Modeling and development of a deep silicon etch process for 200 mm election projection lithography mask fabrication

Dauksher, William J.; Clemens, Stephen; Resnick, Douglas J.; Smith, K. H.; Mangat, Pawitter J. S.; Rauf, Shahid; Ventzek, Peter L. G.; Ashraf, Huma; Lea, L.; Hall, S.; Johnston, Ian; Hopkins, Janet; Chambers, A.; Bhardwaj, J. K.

doi:10.1116/1.1420574

Cited by 9 publications

(3 citation statements)

References 5 publications

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“…Then a time multiplexed dry etching method called Bosch process performed the deep etching using the thick resist as an etch mask. Bosch process is suitable for the deep etching of the substrate because of its very high etch rate of several micrometers per minute and good etch profile controllability 10 . Our optimized deep etching process formed the struts having vertical sidewall angles ranging from 90.90° to 91.89° across the entire mask blank 11 .…”

Section: Methodsmentioning

confidence: 99%

Resolution improvement of EPL stencil mask using thin membrane

et al. 2006

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Electron Projection Lithography (EPL) provides a fundamental advantage in resolution. In this paper, resolution improvement of EPL masks and minimum resolution in EPL exposure are addressed. In order to improve the mask resolution, we applied membranes thinner than typical thickness of 2 um to e-beam scattering layers of the EPL stencil masks. Although strength of the membrane generally deteriorates with decrease in the membrane thickness, the EPL masks having 1-um-thick scattering layers were feasibly fabricated. Reduction of the membrane thickness down to 1 um considerably improved the mask minimum feature size to resolve 120-nm holes and 80-nm lines which corresponded to 30 nm and 20 nm on wafer dimension, respectively, in the 4x demagnification EPL exposure system. The application of the 1-um-thick membrane simultaneously brought the high resolution and good pattern qualities: CD uniformity less than 10 nm in 3σ with pattern sidewall angle range of 90° ± 0.2°. We performed wafer exposure experiments in combination of the EPL exposure tool NSR-EB1A (Nikon) and the 1-um-thick membrane mask, and obtained the resolution performance of 40-nm holes on the wafer. We conclude that the application of the 1-um-thick membrane to the e-beam scattering layer provides high resolution EPL masks with practical CD qualities. The exposure resolution of 40-nm holes on the wafer reveals the EPL exposure system to be a potential solution for contact layers in the future technology node.

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Section: Methodsmentioning

confidence: 99%

Resolution improvement of EPL stencil mask using thin membrane

et al. 2006

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“…It has been found to be difficult to produce good sidewall angle uniformity across the blanks with high etch rate processes. [5] This may require reducing etch rate to achieve uniformity specifications.…”

Section: Mask Fabricationmentioning

confidence: 99%

Analysis of critical parameters for EPL mask fabrication

Lercel¹

2002

Emerging Lithographic Technologies VI

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Electron projection lithography (EPL) requires mask formats that are significantly different from those used in traditional optical lithography. These masks must consist of a thin membrane that is either patterned with transmissive perforations for stencil masks or patterned with a scatterer layer to form a continuous membrane mask. In this paper, the critical requirements for fabrication of EPL masks are discussed. Challenges for mask blank fabrication, image size uniformity, image placement accuracy, and defect control are presented with examples from mask fabrication. The impact of these parameters on EPL mask cost is then discussed. The mask cost is compared for different critical device levels and for different chip sizes. The influence of mask parameters and need for complementary masks drives higher mask costs for certain device levels. By examining the factors influencing mask cost for certain levels, the areas of mask technology that are most critical to controlling mask cost can be identified.

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“…Therefore an anisotropic etch method with high etch rate was necessary for the struts formation. A time multiplexed etch method called Bosch process is potential solution for the struts formation because it has high etch rate and etch profile controllability [8]. In the time multiplexed etch process, a step for etching and a step for depositing are sequentially repeated.…”

Section: Mask Fabricationmentioning

confidence: 99%

200-mm EPL stencil mask fabrication by using SOI substrate

et al. 2003

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We developed 200-mm stencil masks for electron projection lithography (EPL) by using silicon-on-insulator (SOI) substrates. Stress of a 2-µm-thick single crystalline silicon membrane, where patterns were fabricated as openings, was controlled around 10 MPa by adjusting concentration of impurities doped into the SOI layer. Boron and phosphorus were investigated as doping impurities, and it was confirmed that doping both elements were capable of stress control. For forming struts that supported the thin membrane, a time multiplexed etch method was applied. Control of the deep etch parameters made it possible for the SiO 2 stopper layer not to be etched through even if its thickness was sub-microns. To fabricate pattern openings in the membrane, reactive ion etching with high-density plasma was applied and lines down to 140 nm was fabricated in a 200-mm mask. Image placement distortion within a subfield was measured across the 200-mm mask and magnitudes of the image placement distortion were typically ~15 nm (3σ). A 200-mm EPL stencil mask having Selete's actual 70-nm design-rule system on chip (SoC) device pattern was successfully fabricated. We confirmed that the SOI substrates had potential abilities as initial material for 200-mm stencil mask fabrication.

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Modeling and development of a deep silicon etch process for 200 mm election projection lithography mask fabrication

Cited by 9 publications

References 5 publications

Resolution improvement of EPL stencil mask using thin membrane

Resolution improvement of EPL stencil mask using thin membrane

Analysis of critical parameters for EPL mask fabrication

200-mm EPL stencil mask fabrication by using SOI substrate

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