The mask-making process for 45nm-node and beyond demands higher resolution and CD accuracy. To meet the requirements, the multi-layer resist system is developed as one of the solutions. BIL (Bottom Insulating Layer) can correct the profile of CAR (Chemically Amplified Resist). CAR shows profile degradation by photo-acid loss at the boundary of chrome and resist. The photo-acid loss induces excess footing in positive-tone CAR and under-cutting in negative-tone CAR. BIL reduced the profile degradation to less than half of the conventional resist system. BIL requires no extra mask process steps. Final CD linearity of isolated lines was improved by BIL. It is very beneficial for the patterning of sub-resolution assist features. Moreover, BIL with a hard-mask layer showed superior dry-etching bias performance.
The CD requirements for the 45nm-node will become tighter so as it will be difficult to achieve with 65nm node
technologies. In this paper, a method to improve resolution by using DRECE (Dry-etching Resistance Enhancement
bottom-Coating for Eb) will be described. After all, DRECE has five times as high dry-etch resistance than the EB resist,
and this enables to accept higher anisotropic dry etching condition. By optimizing dry etching conditions, the CD
iso-dense bias dropped to 1/3 and the CD shift was reduced to 1/2. Also, there was no negative effect to CD uniformity.
From these results, we propose the use of DRECE for the 45nm-node technology.
A two-layer bottom anti-reflective coating (BARC) concept in which a layer that develops slowly is coated on top of a bottom layer that develops more rapidly was demonstrated. Development rate control was achieved by selection of crosslinker amount and BARC curing conditions. A single-layer BARC was compared with the two-layer BARC concept. The single-layer BARC does not clear out of 200-nm deep vias. When the slower developing single-layer BARC was coated on top of the faster developing layer, the vias were cleared. Lithographic evaluation of the two-layer BARC concept shows the same resolution advantages as the single-layer system. Planarization properties of a two-layer BARC system are better than for a single-layer system, when comparing the same total nominal thicknesses.
Integrated circuit manufacturers are consistently seeking to minimize device feature dimensions in order to reduce chip size and increase integration level. Feature sizes on chips are achieved sub 65nm with the advanced 193nm microlithography process. R&D activities of 45nm process have been started so far, and 193nm lithography is used for this technology. The key parameters for this lithography process are NA of exposure tool, resolution capability of resist, and reflectivity control with bottom anti-reflective coating (BARC). In the point of etching process, single-layer resist process can't be applied because resist thickness is too thin for getting suitable aspect ratio. Therefore, it is necessary to design novel BARC system and develop hard mask materials having high etching selectivity. This system and these materials can be used for 45nm generation lithography. Nissan Chemical Industries, Ltd. and Brewer Science, Inc. have been designed and developed the advanced BARCs for the above propose. In order to satisfy our target, we have developed novel BARC and hard mask materials. We investigated the multi-layer resist process stacked 4 layers (resist / thin BARC / silicon-contained BARC (Si-ARC) / spin on carbon hard mask (SOC)) (4 layers process). 4 layers process showed the excellent lithographic performance and pattern transfer performance. In this paper, we will discuss the detail of our approach and materials for 4 layers process.
A frequent problem encountered by photoresists during the manufacturing of semiconductor device is that activating radiation is reflected back into the photoresist by the substrate. So, it is necessary that the light reflection is reduced from the substrate. One approach to reduce the light reflection is the use of bottom anti-reflective coating (BARC) applied to the substrate beneath the photoresist layer. The BARC technology has been utilized for a few years to minimize the reflectivity. As the chip size is reduced to sub 100nm, the photoresist thickness has to decrease with the aspect ratio being less than 3.0. Therefore, new Organic BARC is strongly required which has the minimum reflectivity with thinner BARC thickness and higher etch selectivity toward resists. Hynix Semiconductor Inc., Nissan Chemical Industries, Ltd., and Brewer Science, Inc. have developed the advanced Organic BARC for achieving the above purpose. As a result, the suitable high performance 248nm Organic BARCs, NCA series, were achieved. Using CF4 gas as etchant, the plasma etch rate of NCA series is about 1.4 times higher than that of conventional 248nm resists. NCA series can be minimizing the substrate reflectivity at below 45nm BARC thickness. NCA series show the excellent litho performance and coating property on real device.
The suitable high performances Organic Bottom Anti-Reflective Coatings (Organic BARCs) for 193nm Bilayer system, NCA900 series, were developed. Using CF4 gas as etchant, the etching rate of NCA900 series were 0.87 times slower than that of conventional 193nm photoresists. With NCA900 series, the reflectivity was less than 1% at over 300nm BARC thickness on polysilicon, silicon oxide and silicon nitride. Using conventional 193nm photoresist, 80nm L/S (1:1) patterns with 0.5-micron DOF were observed on NCA900 series. NCA900 series showed the excellent litho performance and coating property. This paper presents the development of BARCs for 193nm Bilayer system.
A frequent problem encountered by photoresists during the manufacturing of semiconductor device is that activating radiation is reflected back into the photoresist by the substrate. So, it is necessary that the light reflection is reduced from the substrate. One approach to reduce the light reflection is the use of bottom anti-reflective coating (BARC) applied to the substrate beneath the photoresist layer. The BARC technology has been utilized for a few years to minimize the reflectivity. As the chip size is reduced to sub 0.13 micron, the photoresist thickness has to decrease with the aspect ratio being less than 3.0. Therefore, new Organic BARC is strongly required which has the minimum reflectivity with thinner BARC thickness and higher etch selectivity toward resists. Nissan Chemical Industries, Ltd. and Brewer Science, Inc. have developed the advanced Organic BARC for achieving the above purpose. As a result, the suitable high performance NCA3000 series 248nm Organic BARCs were developed. Using CF4 gas as etchant, the plasma etch rate of NCA3000 series is about 1.4-1.6 times higher than that of conventional 248nm resists and 1.1-1.2 times higher than that of the existing product. The NCA3000 series can minimize the substrate reflectivity at below 45nm BARC thickness, shows excellent litho performance and coating properties.
Dyed photo resist and/or Top Anti-Reflective Coatings (TARC) has been used as mold in ion doping layer. However, in sub 0.25-micron pattern, this system is difficult to apply due to their poor CD control ability. As the chip size is shrunk to sub 0.25-micron in ion doping layer, the use of Organic Bottom Anti-Reflective Coatings (BARC) is strongly required. On the other hand, current Organic KrF BARCs does not dissolve in alkaline developer, and the dry etching process is indispensable in order to remove Organic BARCs. For this reason, it is difficult to apply the current Dry type Organic BARCs to the ion doping layer. To solve this problem, Wet Developable Organic BARCs to be applied to sub 0.25-micron, which have alkaline solubility have been required. NCA800 series that are the suitable alkaline developable KrF Organic BARCs, has been developed and achieved. Alkaline solubility of these BARCs was controllable by baking temperature. NCA800 series show the excellent litho performance and coating property.
This paper presents our progress in developing spin-on, thermosetting hardmasks and bottom antireflective coatings (BARCs) for 193-nm trilayer usage. Binder materials that were used in preparing the silicon-containing hardmasks include polymers with pendant alkylsilane function and various polyhedral oligomeric silsesquioxane (POSS) substances, with the hardmasks being very transparent at both 193 and 248 nm. The second generation hardmasks (POSS-containing) offer significant improvements over earlier materials in oxygen (O2) plasma etching resistance. The etching selectivity (O2 plasma) for a trilayer BARC relative to the best-case hardmask is about 31.5:1 (15-second etch), with the selectivity numbers being much higher for longer etching times. The preferred hardmask is both spin-bowl and solution compatible. The new trilayer BARCs use binders that are rich in aromatic content for halogen plasma etching resistance, but the antireflective products also feature optical parameters that allow low reflectivity into the photoresist. The BARCs are very spin-bowl compatible. At about 500-nm film thickness, selected BARCs have provided 80-95% planarity over 200-nm topography. Combining the two thermosetting products (hardmask and BARC) with a thin 193-nm photoresist in a trilayer configuration has given excellent 80-nm L/S (1:1) after exposure and wet-development. A conventional resist has provided 100-nm L/S (1:1.4).
A frequent problem encountered by photoresists during the manufacturing of semiconductor device is that activating radiation is reflected back into the photoresist by the substrate. So, it is necessary that the light reflection is reduced from the substrate. One approach to reduce the light reflection is the use of bottom anti-reflective coating (BARC) applied to the substrate beneath the photoresist layer. The BARC technology has been utilized for a few years to minimize the reflectivity. As the chip size is reduced to sub 0.13-micron, the photoresist thickness has to decrease with the aspect ratio being less than 3.0. Therefore, new Organic BARC is strongly required which has the minimum reflectivity with thinner BARC thickness and higher etch selectivity towards resist. SAMSUNG Electronics has developed the advanced Organic BARC with Nissan Chemical Industries, Ltd. and Brewer Science, Inc. for achieving the above purpose. As a result, the suitable high performance SNAC2002 series KrF Organic BARCs were developed. Using CF4 gas as etchant, the plasma etch rate of SNAC2002 series is about 1.4 times higher than that of conventional KrF resists and 1.25 times higher than the existing product. The SNAC2002 series can minimize the substrate reflectivity at below 40nm BARC thickness, shows excellent litho performance and coating properties.
A frequent problem encountered by photoresists during the manufacturing of semiconductor device is that activating radiation is reflected back into the photoresist by the substrate. So, it is necessary that the light reflection is reduced from the substrate. One approach to reduce the light reflection is the use of bottom anti-reflective coating (BARC) applied to the substrate beneath the photoresist layer. The BARC technology has been utilized for a few years to minimize the reflectivity. Recently, reduction of chip size is speeded up and device feature sizes shift to sub 0.15 micron meter with KrF lithography techniques. The thickness of photoresist is decreasing with reduction of device feature sizes. So, requirements of new 248nm BARC are higher etch rate than the existing 248nm BARC. High etch rate type 248nm BARC developed with the objective being a commercial product. The suitable high performance 248nm BARCs, NCA300 series, were made. Using CF4 gas as etchant, the plasma etch rate of NCA300 series were about 1.6 tiems higher than that of 248nm photoresist and about 1.2 times higher than that of our existing BARCs, DUV42 or DUV44. Using CF4/O2 mixture gas as etchant, the plasma rate of NCA300 series were about 1.5 times higher than that of 248nm photoresist and about 1.1 times higher than that of DUV42 or DUV44.
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