Hsu-Chun Cheng

High reflectance of reflective-type attenuated-phase-shifting masks for extreme ultraviolet lithography with high inspection contrast in deep ultraviolet regimes

Phase-shifting masks are a vital resolution enhance technique that will be used in extreme ultraviolet (EUV) lithography beyond the 20nm node. In this article, we demonstrate a structure for a reflective-type attenuated phase-shifting mask, which is based on a Fabry–Perot structure with common materials in EUV masks. The mask structure not only performs 180° phase shift with high reflectance at EUV wavelength, but also has high inspection contrast at deep ultraviolet (DUV) wavelength. The top layer of mask structures exhibits good conductivity, which can alleviate the charging effect during electron-beam patterning. The reflectance ratio of the absorber stack could be tuned from 32.6% (TaN∕SiO2∕Mo) to 4.4% (TaN∕SiO2∕TaN) by choosing different bottom layers and thickness. The inspection contrast could be raised to 99% with large thickness-control tolerance.

Characterizing Optical Properties of Self-Assembled Gold Nanoparticles for Surface Plasmon Resonance Device Applications

In this study, the optical constants of gold nanoparticles are evaluated for surface plasmon-based sensor applications. Using an effective medium approximation (EMA) and ellipsometry, approaches to monitor the self-assembly of gold nanoparticles are also demonstrated. Spectroscopic ellipsometric parameters measured (tan Ψ, cos Δ) before and after adding gold nanoparticles to a substrate are used to calculate the optical constants of gold nanoparticles. The film thickness is measured by grazing incidence X-ray reflectivity (XRR). The optical constants (refractive index, extinction coefficient) of gold nanoparticles can be obtained from the measured ellipsometric parameters and thickness. We also show that particles density can be well predicted and detected nondestructively by this method.

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 etchingcharacteristics and thermal stability of BCB- and FLARE-based BARC layers are also described.

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

For reduction interconnect signal delay, low dielectric constant (K) materials are being introduced to replace conventional dielectrics in next generation IC technologies. In the advanced lithography processes, a bottom antireflective coating (BARC) layer for patterning low-K materials is essential. Nitride-based (silicon nitride, silicon oxynitride) films have been demonstrated to have suitable optical characteristics for both KrF and ArF lithography BARC applications. However, dielectric constants of nitride films are about 4/spl sim/8. Therefore, the nitride films should be removed after pattering low-K materials. Here we demonstrate low-K materials for both KrF and ArF lithography BARC applications. The antireflective layer is composed of diluted low-K materials, such as BCB, FLARE, and SiLK.

Enhance Extreme UltraViolet Lithography mask inspection contrast by using Fabry-Perot type antireflective coatings

In this paper, we demonstrate two antireflective coatings (ARC) structures enable the absorber stacks to meet the exposure and inspection requirements at the same time. The absorber stack is comprised of TaN or Cr and a single-layer antireflective coatings. Si/sub 3/N/sub 4/ layer is shown with lower reflectance and higher inspection contrast than SiO/sub 2/ layer. Fabry-Perot type ARC structures perform better contrast and thickness variation tolerance than the single-layer ARC structure.

Direct imprint in metal film stacks with low pressure and low temperature for optical elements applications

Nanoimprint lithography (NIL) has great potential as a candidate of next generation lithography for its low cost, high throughput and high resolution [l]. The imprint process is accomplished by heating a resist above its glass transition temperature (Tg) and imparting a force to transfer the image into the heated resist, Recently, a process of direct imprint in gold film at room temperature with ultra high pressure (hundreds MPa) was reported [2]. This method is a promising way to fabricate optical elements on gold films but there is a drawback of high pressure. Therefore, reducing imprint pressure would accomplish this method for optical elements fabrications. In this paper, we improve the direct imprint process by using a sharp mold and inserting a soft pad, which is the diluted resist (Sumitomo NEB22, Tg 105 OC) between the gold film and the substrate. The diagram of the gold film stack and the imprint mold was shown in Fig. 1. The silicon mold that be used in our experiments was fabricated using electron beam lithography followed by the anisotropic reactive ion etching (HE) process as shown in Fig. 2. The bias and RF power of RIE are the critical parameters for mold profile controlling. The pattern area of the moId is 10 mm x10 mm with 350 nm period gratings. In order to understand the influence of temperature in the direct imprint process, we imprinted the film stacks with different temperatures using a testing mold. As shown in Fig. 3, there are optical microscopic (OM) images of gold film stacks after imprint process. At low imprint temperature, even the room temperature, the pattern of the testing mold transfer onto the gold film stack completely. When the imprint temperature over Tg, the resist in bottom layer overflowed the top gold film cause poor pattern quality. This result indicates that the temperature of direct imprint process must be maintained below the glass transition temperature of the bottom soft pad to avoid pattern distortion. Fig. 4 shows the scanning electron microscope (SEM) image of the cross-section of gold film stack patterned using direct imprint method. The process conditions of this image are 380 psi pressure and 80 OC heating temperature with 2 minutes duration. The imprint pressure is only 0.1 % of the previous method [I]. Besides, it is clearly observe that the surface of the gold film stack shows shallow sinusoidal variation, which is different from the shape of the sharp mold. According this result, we can obtain desired curvature of shape using different imprint pressure. The details will present in this conference.

Diluted low dielectric constant materials as bottom antireflective coating layers for both KrF and ArF lithography

For reduction interconnect signal delay, low dielectric constant (K) materials are being introduced to replace conventional dielectrics in next generation IC technologies. In the advanced lithography processes, a bottom antireflective coating (BARC) layer for patterning low-K materials is essential. Nitride-based (silicon nitride, silicon oxynitride) films have been demonstrated to have suitable optical characteristics for both KrF and ArF lithography BARC applications. However, dielectric constants of nitride films are about 4/spl sim/8. Therefore, the nitride films should be removed after pattering low-K materials. Here we demonstrate low-K materials for both KrF and ArF lithography BARC applications. The antireflective layer is composed of diluted low-K materials, such as BCB, FLARE, and SiLK.

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

Abstract 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 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 SILK films as bottom antireflective coating layers for both KrF and ArF lithography

For advanced lithography processes, a BARC layer for patterning low dielectric materials is essential. Here we demonstrate new bottom antireflective coating (BARC) materials for both KrF and ArF lithography. The antireflective layer is composed of a low dielectric constant material SILK and its etching hard mask layer, such as an oxide or nitride film. The SILK is a commercial low dielectric material, which shows good etching and electrical characteristics. We report optical constants of the SILK film in the ultraviolet spectral region.