Understanding of hydrogen silsesquioxane electron resist for sub-5-nm-half-pitch lithography

Yang, Joel K. W.; Cord, B.; Duan, Huigao; Berggren, Karl K.; Klingfus, Joseph; Nam, Sung Wook; Kim, Ki Bum; Rooks, M. J.

doi:10.1116/1.3253652

Cited by 161 publications

(123 citation statements)

References 17 publications

(19 reference statements)

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“…However, superior resolution ͑9 nm pitch͒ obtained on Raith's prototype RAITH150 Mark II system ͑which differs from MIT's RAITH150 primarily in having a spot size that is 2 -3 nm smaller͒ suggests that beam diameter does, in fact, affect minimum feature size, even when the beam is much narrower than the minimum feature size. 14 Another possible reason for the discrepancy between our theoretical and observed resolution is that the imaging resolution of the RAITH150 may be lower than its lithographic resolution. When the RAITH150 is writing patterns, the beam dwell time on a single pixel is typically on the order of 1 s. At these beam speeds, the bandwidth of environmental noise capable of distorting or blurring patterns is on the order of 100 kHz-1 MHz or larger.…”

Section: Discussioncontrasting

confidence: 39%

“…HSQ being the resist used in the vast majority of our resolution experiments, the logical next step was to investigate the development mechanics of HSQ. Unlike PMMA and most other resists, HSQ has a highly nonlinear development rate, as demonstrated by Yang et al 14 The reason for this self-limiting behavior is unknown, but we hypothesize that it is due to a combination of negative charge buildup on the resist surface during development and/or cross-linked material in the developing resist. When combined with the fact that mass transfer issues are known to slow down development rates for small, deep features ͑such as the gaps in our dense HSQ gratings͒ by limiting the flow of developer into the reaction site and reaction product out of the reaction site, 15 it seems plausible that, in gaps below a certain threshold width, undeveloped HSQ cannot dissolve quickly enough to create a gap visible to SEM/TEM imaging before the reaction self-limits.…”

Section: Discussionmentioning

confidence: 90%

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Limiting factors in sub-10nm scanning-electron-beam lithography

Cord¹,

Yang²,

Duan³

et al. 2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Achieving the highest possible resolution using scanning-electron-beam lithography ͑SEBL͒ has become an increasingly urgent problem in recent years, as advances in various nanotechnology applications ͓F. feature sizes well into the sub-10 nm domain, close to the resolution limit of the current generation of SEBL processes. In this work, the authors have used a combination of calculation, modeling, and experiment to investigate the relative effects of resist contrast, beam scattering, secondary electron generation, system spot size, and metrology limitations on SEBL process resolution. In the process of investigating all of these effects, they have also successfully yielded dense structures with a pitch of 12 nm at voltages as low as 10 keV.

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Section: Discussioncontrasting

confidence: 39%

Section: Discussionmentioning

confidence: 90%

Limiting factors in sub-10nm scanning-electron-beam lithography

Cord¹,

Yang²,

Duan³

et al. 2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…First, we use EBL on negative tone hydrogensilsesquioxane (HSQ) resist (step I Figure 1a). HSQ features a high-patterning resolution below 10 nm, 32 as well as a highpostprocessing stability due to its inert inorganic SiO x nature. After EBL patterning, a 50 nm thick gold film is deposited by electron beam evaporation at low temperature (step II) to reduce the gold grain size by approximately a factor of 2 as compared to room temperature evaporation ( Figure S1).…”

mentioning

confidence: 99%

In-Plane Plasmonic Antenna Arrays with Surface Nanogaps for Giant Fluorescence Enhancement

et al. 2017

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Optical nanoantennas have a great potential for enhancing light-matter interactions at the nanometer scale, yet fabrication accuracy and lack of scalability currently limit ultimate antenna performance and applications. In most designs, the region of maximum field localization and enhancement (i.e., hotspot) is not readily accessible to the sample because it is buried into the nanostructure. Moreover, current large-scale fabrication techniques lack reproducible geometrical control below 20 nm. Here, we describe a new nanofabrication technique that applies planarization, etch back, and template stripping to expose the excitation hotspot at the surface, providing a major improvement over conventional electron beam lithography methods. We present large flat surface arrays of in-plane nanoantennas, featuring gaps as small as 10 nm with sharp edges, excellent reproducibility and full surface accessibility of the hotspot confined region. The novel fabrication approach drastically improves the optical performance of plasmonic nanoantennas to yield giant fluorescence enhancement factors up to 10 4 −10 5 times, together with nanoscale detection volumes in the 20 zL range. The method is fully scalable and adaptable to a wide range of antenna designs. We foresee broad applications by the use of these in-plane antenna geometries ranging from large-scale ultrasensitive sensor chips to microfluidics and live cell membrane investigations. KEYWORDS: Optical nanoantennas, template stripping, electron beam lithography, fluorescence enhancement, plasmonics O ptical nanoantennas take advantage of the plasmonic response of noble metals to strongly confine light energy into nanoscale dimensions and breach the classical diffraction limit. 1−3 This confinement leads to a drastic enhancement of the interactions between a single quantum emitter and the light field, 4−7 enabling large fluorescence gains above a thousand fold, 8−13 ultrafast picosecond emission, 14−16 and photobleaching reduction. 17,18 As such, optical antennas hold great interest for ultrasensitive biosensing, especially for the detection of single molecules at biologically relevant micromolar concentrations. 19−21 Biosensing applications of nanoantennas require the largescale availability of narrow accessible gaps. Not only should nanogaps with sub-20 nm dimensions be reproducibly fabricated but also the gap region (plasmonic hotspot) must remain accessible to probe the target molecules. Despite impressive recent progress using electron beam, 22 focused ion beam, 23 or stencil lithographies 24−26 or alternatively with bottom-up self-assembly techniques, 6,7,9,13,16,27−30 the challenges of reliable narrow gap fabrication and hotspot accessibility remain major hurdles limiting the impact and performance of optical nanoantennas. For instance, when aiming for the fabrication of aperture antennas, electron beam lithography (EBL) using a positive-tone resist requires metal dry etching, which produces high line-edge roughness that are not suited for the definition ...

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“…20,21 In order to resolve dense patterns, we increased the development time from 120 to 160 s. Figure 7(b) shows the result of this increase for dense patterns (1:1 L/S). Moreover, the effect on increased development time on the semidense features is shown in Fig.…”

Section: Effects Of Longer Development Timementioning

confidence: 99%

Process development for high resolution hydrogen silsesquioxane patterning using a commercial scanner for extreme ultraviolet lithography

Desai

Mellish

Bennett

et al. 2017

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The semiconductor industry is transitioning toward the use of extreme ultraviolet (EUV) lithography as a next generation patterning technology. There are currently only a limited number of high resolution EUV photoresists reported with EUV patterning capabilities, and those are generally tested using EUV-interference lithography. One such resist is the more commonly known electron beam resist, hydrogen silsesquioxane (HSQ), which is also sensitive to EUV exposure. In the present work, high resolution, dense, subdense patterning of HSQ resist on 300 mm wafers was demonstrated using ASML's NXE 3300B scanner. The critical dimensions analyzed ranged from 18 to 10 nm. Resolution down to 10.0 on 21.0 nm spacing was achieved with 6.5 nm line width roughness. This demonstration of high resolution EUV patterning of HSQ on a commercial scanner makes this process potentially viable for high volume manufacturing.

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Understanding of hydrogen silsesquioxane electron resist for sub-5-nm-half-pitch lithography

Cited by 161 publications

References 17 publications

Limiting factors in sub-10nm scanning-electron-beam lithography

Limiting factors in sub-10nm scanning-electron-beam lithography

In-Plane Plasmonic Antenna Arrays with Surface Nanogaps for Giant Fluorescence Enhancement

Process development for high resolution hydrogen silsesquioxane patterning using a commercial scanner for extreme ultraviolet lithography

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