Electron-beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in situ electron-beam-induced desorption

Abstract

TitleElectron beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in-situ electron beam induced desorption AbstractHydrogen Silsesquioxane (HSQ) is used as a high-resolution resist with resolution down below 10-nm half-pitch. This material or materials with related functionalities could have widespread impact in nanolithography and nanoscience applications if the exposure mechanism was understood and instabilities controlled. Here we have directly investigated the exposure mechanism using vibrational spectroscopy (both Raman and Fourier transform Infrared) and electron beam desorption spectroscopy (EBDS). In the non-networked HSQ system, silicon atoms sit at the corners of a cubic structure. Each silicon is bonded to a hydrogen atom and bridges 3 oxygen atoms (formula: HSiO 3/2 ). For the first time, we have shown, via changes in the Si-H 2 peak at ~2200 cm -1 in the Raman spectra and and the release of SiH x products in EBID, that electron-beam-exposed material crosslinks via a redistribution reaction. In addition, we observe the release of significantly more H 2 than SiH 2 during EBID, which is indicative of additional reaction mechanisms. Additionally, we compare the behavior of HSQ in response to both thermal and electron-beam induced reactions.

Resist–substrate interface tailoring for generating high-density arrays of Ge and Bi2Se3 nanowires by electron beam lithography

“…The asymmetric Si-O-Si stretching modes for cage and network HSQ structures have absorbance peaks labeled as (Si-O-Si) cage can be attributed to the cage and network structures, respectively, as reported previously. 26,27 The greater intensity of the as (Si-O-Si) cage and d(H-Si-O) absorbance peaks in Fig. S4 22 with respect to the as (Si-O-Si) net and d(O-Si-O) peaks, respectively, is consistent with a high concentration of the cage species with respect to that of the network analog prior to electron beam exposure or high temperature thermal treatment.…”

Aged hydrogen silsesquioxane for sub-10nm line patterns

“…2.7, and depart slightly from the ideal value of n = 3. Previous reports indicate that the growth of HSQ nuclei is three-dimensional at sites with the cage structure [11][12][13][14], which is the most plausible mechanism for our case here since the distribution of nuclei cannot be totally random. Then, the nucleation cannot take place absolutely homogeneously either [16].…”

“…(c) LER for the line arrays versus HSQ age. exposed to an electron beam [8,10,11]. In fact, however, both the network and cage structures usually co-exist in thin HSQ films after being spun, but with a higher fraction of cages.…”

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

“…4 At this time, there are no reports in the literature that explain the exact mechanism by which HSQ responds to EUV light; however, the exposure mechanism of HSQ resist with the electron beams has been reported. 5,6 During electron beam exposure, the Si-H bond of HSQ resist breaks, resulting in Si-O crosslinking and generation of water as a by-product. 5 Another reported exposure mechanism suggests that after electron beam exposure, the HSQ experiences a redistribution reaction, which subsequently causes crosslinking via oxygen bridges between the HSQ molecules and generation of silane (SiH 4 ).…”

“…5 Another reported exposure mechanism suggests that after electron beam exposure, the HSQ experiences a redistribution reaction, which subsequently causes crosslinking via oxygen bridges between the HSQ molecules and generation of silane (SiH 4 ). 6 In EUV exposure, high energy EUV photons get absorbed in the photoresist which then generates photoelectrons. These photoelectrons further experience scattering in the photoresist, generating secondary electrons, which can participate in resist exposure.…”