As the semiconductor manufacturing industry develops into the cutting-edge technology, the thick and high etch resistant material is required. Amorphous carbon layer (ACL), currently widely-used deposition-type film, can meet the requirement for etch resistance, but it has intrinsic problems such as darkness, defect control difficulty and low throughput which give limits to its further application. In order to overcome these problems, a novel thick spin-on carbon hardmask (SOH) is introduced in this paper. We designed the material from molecular level to achieve high etch resistance, good optical property, long shelf life and high thickness. Up to 3 micron-thick films with high transparency and etch resistance were successfully fabricated by spin-coating process. With long-enough shelf life for usage, we expect that this novel SOH can expand the possibility of spin-on material.
A thick spin-on carbon hardmask (SOH) material is designed to overcome inherent problems of amorphous deposited carbon layer (ACL) and thick photoresist. For ACL in use of semiconductor production process, especially when film thickness from sub-micrometer up to few micrometers is required, not only its inherent low transparency at long wavelength light often causes alignment problems with under layers, but also considerable variation of film thickness within a wafer can also cause patterning problems. To avoid these issues, a thick SOH is designed with monomers of high transparency and good solubility at the same time. In comparison with photoresist, the SOH has good etch resistance and high thermal stability, and it provides wide process window of decreased film thickness and increased thermal budget up to 400°C after processes such as high temperature deposition of SiON. In order to achieve high thickness along with uniform film, many solvent factors was considered such as solubility parameter, surface tension, vapor pressure, and others. By optimizing many solvent factors, we were able to develop a product with a good coating performance
For fine patterning, there are two possible hard mask integration schemes: quad-layer and tri-layer systems. Due to the different structures and processes between quad- and tri- layer systems, each system needs specific chemical and physical properties of the hard mask. In this paper, we report the properties of the carbon-based spin-on hard mask (CSOH) candidates for various hard mask integrations.
For multilayer process, importance of carbon-based spin-on hardmask material that replaces amorphous carbon layer (ACL) is ever increasing. Carbon-based spin-on hardmask is an organic polymer with high carbon content formulated in organic solvents for spin-coating application that is cured through baking. In comparison to CVD process for ACL, carbon-based spin-on hardmask material can offer several benefits: lower cost of ownership (CoO) and improved process time, as well as better gap-fill and planarization performances. Thus carbon-based spin-on hardmask material of high etch resistance, good gap-fill properties and global planarization performances over various pattern topographies are desired to achieve the fine patterning and high aspect ratio (A/R). In particular, good level of global planarization of spin coated layer over the underlying pattern topographies is important for self-aligned double patterning (SADP) process as it dictates the photolithographic margin. Herein, we report a copolymer carbon-based spin-on hardmask resin formulation that exhibits favorable film shrinkage profile and good etch resistance properties. By combining the favorable characteristics of each resin – one resin with good shrinkage property and the other with excellent etch resistance into the copolymer, it was possible to achieve a carbonbased spin-on hardmask formulation with desirable level of etch resistance and the planarization performances across various underlying substrate pattern topographies.
In the recent semiconductor industry, as the device shrinks, spin-on dielectric (SOD) has been adopted as a
widely used material because of its excellent gap-fill, efficient throughput on mass production and highly competitive
initial cost of ownership. Among various semiconductor applications, SOD is especially valued as the suitable gap-fill
material for shallow trench isolation (STI), because the previously adopted technology, high density plasma chemical
vapor deposition (HDP-CVD), has a significant problem with void-free gap-fill on patterns with high aspect ratios. As
SOD is spin-coated on those narrow patterns, planarization is one of the important requirements. On the course of our
efforts on developing novel modified SOD materials, we discovered that the reactivity of each SOD resins has
meaningful correlation with the degree of planarization. In this paper, three experiments have been illustrated to prove
this correlation, 1) step coverage test, 2) humid air bubble test, and 3) film thickness shrinkage upon prebake. The SOD
resin with lower reactivity turned out to exhibit 1) larger size of circle around silica-beads, 2) slower molecular weight
growth under humid bubble condition, and 3) higher shrinkage upon prebake.
As the feature sizes of integrated circuits shrink, thinner photoresist coating should be used in order to avoid
high aspect ratio which can cause pattern collapse. Especially for 193 nm lithography, photoresist coating is too thin to
subsequent etching step. One of the solutions to this problem is using hardmasks which have good etch selectivity to
adjacent layers. In this paper, silicon-based anti-reflective spin-on hardmasks (Si-SOH) are described. One of the
major problems of silicon based polymers in the hardmask compositions is poor storage stability because silanol group is
reactive enough to condense each other, which can instigate molecular weight increase to yield gel-type particles. The
storage stability of our hardmask materials have been improved by thermodynamically controlled synthesis and reactive
mask strategy. Especially the reactive masked silanol groups can take part in crosslinking reaction under the process
conditions without additional deprotection step. Although this strategy could encounter intermixing problems with
other layers, we can produce silicon-based hardmasks without any deleterious effects. These hardmasks show antireflective
properties and great etch selectivity to both photoresists and organic hardmasks (C-SOH).
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