Electron multi-beam mask writers play a key role to expand EUV lithography usage in device mass production. It was in May 2021 when the MBMTM-2000 was released by NuFlare Technology, Inc. Since then, it has been installed at sites of mask manufactures. Accordingly, it supports their mask development and production. On top of reliable inherited mask writing technologies, newly developed technologies, which have achieved objectives, enable the multi-beam writer to make many contributions. In June 2022, the MBMTM-2000PLUS for the 2 nm node device development eventually debuted. The increased beam current density, 3.2 A/cm2 allows this latest mask writer to print a mask with productive writing time even using lower sensitivity resists. A charge effect reduction (CER) is a hardware solution to reduce amount of the resist surface charge. Thanks to adapting CER2.0, which is upgrade version of CER1.0, the image placement error caused by the resist surface charge effect in the MBMTM-2000PLUS is reduced by 50% as compared with the MBMTM-2000 with optics CER1.0. This successor also takes over essential functions including pixel level dose correction (PLDC), charge effect correction (CEC), and glass thermal expansion correction (GTEC) from the MBM-2000. In this paper, the current performance of MBM series mask writers and the key architectures above-mentioned have been discussed. We also explain our strategies to keep continuous throughput improvement by optimizing items such as beam size, data transfer speed, beam current density and so on. Our roadmap indicates that NuFlare Technology, Inc. makes contribution to the high-NA EUV ecosystem.
Multi-beam mask writer MBM-2000PLUS has been released for the 3nm+ technology node. It is designed with the capability of low dose sensitivity resist over 150 uC/cm^2 in the writing of leading-edge EUV and optical blanks without constraint by beam exposure time. Furthermore, taking advantage of multi-beam writing strategy and its high beam current density, ultra-high throughput writing is also available by selective pixel size. This selective pixel size will make it possible to product both leading edge and middle grade masks efficiently. In this paper, the relation between the pixel size, throughput and precision is discussed and demonstrated by writing experiments in MBM-2000PLUS.
MBM-2000, the latest multi-beam mask writer of Nuflare Technology, Inc. (NFT), have achieved reasonable writing time in mask fabrication of 3nm semiconductor technology node, which demand small curvilinear patterns in EUV masks and curvilinear OPC patterns in optical masks. For less line edge roughness and better pattern fidelity, however, the demand of lower dose sensitivity resists keeps increasing. In such a situation, the beam exposure time can be the main bottleneck of the writing time. In order to meet the demand, NFT has developed MBM-2000PLUS, which achieved high beam current density of beamlets ×1.3 larger than MBM-2000. As the result, the writing time became constant up to 170 μC/cm2 exposure dose condition without confinement by beam exposure time. Even at the region of exposure dose confinement, the writing time became 20% less than MBM-2000 at 200 μC/cm2 dose condition. In addition, charge effect reduction (CER), which is an electron optics system reducing resist charge effect, has been upgraded from MBM-2000 for improving image placement accuracy. Furthermore, MBM-2000PLUS inherits pixel level dose correction (PLDC) function from MBM-2000 as the solution for less edge placement error and better pattern fidelity. In this paper, those features of MBM- 2000PLUS are highlighted including improvement of pattern fidelity by PLDC function. In order to verify PLDC, a new methodology of quantitative evaluation of pattern fidelity using sine-shape pattern is introduced.
MBM-2000, the latest multi-beam mask writer of Nuflare Technology, Inc. (NFT), have achieved reasonable writing time in mask fabrication of 3nm semiconductor technology node, which demand small curvilinear patterns in EUV masks and curvilinear OPC patterns in optical masks. For less line edge roughness and better pattern fidelity, however, the demand of lower dose sensitivity resists keeps increasing. In such a situation, the beam exposure time can be the main bottleneck of the writing time. In order to meet the demand, NFT has developed MBM-2000PLUS, which achieved high beam current density of beamlets ×1.3 larger than MBM-2000. As the result, the writing time became constant up to 170 μC/cm2 exposure dose condition without confinement by beam exposure time. Even at the region of exposure dose confinement, the writing time became 20% less than MBM-2000 at 200 μC/cm2 dose condition. In addition, charge effect reduction (CER), which is an electron optics system reducing resist charge effect, has been upgraded from MBM-2000 for improving image placement accuracy. Furthermore, MBM-2000PLUS inherits pixel level dose correction (PLDC) function from MBM-2000 as the solution for less edge placement error and better pattern fidelity. In this paper, those features of MBM2000PLUS are highlighted including improvement of pattern fidelity by PLDC function. In order to verify PLDC, a new methodology of quantitative evaluation of pattern fidelity using sine-shape pattern is introduced.
NuFlare Technology, Inc. has developed the charge effect correction (CEC) system, in which the predicted placement errors caused by resist surface charge effect are compensated. Due to good reproducibility of these exposure-dose-dependent and time-dependent behaviors, CEC has successfully improved image placement accuracy in single variable-shaped electron beam mask (EBM) writers. The physical mechanism of resist charging, however, has remained unclear. Considering large difference in beam current densities between EBM and multi-beam mask writers (MBM), it is concerning that unexpected charge phenomena occur. Therefore, it is required to reveal the mechanism and to show the resist charging is still predictable in MBM by a common charging model. In order to provide validity of CEC consistently with EBM and MBM, the surface charge densities caused in EBM writers and MBM-2000 were experimentally evaluated from those placement errors. The charge densities strongly depend on the resist thickness meanwhile they do not change significantly by the writers. Furthermore, equations to reproduce those experimental results are proposed in terms of a physical model, which takes into account low-energy secondary electrons drawn to resist surface by an already-existing surface charge and vertical flow of the charge in the resist.
The multi-beam mask writer MBM-2000 is released for the 3 nm technology node. It is designed to expose EUV blanks and leading edge photomasks at high throughput with beamlets of total current 1.6 uA. The curve data format supported by MBF 2.0 enables full-mask writing of curvilinear patterns by reducing data volume and computation cost of rasterizing. To maximize the performance of multi-beam writing, MBM-2000 is equipped with pixel level dose correction (PLDC) which improves pattern fidelity and patterning resolution. In this paper, we have reported and discussed the writing results of MBM-2000.
A multi-beam mask writer, MBM-2000 is developed for the N3 semiconductor production. It is designed to accomplish high throughput with 16-nm beam and large current density 2.5 A/cm2. It is equipped with curve data format MBF2.0 to allow writing of small curve patterns in EUV masks and curvilinear OPC patterns in optical masks. To improve patterning resolution, pixel-level dose correction (PLDC) is implemented which corrects and enhances profile of dose deposited in resist. Writing tests have proven the global position accuracy that meets MBM-2000’s specification and the effectiveness of fidelity improvement function of PLDC.
A multi-beam mask writer MBM-2000 is developed for the 3 nm technology node. It is designed to expose EUV blanks with beamlets of total current 1.6 uA at high throughput. It also supports writing leading-edge photomasks by equipping a correction function for glass thermal expansion and high-speed data path. Fast writing modes are provided for middle-grade photomask writing. Inline function of pixel level dose correction (PLDC) is implemented to reduce mask turnaround time by replacing offline corrections with PLDC, with additional benefit of fidelity improvement by dose enhancement. In this paper, writing results of MBM-2000 are reported and discussed.
This paper covers the writing performance of our multi-beam mask writer, MBM-1000, which has been developed for the 5 nm technology node. It exposes low sensitivity resist faster than VSB writers and prints complex patterns with better fidelity. We will describe its writing performance and compare it with our VSB writer, EBM-9500 PLUS. MBM-1000 has pixel-level dose correction (PLDC). PLDC modulates dose profile at pixel level to improve pattern fidelity and patterning resolution. It is integrated with MBM-1000 data path and runs inline. We will also report functions and writing results of MBM-1000 with PLDC.
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