxypropyl methacrylate) as references. In addition to the superior etch performance, these materials showed good resist profiles and via filling performance without voids in via holes. On the basis of our findings, this technology of using the novel dextrin derivatives as sacrificial materials under a resist can be applied in devices of 45 nm node and higher.

Novel spin-on hard mask with Si-containing bottom antireflective coating for nanolithography

ArF lithography has continued with the increase of numerical aperture (NA) and the decrease of resist thickness, which are causing several problems both in mass production and development stage. NA is going to exceed unity in immersion, which necessitates the use of dual bottom antireflective coating (BARC) with increased process complexity and cost. Resist thickness, on the other hand, is expected to further decrease below 100nm. Therefore, it is inevitable to use additional hard masks, which increases production cost due to chemical vapor deposition (CVD) process. Here the author discloses the novel spin-on hard (SOH) mask system with dual BARC property to overcome both problems aforementioned. This SOH mask composed of two layers of Si-containing BARC and carbon materials shows high etch selectivity between thin resist and several substrates. Composition and etch chemistries of two layers are intensively studied to give CVD-comparable step-by-step etch selectivity to transfer various patterns of thin resist including line/space and contact holes to the various substrates. In addition, optical properties of two layers are finely designed from comprehensive optical simulation to be applied to various generations of ArF lithography from dry to immersion process. In this study, the Si-BARC with high silicon content showed the fastest etching rate related with resist and showed also high etching resistance toward underlying spin-on carbon. The author obtained good etch profile of 60nm L/S patterns using Si-BARC with 36% silicon content as a SOH mask. This novel system is under extensive optimization to be applied to various generations of ArF lithography from mass production to the most pioneering semiconductor devices utilizing immersion lithography.

Study of Self Cross-Link Bottom Antireflective Coating and Gap Fill Materials for Sublimate Defect Reduction in ArF Lithography

Sublimate reduction from the new bottom antireflective coating (BARC) and gap fill materials in bake process was investigated by means of absorption spectroscopy and the quantitative analysis of sublimation using the quartz crystal microbalance (QCM) sensing element. The small molecular components in BARC and gap fill materials were found to be related to a decrease in the number of sublimate defect. The application of the newly developed BARC and gap fill materials of the polymers with a self cross-link reaction system showed lower sublimate amount. In addition, good resist profiles and 130 nm via fill performance in the via-first dual damascene process were achieved using this self cross-link polymer system. This new system is one of the most promising systems ready to be tested for the mass production of 32–45 nm node IC devices and beyond.

Numerical Investigations on Requirements for BARC Materials for Hyper NA Immersion Lithography

Requirement on substrate reflectance was estimated numerically based on an optical simulation for hyper-NA (numerical aperture) lithography with the water immersion technique. Conditions to minimize the substrate reflectance were further calculated for dual BARC (bottom antireflective coating) layers with NA varying from 1.0 to 1.4. In addition, margins of the conditions were estimated based on the requirements on substrate reflectance. Based on these numerical results, requirements for materials to be used for dual BARC layers are discussed.

A Study of an Organic Bottom Antireflective Coating for 157-nm Lithography

In 157-nm lithography, an organic bottom-antireflective-coating (BARC), which has been mainly used as an antireflective technology in KrF or ArF lithography, is needed to reduce reflection from the substrate under the resist. To apply a conventional BARC to 157-nm lithography, the BARC thickness must be less than that used in KrF or ArF lithography. This is because conventional BARCs have a lower dry-etching rate than resists with a fluorinated polymer resist for 157-nm lithography and the thickness of the remaining resist after BARC dry-etching may be greatly reduced. Moreover, the substrate reflection under a conventional thin BARC cannot be completely controlled since the k-value of the extinction coefficient at a 157-nm wavelength is small. Therefore, a BARC material for 157-nm lithography must have a higher k-value at the 157-nm wavelength, a higher dry-etching rate than resists with a fluorinated polymer, good matching between the fluorinated resist and the BARC material to ensure a good resist pattern shape, and low outgassing from the BARC material during exposure. In this paper, we evaluate newly developed BARC materials for 157-nm lithography. We found that the k-value of one new BARC material (NCA660) was 0.41 (1.6 times that of a conventional BARC (DUV30J; Brewer Science, Inc)), and the ratio of the dry-etching rate to that of a KrF resist was 2.0 (twice that of DUV30J). These improvements were achieved by introducing a chromophore containing an I-atom of halogen into a heterocyclic polymer. Furthermore, the film thickness loss (used to evaluate outgassing from this BARC material when irradiated by 157-nm light) was close to 0 nm (irradiation condition: 100 mJ/cm2), and a resist pattern with no footing was obtained in four typical kinds of fluorinated resist on this BARC material. We concluded that this BARC material was suitable for 157-nm lithography.

Novel Organic Bottom Antireflective Coating Materials for 193 nm Lithography

We designed novel hybrid type bottom antireflective coating (BARC) materials for ArF lithography. The optimum extinction coefficient (k) value of the new organic BARC materials (HEART004) is 0.71 at a 32 nm film thickness. Its plasma etch rate is higher than that of ArF photoresist under Cl2/O2 plasma etch conditions. The critical dimension (CD) uniformity of 0.13 µm L/S patterns could be controlled below 10 nm and the etch bias, which represents the CD difference before and after BARC etching, could be less than 10 nm. Our new organic BARC materials show a good compatibility with both (meth)acrylate-type photoresist (PAR101, PAR710) and cycloolefin/maleic-anhydride-type photoresist (DHA1001) without any undercut or footing.

Bottom Anti-Reflective Coatings for DUV Lithography.

Bottom anti-reflective coatings (BARC) provide a production proven solution to improve linearity, depth-of-focus, CD control and process latitudes of photoresists. A series of BARCs compatible with chemically amplified deep ultra-violet (DUV) photoresists exhibiting different k values ranging from 0.1 to 0.6 at the DUV wavelength (248nm) has been developed. The relationship between the k values and the etch rates of the BARC polymers with different dye concentrations in the polymer has been investigated. As a result, BARCs with targeted k values and etch rates can be provided. Formulation aspects of the BARC materials including edge bead remover (EBR) compatibility and evaluation results of these BARCs with different DUV resists are also discussed.