Line edge roughness evolutions in EUV resist patterns are investigated. Three dimensional scanning electron microscopy
images show the pattern sidewall roughness to be highly anisotropic and the roughness to be propagating from the resistsubstrate
interface up the resist pattern sidewall. In ultrathin resist films, (film thickness ca. 100 nm and below)
roughness is found to be fully correlated from the resist-substrate interface to the resist-air interface. This behavior is
seen regardless of the resist platforms being used.
Underlayer stack roughness contributions to the pattern sidewall roughness leading to resist LER were examined and no
correlations between the two were found. At the same time, the chemical properties of the underlayer stacks are shown
to have strong influences on the resist roughness and process performance. Exact mechanisms behind this are not clearly
understood at present.
As IC manufactures explore different paths to meet the resolution requirements for next generation technology,
patterning schemes which utilize a double photoresist patterning process are under extensive evaluation. One dual
patterning process under consideration uses a 172nm UV cure to render the first photoresist pattern insoluble to the
casting solvents and developer chemistries used to define the second photoresist pattern. Line-space resist patterning is
used to understand the effect of the 172nm UV light on the SiBARC, under-layer film stack and how it influences the
patterned CD. This is followed by cross-grid and pitch-split double patterning using 172 nm UV light of varying dose to
freeze the first photoresist layer patterned using a tri-layer film configuration. In the final section we discuss the effects
of the 172nm UV cure on the SiBARC film thickness and optical properties. Simulations are run to understand the
change in the focus-exposure process window due to changes in the SiBARC film due to the 172nm UV cure.
This work discusses the requirements and performance of Honeywell's middle layer material, UVAS, for tri-layer
patterning. UVAS is a high Si content polymer synthesized directly from Si containing starting monomer components.
The monomers are selected to produce a film that meets the requirements as a middle layer for tri-layer patterning (TLP)
and gives us a level of flexibility to adjust the properties of the film to meet the customer's specific photoresist and
patterning requirements. Results of simulations of the substrate reflectance versus numerical aperture, UVAS thickness,
and under layer film are presented. ArF photoresist line profiles and process latitude versus UVAS bake at temperatures
as low as 150ºC are presented and discussed. Immersion lithographic patterning of ArF photoresist line space and contact
hole features will be presented. A sequence of SEM images detailing the plasma etch transfer of line space photoresist
features through the middle and under layer films comprising the TLP film stack will be presented. Excellent etch
selectivity between the UVAS and the organic under layer film exists as no edge erosion or faceting is observed as a
result of the etch process. A detailed study of the impact of a PGMEA solvent photoresist rework process on the
lithographic process window of a TLP film stack was performed with the results indicating that no degradation to the
UVAS film occurs.
As IC manufactures explore different paths to meet the resolution requirements for next generation technology,
patterning schemes which utilize a double photoresist patterning process are under extensive evaluation. One dual
patterning process under consideration uses a 172nm UV cure to render the first photoresist pattern insoluble to the
casting solvents and developer chemistries used to define the second photoresist pattern. In this work we investigate the
change in the material properties such as thickness, optical, bond structure, adhesion and stability of the SiBARC film
due to the UV cure. Simulations are included to assess the change in substrate reflectance due to the change in the optical
properties of the SiBARC film as a result of the UV cure. Single patterned photoresist line space features versus UV cure
dose of the SiBARC - under layer film stack is presented. This is followed by cross-grid and pitch-split double patterning using 172 nm UV light of varying dose to freeze the first photoresist layer patterned using a tri-layer film configuration.
Bottom Anti Reflective Coating (BARC) materials are generally used to minimize reflection of incident light from the
substrate (Rsub). As IC manufactures move to high NA systems to meet the patterning requirements for next generation
technology as well as the use of new lower dielectric constant materials in the back-end-of-line dielectric, the
requirements for developing BARC materials with new properties such as faster strip rate and properly tuned optical
properties (n = refractive index and k=extinction coefficient) are essential. Some photoresist patterning schemes may
also require a dual BARC system such as tri-layer patterning (TLP), which is undergoing extensive evaluation in
academia and industries. This work focuses on Honeywell's next generation DUO193 material (DUO193FS), which is a
siloxane-based polymer with an organic 193 nm chromophore attached to it. The effects of additives for adjusting strip
rate in a wet chemical stripper, while maintaining chemical resistance to a photoresist developer, 2.38% TMAH in water
are discussed. Different spectroscopic studies are performed to elucidate the mechanism of faster strip rate. Solvation of
silanol groups and their orientation in the presence of additives are found to be secondary mechanism. The primary
reason for enhanced strip rate is attributed to the addition of additives A and B, which lower bulk density of the solid
film. DUO193FS can be stand alone BARC or used with another BARC as part of a dual BARC system to further
minimize Rsub, maintaining resistance to 2.38% TMAH, planarizing any underlying topography and keeping the final
film strip rate high.
This work discusses the requirements and performance of Honeywell's middle layer material, UVAS, for trilayer patterning. UVAS is a high Si content polymer synthesized directly from Si containing starting monomer components. The monomers are selected to produce a film that meets the requirements as a middle layer for trilayer patterning and gives us a level of flexibility to adjust the properties of the film to meet the customer's specific photoresist and patterning requirements. Results of simulations of the substrate reflectance versus numerical aperture, UVAS thickness, and under layer film are presented. Immersion lithographic patterning of ArF photoresist line space and contact hole features will be presented. A sequence of SEM images detailing the plasma etch transfer of line space photoresist features through the middle and under layer films comprising the TLP film stack will presented. Excellent etch selectivity between the UVAS and the organic under layer film exists as no edge erosion or faceting is observed as a result of the etch process. The results of simulations of Rsub versus NA, and the thickness of each film comprising a two layer antireflective film stack will also be discussed.
This work discusses the development and characterization of Honeywell's middle layer material, UVAS, for trilayer
patterning. The UVAS polymer contains high Si content constructed by polymerizing multiple monomers selected to
produce a film that meets the requirements as a middle layer for trilayer patterning. Results of ArF photoresist patterning
evaluations, plasma and wet etch studies, and photoresist and full stack rework tests will be presented and discussed. ArF
photoresist patterning tests show that UVAS exhibits organic BARC like performance with respect to MEEF (Mask
Error Enhancement Factor), DOF (Depth of Focus) and EL (Exposure Latitude). Shelf life data shows that UVAS
maintains very stable properties even after 6 months storage at room temperature. We will also briefly discuss
investigation of amine or nitrogen-based contaminant blocking by the UVAS middle layer.
Bo Li, Kim Do, Jason Stuck, Songyuan Xie, Roger Leung, Tiffany Nguyen, Jaswinder Gill, Lei Jin, Wenya Fan, Shilpa Thanawala, Faith Zhou, Nancy Iwamoto, Emma Brouk, Joseph Kennedy
A spin-on sacrificial 193 nm UV absorbing organosiloxane film was developed to facilitate ArF photoresist (PR) patterning. To improve lithographic compatibility with acrylate based photoresists, different performance additives were evaluated as photoresist adhesion promoter. The results suggested that the type and loading of the photoresist adhesion promoter had a large impact on the profile and focus latitude of the patterned photoresist features. An efficient photoresist adhesion promoter candidate was identified, which has minimum impact on other solution and film properties. This work has led to the development of DUO 193 organosiloxane based bottom anti-reflective coating. Application of this film as a blanket level bottom anti-reflective coating or as a fill material for via first trench last (VFTL) dual damascene patterning is possible. The SiO structure intrinsic to this film provides a high degree of plasma etch selectivity to the thin ArF photoresists in use today. Furthermore, an equivalent plasma etch rate between DUO 193 and the low dielectric constant SiOCH films used as the dielectric layer in the backend Cu interconnect structure is possible without compromising the photoresist etch selectivity. Equivalent etch rate is necessary for complete elimination of the “fencing” or “shell” defects found at the base of the etched trench feature located at the perimeter of the top of the via. Advanced ArF PR features of 100 nm in width (and smaller) have been routinely patterned on DUO 193 film. Via fill, plasma etch rate, wet etch rate, ArF PR patterning and shelf life data will be discussed in this presentation.
A sacrificial, spin-on 193nm UV absorbing organosiloxane film has been developed to enable via first trench last (VFTL) copper dual-damascene patterning. The SiO structure intrinsic to the Duo193 BARC provides the required plasma etch selectivity to the thin ArF photoresists in use today. Furthermore, an equivalent plasma etch rate between Duo193 and the low dielectric constant SiOCH films, used as the dielectric layer in the backend Cu interconnect structures, is possible without compromising the photoresist etch selectivity. An equivalent etch rate is a necessary for complete elimination of 'fence' or 'shell' defect found with organic-based BARCs. This work has led to the development of Duo193 organosiloxane based bottom antireflective coatings. Tunable formulation variables, such as BARC solution pH to modulate film acidity, can have a significant effect on bulk and surface film properties. In addition to solution pH, the effect of BARC film bake temperature on wet chemical strip rates was also studied. ArF lithography, plasma etch and selective removal are discussed to focus on the process integration benefits of the planarizing, organosiloxane BARC material.
A sacrificial, spin-on 248nm UV absorbing organosiloxane film has been developed to enable via first trench last (VFTL) dual-damascene patterning. Amongst other design objectives one key material requirement was that the film be SiO based to facilitate trench etch. Because our starting organosiloxane polymer is transparent a chromophores that absorbs at 248 nm had to be included. Anthracene was selected as it offered the largest amount of absorption per mole. Unfortunately, commercially available anthracene moieties with different functional groups when added directly to the organosiloxane polymer solution resulted in films of very marginal quality. The primary issue was the poor solubility and thermal stability of the anthracene compound within the organosiloxane matrix. To address this fundamental problem the chromophore was stabilized by chemically attaching it to ethyl-orthosilicate. The resulting molecule, 9-anthracene carboxy-methyl triethoxysilane (TESAC) was developed. By combining the appropriate amounts of TESAC, TEOS and other organo-TEOS monomers with the appropriate solvents and a catalyst a stable, 248nm light absorbing anthracene-organosiloxane polymer was developed. This work has led to the development of Duo248 organosiloxane based bottom antireflective coatings. Topics such as the development of TESAC, lithography, plasma etch and selective removal will be discussed.
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