In this study, the four ArF resists having methacrylate structure have been evaluated to check the reliability of
process through-put enhancement in track by applying the different baking time. The dense L/S and isolated
patterns of T80nm and T66nm node device are investigated for these models. The chemical properties of
applied resists are slightly different for each other in the respect of protecting ratio and molecular weight. The
applied resist thickness are 2,000Å and 1,700Å for the patterning of T80nm and T66nm node device,
respectively. The process margins of evaluated patterns for T80nm node device show the almost similar
results for DOF and E/L for 90s, 60s and 45s baking time conditions. And the LER of these patterns also is not
much changed by the different baking time conditions. Form the experimental results, it is confirmed that the
less baking time below 60s for T80nm node pattern is available to apply for enhancing the through-put in litho
process. The process margins and LER of evaluated patterns for T66nm node device are slightly affected by
their chemical properties like molecular weight and protecting ratio of resin for the different baking time
conditions. However, the more improved pattern profile and process margin can be obtained by optimizing the
chemical properties in the certain experimental range. And also, it is found that the less baking time below 45s
can be applied for the reliable patterning process of T80nm and T66nm node device through the crosssectional
SEM views with the more optimizing the material compositions.
In this study, the four different types of ArF and KrF OBARC have been evaluated to know the implantation blocking and gap fill performance for 80nm node device application. The boron implantation conditions of 11B and 49BF2 are processed and the minimum energy for implantation blocking of these OBARC are obtained by SIMS analysis. The minimum energy of ArF and KrF OBARC are about 13.0KeV and 15.0KeV, respectively. The chemical density of each OBARC is also calculated from the minimum blocking energy. Their values of ArF and KrF OBARC are about 0.8g/cm3 and 1.0g/cm3, respectively. The minimum energy trends among the tested materials show the almost similar results with those of chemical density as expected. Even though the OBARC are composed of the similar chemical structure, they induce the different chemical density because of their own molecular weight and other additional structure as like chromophore. Both of KrF and ArF OBARC show the good gap fill performance on 0.2μm size of via substrate and real topology pattern without void. It seems that the gap fill property is not much affected by the chemical structure or molecular weight of OBARC. It is thought that OBARC is an effective material for gap fill application than other resists, especially for deep topology patterns. In general, the etch rate of OBARC is slightly faster than that of ArF resist or similar with that in this experimental condition. The OBARC having high chemical density shows the slower etch rate and that of OBARC is inversely proportional to the chemical density of it. Therefore, it is confirmed that the OBARC is able to apply for implantation blocking purpose without gap fill void in real device below 80nm, since they have the good characteristics for gap fill, reflectivity control from substrate and implantation blocking property at a certain coating thickness.
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 new thin BARC has been developed for the application of small size patterning below 100nm by the optimized simulation and the evaluations on each substrate condition of silicon nitride and silicon oxide. The optical parameters of thin BARC of Exp225 are 1.81 and 0.58 for n and k values, respectively. They are obtained by the simulation for the lower reflectivity at the conditions of silicon nitride and silicon oxide. The optimized BARC thickness of Exp225 are 320Å and 460Å for silicon nitride and oxide substrate, respectively, at the condition of reflectivity. These thickness are much lower than those of commercial BARC of DUV44 for the same substrate conditions. The pattern profile and process margin are compared between the inorganic SiON and organic BARC. The dense L/S pattern profile of 100nm size on SiON shows the severe standing wave and undercutting. However, the pattern on Exp225 is much stable and gives wider depth of focus margin than that of SiON condition. The 85nm dense L/S pattern with feasible process margin is obtained by the application of Exp225 at the thickness of 320Å. The baking temperature is also investigated for the application of mass production. The most optimized baking temperature ranges of Exp225 are between 205°C and 225°C. From the experimental results, it is confirmed that the application of thin BARC is much effective for the small size patterning of 80nm node device. And it is thought that 80nm node device by KrF lithography is possible under the conditions of thin BARC, high contrast resist and high NA exposure tool.
The demand for manufacturing integrated circuit with high circuit speed and high packing density requires reduced feature sizes in ULSI structures. As the device feature size shrinks below sub-130 nm it needs the tight control of defect reduction in lithography process. Especially, resist peeling at the wafer edge is one of the major sources for particle generation. The WEE process removes resist up to a width of a few mm from the wafer edge in order to prevent particle generation in succeeding process. The defect induced form wafer edge after WEE has given the critical damage to electrical properties and device yield. In this paper, we have applied novel WEE kit to reduce the rainbow bandwidth caused by WEE step in wafer wedge. The novel WEE kit consists of chrome slit and lens assembly to minimize the scattering of UV beam from the optic fiber in comparison with the conventional WEE kit. The change of rainbow bandwidth was also characterized by OM and SEM. With the novel WEE kit the bandwidth of rainbow is reduced to 5 micrometers , while the conventional WEE kit has been induced 20 micrometers of bandwidth on bare silicon wafer. In the case of patterned wafer, the bandwidth of rainbow is reduced to 60 micrometers for the novel WEE kit, while the conventional WEE kit has induced 230 micrometers of bandwidth. Therefore, ti is confirmed that the application of novel WEE kit has induced 230 micrometers of bandwidth. Therefore, it is confirmed that the application of novel WEE kit for patterned process makes less rainbow defect and finally increases the device yield for mass production.
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